mebbe

* merging georgio/lp-psqv2-integration

* use authenicator on the responder's side

* nym-lp crate compiling

* moved the e2e test to nym-lp

* move key generation to peer

* moved principal generation

* update KKTResponder

* encapsulation key parsing

* Adding concrete types within KKT exchange

* initiator side of the full handshake

* responder side of the handshake and full e2e test

* fixed unit-tests within nym-kkt

* LpSession cleanup

* helpers for Transport

* revamp of the transport traits and initial work on client-side transport

* compiling nym-crypto

* 'working' client-entry dvpn reg

* Fix key conversion

* Slightly reduce use of rand08

* reverted back to libcrux repo refs

* intial telescoping reg

* removing dead code

* wip

* moved data encryption into the state machine

* restoring nym-lp tests

* update lp api model

* Add receiver index derivation

* Add receiver index derivation

* use derived receiver index

* feat: add kem key generation to nodes

* generate fresh x25519, mlkem768 and mceliece keys on config migration

* add lp peer config

* nym-node startup cleanup

* removed dependency on pre-rand09 from nym-lp

* re-expose LP information on the http API

* fixed tests compilation

* add peer config happy path tests

* formatting

* add more tests and fix bug

* better docs

* clippy and formatting issues

* return error on mceliece within NestedSession

* wasm fixes

* removed legacy nym-vpn-lib-wasm

* fixing wasm for real this time

* additional fixes

* add payload to kkt

* make clippy happy

* moved LP to nym-node crate

* cargo fmt

* integrate lpconfig payload

* fix response size trait impl

* Migrate receiver index

* Change receiver index to u32 and regorganize crates

* clippy

* hopefully final wasm fixes

* simple conversion method from semver to ciphersuite

* updated nym-node config template

* chore: remove duplicated code

---------

Co-authored-by: Georgio Nicolas <me@georgio.xyz>

.github/workflows/cd-docs.yml

@@ -6,6 +6,8 @@ on:
 jobs:
   build:
     runs-on: arc-ubuntu-22.04
+    env:
+      NEXT_PUBLIC_SITE_URL: https://nymtech.net/docs
     defaults:
       run:
         working-directory: documentation/docs
@@ -41,6 +43,8 @@ jobs:
         run: pnpm i
       - name: Build project
         run: pnpm run build
+      - name: Generate sitemap
+        run: npx next-sitemap
       - name: Move files to /dist/
         run: ../scripts/move-to-dist.sh
 

.github/workflows/ci-build-vpn-api-wasm.yml

@@ -1,42 +0,0 @@
-name: ci-build-vpn-api-wasm
-
-on:
-  pull_request:
-    paths:
-      - 'common/**'
-      - 'nym-credential-proxy/**'
-      - '.github/workflows/ci-build-vpn-api-wasm.yml'
-
-jobs:
-  wasm:
-    runs-on: arc-linux-latest
-    env:
-      CARGO_TERM_COLOR: always
-      RUSTUP_PERMIT_COPY_RENAME: 1
-    steps:
-      - name: Check out repository code
-        uses: actions/checkout@v6
-
-      - name: Install Rust toolchain
-        uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: ${{ vars.REQUIRED_RUSTC_VERSION }}
-          target: wasm32-unknown-unknown
-          override: true
-          components: rustfmt, clippy
-
-      - name: Install wasm-pack
-        run: curl https://rustwasm.github.io/wasm-pack/installer/init.sh -sSf | sh
-
-      - name: Install wasm-opt
-        uses: ./.github/actions/install-wasm-opt
-        with:
-          version: '116'
-
-      - name: Install wasm-bindgen-cli
-        run: cargo install wasm-bindgen-cli
-
-      - name: "Build"
-        run: make
-        working-directory: nym-credential-proxy/vpn-api-lib-wasm

.github/workflows/ci-check-ns-api-version.yml

@@ -16,7 +16,7 @@ jobs:
         uses: actions/checkout@v6
 
       - name: Get version from cargo.toml
-        uses: mikefarah/yq@v4.52.2
+        uses: mikefarah/yq@v4.52.4
         id: get_version
         with:
           cmd: yq -oy '.package.version' ${{ env.WORKING_DIRECTORY }}/Cargo.toml

.github/workflows/ci-check-nym-stats-api-version.yml

@@ -16,7 +16,7 @@ jobs:
         uses: actions/checkout@v6
 
       - name: Get version from cargo.toml
-        uses: mikefarah/yq@v4.52.2
+        uses: mikefarah/yq@v4.52.4
         id: get_version
         with:
           cmd: yq -oy '.package.version' ${{ env.WORKING_DIRECTORY }}/Cargo.toml

.github/workflows/ci-crates-publish-dry-run.yml

@@ -15,6 +15,9 @@ env:
 jobs:
   publish-dry-run:
     runs-on: arc-linux-latest
+    timeout-minutes: 35
+    env:
+      RUSTUP_PERMIT_COPY_RENAME: 1
     steps:
       - name: Checkout repo
         uses: actions/checkout@v6
@@ -59,20 +62,60 @@ jobs:
       - name: Bump versions (local only)
         run: |
           cargo workspaces version custom ${{ inputs.version }} \
-            --allow-branch ${{ github.ref_name }} \
             --no-git-commit \
+            --yes
+
+      - name: Preflight publish checks
+        run: |
+          python3 tools/internal/check_publish_preflight.py
 
       # Dry run may show cascading dependency errors because packages aren't
       # actually uploaded - these are expected and ignored. We check for real
       # errors like packaging failures, missing metadata, or invalid Cargo.toml.
       - name: Publish (dry run)
         run: |
-          output=$(cargo workspaces publish --dry-run --allow-dirty 2>&1) || true
-          echo "$output"
+          set +e
+          publish_status=1
+          max_attempts=2
+          attempt=1
+          rm -f /tmp/publish-dry-run.log
 
-          # Check for real errors (not cascading dependency errors)
-          # Cascading errors mention "crates.io index", real errors mention "Cargo.toml"
-          echo "$output" | grep -i "Cargo.toml" && exit 1 || true
+          while [ "$attempt" -le "$max_attempts" ]; do
+            echo "Dry-run publish attempt ${attempt}/${max_attempts}"
+            cargo workspaces publish --dry-run --allow-dirty 2>&1 | tee /tmp/publish-dry-run.log
+            publish_status=${PIPESTATUS[0]}
+
+            if [ "$publish_status" -eq 0 ]; then
+              break
+            fi
+
+            # Retry once for interruption/runner issues.
+            if [ "$attempt" -lt "$max_attempts" ] && \
+              { [ "$publish_status" -eq 130 ] || [ "$publish_status" -eq 137 ]; }; then
+              echo "Publish dry-run interrupted (exit ${publish_status}), retrying in 10s..."
+              sleep 10
+              attempt=$((attempt + 1))
+              continue
+            fi
+
+            break
+          done
+          set -e
+
+          if grep -Eiq \
+            "failed to verify manifest|failed to parse manifest|invalid Cargo.toml|error: package .* has no (description|license|repository)" \
+            /tmp/publish-dry-run.log; then
+            echo "Detected real packaging/manifest errors"
+            exit 1
+          fi
+
+          # In dry-run mode, non-zero publish status is expected due to
+          # dependency-cascade failures against crates.io index.
+          if [ "$publish_status" -ne 0 ]; then
+            echo "Dry-run publish returned non-zero (${publish_status}) but no real manifest blockers were detected."
+          fi
+
+          echo "Only expected dry-run dependency cascade errors detected (if any)."
 
       # Show the list of packages published
       - name: Show package versions

.github/workflows/ci-crates-publish-resume.yml

@@ -17,6 +17,8 @@ on:
 jobs:
   publish:
     runs-on: arc-linux-latest
+    env:
+      RUSTUP_PERMIT_COPY_RENAME: 1
     steps:
       - name: Checkout repo
         uses: actions/checkout@v6

.github/workflows/ci-crates-publish.yml

@@ -17,6 +17,8 @@ on:
 jobs:
   publish:
     runs-on: arc-linux-latest
+    env:
+      RUSTUP_PERMIT_COPY_RENAME: 1
     steps:
       - name: Checkout repo
         uses: actions/checkout@v6

.github/workflows/ci-crates-version-bump.yml

@@ -15,6 +15,8 @@ env:
 jobs:
   version-bump:
     runs-on: arc-linux-latest
+    env:
+      RUSTUP_PERMIT_COPY_RENAME: 1
     permissions:
       contents: write
     steps:

.github/workflows/ci-nym-wallet-storybook.yml

@@ -51,25 +51,3 @@ jobs:
           REMOTE_USER: ${{ secrets.CI_WWW_REMOTE_USER }}
           TARGET: ${{ secrets.CI_WWW_REMOTE_TARGET }}/wallet-${{ env.GITHUB_REF_SLUG }}
           EXCLUDE: "/dist/, /node_modules/"
-
-      - name: Matrix - Node Install
-        run: npm install
-        working-directory: .github/workflows/support-files
-
-      - name: Matrix - Send Notification
-        env:
-          NYM_NOTIFICATION_KIND: nym-wallet
-          NYM_PROJECT_NAME: "nym-wallet"
-          NYM_CI_WWW_BASE: "${{ secrets.NYM_CI_WWW_BASE }}"
-          NYM_CI_WWW_LOCATION: "wallet-${{ env.GITHUB_REF_SLUG }}"
-          GIT_COMMIT_MESSAGE: "${{ github.event.head_commit.message }}"
-          GIT_BRANCH: "${GITHUB_REF##*/}"
-          IS_SUCCESS: "${{ job.status == 'success' }}"
-          MATRIX_SERVER: "${{ secrets.MATRIX_SERVER }}"
-          MATRIX_ROOM: "${{ secrets.MATRIX_ROOM }}"
-          MATRIX_USER_ID: "${{ secrets.MATRIX_USER_ID }}"
-          MATRIX_TOKEN: "${{ secrets.MATRIX_TOKEN }}"
-          MATRIX_DEVICE_ID: "${{ secrets.MATRIX_DEVICE_ID }}"
-        uses: docker://keybaseio/client:stable-node
-        with:
-          args: .github/workflows/support-files/notifications/entry_point.sh

.github/workflows/nightly-build.yml

@@ -10,8 +10,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust: [stable, beta]
-        os: [ubuntu-22.04, windows-latest, macos-latest]
+        rust: [ stable, beta ]
+        os: [ ubuntu-22.04, windows-latest, macos-latest ]
     runs-on: ${{ matrix.os }}
     env:
       CARGO_TERM_COLOR: always
@@ -93,38 +93,3 @@ jobs:
         with:
           command: clippy
           args: --workspace --all-targets -- -D warnings
-
-  notification:
-    needs: build
-    runs-on: custom-linux
-    steps:
-      - name: Collect jobs status
-        uses: technote-space/workflow-conclusion-action@v3
-      - name: Check out repository code
-        uses: actions/checkout@v6
-      - name: install npm
-        uses: actions/setup-node@v4
-        if: env.WORKFLOW_CONCLUSION == 'failure'
-        with:
-          node-version: 20
-      - name: Matrix - Node Install
-        if: env.WORKFLOW_CONCLUSION == 'failure'
-        run: npm install
-        working-directory: .github/workflows/support-files
-      - name: Matrix - Send Notification
-        if: env.WORKFLOW_CONCLUSION == 'failure'
-        env:
-          NYM_NOTIFICATION_KIND: nightly
-          NYM_PROJECT_NAME: "Nym nightly build"
-          GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
-          GIT_COMMIT_MESSAGE: "${{ github.event.head_commit.message }}"
-          GIT_BRANCH: "${GITHUB_REF##*/}"
-          IS_SUCCESS: "${{ env.WORKFLOW_CONCLUSION == 'success' }}"
-          MATRIX_SERVER: "${{ secrets.MATRIX_SERVER }}"
-          MATRIX_ROOM: "${{ secrets.MATRIX_ROOM_NIGHTLY }}"
-          MATRIX_USER_ID: "${{ secrets.MATRIX_USER_ID }}"
-          MATRIX_TOKEN: "${{ secrets.MATRIX_TOKEN }}"
-          MATRIX_DEVICE_ID: "${{ secrets.MATRIX_DEVICE_ID }}"
-        uses: docker://keybaseio/client:stable-node
-        with:
-          args: .github/workflows/support-files/notifications/entry_point.sh

.github/workflows/nightly-nym-wallet-build.yml

@@ -10,7 +10,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-22.04, macos-latest, windows-latest]
+        os: [ ubuntu-22.04, macos-latest, windows-latest ]
     runs-on: ${{ matrix.os }}
     env:
       CARGO_TERM_COLOR: always
@@ -55,38 +55,3 @@ jobs:
         with:
           command: clippy
           args: ${{ env.MANIFEST_PATH }} --workspace --all-targets -- -D warnings
-
-  notification:
-    needs: build
-    runs-on: custom-linux
-    steps:
-      - name: Collect jobs status
-        uses: technote-space/workflow-conclusion-action@v3
-      - name: Check out repository code
-        uses: actions/checkout@v6
-      - name: install npm
-        uses: actions/setup-node@v4
-        if: env.WORKFLOW_CONCLUSION == 'failure'
-        with:
-          node-version: 20
-      - name: Matrix - Node Install
-        if: env.WORKFLOW_CONCLUSION == 'failure'
-        run: npm install
-        working-directory: .github/workflows/support-files
-      - name: Matrix - Send Notification
-        if: env.WORKFLOW_CONCLUSION == 'failure'
-        env:
-          NYM_NOTIFICATION_KIND: nightly
-          NYM_PROJECT_NAME: "nym-wallet-nightly-build"
-          GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
-          GIT_COMMIT_MESSAGE: "${{ github.event.head_commit.message }}"
-          GIT_BRANCH: "${GITHUB_REF##*/}"
-          IS_SUCCESS: "${{ env.WORKFLOW_CONCLUSION == 'success' }}"
-          MATRIX_SERVER: "${{ secrets.MATRIX_SERVER }}"
-          MATRIX_ROOM: "${{ secrets.MATRIX_ROOM_NIGHTLY }}"
-          MATRIX_USER_ID: "${{ secrets.MATRIX_USER_ID }}"
-          MATRIX_TOKEN: "${{ secrets.MATRIX_TOKEN }}"
-          MATRIX_DEVICE_ID: "${{ secrets.MATRIX_DEVICE_ID }}"
-        uses: docker://keybaseio/client:stable-node
-        with:
-          args: .github/workflows/support-files/notifications/entry_point.sh

.github/workflows/nightly-security-audit.yml

@@ -24,34 +24,3 @@ jobs:
         with:
           name: report
           path: .github/workflows/support-files/notifications/deny.message
-  notification:
-    needs: cargo-deny
-    runs-on: custom-linux
-    steps:
-      - name: Check out repository code
-        uses: actions/checkout@v6
-      - name: Download report from previous job
-        uses: actions/download-artifact@v7
-        with:
-          name: report
-          path: .github/workflows/support-files/notifications
-      - name: install npm
-        uses: actions/setup-node@v4
-        with:
-          node-version: 20
-      - name: Matrix - Node Install
-        run: npm install
-        working-directory: .github/workflows/support-files
-      - name: Matrix - Send Notification
-        env:
-          NYM_NOTIFICATION_KIND: security
-          NYM_PROJECT_NAME: "Daily security report"
-          GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
-          MATRIX_SERVER: "${{ secrets.MATRIX_SERVER }}"
-          MATRIX_ROOM: "${{ secrets.MATRIX_ROOM_AUDIT }}"
-          MATRIX_USER_ID: "${{ secrets.MATRIX_USER_ID }}"
-          MATRIX_TOKEN: "${{ secrets.MATRIX_TOKEN }}"
-          MATRIX_DEVICE_ID: "${{ secrets.MATRIX_DEVICE_ID }}"
-        uses: docker://keybaseio/client:stable-node
-        with:
-          args: .github/workflows/support-files/notifications/entry_point.sh

.github/workflows/push-credential-proxy.yaml

@@ -26,7 +26,7 @@ jobs:
           git config --global user.name "Lawrence Stalder"
 
       - name: Get version from cargo.toml
-        uses: mikefarah/yq@v4.52.2
+        uses: mikefarah/yq@v4.52.4
         id: get_version
         with:
           cmd: yq -oy '.package.version' ${{ env.WORKING_DIRECTORY }}/nym-credential-proxy/Cargo.toml

.github/workflows/push-data-observatory.yaml

@@ -26,7 +26,7 @@ jobs:
           git config --global user.name "Lawrence Stalder"
 
       - name: Get version from cargo.toml
-        uses: mikefarah/yq@v4.52.2
+        uses: mikefarah/yq@v4.52.4
         id: get_version
         with:
           cmd: yq -oy '.package.version' ${{ env.WORKING_DIRECTORY }}/Cargo.toml

.github/workflows/push-network-monitor.yaml

@@ -26,7 +26,7 @@ jobs:
           git config --global user.name "Lawrence Stalder"
 
       - name: Get version from cargo.toml
-        uses: mikefarah/yq@v4.52.2
+        uses: mikefarah/yq@v4.52.4
         id: get_version
         with:
           cmd: yq -oy '.package.version' ${{ env.WORKING_DIRECTORY }}/nym-network-monitor/Cargo.toml

.github/workflows/push-nym-api.yaml

@@ -26,7 +26,7 @@ jobs:
           git config --global user.name "Lawrence Stalder"
 
       - name: Get version from cargo.toml
-        uses: mikefarah/yq@v4.52.2
+        uses: mikefarah/yq@v4.52.4
         id: get_version
         with:
           cmd: yq -oy '.package.version' ${{ env.WORKING_DIRECTORY }}/nym-api/Cargo.toml

.github/workflows/push-nym-node.yaml

@@ -26,7 +26,7 @@ jobs:
           git config --global user.name "Lawrence Stalder"
 
       - name: Get version from cargo.toml
-        uses: mikefarah/yq@v4.52.2
+        uses: mikefarah/yq@v4.52.4
         id: get_version
         with:
           cmd: yq -oy '.package.version' ${{ env.WORKING_DIRECTORY }}/Cargo.toml

.github/workflows/push-nym-statistics-api.yaml

@@ -26,7 +26,7 @@ jobs:
           git config --global user.name "Lawrence Stalder"
 
       - name: Get version from cargo.toml
-        uses: mikefarah/yq@v4.52.2
+        uses: mikefarah/yq@v4.52.4
         id: get_version
         with:
           cmd: yq -oy '.package.version' ${{ env.WORKING_DIRECTORY }}/Cargo.toml

.github/workflows/push-nyx-chain-watcher.yaml

@@ -26,7 +26,7 @@ jobs:
           git config --global user.name "Lawrence Stalder"
 
       - name: Get version from cargo.toml
-        uses: mikefarah/yq@v4.52.2
+        uses: mikefarah/yq@v4.52.4
         id: get_version
         with:
           cmd: yq -oy '.package.version' ${{ env.WORKING_DIRECTORY }}/Cargo.toml

.github/workflows/push-validator-rewarder.yaml

@@ -26,7 +26,7 @@ jobs:
           git config --global user.name "Lawrence Stalder"
 
       - name: Get version from cargo.toml
-        uses: mikefarah/yq@v4.52.2
+        uses: mikefarah/yq@v4.52.4
         id: get_version
         with:
           cmd: yq -oy '.package.version' ${{ env.WORKING_DIRECTORY }}/Cargo.toml

.github/workflows/resume-publish-crates-io.yml

@@ -25,6 +25,10 @@ jobs:
       - name: Install cargo-workspaces
         run: cargo install cargo-workspaces
 
+      - name: Preflight publish checks
+        run: |
+          python3 tools/internal/check_publish_preflight.py
+
       - name: Publish remaining crates
         env:
           CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}

.github/workflows/support-files/README.md

@@ -4,51 +4,23 @@ This is a collection of scripts and files to support GitHub Actions.
 
 ## Sending Notifications
 
-These scripts send CI notifications to Matrix by creating messages from templates and env vars passed from GitHub Actions.
-
-### Adding notifications to a GitHub Action
-
-```
-jobs:
-  build:
-    ...
-    - name: Notifications - Node Install
-      run: npm install
-      working-directory: .github/workflows/support-files/notifications
-    - name: Notifications - Send
-      env:
-        NYM_NOTIFICATION_KIND: "my-component"
-        GIT_BRANCH: "${GITHUB_REF##*/}"
-        MATRIX_SERVER: "${{ secrets.MATRIX_SERVER }}"
-        MATRIX_ROOM: "${{ secrets.MATRIX_ROOM }}"
-        MATRIX_USER_ID: "${{ secrets.MATRIX_USER_ID }}"
-        MATRIX_TOKEN: "${{ secrets.MATRIX_TOKEN }}"
-        MATRIX_DEVICE_ID: "${{ secrets.MATRIX_DEVICE_ID }}"
-        IS_SUCCESS: "${{ job.status == 'success' }}"
-      uses: docker://keybaseio/client:stable-node
-      with:
-        args: .github/workflows/support-files/notifications/entry_point.sh
-```
-
-Notifications are run by adding the snippet above to a GitHub Action, and:
-
-1. Installing node packages needed at run time
-2. Set the env vars as required:
-    - `NYM_NOTIFICATION_KIND` matches the directory in `.github/workflows/support-files/${NYM_NOTIFICATION_KIND}` to provide the templates and extra scripting in `index.js`
-    - Matrix credentials, room and other env vars for the status of the build and repo
-3. Replacing the default entry point shell script on the `keybaseio/client:stable-node` docker image to run `.github/workflows/support-files/notifications/entry_point.sh`
+These scripts send CI notifications to Matrix by creating messages from templates and env vars passed from GitHub
+Actions.
 
 ### Running locally
 
 You will need:
+
 - Node 16 LTS
 - npm
 
-Copy `.github/workflows/support-files/.env.example` to `.github/workflows/support-files/.env` and valid Matrix credentials.
+Copy `.github/workflows/support-files/.env.example` to `.github/workflows/support-files/.env` and valid Matrix
+credentials.
 
 Then run `npm install` to get dependencies.
 
-Start development mode for the notification type you want either by passing the value as an env var called `NYM_NOTIFICATION_KIND` or set the `.env` file values correctly.
+Start development mode for the notification type you want either by passing the value as an env var called
+`NYM_NOTIFICATION_KIND` or set the `.env` file values correctly.
 
 ```bash
 cd .github/workflows/support-files

.github/workflows/support-files/notifications/entry_point.sh

@@ -1,10 +0,0 @@
-#!/usr/bin/env bash
-
-# pass exit codes out to GitHub Actions
-set -euxo pipefail
-
-# change to the directory that contains this script
-cd "${0%/*}"
-
-# run the node script
-node send_message.js

.github/workflows/support-files/notifications/send_message.js

@@ -1,126 +0,0 @@
-require('dotenv').config();
-
-const { sendMatrixMessage } = require('./send_message_to_matrix');
-
-let context = {
-  kinds: ['nym-wallet', 'ts-packages', 'network-explorer', 'nightly', 'nym-connect','security','ci-docs','cd-docs','ci-dev','cd-dev'],
-};
-
-/**
- * Validate that all required env and context vars are available
- */
-function validateContext() {
-  if (!context.env.NYM_NOTIFICATION_KIND) {
-    throw new Error(
-      'Please set env var NYM_NOTIFICATION_KIND with the project kind that matches a directory in ".github/workflows/support-files"',
-    );
-  }
-  if (!context.kinds.includes(context.env.NYM_NOTIFICATION_KIND)) {
-    throw new Error(`Env var NYM_NOTIFICATION_KIND is not in ${context.kinds}`);
-  }
-  if (!context.env.NYM_PROJECT_NAME) {
-    throw new Error(
-      'Please set env var NYM_PROJECT_NAME with the project name for displaying in notification messages',
-    );
-  }
-  if (context.env.MATRIX_ROOM) {
-    if (!context.env.MATRIX_SERVER) {
-      throw new Error(
-        'Matrix server is not defined. Please set env var MATRIX_SERVER',
-      );
-    }
-    if (!context.env.MATRIX_USER_ID) {
-      throw new Error(
-        'Matrix user id is not defined. Please set env var MATRIX_USER_ID',
-      );
-    }
-    if (!context.env.MATRIX_TOKEN) {
-      throw new Error(
-        'Matrix token is not defined. Please set env var MATRIX_TOKEN',
-      );
-    }
-    if (!context.env.MATRIX_DEVICE_ID) {
-      throw new Error(
-        'Matrix device id is not defined. Please set env var MATRIX_DEVICE_ID',
-      );
-    }
-  }
-}
-
-/**
- * Creates a context that will be available in the templates for rendering notifications
- */
-function createTemplateContext() {
-  const options = { dateStyle: 'full', timeStyle: 'long' };
-  context.timestamp = new Date().toLocaleString(undefined, options);
-
-  // add environment to template context and validate
-  context.env = process.env;
-  try {
-    validateContext();
-  } catch (e) {
-    if(process.env.SHOW_DEBUG) {
-      // recursively print the context for easy debugging and rethrow the error
-      console.dir({ context }, { depth: null });
-    }
-    throw e;
-  }
-
-  context.kind = context.env.NYM_NOTIFICATION_KIND;
-
-  if (!context.env.GIT_BRANCH_NAME) {
-    context.env.GIT_BRANCH_NAME = context.env.GITHUB_REF.split('/')
-      .slice(2)
-      .join('/');
-  }
-
-  context.status = process.env.IS_SUCCESS === 'true' ? 'success' : 'failure';
-}
-
-/**
- * Uses the `kind` set in the context to process the context and generate a notification message
- * @returns {Promise<string>} A string notification message body
- */
-async function processKindScript() {
-  const script = require(`../${context.kind}`);
-  if (!script.addToContextAndValidate) {
-    throw new Error(
-      `"./${context.kind}/index.js" does not export a method called "async addToContextAndValidate(context)"`,
-    );
-  }
-  if (!script.getMessageBody) {
-    throw new Error(
-      `"./${context.kind}/index.js" does not export a method called "async getMessageBody(context)"`,
-    );
-  }
-
-  // call the script to modify and validate the context
-  await script.addToContextAndValidate(context);
-
-  // let the script create a message body and return the result as a string for sending
-  return await script.getMessageBody(context);
-}
-
-/**
- * The main function, as async so that await syntax is available
- */
-async function main() {
-  createTemplateContext();
-  console.log(`Sending notification for kind "${context.kind}"...`);
-  const messageBody = await processKindScript();
-  if(process.env.SHOW_DEBUG) {
-    console.log('-----------------------------------------');
-    console.log(messageBody);
-    console.log('-----------------------------------------');
-  }
-  if(context.env.MATRIX_ROOM) {
-    await sendMatrixMessage(context, messageBody, context.env.MATRIX_ROOM)
-  }
-  if(context.env.MATRIX_ROOM_OF_SHAME && context.env.IS_SUCCESS !== 'true') {
-    // when a job fails
-    await sendMatrixMessage(context, messageBody, context.env.MATRIX_ROOM_OF_SHAME)
-  }
-}
-
-// call main function and let NodeJS handle the promise
-main();

.github/workflows/support-files/notifications/send_message_to_matrix.js

@@ -1,67 +0,0 @@
-const sdk = require('matrix-js-sdk');
-global.Olm = require('olm');
-const { LocalStorage } = require('node-localstorage');
-const localStorage = new LocalStorage('./scratch');
-const {
-  LocalStorageCryptoStore,
-} = require('matrix-js-sdk/lib/crypto/store/localStorage-crypto-store');
-var showdown  = require('showdown');
-
-// hide all matrix client output
-console.error = (error) => console.log('❌ error: ', error);
-process.stderr.write = () => {};
-process.stdout.write = () => {};
-
-
-function createClient(context, room, message) {
-  const server = context.env.MATRIX_SERVER;
-  const token = context.env.MATRIX_TOKEN;
-  const deviceId = context.env.MATRIX_DEVICE_ID;
-  const userId = context.env.MATRIX_USER_ID;
-
-  const client = sdk.createClient({
-    baseUrl: server,
-    accessToken: token,
-    userId,
-    deviceId,
-    sessionStore: new sdk.WebStorageSessionStore(localStorage),
-    cryptoStore: new LocalStorageCryptoStore(localStorage),
-  });
-
-  client.on('sync', async function(state, prevState, res) {
-    if (state !== 'PREPARED') return;
-    client.setGlobalErrorOnUnknownDevices(false);
-    try {
-      await client.joinRoom(room);
-      await client.sendEvent(
-        room,
-        'm.room.message',
-        {
-          msgtype: 'm.text',
-          format: 'org.matrix.custom.html',
-          body: message,
-          formatted_body: message,
-        },
-        '',
-      );
-    } catch (error) {
-      console.error('Job failed: ' + error.message);
-    }
-    client.stopClient();
-    process.exit(0);
-  });
-
-  return client;
-}
-
-async function sendMatrixMessage(contextArg, messageAsMarkdown, roomId) {
-  const converter = new showdown.Converter();
-  const messageAsHtml = converter.makeHtml(messageAsMarkdown);
-  const client = createClient(contextArg, roomId, messageAsHtml);
-  await client.initCrypto();
-  await client.startClient({ initialSyncLimit: 1 });
-}
-
-module.exports = {
-  sendMatrixMessage,
-};

.gitignore

@@ -76,3 +76,4 @@ CLAUDE.md
 .claude/settings.json
 
 /notes
+/target-otel

CHANGELOG.md

@@ -4,6 +4,82 @@ Post 1.0.0 release, the changelog format is based on [Keep a Changelog](https://
 
 ## [Unreleased]
 
+## [2026.4-quark] (2026-02-24)
+
+- Enhance CI workflow with feature inputs ([#6462])
+- Chore/revert 6433 ([#6445])
+- Lp/stateless handshake ([#6437])
+- build(deps-dev): bump webpack from 5.98.0 to 5.105.0 in /wasm/client/internal-dev ([#6435])
+- build(deps-dev): bump webpack from 5.102.1 to 5.104.1 ([#6432])
+- build(deps-dev): bump webpack from 5.98.0 to 5.105.0 in /wasm/mix-fetch/internal-dev ([#6431])
+- build(deps-dev): bump webpack from 5.94.0 to 5.104.1 in /nym-credential-proxy/vpn-api-lib-wasm/internal-dev ([#6430])
+- build(deps-dev): bump webpack from 5.77.0 to 5.104.1 in /wasm/zknym-lib/internal-dev ([#6429])
+- build(deps-dev): bump webpack from 5.76.0 to 5.105.0 in /clients/native/examples/js-examples/websocket ([#6428])
+- HTTP & DNS Improvements ([#6423])
+- Endpoint for  exit GW IPs ([#6418])
+- build(deps): bump bytes from 1.6.0 to 1.11.1 in /contracts ([#6416])
+- build(deps): bump @isaacs/brace-expansion from 5.0.0 to 5.0.1 ([#6415])
+- build(deps): bump bytes from 1.11.0 to 1.11.1 ([#6414])
+- build(deps): bump mikefarah/yq from 4.50.1 to 4.52.2 ([#6407])
+- build(deps-dev): bump eslint from 8.57.1 to 9.26.0 ([#6405])
+- Update reqwest to v0.13.1 ([#6401])
+- build(deps): bump next from 15.5.9 to 16.1.5 in /documentation/docs ([#6387])
+- build(deps): bump next from 15.4.10 to 16.1.5 in /nym-node-status-api/nym-node-status-ui ([#6385])
+- build(deps): bump lodash from 4.17.21 to 4.17.23 ([#6369])
+- build(deps): bump lodash-es from 4.17.21 to 4.17.23 ([#6360])
+- build(deps-dev): bump lodash from 4.17.21 to 4.17.23 in /sdk/typescript/codegen/contract-clients ([#6359])
+- build(deps): bump lodash from 4.17.21 to 4.17.23 in /sdk/typescript/packages/nodejs-client ([#6354])
+- build(deps): bump lodash from 4.17.21 to 4.17.23 in /documentation/docs ([#6353])
+- build(deps): bump lodash from 4.17.21 to 4.17.23 in /clients/native/examples/js-examples/websocket ([#6351])
+- build(deps): bump lodash-es from 4.17.21 to 4.17.23 in /documentation/docs ([#6350])
+- build(deps): bump diff from 5.2.0 to 5.2.2 in /documentation/docs ([#6345])
+- Max/crates publishing tweaks ([#6343])
+- build(deps): bump h3 from 1.15.4 to 1.15.5 ([#6339])
+- build(deps): bump h3 from 1.15.4 to 1.15.5 in /documentation/docs ([#6332])
+- build(deps): bump undici from 6.21.3 to 6.23.0 in /documentation/docs ([#6325])
+- build(deps): bump rsa from 0.9.8 to 0.9.10 ([#6311])
+- build(deps): bump qs and express in /wasm/mix-fetch/internal-dev ([#6308])
+- build(deps): bump qs and express in /clients/native/examples/js-examples/websocket ([#6307])
+- feat: introduce on-disk cache persistance for major nym-api caches ([#6302])
+- Fix migrations in the Data Observatory ([#6271])
+
+[#6462]: https://github.com/nymtech/nym/pull/6462
+[#6445]: https://github.com/nymtech/nym/pull/6445
+[#6437]: https://github.com/nymtech/nym/pull/6437
+[#6435]: https://github.com/nymtech/nym/pull/6435
+[#6432]: https://github.com/nymtech/nym/pull/6432
+[#6431]: https://github.com/nymtech/nym/pull/6431
+[#6430]: https://github.com/nymtech/nym/pull/6430
+[#6429]: https://github.com/nymtech/nym/pull/6429
+[#6428]: https://github.com/nymtech/nym/pull/6428
+[#6423]: https://github.com/nymtech/nym/pull/6423
+[#6418]: https://github.com/nymtech/nym/pull/6418
+[#6416]: https://github.com/nymtech/nym/pull/6416
+[#6415]: https://github.com/nymtech/nym/pull/6415
+[#6414]: https://github.com/nymtech/nym/pull/6414
+[#6407]: https://github.com/nymtech/nym/pull/6407
+[#6405]: https://github.com/nymtech/nym/pull/6405
+[#6401]: https://github.com/nymtech/nym/pull/6401
+[#6387]: https://github.com/nymtech/nym/pull/6387
+[#6385]: https://github.com/nymtech/nym/pull/6385
+[#6369]: https://github.com/nymtech/nym/pull/6369
+[#6360]: https://github.com/nymtech/nym/pull/6360
+[#6359]: https://github.com/nymtech/nym/pull/6359
+[#6354]: https://github.com/nymtech/nym/pull/6354
+[#6353]: https://github.com/nymtech/nym/pull/6353
+[#6351]: https://github.com/nymtech/nym/pull/6351
+[#6350]: https://github.com/nymtech/nym/pull/6350
+[#6345]: https://github.com/nymtech/nym/pull/6345
+[#6343]: https://github.com/nymtech/nym/pull/6343
+[#6339]: https://github.com/nymtech/nym/pull/6339
+[#6332]: https://github.com/nymtech/nym/pull/6332
+[#6325]: https://github.com/nymtech/nym/pull/6325
+[#6311]: https://github.com/nymtech/nym/pull/6311
+[#6308]: https://github.com/nymtech/nym/pull/6308
+[#6307]: https://github.com/nymtech/nym/pull/6307
+[#6302]: https://github.com/nymtech/nym/pull/6302
+[#6271]: https://github.com/nymtech/nym/pull/6271
+
 ## [2026.3-parmigiano] (2026-02-10)
 
 - chore: disable LP on parmigiano branch ([#6422])

Cargo.toml

@@ -74,7 +74,6 @@ members = [
     "common/nym-id",
     "common/nym-kcp",
     "common/nym-lp",
-    "common/nym-lp-common",
     "common/nym-kkt",
     "common/nym-metrics",
     "common/nym_offline_compact_ecash",
@@ -129,7 +128,6 @@ members = [
     "nym-browser-extension/storage",
     "nym-credential-proxy/nym-credential-proxy",
     "nym-credential-proxy/nym-credential-proxy-requests",
-    "nym-credential-proxy/vpn-api-lib-wasm",
     "nym-data-observatory",
     "nym-ip-packet-client",
     "nym-network-monitor",
@@ -173,8 +171,9 @@ members = [
     "wasm/mix-fetch",
     "wasm/node-tester",
     "wasm/zknym-lib",
-    "nym-gateway-probe",
-    "integration-tests", "common/nym-lp-transport", "common/nym-kkt-ciphersuite",
+    #    "nym-gateway-probe",
+    "integration-tests",
+    "common/nym-kkt-ciphersuite", "common/nym-kkt-context",
 ]
 
 default-members = [
@@ -274,6 +273,7 @@ futures = "0.3.31"
 futures-util = "0.3"
 generic-array = "0.14.7"
 getrandom = "0.2.10"
+getrandom03 = { package = "getrandom", version = "=0.3.3" }
 glob = "0.3"
 handlebars = "3.5.5"
 hex = "0.4.3"
@@ -309,8 +309,10 @@ nix = "0.30.1"
 notify = "5.1.0"
 num_enum = "0.7.5"
 once_cell = "1.21.3"
-opentelemetry = "0.19.0"
-opentelemetry-jaeger = "0.18.0"
+opentelemetry = "0.31.0"
+opentelemetry_sdk = "0.31.0"
+opentelemetry-otlp = "0.31.0"
+tonic = "0.14.4"
 parking_lot = "0.12.3"
 pem = "0.8"
 petgraph = "0.6.5"
@@ -322,6 +324,7 @@ quote = "1"
 rand = "0.8.5"
 rand09 = { package = "rand", version = "=0.9.2" }
 rand_chacha = "0.3"
+rand_chacha09 = { package = "rand_chacha", version = "=0.9.0" }
 rand_core = "0.6.3"
 rand_distr = "0.4"
 rayon = "1.5.1"
@@ -368,9 +371,8 @@ tower = "0.5.2"
 tower-http = "0.6.6"
 tracing = "0.1.41"
 tracing-log = "0.2"
-tracing-opentelemetry = "0.19.0"
+tracing-opentelemetry = "0.32.1"
 tracing-subscriber = "0.3.20"
-tracing-tree = "0.2.2"
 tracing-indicatif = "0.3.9"
 tracing-test = "0.2.5"
 ts-rs = "10.1.0"
@@ -391,6 +393,17 @@ zeroize = "1.7.0"
 
 prometheus = { version = "0.14.0" }
 
+
+# libcrux
+libcrux-kem = { git = "https://github.com/cryspen/libcrux", rev = "b17f8687b67cdcfc10b55aeecc998bbbca28f775" }
+libcrux-ecdh = { git = "https://github.com/cryspen/libcrux", rev = "b17f8687b67cdcfc10b55aeecc998bbbca28f775" }
+libcrux-curve25519 = { git = "https://github.com/cryspen/libcrux", rev = "b17f8687b67cdcfc10b55aeecc998bbbca28f775" }
+libcrux-chacha20poly1305 = { git = "https://github.com/cryspen/libcrux", rev = "b17f8687b67cdcfc10b55aeecc998bbbca28f775" }
+libcrux-psq = { git = "https://github.com/cryspen/libcrux", rev = "b17f8687b67cdcfc10b55aeecc998bbbca28f775" }
+libcrux-ml-kem = { git = "https://github.com/cryspen/libcrux", rev = "b17f8687b67cdcfc10b55aeecc998bbbca28f775" }
+libcrux-sha3 = { git = "https://github.com/cryspen/libcrux", rev = "b17f8687b67cdcfc10b55aeecc998bbbca28f775" }
+libcrux-traits = { git = "https://github.com/cryspen/libcrux", rev = "b17f8687b67cdcfc10b55aeecc998bbbca28f775" }
+
 # Workspace dep definitions required by crates.io publication - we need a workspace version since `cargo workspaces` doesn't work with path imports from crate manifests
 nym-api-requests = { version = "1.20.4", path = "nym-api/nym-api-requests" }
 nym-authenticator-requests = { version = "1.20.4", path = "common/authenticator-requests" }
@@ -435,7 +448,8 @@ nym-http-api-common = { version = "1.20.4", path = "common/http-api-common", def
 nym-id = { version = "1.20.4", path = "common/nym-id" }
 nym-ip-packet-client = { version = "1.20.4", path = "nym-ip-packet-client" }
 nym-ip-packet-requests = { version = "1.20.4", path = "common/ip-packet-requests" }
-nym-kkt-ciphersuite = { path = "common/nym-kkt-ciphersuite" }
+nym-kkt = { version = "0.1.0", path = "common/nym-kkt" }
+nym-kkt-ciphersuite = { version = "1.20.4", path = "common/nym-kkt-ciphersuite" }
 nym-metrics = { version = "1.20.4", path = "common/nym-metrics" }
 nym-mixnet-client = { version = "1.20.4", path = "common/client-libs/mixnet-client" }
 nym-mixnet-contract-common = { version = "1.20.4", path = "common/cosmwasm-smart-contracts/mixnet-contract" }

Makefile

@@ -104,11 +104,11 @@ $(eval $(call add_cargo_workspace,wallet,nym-wallet))
 sdk-wasm: sdk-wasm-build sdk-wasm-test sdk-wasm-lint
 
 sdk-wasm-build:
-	$(MAKE) -C nym-browser-extension/storage wasm-pack
+# 	$(MAKE) -C nym-browser-extension/storage wasm-pack
 	$(MAKE) -C wasm/client
 	$(MAKE) -C wasm/node-tester
 	$(MAKE) -C wasm/mix-fetch
-	$(MAKE) -C wasm/zknym-lib
+# 	$(MAKE) -C wasm/zknym-lib
 	# $(MAKE) -C wasm/full-nym-wasm
 
 # run this from npm/yarn to ensure tools are in the path, e.g. yarn build:sdk from root of repo
@@ -119,13 +119,14 @@ sdk-typescript-build:
 	yarn --cwd sdk/typescript/codegen/contract-clients build
 
 # NOTE: These targets are part of the main workspace (but not as wasm32-unknown-unknown)
-WASM_CRATES = extension-storage nym-client-wasm nym-node-tester-wasm zknym-lib
+# WASM_CRATES = extension-storage nym-client-wasm nym-node-tester-wasm zknym-lib
+WASM_CRATES = nym-client-wasm nym-node-tester-wasm
 
 sdk-wasm-test:
 	#cargo test $(addprefix -p , $(WASM_CRATES)) --target wasm32-unknown-unknown -- -Dwarnings
 
 sdk-wasm-lint:
-	cargo clippy $(addprefix -p , $(WASM_CRATES)) --target wasm32-unknown-unknown -- -Dwarnings
+	RUSTFLAGS='--cfg getrandom_backend="wasm_js"' cargo clippy $(addprefix -p , $(WASM_CRATES)) --target wasm32-unknown-unknown -- -Dwarnings
 	$(MAKE) -C wasm/mix-fetch check-fmt
 
 # Add to top-level targets

clients/native/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "nym-client"
-version = "1.1.70"
+version = "1.1.72"
 authors = ["Dave Hrycyszyn <futurechimp@users.noreply.github.com>", "Jędrzej Stuczyński <andrew@nymtech.net>"]
 description = "Implementation of the Nym Client"
 edition = "2021"

clients/native/examples/js-examples/websocket/package-lock.json

@@ -513,9 +513,9 @@
       }
     },
     "node_modules/ajv": {
-      "version": "8.17.1",
-      "resolved": "https://registry.npmjs.org/ajv/-/ajv-8.17.1.tgz",
-      "integrity": "sha512-B/gBuNg5SiMTrPkC+A2+cW0RszwxYmn6VYxB/inlBStS5nx6xHIt/ehKRhIMhqusl7a8LjQoZnjCs5vhwxOQ1g==",
+      "version": "8.18.0",
+      "resolved": "https://registry.npmjs.org/ajv/-/ajv-8.18.0.tgz",
+      "integrity": "sha512-PlXPeEWMXMZ7sPYOHqmDyCJzcfNrUr3fGNKtezX14ykXOEIvyK81d+qydx89KY5O71FKMPaQ2vBfBFI5NHR63A==",
       "dependencies": {
         "fast-deep-equal": "^3.1.3",
         "fast-uri": "^3.0.1",
@@ -3067,9 +3067,9 @@
       }
     },
     "node_modules/qs": {
-      "version": "6.14.1",
-      "resolved": "https://registry.npmjs.org/qs/-/qs-6.14.1.tgz",
-      "integrity": "sha512-4EK3+xJl8Ts67nLYNwqw/dsFVnCf+qR7RgXSK9jEEm9unao3njwMDdmsdvoKBKHzxd7tCYz5e5M+SnMjdtXGQQ==",
+      "version": "6.14.2",
+      "resolved": "https://registry.npmjs.org/qs/-/qs-6.14.2.tgz",
+      "integrity": "sha512-V/yCWTTF7VJ9hIh18Ugr2zhJMP01MY7c5kh4J870L7imm6/DIzBsNLTXzMwUA3yZ5b/KBqLx8Kp3uRvd7xSe3Q==",
       "dev": true,
       "dependencies": {
         "side-channel": "^1.1.0"
@@ -4989,9 +4989,9 @@
       }
     },
     "ajv": {
-      "version": "8.17.1",
-      "resolved": "https://registry.npmjs.org/ajv/-/ajv-8.17.1.tgz",
-      "integrity": "sha512-B/gBuNg5SiMTrPkC+A2+cW0RszwxYmn6VYxB/inlBStS5nx6xHIt/ehKRhIMhqusl7a8LjQoZnjCs5vhwxOQ1g==",
+      "version": "8.18.0",
+      "resolved": "https://registry.npmjs.org/ajv/-/ajv-8.18.0.tgz",
+      "integrity": "sha512-PlXPeEWMXMZ7sPYOHqmDyCJzcfNrUr3fGNKtezX14ykXOEIvyK81d+qydx89KY5O71FKMPaQ2vBfBFI5NHR63A==",
       "requires": {
         "fast-deep-equal": "^3.1.3",
         "fast-uri": "^3.0.1",
@@ -6870,9 +6870,9 @@
       }
     },
     "qs": {
-      "version": "6.14.1",
-      "resolved": "https://registry.npmjs.org/qs/-/qs-6.14.1.tgz",
-      "integrity": "sha512-4EK3+xJl8Ts67nLYNwqw/dsFVnCf+qR7RgXSK9jEEm9unao3njwMDdmsdvoKBKHzxd7tCYz5e5M+SnMjdtXGQQ==",
+      "version": "6.14.2",
+      "resolved": "https://registry.npmjs.org/qs/-/qs-6.14.2.tgz",
+      "integrity": "sha512-V/yCWTTF7VJ9hIh18Ugr2zhJMP01MY7c5kh4J870L7imm6/DIzBsNLTXzMwUA3yZ5b/KBqLx8Kp3uRvd7xSe3Q==",
       "dev": true,
       "requires": {
         "side-channel": "^1.1.0"

clients/socks5/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "nym-socks5-client"
-version = "1.1.70"
+version = "1.1.72"
 authors = ["Dave Hrycyszyn <futurechimp@users.noreply.github.com>"]
 description = "A SOCKS5 localhost proxy that converts incoming messages to Sphinx and sends them to a Nym address"
 edition = "2021"

common/bin-common/Cargo.toml

@@ -19,12 +19,15 @@ serde_json = { workspace = true, optional = true }
 
 ## tracing
 tracing-subscriber = { workspace = true, features = ["env-filter"], optional = true }
-tracing-tree = { workspace = true, optional = true }
 tracing = { workspace = true, optional = true }
-opentelemetry-jaeger = { workspace = true, features = ["rt-tokio", "collector_client", "isahc_collector_client"], optional = true }
 tracing-opentelemetry = { workspace = true, optional = true }
 utoipa = { workspace = true, optional = true }
-opentelemetry = { workspace = true, features = ["rt-tokio"], optional = true }
+opentelemetry = { workspace = true, features = ["trace"], optional = true }
+
+## otel-otlp (modern OTLP export to SigNoz/any OTLP collector)
+opentelemetry_sdk = { workspace = true, features = ["trace"], optional = true }
+opentelemetry-otlp = { workspace = true, features = ["grpc-tonic", "trace", "tls-roots"], optional = true }
+tonic = { workspace = true, optional = true }
 
 
 [build-dependencies]
@@ -35,13 +38,14 @@ default = []
 openapi = ["utoipa"]
 output_format = ["serde_json", "dep:clap"]
 bin_info_schema = ["schemars"]
-basic_tracing = ["dep:tracing", "tracing-subscriber"]
-tracing = [
+basic_tracing = ["dep:tracing", "dep:tracing-subscriber"]
+otel-otlp = [
     "basic_tracing",
-    "tracing-tree",
-    "opentelemetry-jaeger",
-    "tracing-opentelemetry",
-    "opentelemetry",
+    "dep:opentelemetry",
+    "dep:opentelemetry_sdk",
+    "dep:opentelemetry-otlp",
+    "dep:tracing-opentelemetry",
+    "dep:tonic",
 ]
 clap = ["dep:clap", "dep:clap_complete", "dep:clap_complete_fig"]
 models = []

common/bin-common/src/logging/mod.rs

@@ -4,16 +4,9 @@
 use serde::{Deserialize, Serialize};
 use std::io::IsTerminal;
 
-#[cfg(feature = "tracing")]
-pub use opentelemetry;
-#[cfg(feature = "tracing")]
-pub use opentelemetry_jaeger;
-#[cfg(feature = "tracing")]
-pub use tracing_opentelemetry;
+// Re-export tracing_subscriber for consumers that need to compose layers
 #[cfg(feature = "basic_tracing")]
 pub use tracing_subscriber;
-#[cfg(feature = "tracing")]
-pub use tracing_tree;
 
 #[derive(Debug, Default, Copy, Clone, Deserialize, PartialEq, Eq, Serialize)]
 #[serde(deny_unknown_fields)]
@@ -69,40 +62,106 @@ pub fn setup_tracing_logger() {
     build_tracing_logger().init()
 }
 
-// TODO: This has to be a macro, running it as a function does not work for the file_appender for some reason
-#[cfg(feature = "tracing")]
-#[macro_export]
-macro_rules! setup_tracing {
-    ($service_name: expr) => {
-        use nym_bin_common::logging::tracing_subscriber::layer::SubscriberExt;
-        use nym_bin_common::logging::tracing_subscriber::util::SubscriberInitExt;
+/// Initialize an OpenTelemetry tracing layer that exports spans via OTLP/gRPC.
+///
+/// This produces a layer compatible with `tracing_subscriber::registry()` that
+/// sends traces to any OTLP-compatible collector (SigNoz, Grafana Tempo, etc).
+///
+/// Returns both the tracing layer and the [`SdkTracerProvider`] so the caller
+/// can invoke [`SdkTracerProvider::shutdown`] for graceful flush on exit.
+///
+/// # Arguments
+/// * `service_name` - The service name reported to the collector (e.g. "nym-node")
+/// * `endpoint` - The OTLP/gRPC collector endpoint (e.g. "http://localhost:4317"
+///   or "https://ingest.eu.signoz.cloud:443" for SigNoz Cloud)
+/// * `ingestion_key` - Optional SigNoz Cloud ingestion key. When provided, it is
+///   sent as the `signoz-ingestion-key` gRPC metadata header on every export.
+/// * `environment` - Deployment environment label (e.g. "sandbox", "mainnet", "canary").
+///   Attached as the `deployment.environment` OTel resource attribute.
+/// * `sample_ratio` - Trace sampling ratio in 0.0..=1.0 (e.g. 0.1 = 10% of traces).
+///   Used to limit cost when exporting from many nodes; clamped to [0.0, 1.0].
+/// * `export_timeout_secs` - Timeout in seconds for each OTLP export batch. Prevents
+///   unbounded blocking if the collector is slow or unreachable.
+#[cfg(feature = "otel-otlp")]
+pub fn init_otel_layer<S>(
+    service_name: &str,
+    endpoint: &str,
+    ingestion_key: Option<&str>,
+    environment: &str,
+    sample_ratio: f64,
+    export_timeout_secs: u64,
+) -> Result<
+    (
+        tracing_opentelemetry::OpenTelemetryLayer<S, opentelemetry_sdk::trace::SdkTracer>,
+        opentelemetry_sdk::trace::SdkTracerProvider,
+    ),
+    Box<dyn std::error::Error + Send + Sync>,
+>
+where
+    S: tracing::Subscriber + for<'a> tracing_subscriber::registry::LookupSpan<'a>,
+{
+    use opentelemetry::trace::TracerProvider as _;
+    use opentelemetry_otlp::WithExportConfig;
+    use opentelemetry_otlp::WithTonicConfig;
+    use opentelemetry_sdk::trace::Sampler;
+    use std::time::Duration;
 
-        let registry = nym_bin_common::logging::tracing_subscriber::Registry::default()
-            .with(nym_bin_common::logging::tracing_subscriber::EnvFilter::from_default_env())
-            .with(
-                nym_bin_common::logging::tracing_tree::HierarchicalLayer::new(4)
-                    .with_targets(true)
-                    .with_bracketed_fields(true),
-            );
+    // Validate endpoint URI early to fail with a clear message
+    if !endpoint.starts_with("http://") && !endpoint.starts_with("https://") {
+        return Err(format!(
+            "invalid OTLP endpoint URI: {endpoint} (must start with http:// or https://)"
+        )
+        .into());
+    }
 
-        let tracer = nym_bin_common::logging::opentelemetry_jaeger::new_collector_pipeline()
-            .with_endpoint("http://44.199.230.10:14268/api/traces")
-            .with_service_name($service_name)
-            .with_isahc()
-            .with_trace_config(
-                nym_bin_common::logging::opentelemetry::sdk::trace::config().with_sampler(
-                    nym_bin_common::logging::opentelemetry::sdk::trace::Sampler::TraceIdRatioBased(
-                        0.1,
-                    ),
-                ),
-            )
-            .install_batch(nym_bin_common::logging::opentelemetry::runtime::Tokio)
-            .expect("Could not init tracer");
+    let sample_ratio_clamped = sample_ratio.clamp(0.0, 1.0);
 
-        let telemetry = nym_bin_common::logging::tracing_opentelemetry::layer().with_tracer(tracer);
+    let mut builder = opentelemetry_otlp::SpanExporter::builder()
+        .with_tonic()
+        .with_endpoint(endpoint)
+        .with_timeout(Duration::from_secs(export_timeout_secs));
 
-        registry.with(telemetry).init();
-    };
+    // Explicitly configure TLS when the endpoint uses HTTPS
+    if endpoint.starts_with("https://") {
+        builder =
+            builder.with_tls_config(tonic::transport::ClientTlsConfig::new().with_native_roots());
+    }
+
+    if let Some(key) = ingestion_key {
+        let mut metadata = tonic::metadata::MetadataMap::new();
+        metadata.insert(
+            "signoz-ingestion-key",
+            key.parse()
+                .map_err(|_| "invalid ingestion key format (value redacted)")?,
+        );
+        builder = builder.with_metadata(metadata);
+    }
+
+    let exporter = builder
+        .build()
+        .map_err(|e| format!("failed to build OTLP exporter for endpoint {endpoint}: {e}"))?;
+
+    let tracer_provider = opentelemetry_sdk::trace::SdkTracerProvider::builder()
+        .with_sampler(Sampler::TraceIdRatioBased(sample_ratio_clamped))
+        .with_batch_exporter(exporter)
+        .with_resource(
+            opentelemetry_sdk::Resource::builder()
+                .with_service_name(service_name.to_owned())
+                .with_attribute(opentelemetry::KeyValue::new(
+                    "deployment.environment",
+                    environment.to_owned(),
+                ))
+                .build(),
+        )
+        .build();
+
+    opentelemetry::global::set_tracer_provider(tracer_provider.clone());
+    let tracer = tracer_provider.tracer(service_name.to_owned());
+
+    Ok((
+        tracing_opentelemetry::layer().with_tracer(tracer),
+        tracer_provider,
+    ))
 }
 
 pub fn banner(crate_name: &str, crate_version: &str) -> String {

common/client-core/Cargo.toml

@@ -121,6 +121,10 @@ features = ["wasm-bindgen"]
 workspace = true
 features = ["full"]
 
+[target."cfg(target_arch = \"wasm32\")".dependencies.getrandom03]
+workspace = true
+features = ["wasm_js"]
+
 [dev-dependencies]
 tempfile = { workspace = true }
 

common/client-core/src/client/helpers/wasm.rs

@@ -15,3 +15,13 @@ pub(crate) fn get_time_now() -> Instant {
 pub(crate) fn new_interval_stream(polling_rate: Duration) -> IntervalStream {
     gloo_timers::future::IntervalStream::new(polling_rate.as_millis() as u32)
 }
+
+#[unsafe(no_mangle)]
+unsafe extern "Rust" fn __getrandom_v03_custom(
+    dest: *mut u8,
+    len: usize,
+) -> Result<(), getrandom03::Error> {
+    let _ = dest;
+    let _ = len;
+    Err(getrandom03::Error::UNSUPPORTED)
+}

common/client-libs/mixnet-client/src/client.rs

@@ -128,54 +128,95 @@ impl ManagedConnection {
 
     async fn run(self) {
         let address = self.address;
+        let reconnection_attempt = self.current_reconnection.load(Ordering::Acquire);
+        let connect_start = tokio::time::Instant::now();
         let connection_fut = TcpStream::connect(address);
 
         let conn = match tokio::time::timeout(self.connection_timeout, connection_fut).await {
             Ok(stream_res) => match stream_res {
                 Ok(stream) => {
-                    debug!("Managed to establish connection to {}", self.address);
+                    let connect_ms = connect_start.elapsed().as_millis() as u64;
+                    debug!(
+                        peer = %address,
+                        connect_ms,
+                        "Managed to establish connection to {}", self.address
+                    );
 
+                    let noise_start = tokio::time::Instant::now();
                     let noise_stream =
                         match upgrade_noise_initiator(stream, &self.noise_config).await {
                             Ok(noise_stream) => noise_stream,
                             Err(err) => {
-                                error!("Failed to perform Noise handshake with {address} - {err}");
-                                // we failed to finish the noise handshake - increase reconnection attempt
+                                let noise_handshake_ms = noise_start.elapsed().as_millis() as u64;
+                                warn!(
+                                    event = "connection.failed.noise",
+                                    peer = %address,
+                                    error = %err,
+                                    connect_ms,
+                                    noise_handshake_ms,
+                                    reconnection_attempt,
+                                    exit_reason = "noise_error",
+                                    "Failed to perform Noise initiator handshake with {address}"
+                                );
                                 self.current_reconnection.fetch_add(1, Ordering::SeqCst);
                                 return;
                             }
                         };
-                    // if we managed to connect AND do the noise handshake, reset the reconnection count (whatever it might have been)
+                    let noise_handshake_ms = noise_start.elapsed().as_millis() as u64;
                     self.current_reconnection.store(0, Ordering::Release);
-                    debug!("Noise initiator handshake completed for {:?}", address);
+                    debug!(
+                        peer = %address,
+                        connect_ms,
+                        noise_handshake_ms,
+                        "Noise initiator handshake completed for {:?}", address
+                    );
                     Framed::new(noise_stream, NymCodec)
                 }
                 Err(err) => {
-                    debug!("failed to establish connection to {address} (err: {err})",);
+                    let connect_ms = connect_start.elapsed().as_millis() as u64;
+                    warn!(
+                        event = "connection.failed.connect",
+                        peer = %address,
+                        error = %err,
+                        connect_ms,
+                        reconnection_attempt,
+                        exit_reason = "connect_error",
+                        "failed to establish connection to {address}"
+                    );
                     return;
                 }
             },
             Err(_) => {
-                debug!(
+                let connect_ms = connect_start.elapsed().as_millis() as u64;
+                warn!(
+                    event = "connection.failed.timeout",
+                    peer = %address,
+                    timeout_ms = self.connection_timeout.as_millis() as u64,
+                    connect_ms,
+                    reconnection_attempt,
+                    exit_reason = "timeout",
                     "failed to connect to {address} within {:?}",
                     self.connection_timeout
                 );
-
-                // we failed to connect - increase reconnection attempt
                 self.current_reconnection.fetch_add(1, Ordering::SeqCst);
                 return;
             }
         };
 
-        // Take whatever the receiver channel produces and put it on the connection.
-        // We could have as well used conn.send_all(receiver.map(Ok)), but considering we don't care
-        // about neither receiver nor the connection, it doesn't matter which one gets consumed
         if let Err(err) = self.message_receiver.map(Ok).forward(conn).await {
-            warn!("Failed to forward packets to {address}: {err}");
+            warn!(
+                event = "connection.forward_error",
+                peer = %address,
+                error = %err,
+                exit_reason = "forward_error",
+                "Failed to forward packets to {address}: {err}"
+            );
         }
 
         debug!(
-            "connection manager to {address} is finished. Either the connection failed or mixnet client got dropped",
+            peer = %address,
+            exit_reason = "sender_dropped",
+            "connection manager to {address} finished"
         );
     }
 }
@@ -272,16 +313,18 @@ impl SendWithoutResponse for Client {
         trace!("Sending packet to {address}");
 
         // TODO: optimisation for the future: rather than constantly using legacy encoding,
-        // once we're addressing by node_id (and thus have full node info here),
-        // we could simply infer supported encoding based on their version
+        // use the mix packet type / flags to pick encoding per packet
         let framed_packet =
             FramedNymPacket::from_mix_packet(packet, self.config.use_legacy_packet_encoding);
 
         let Some(sender) = self.active_connections.get_mut(&address) else {
             // there was never a connection to begin with
-            debug!("establishing initial connection to {address}");
-            // it's not a 'big' error, but we did not manage to send the packet, but queue the packet
-            // for sending for as soon as the connection is created
+            debug!(
+                event = "mixclient.try_send",
+                peer = %address,
+                result = "not_connected",
+                "establishing initial connection to {address}"
+            );
             self.make_connection(address, framed_packet);
             return Err(io::Error::new(
                 io::ErrorKind::NotConnected,
@@ -289,15 +332,24 @@ impl SendWithoutResponse for Client {
             ));
         };
 
+        let channel_capacity = sender.channel.max_capacity();
+        let channel_available = sender.channel.capacity();
+        let channel_used = channel_capacity - channel_available;
+
         let sending_res = sender.channel.try_send(framed_packet);
         drop(sender);
 
         sending_res.map_err(|err| {
             match err {
                 TrySendError::Full(_) => {
-                    debug!("Connection to {address} seems to not be able to handle all the traffic - dropping the current packet");
-                    // it's not a 'big' error, but we did not manage to send the packet
-                    // if the queue is full, we can't really do anything but to drop the packet
+                    warn!(
+                        event = "mixclient.try_send",
+                        peer = %address,
+                        result = "full_dropped",
+                        channel_capacity,
+                        channel_used,
+                        "dropping packet: connection buffer to {address} is full ({channel_used}/{channel_capacity})"
+                    );
                     io::Error::new(
                         io::ErrorKind::WouldBlock,
                         "connection queue is full",
@@ -305,11 +357,13 @@ impl SendWithoutResponse for Client {
                 }
                 TrySendError::Closed(dropped) => {
                     debug!(
-                        "Connection to {address} seems to be dead. attempting to re-establish it...",
+                        event = "mixclient.try_send",
+                        peer = %address,
+                        result = "closed_reconnecting",
+                        channel_capacity,
+                        channel_used,
+                        "connection to {address} dead, attempting re-establishment"
                     );
-
-                    // it's not a 'big' error, but we did not manage to send the packet, but queue
-                    // it up to send it as soon as the connection is re-established
                     self.make_connection(address, dropped);
                     io::Error::new(
                         io::ErrorKind::ConnectionAborted,

common/client-libs/validator-client/src/client.rs

@@ -20,7 +20,7 @@ use nym_api_requests::ecash::{
 };
 use nym_api_requests::models::{
     ApiHealthResponse, GatewayCoreStatusResponse, HistoricalPerformanceResponse,
-    MixnodeCoreStatusResponse, NymNodeDescriptionV1,
+    MixnodeCoreStatusResponse, NymNodeDescriptionV1, NymNodeDescriptionV2,
 };
 use nym_api_requests::nym_nodes::{
     NodesByAddressesResponse, SemiSkimmedNodesWithMetadata, SkimmedNode, SkimmedNodesWithMetadata,
@@ -273,18 +273,18 @@ impl<C, S> Client<C, S> {
         Ok(history)
     }
 
-    // #[deprecated(note = "use get_all_cached_described_nodes_v2 instead")]
+    #[deprecated(note = "use get_all_cached_described_nodes_v2 instead")]
     pub async fn get_all_cached_described_nodes(
         &self,
     ) -> Result<Vec<NymNodeDescriptionV1>, ValidatorClientError> {
         Ok(self.nym_api.get_all_described_nodes().await?)
     }
 
-    // pub async fn get_all_cached_described_nodes_v2(
-    //     &self,
-    // ) -> Result<Vec<NymNodeDescriptionV2>, ValidatorClientError> {
-    //     Ok(self.nym_api.get_all_described_nodes_v2().await?)
-    // }
+    pub async fn get_all_cached_described_nodes_v2(
+        &self,
+    ) -> Result<Vec<NymNodeDescriptionV2>, ValidatorClientError> {
+        Ok(self.nym_api.get_all_described_nodes_v2().await?)
+    }
 
     pub async fn get_all_cached_bonded_nym_nodes(
         &self,
@@ -473,7 +473,7 @@ impl NymApiClient {
         Ok(self.nym_api.health().await?)
     }
 
-    // #[deprecated(note = "use .get_all_described_nodes_v2 instead")]
+    #[deprecated(note = "use .get_all_described_nodes_v2 instead")]
     pub async fn get_all_described_nodes(
         &self,
     ) -> Result<Vec<NymNodeDescriptionV1>, ValidatorClientError> {
@@ -495,29 +495,29 @@ impl NymApiClient {
         Ok(descriptions)
     }
 
-    // pub async fn get_all_described_nodes_v2(
-    //     &self,
-    // ) -> Result<Vec<NymNodeDescriptionV2>, ValidatorClientError> {
-    //     // TODO: deal with paging in macro or some helper function or something, because it's the same pattern everywhere
-    //     let mut page = 0;
-    //     let mut descriptions = Vec::new();
-    //
-    //     loop {
-    //         let mut res = self
-    //             .nym_api
-    //             .get_nodes_described_v2(Some(page), None)
-    //             .await?;
-    //
-    //         descriptions.append(&mut res.data);
-    //         if descriptions.len() < res.pagination.total {
-    //             page += 1
-    //         } else {
-    //             break;
-    //         }
-    //     }
-    //
-    //     Ok(descriptions)
-    // }
+    pub async fn get_all_described_nodes_v2(
+        &self,
+    ) -> Result<Vec<NymNodeDescriptionV2>, ValidatorClientError> {
+        // TODO: deal with paging in macro or some helper function or something, because it's the same pattern everywhere
+        let mut page = 0;
+        let mut descriptions = Vec::new();
+
+        loop {
+            let mut res = self
+                .nym_api
+                .get_nodes_described_v2(Some(page), None)
+                .await?;
+
+            descriptions.append(&mut res.data);
+            if descriptions.len() < res.pagination.total {
+                page += 1
+            } else {
+                break;
+            }
+        }
+
+        Ok(descriptions)
+    }
 
     pub async fn get_all_bonded_nym_nodes(
         &self,

common/client-libs/validator-client/src/nym_api/mod.rs

@@ -17,7 +17,7 @@ use nym_api_requests::ecash::VerificationKeyResponse;
 use nym_api_requests::models::{
     AnnotationResponse, ApiHealthResponse, BinaryBuildInformationOwned, ChainBlocksStatusResponse,
     ChainStatusResponse, KeyRotationInfoResponse, NodePerformanceResponse, NodeRefreshBody,
-    NymNodeDescriptionV1, PerformanceHistoryResponse, RewardedSetResponse,
+    NymNodeDescriptionV1, NymNodeDescriptionV2, PerformanceHistoryResponse, RewardedSetResponse,
     SignerInformationResponse,
 };
 use nym_api_requests::nym_nodes::{
@@ -117,7 +117,7 @@ pub trait NymApiClientExt: ApiClient {
     }
 
     #[tracing::instrument(level = "debug", skip_all)]
-    // #[deprecated(note = "use .get_nodes_described_v2 instead")]
+    #[deprecated(note = "use .get_nodes_described_v2 instead")]
     async fn get_nodes_described(
         &self,
         page: Option<u32>,
@@ -144,32 +144,32 @@ pub trait NymApiClientExt: ApiClient {
         .await
     }
 
-    // #[tracing::instrument(level = "debug", skip_all)]
-    // async fn get_nodes_described_v2(
-    //     &self,
-    //     page: Option<u32>,
-    //     per_page: Option<u32>,
-    // ) -> Result<PaginatedResponse<NymNodeDescriptionV2>, NymAPIError> {
-    //     let mut params = Vec::new();
-    //
-    //     if let Some(page) = page {
-    //         params.push(("page", page.to_string()))
-    //     }
-    //
-    //     if let Some(per_page) = per_page {
-    //         params.push(("per_page", per_page.to_string()))
-    //     }
-    //
-    //     self.get_json(
-    //         &[
-    //             routes::V2_API_VERSION,
-    //             routes::NYM_NODES_ROUTES,
-    //             routes::NYM_NODES_DESCRIBED,
-    //         ],
-    //         &params,
-    //     )
-    //     .await
-    // }
+    #[tracing::instrument(level = "debug", skip_all)]
+    async fn get_nodes_described_v2(
+        &self,
+        page: Option<u32>,
+        per_page: Option<u32>,
+    ) -> Result<PaginatedResponse<NymNodeDescriptionV2>, NymAPIError> {
+        let mut params = Vec::new();
+
+        if let Some(page) = page {
+            params.push(("page", page.to_string()))
+        }
+
+        if let Some(per_page) = per_page {
+            params.push(("per_page", per_page.to_string()))
+        }
+
+        self.get_json(
+            &[
+                routes::V2_API_VERSION,
+                routes::NYM_NODES_ROUTES,
+                routes::NYM_NODES_DESCRIBED,
+            ],
+            &params,
+        )
+        .await
+    }
 
     async fn get_current_rewarded_set(&self) -> Result<RewardedSetResponse, NymAPIError> {
         self.get_rewarded_set().await
@@ -302,8 +302,8 @@ pub trait NymApiClientExt: ApiClient {
         Ok(SkimmedNodesWithMetadata::new(nodes, metadata))
     }
 
-    // #[deprecated(note = "use .get_all_described_nodes_v2 instead")]
-    // #[allow(deprecated)]
+    #[deprecated(note = "use .get_all_described_nodes_v2 instead")]
+    #[allow(deprecated)]
     async fn get_all_described_nodes(&self) -> Result<Vec<NymNodeDescriptionV1>, NymAPIError> {
         // TODO: deal with paging in macro or some helper function or something, because it's the same pattern everywhere
         let mut page = 0;
@@ -323,24 +323,24 @@ pub trait NymApiClientExt: ApiClient {
         Ok(descriptions)
     }
 
-    // async fn (&self) -> Result<Vec<NymNodeDescriptionV2>, NymAPIError> {
-    //     // TODO: deal with paging in macro or some helper function or something, because it's the same pattern everywhere
-    //     let mut page = 0;
-    //     let mut descriptions = Vec::new();
-    //
-    //     loop {
-    //         let mut res = self.get_nodes_described_v2(Some(page), None).await?;
-    //
-    //         descriptions.append(&mut res.data);
-    //         if descriptions.len() < res.pagination.total {
-    //             page += 1
-    //         } else {
-    //             break;
-    //         }
-    //     }
-    //
-    //     Ok(descriptions)
-    // }
+    async fn get_all_described_nodes_v2(&self) -> Result<Vec<NymNodeDescriptionV2>, NymAPIError> {
+        // TODO: deal with paging in macro or some helper function or something, because it's the same pattern everywhere
+        let mut page = 0;
+        let mut descriptions = Vec::new();
+
+        loop {
+            let mut res = self.get_nodes_described_v2(Some(page), None).await?;
+
+            descriptions.append(&mut res.data);
+            if descriptions.len() < res.pagination.total {
+                page += 1
+            } else {
+                break;
+            }
+        }
+
+        Ok(descriptions)
+    }
 
     #[tracing::instrument(level = "debug", skip_all)]
     async fn get_nym_nodes(

common/commands/src/validator/mixnet/query/query_all_gateways.rs

@@ -14,7 +14,7 @@ pub struct Args {
 }
 
 pub async fn query(args: Args, client: &QueryClientWithNyxd) {
-    match client.get_all_cached_described_nodes().await {
+    match client.get_all_cached_described_nodes_v2().await {
         Ok(res) => match args.identity_key {
             Some(identity_key) => {
                 let node = res.iter().find(|node| {

common/commands/src/validator/mixnet/query/query_all_mixnodes.rs

@@ -14,7 +14,7 @@ pub struct Args {
 }
 
 pub async fn query(args: Args, client: &QueryClientWithNyxd) {
-    match client.get_all_cached_described_nodes().await {
+    match client.get_all_cached_described_nodes_v2().await {
         Ok(res) => match args.identity_key {
             Some(identity_key) => {
                 let node = res.iter().find(|node| {

common/crypto/Cargo.toml

@@ -21,10 +21,13 @@ generic-array = { workspace = true, optional = true }
 hkdf = { workspace = true, optional = true }
 hmac = { workspace = true, optional = true }
 jwt-simple = { workspace = true, optional = true }
+libcrux-psq = { workspace = true, optional = true }
+libcrux-curve25519 = { workspace = true, optional = true }
 cipher = { workspace = true, optional = true }
 x25519-dalek = { workspace = true, features = ["static_secrets"], optional = true }
 ed25519-dalek = { workspace = true, features = ["rand_core"], optional = true }
 rand = { workspace = true, optional = true }
+rand09 = { workspace = true, optional = true }
 serde_bytes = { workspace = true, optional = true }
 serde = { workspace = true, features = ["derive"], optional = true }
 sha2 = { workspace = true, optional = true }
@@ -39,17 +42,18 @@ nym-pemstore = { workspace = true }
 [dev-dependencies]
 anyhow = { workspace = true }
 rand_chacha = { workspace = true }
-serde_json = { workspace = true }
 nym-test-utils = { workspace = true }
+serde_json = { workspace = true }
 
 
 [features]
 default = []
 aead = ["dep:aead", "aead/std", "aes-gcm-siv", "generic-array"]
 naive_jwt = ["asymmetric", "jwt-simple"]
+libcrux_x25519 = ["libcrux-psq", "libcrux-curve25519"]
 serde = ["dep:serde", "serde_bytes", "ed25519-dalek/serde", "x25519-dalek/serde"]
 asymmetric = ["x25519-dalek", "ed25519-dalek", "curve25519-dalek", "sha2", "zeroize"]
-hashing = ["blake3", "digest", "hkdf", "hmac", "generic-array", "sha2", "zeroize"]
+hashing = ["blake3", "digest", "hkdf", "hmac", "generic-array", "sha2", "zeroize", "rand09"]
 stream_cipher = ["aes", "ctr", "cipher", "generic-array"]
 sphinx = ["nym-sphinx-types", "nym-sphinx-types/sphinx"]
 

common/crypto/src/asymmetric/x25519/mod.rs

@@ -17,6 +17,9 @@ use serde::{Deserialize, Deserializer, Serialize, Serializer};
 #[cfg(feature = "serde")]
 pub mod serde_helpers;
 
+#[cfg(feature = "libcrux_x25519")]
+pub use libcrux_psq::handshake::types::{DHKeyPair, DHPrivateKey, DHPublicKey};
+
 /// Size of a X25519 private key
 pub const PRIVATE_KEY_SIZE: usize = 32;
 
@@ -45,6 +48,9 @@ pub enum KeyRecoveryError {
         #[source]
         source: bs58::decode::Error,
     },
+
+    #[error("the x25519 private key could not be converted to its PSQ representation")]
+    IncompatiblePSQPrivateKey,
 }
 
 #[derive(Zeroize, ZeroizeOnDrop)]
@@ -413,6 +419,88 @@ impl AsRef<[u8]> for PrivateKey {
     }
 }
 
+// libcrux-psq conversion
+#[cfg(feature = "libcrux_x25519")]
+impl TryFrom<PrivateKey> for libcrux_psq::handshake::types::DHPrivateKey {
+    type Error = KeyRecoveryError;
+
+    fn try_from(
+        key: PrivateKey,
+    ) -> Result<libcrux_psq::handshake::types::DHPrivateKey, Self::Error> {
+        Self::try_from(&key)
+    }
+}
+
+#[cfg(feature = "libcrux_x25519")]
+impl From<libcrux_psq::handshake::types::DHPrivateKey> for PrivateKey {
+    fn from(key: libcrux_psq::handshake::types::DHPrivateKey) -> PrivateKey {
+        // SAFETY: the DHPrivateKey is guaranteed to be 32 bytes in length
+        #[allow(clippy::unwrap_used)]
+        PrivateKey::from_bytes(key.as_ref()).unwrap()
+    }
+}
+
+#[cfg(feature = "libcrux_x25519")]
+impl TryFrom<&PrivateKey> for libcrux_psq::handshake::types::DHPrivateKey {
+    type Error = KeyRecoveryError;
+
+    fn try_from(
+        key: &PrivateKey,
+    ) -> Result<libcrux_psq::handshake::types::DHPrivateKey, Self::Error> {
+        let mut private_key_bytes = zeroize::Zeroizing::new(key.to_bytes());
+        libcrux_curve25519::clamp(&mut private_key_bytes);
+        match libcrux_psq::handshake::types::DHPrivateKey::from_bytes(&private_key_bytes) {
+            Ok(key) => Ok(key),
+            Err(_) => Err(KeyRecoveryError::IncompatiblePSQPrivateKey),
+        }
+    }
+}
+
+#[cfg(feature = "libcrux_x25519")]
+impl From<&libcrux_psq::handshake::types::DHPrivateKey> for PrivateKey {
+    fn from(key: &libcrux_psq::handshake::types::DHPrivateKey) -> PrivateKey {
+        // SAFETY: the DHPrivateKey is guaranteed to be 32 bytes in length
+        #[allow(clippy::unwrap_used)]
+        PrivateKey::from_bytes(key.as_ref()).unwrap()
+    }
+}
+
+#[cfg(feature = "libcrux_x25519")]
+impl From<PublicKey> for libcrux_psq::handshake::types::DHPublicKey {
+    fn from(key: PublicKey) -> libcrux_psq::handshake::types::DHPublicKey {
+        libcrux_psq::handshake::types::DHPublicKey::from_bytes(key.as_bytes())
+    }
+}
+
+#[cfg(feature = "libcrux_x25519")]
+impl From<libcrux_psq::handshake::types::DHPublicKey> for PublicKey {
+    fn from(key: libcrux_psq::handshake::types::DHPublicKey) -> PublicKey {
+        // SAFETY: the DHPublicKey is guaranteed to be 32 bytes in length
+        #[allow(clippy::unwrap_used)]
+        PublicKey::from_bytes(key.as_ref()).unwrap()
+    }
+}
+
+#[cfg(feature = "libcrux_x25519")]
+impl TryFrom<KeyPair> for libcrux_psq::handshake::types::DHKeyPair {
+    type Error = KeyRecoveryError;
+
+    fn try_from(
+        key: KeyPair,
+    ) -> Result<libcrux_psq::handshake::types::DHKeyPair, KeyRecoveryError> {
+        Ok(libcrux_psq::handshake::types::DHKeyPair::from(
+            libcrux_psq::handshake::types::DHPrivateKey::try_from(&key.private_key)?,
+        ))
+    }
+}
+
+#[cfg(feature = "libcrux_x25519")]
+impl From<libcrux_psq::handshake::types::DHKeyPair> for KeyPair {
+    fn from(key: libcrux_psq::handshake::types::DHKeyPair) -> KeyPair {
+        KeyPair::from(PrivateKey::from(key.sk()))
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -421,6 +509,21 @@ mod tests {
 
     fn assert_zeroize<T: Zeroize>() {}
 
+    #[test]
+    fn test_key_conversion() {
+        let dalek_kp = super::KeyPair::new(&mut rand::thread_rng());
+
+        let mut dalek_private_key_bytes = dalek_kp.private_key().as_bytes().to_owned();
+
+        libcrux_curve25519::clamp(&mut dalek_private_key_bytes);
+        let libcrux_private_key =
+            libcrux_psq::handshake::types::DHPrivateKey::from_bytes(&dalek_private_key_bytes)
+                .unwrap();
+        let libcrux_public_key = libcrux_private_key.to_public();
+
+        assert_eq!(libcrux_public_key.as_ref(), dalek_kp.public_key.as_bytes());
+    }
+
     #[test]
     fn private_key_is_zeroized() {
         assert_zeroize::<PrivateKey>();

common/crypto/src/asymmetric/x25519/serde_helpers.rs

@@ -44,3 +44,25 @@ pub mod option_bs58_x25519_pubkey {
         }
     }
 }
+
+#[cfg(feature = "libcrux_x25519")]
+pub mod bs58_dh_public_key {
+    use crate::asymmetric::x25519;
+    use serde::{Deserialize, Deserializer, Serializer};
+
+    pub fn serialize<S: Serializer>(
+        key: &libcrux_psq::handshake::types::DHPublicKey,
+        serializer: S,
+    ) -> Result<S::Ok, S::Error> {
+        let x25519: x25519::PublicKey = (*key).into();
+        serializer.serialize_str(&x25519.to_base58_string())
+    }
+
+    pub fn deserialize<'de, D: Deserializer<'de>>(
+        deserializer: D,
+    ) -> Result<libcrux_psq::handshake::types::DHPublicKey, D::Error> {
+        let s = String::deserialize(deserializer)?;
+        let x25519 = x25519::PublicKey::from_base58_string(s).map_err(serde::de::Error::custom)?;
+        Ok(x25519.into())
+    }
+}

common/crypto/src/hkdf.rs

@@ -109,3 +109,152 @@ impl DerivationMaterial {
         }
     }
 }
+
+pub mod blake3 {
+
+    //! Key Derivation Functions using Blake3.
+
+    use blake3::Hasher;
+
+    use rand09::{RngCore, rng};
+    use zeroize::Zeroize;
+
+    pub fn derive_key_blake3_multi_input(
+        info: &str,
+        input_key_material: &[&[u8]],
+        salt: &[u8],
+    ) -> [u8; 32] {
+        let mut hasher = Hasher::new_derive_key(info);
+
+        for input_key in input_key_material {
+            hasher.update(input_key);
+        }
+
+        hasher.update(salt);
+
+        hasher.finalize().as_bytes().to_owned()
+    }
+
+    /// Derives a 32-byte key using Blake3's key derivation mode.
+    ///
+    /// Uses Blake3's built-in `derive_key` function with domain separation via context string.
+    ///
+    /// # Arguments
+    /// * `info` - Context string for domain separation (e.g., "nym-lp-psk-v1")
+    /// * `input_key_material` - Input key material (shared secret from ECDH, etc.)
+    /// * `salt` - Additional salt for freshness (nonce)
+    ///
+    /// # Returns
+    /// 32-byte derived key suitable for use as PSK
+    ///
+    /// # Example
+    /// ```ignore
+    /// let psk = derive_key_blake3("nym-lp-psk-v1", shared_secret.as_bytes(), &salt);
+    /// ```
+    pub fn derive_key_blake3(info: &str, input_key_material: &[u8], salt: &[u8]) -> [u8; 32] {
+        derive_key_blake3_multi_input(info, &[input_key_material], salt)
+    }
+
+    pub fn derive_fresh_key_blake3_multi_input(
+        info: &str,
+        input_key_material: &[&[u8]],
+    ) -> [u8; 32] {
+        let mut salt = [0u8; 32];
+        rng().fill_bytes(&mut salt);
+
+        let derived_key = derive_key_blake3_multi_input(info, input_key_material, &salt);
+
+        // Zeroize salt
+        salt.zeroize();
+
+        derived_key
+    }
+
+    /// Derives a fresh 32-byte key using Blake3's key derivation mode.
+    /// The function calls a random number generator to generate a fresh salt.
+    /// Uses Blake3's built-in `derive_key` function with domain separation via context string.
+    ///
+    /// # Arguments
+    /// * `info` - Context string for domain separation (e.g., "nym-lp-psk-v1")
+    /// * `input_key_material` - Input key material (shared secret from ECDH, etc.)
+    ///
+    /// # Returns
+    /// 32-byte derived key suitable for use as PSK
+    ///
+    /// # Example
+    /// ```ignore
+    /// let psk = derive_fresh_key_blake3("nym-lp-psk-v1", shared_secret.as_bytes());
+    /// ```
+    pub fn derive_fresh_key_blake3(info: &str, input_key_material: &[u8]) -> [u8; 32] {
+        derive_fresh_key_blake3_multi_input(info, &[input_key_material])
+    }
+
+    #[cfg(test)]
+    mod tests {
+        use super::*;
+
+        #[test]
+        fn test_deterministic_derivation() {
+            let context = "test-context";
+            let key_material = b"shared_secret_12345";
+            let salt = b"salt_67890";
+
+            let key1 = derive_key_blake3(context, key_material, salt);
+            let key2 = derive_key_blake3(context, key_material, salt);
+
+            assert_eq!(key1, key2, "Same inputs should produce same output");
+        }
+
+        #[test]
+        fn test_different_contexts_produce_different_keys() {
+            let key_material = b"shared_secret";
+            let salt = b"salt";
+
+            let key1 = derive_key_blake3("context1", key_material, salt);
+            let key2 = derive_key_blake3("context2", key_material, salt);
+
+            assert_ne!(
+                key1, key2,
+                "Different contexts should produce different keys"
+            );
+        }
+
+        #[test]
+        fn test_different_salts_produce_different_keys() {
+            let context = "test-context";
+            let key_material = b"shared_secret";
+
+            let key1 = derive_key_blake3(context, key_material, b"salt1");
+            let key2 = derive_key_blake3(context, key_material, b"salt2");
+
+            assert_ne!(key1, key2, "Different salts should produce different keys");
+        }
+
+        #[test]
+        fn test_different_key_material_produces_different_keys() {
+            let context = "test-context";
+            let salt = b"salt";
+
+            let key1 = derive_key_blake3(context, b"secret1", salt);
+            let key2 = derive_key_blake3(context, b"secret2", salt);
+
+            assert_ne!(
+                key1, key2,
+                "Different key material should produce different keys"
+            );
+        }
+
+        #[test]
+        fn test_output_length() {
+            let key = derive_key_blake3("test", b"key", b"salt");
+            assert_eq!(key.len(), 32, "Output should be exactly 32 bytes");
+        }
+
+        #[test]
+        fn test_empty_inputs() {
+            // Should not panic with empty inputs
+            let key = derive_key_blake3("test", b"", b"");
+            assert_eq!(key.len(), 32);
+        }
+    }
+}

common/crypto/src/kdf.rs

@@ -1,98 +0,0 @@
-// Copyright 2025 - Nym Technologies SA <contact@nymtech.net>
-// SPDX-License-Identifier: Apache-2.0
-
-//! Key Derivation Functions using Blake3.
-
-/// Derives a 32-byte key using Blake3's key derivation mode.
-///
-/// Uses Blake3's built-in `derive_key` function with domain separation via context string.
-///
-/// # Arguments
-/// * `context` - Context string for domain separation (e.g., "nym-lp-psk-v1")
-/// * `key_material` - Input key material (shared secret from ECDH, etc.)
-/// * `salt` - Additional salt for freshness (timestamp + nonce)
-///
-/// # Returns
-/// 32-byte derived key suitable for use as PSK
-///
-/// # Example
-/// ```ignore
-/// let psk = derive_key_blake3("nym-lp-psk-v1", shared_secret.as_bytes(), &salt);
-/// ```
-pub fn derive_key_blake3(context: &str, key_material: &[u8], salt: &[u8]) -> [u8; 32] {
-    // Concatenate key_material and salt as input
-    let input = [key_material, salt].concat();
-
-    // Use Blake3's derive_key with context for domain separation
-    // blake3::derive_key returns [u8; 32] directly
-    blake3::derive_key(context, &input)
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn test_deterministic_derivation() {
-        let context = "test-context";
-        let key_material = b"shared_secret_12345";
-        let salt = b"salt_67890";
-
-        let key1 = derive_key_blake3(context, key_material, salt);
-        let key2 = derive_key_blake3(context, key_material, salt);
-
-        assert_eq!(key1, key2, "Same inputs should produce same output");
-    }
-
-    #[test]
-    fn test_different_contexts_produce_different_keys() {
-        let key_material = b"shared_secret";
-        let salt = b"salt";
-
-        let key1 = derive_key_blake3("context1", key_material, salt);
-        let key2 = derive_key_blake3("context2", key_material, salt);
-
-        assert_ne!(
-            key1, key2,
-            "Different contexts should produce different keys"
-        );
-    }
-
-    #[test]
-    fn test_different_salts_produce_different_keys() {
-        let context = "test-context";
-        let key_material = b"shared_secret";
-
-        let key1 = derive_key_blake3(context, key_material, b"salt1");
-        let key2 = derive_key_blake3(context, key_material, b"salt2");
-
-        assert_ne!(key1, key2, "Different salts should produce different keys");
-    }
-
-    #[test]
-    fn test_different_key_material_produces_different_keys() {
-        let context = "test-context";
-        let salt = b"salt";
-
-        let key1 = derive_key_blake3(context, b"secret1", salt);
-        let key2 = derive_key_blake3(context, b"secret2", salt);
-
-        assert_ne!(
-            key1, key2,
-            "Different key material should produce different keys"
-        );
-    }
-
-    #[test]
-    fn test_output_length() {
-        let key = derive_key_blake3("test", b"key", b"salt");
-        assert_eq!(key.len(), 32, "Output should be exactly 32 bytes");
-    }
-
-    #[test]
-    fn test_empty_inputs() {
-        // Should not panic with empty inputs
-        let key = derive_key_blake3("test", b"", b"");
-        assert_eq!(key.len(), 32);
-    }
-}

common/crypto/src/lib.rs

@@ -10,8 +10,6 @@ pub mod crypto_hash;
 pub mod hkdf;
 #[cfg(feature = "hashing")]
 pub mod hmac;
-#[cfg(feature = "hashing")]
-pub mod kdf;
 #[cfg(all(feature = "asymmetric", feature = "hashing", feature = "stream_cipher"))]
 pub mod shared_key;
 pub mod symmetric;

common/nym-kkt-ciphersuite/Cargo.toml

@@ -1,5 +1,6 @@
 [package]
 name = "nym-kkt-ciphersuite"
+description = "Nym KKT ciphersuite"
 authors.workspace = true
 repository.workspace = true
 homepage.workspace = true
@@ -9,15 +10,17 @@ license.workspace = true
 rust-version.workspace = true
 readme.workspace = true
 version.workspace = true
+publish = false
 
 [dependencies]
 thiserror = { workspace = true }
 num_enum = { workspace = true }
 strum = { workspace = true }
 strum_macros = { workspace = true }
+semver = { workspace = true }
 
 blake3 = { workspace = true, optional = true }
-libcrux-sha3 = { git = "https://github.com/cryspen/libcrux", optional = true }
+libcrux-sha3 = { workspace = true, optional = true }
 
 [features]
 digests = ["blake3", "libcrux-sha3"]

common/nym-kkt-ciphersuite/src/lib.rs

@@ -3,10 +3,12 @@
 
 use crate::error::KKTCiphersuiteError;
 use num_enum::{IntoPrimitive, TryFromPrimitive};
-use std::collections::HashMap;
+use std::collections::BTreeMap;
 use std::fmt::Display;
 use strum_macros::{Display, EnumIter, EnumString};
 
+pub use strum::IntoEnumIterator;
+
 pub mod error;
 
 pub const DEFAULT_HASH_LEN: usize = 32;
@@ -45,10 +47,13 @@ pub mod xwing {
     pub const PUBLIC_KEY_LENGTH: usize = x25519::PUBLIC_KEY_LENGTH + ml_kem768::PUBLIC_KEY_LENGTH;
 }
 
-pub type KEMKeyDigests = KeyDigests;
-pub type SigningKeyDigests = KeyDigests;
+pub type KEMKeyDigests = BTreeMap<HashFunction, Vec<u8>>;
 
-pub type KeyDigests = HashMap<HashFunction, Vec<u8>>;
+pub mod node_compatibility {
+    /// Indicates the initial version where kkt has been introduced
+    /// 1.27.0 Raclette release
+    pub const INTRODUCTION: semver::Version = semver::Version::new(1, 27, 0);
+}
 
 #[derive(
     Clone,
@@ -62,6 +67,8 @@ pub type KeyDigests = HashMap<HashFunction, Vec<u8>>;
     EnumIter,
     EnumString,
     Display,
+    Ord,
+    PartialOrd,
 )]
 #[strum(ascii_case_insensitive)]
 #[strum(serialize_all = "lowercase")]
@@ -204,23 +211,26 @@ impl SignatureScheme {
     EnumIter,
     EnumString,
     Display,
+    Default,
+    Ord,
+    PartialOrd,
 )]
 #[strum(ascii_case_insensitive)]
 #[strum(serialize_all = "lowercase")]
 #[repr(u8)]
 pub enum KEM {
-    XWing = 0,
+    // unsupported
+    // XWing = 0,
+    #[default]
     MlKem768 = 1,
     McEliece = 2,
-    X25519 = 255,
 }
 
 impl KEM {
-    pub fn encapsulation_key_length(&self) -> usize {
+    pub const fn encapsulation_key_length(&self) -> usize {
         match self {
             KEM::MlKem768 => ml_kem768::PUBLIC_KEY_LENGTH,
-            KEM::XWing => xwing::PUBLIC_KEY_LENGTH,
-            KEM::X25519 => x25519::PUBLIC_KEY_LENGTH,
+            // KEM::XWing => xwing::PUBLIC_KEY_LENGTH,
             KEM::McEliece => mceliece::PUBLIC_KEY_LENGTH,
         }
     }
@@ -238,6 +248,17 @@ pub struct Ciphersuite {
     signature_length: usize,
 }
 
+impl Default for Ciphersuite {
+    fn default() -> Self {
+        Ciphersuite::new(
+            KEM::MlKem768,
+            HashFunction::Blake3,
+            SignatureScheme::Ed25519,
+            HashLength::Default,
+        )
+    }
+}
+
 impl Ciphersuite {
     pub fn new(
         kem: KEM,
@@ -257,6 +278,51 @@ impl Ciphersuite {
         }
     }
 
+    /// Determine optimal `Ciphersuite` based on remote's node's version
+    pub fn from_node_version(semver: semver::Version) -> Option<Self> {
+        if semver < node_compatibility::INTRODUCTION {
+            // node can't possibly support any Ciphersuite
+            return None;
+        }
+        // currently there are no other branches known to the client
+        // once changes to defaults are introduced, follow pattern similar to the one implemented in
+        // `common/authenticator-requests/src/version.rs`
+        Some(Ciphersuite::new(
+            KEM::MlKem768,
+            HashFunction::Blake3,
+            SignatureScheme::Ed25519,
+            HashLength::Default,
+        ))
+    }
+
+    #[must_use]
+    pub fn with_kem(mut self, kem: KEM) -> Self {
+        self.kem = kem;
+        self.encapsulation_key_length = kem.encapsulation_key_length();
+        self
+    }
+
+    #[must_use]
+    pub fn with_signature_scheme(mut self, signature_scheme: SignatureScheme) -> Self {
+        self.signature_scheme = signature_scheme;
+        self.signing_key_length = signature_scheme.signing_key_length();
+        self.verification_key_length = signature_scheme.verification_key_length();
+        self.signature_length = signature_scheme.signature_length();
+        self
+    }
+
+    #[must_use]
+    pub fn with_hash_function(mut self, hash_function: HashFunction) -> Self {
+        self.hash_function = hash_function;
+        self
+    }
+
+    #[must_use]
+    pub fn with_hash_length(mut self, hash_length: HashLength) -> Self {
+        self.hash_length = hash_length;
+        self
+    }
+
     pub fn kem_key_len(&self) -> usize {
         self.encapsulation_key_length
     }

common/nym-kkt-context/Cargo.toml

@@ -1,6 +1,5 @@
 [package]
-name = "nym-lp-transport"
-version = "0.1.0"
+name = "nym-kkt-context"
 authors.workspace = true
 repository.workspace = true
 homepage.workspace = true
@@ -9,15 +8,14 @@ edition.workspace = true
 license.workspace = true
 rust-version.workspace = true
 readme.workspace = true
+version.workspace = true
 publish = false
 
 [dependencies]
-tokio = { workspace = true, features = ["net", "io-util"] }
-nym-test-utils = { path = "../test-utils", optional = true }
-tracing = { workspace = true }
+num_enum = { workspace = true }
+thiserror = { workspace = true }
 
-[features]
-io-mocks = ["nym-test-utils"]
+nym-kkt-ciphersuite = { path = "../nym-kkt-ciphersuite" }
 
 [lints]
 workspace = true

common/nym-kkt-context/src/lib.rs

@@ -1,13 +1,38 @@
-// Copyright 2025 - Nym Technologies SA <contact@nymtech.net>
+// Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
 // SPDX-License-Identifier: Apache-2.0
 
-use crate::ciphersuite::CIPHERSUITE_ENCODING_LEN;
-use crate::{KKT_VERSION, ciphersuite::Ciphersuite, error::KKTError, frame::KKT_SESSION_ID_LEN};
 use num_enum::{IntoPrimitive, TryFromPrimitive};
+use nym_kkt_ciphersuite::{CIPHERSUITE_ENCODING_LEN, Ciphersuite};
 use std::fmt::Display;
+use thiserror::Error;
+
+// This must be less than 4 bits
+pub const KKT_VERSION: u8 = 1;
+const _: () = assert!(KKT_VERSION < 1 << 4);
 
 pub const KKT_CONTEXT_LEN: usize = 3 + CIPHERSUITE_ENCODING_LEN;
 
+#[derive(Debug, Error)]
+pub enum KKTContextEncodingError {
+    #[error("KKT Message Count Limit Reached")]
+    MessageCountLimitReached,
+
+    #[error("{version} is not a valid KKT version")]
+    InvalidVersion { version: u8 },
+
+    #[error("{raw} is not a valid KKTStatus")]
+    InvalidStatus { raw: u8 },
+
+    #[error("{raw} is not a valid KKTRole")]
+    InvalidRole { raw: u8 },
+
+    #[error("{raw} is not a valid KKTMode")]
+    InvalidMode { raw: u8 },
+
+    #[error(transparent)]
+    InvalidCiphersuite(#[from] nym_kkt_ciphersuite::error::KKTCiphersuiteError),
+}
+
 // bitmask used: 0b1110_0000
 #[derive(Clone, Copy, PartialEq, Debug, IntoPrimitive, TryFromPrimitive)]
 #[repr(u8)]
@@ -15,11 +40,11 @@ pub enum KKTStatus {
     Ok = 0b0000_0000,
     InvalidRequestFormat = 0b0010_0000,
     InvalidResponseFormat = 0b0100_0000,
-    InvalidSignature = 0b0110_0000,
-    UnsupportedCiphersuite = 0b1000_0000,
-    UnsupportedKKTVersion = 0b1010_0000,
-    InvalidKey = 0b1100_0000,
-    Timeout = 0b1110_0000,
+    UnsupportedCiphersuite = 0b0110_0000,
+    UnsupportedKKTVersion = 0b1000_0000,
+    InvalidKey = 0b1010_0000,
+    Timeout = 0b1100_0000,
+    UnverifiedKEMKey = 0b1110_0000,
 }
 
 impl Display for KKTStatus {
@@ -28,10 +53,10 @@ impl Display for KKTStatus {
             KKTStatus::Ok => "Ok",
             KKTStatus::InvalidRequestFormat => "Invalid Request Format",
             KKTStatus::InvalidResponseFormat => "Invalid Response Format",
-            KKTStatus::InvalidSignature => "Invalid Signature",
             KKTStatus::UnsupportedCiphersuite => "Unsupported Ciphersuite",
             KKTStatus::UnsupportedKKTVersion => "Unsupported KKT Version",
             KKTStatus::InvalidKey => "Invalid Key",
+            KKTStatus::UnverifiedKEMKey => "Could not verify received encapsulation key",
             KKTStatus::Timeout => "Timeout",
         })
     }
@@ -43,7 +68,16 @@ impl Display for KKTStatus {
 pub enum KKTRole {
     Initiator = 0b0000_0000,
     Responder = 0b0000_0001,
-    AnonymousInitiator = 0b0000_0010,
+}
+
+impl KKTRole {
+    pub const fn is_initiator(&self) -> bool {
+        matches!(self, KKTRole::Initiator)
+    }
+
+    pub const fn is_responder(&self) -> bool {
+        matches!(self, KKTRole::Responder)
+    }
 }
 
 // bitmask used: 0b0001_1100
@@ -54,6 +88,16 @@ pub enum KKTMode {
     Mutual = 0b0000_0100,
 }
 
+impl KKTMode {
+    pub const fn is_one_way(&self) -> bool {
+        matches!(self, KKTMode::OneWay)
+    }
+
+    pub const fn is_mutual(&self) -> bool {
+        matches!(self, KKTMode::Mutual)
+    }
+}
+
 #[derive(Copy, Clone, Debug, PartialEq)]
 pub struct KKTContext {
     version: u8,
@@ -63,24 +107,20 @@ pub struct KKTContext {
     role: KKTRole,
     ciphersuite: Ciphersuite,
 }
+
 impl KKTContext {
-    pub fn new(role: KKTRole, mode: KKTMode, ciphersuite: Ciphersuite) -> Result<Self, KKTError> {
-        if role == KKTRole::AnonymousInitiator && mode != KKTMode::OneWay {
-            return Err(KKTError::IncompatibilityError {
-                info: "Anonymous Initiator can only use OneWay mode",
-            });
-        }
-        Ok(Self {
+    pub fn new(role: KKTRole, mode: KKTMode, ciphersuite: Ciphersuite) -> Self {
+        Self {
             version: KKT_VERSION,
             message_sequence: 0,
             status: KKTStatus::Ok,
             mode,
             role,
             ciphersuite,
-        })
+        }
     }
 
-    pub fn derive_responder_header(&self) -> Result<Self, KKTError> {
+    pub fn derive_responder_header(&self) -> Result<Self, KKTContextEncodingError> {
         let mut responder_header = *self;
 
         responder_header.increment_message_sequence_count()?;
@@ -89,12 +129,12 @@ impl KKTContext {
         Ok(responder_header)
     }
 
-    pub fn increment_message_sequence_count(&mut self) -> Result<(), KKTError> {
+    pub fn increment_message_sequence_count(&mut self) -> Result<(), KKTContextEncodingError> {
         if self.message_sequence + 1 < (1 << 4) {
             self.message_sequence += 1;
             Ok(())
         } else {
-            Err(KKTError::MessageCountLimitReached)
+            Err(KKTContextEncodingError::MessageCountLimitReached)
         }
     }
 
@@ -118,9 +158,10 @@ impl KKTContext {
     }
 
     pub fn body_len(&self) -> usize {
-        if self.status != KKTStatus::Ok
-            || (self.mode == KKTMode::OneWay
-                && (self.role == KKTRole::Initiator || self.role == KKTRole::AnonymousInitiator))
+        if (self.status != KKTStatus::Ok && self.status != KKTStatus::UnverifiedKEMKey)
+            ||
+            // no payload
+            (self.mode == KKTMode::OneWay && self.role == KKTRole::Initiator)
         {
             0
         } else {
@@ -128,37 +169,18 @@ impl KKTContext {
         }
     }
 
-    pub fn signature_len(&self) -> usize {
-        match self.role {
-            KKTRole::Initiator | KKTRole::Responder => self.ciphersuite.signature_len(),
-            KKTRole::AnonymousInitiator => 0,
-        }
-    }
-
     pub const fn header_len(&self) -> usize {
         KKT_CONTEXT_LEN
     }
 
-    pub const fn session_id_len(&self) -> usize {
-        // note: if anyone decides to update this function and changes the constant value,
-        // you will have to adjust encoding/decoding functions
-
-        // match self.role {
-        //     KKTRole::Initiator | KKTRole::Responder => SESSION_ID_LENGTH,
-        // It doesn't make sense to send a session_id if we send messages in the clear
-        //     KKTRole::AnonymousInitiator => 0,
-        // }
-        KKT_SESSION_ID_LEN
-    }
-
     pub fn full_message_len(&self) -> usize {
-        self.body_len() + self.signature_len() + self.header_len() + self.session_id_len()
+        self.body_len() + self.header_len()
     }
 
-    pub fn encode(&self) -> Result<[u8; KKT_CONTEXT_LEN], KKTError> {
+    pub fn encode(&self) -> Result<[u8; KKT_CONTEXT_LEN], KKTContextEncodingError> {
         let mut header_bytes = [0u8; KKT_CONTEXT_LEN];
         if self.message_sequence >= 1 << 4 {
-            return Err(KKTError::MessageCountLimitReached);
+            return Err(KKTContextEncodingError::MessageCountLimitReached);
         }
 
         let ciphersuite_bytes = self.ciphersuite.encode();
@@ -175,15 +197,17 @@ impl KKTContext {
         Ok(header_bytes)
     }
 
-    pub fn try_decode(header_bytes: [u8; KKT_CONTEXT_LEN]) -> Result<Self, KKTError> {
+    pub fn try_decode(
+        header_bytes: [u8; KKT_CONTEXT_LEN],
+    ) -> Result<Self, KKTContextEncodingError> {
         let kkt_version = (header_bytes[0] & 0b1111_0000) >> 4;
         let message_sequence_counter = header_bytes[0] & 0b0000_1111;
 
         // We only check if stuff is valid here, not necessarily if it's compatible
 
         if kkt_version > KKT_VERSION {
-            return Err(KKTError::FrameDecodingError {
-                info: format!("Header - Invalid KKT Version: {kkt_version}"),
+            return Err(KKTContextEncodingError::InvalidVersion {
+                version: kkt_version,
             });
         }
 
@@ -191,16 +215,15 @@ impl KKTContext {
         let raw_kkt_role = header_bytes[1] & 0b0000_0011;
         let raw_kkt_mode = header_bytes[1] & 0b0001_1100;
 
-        let status =
-            KKTStatus::try_from(raw_kkt_status).map_err(|_| KKTError::FrameDecodingError {
-                info: format!("Header - Invalid KKT Status: {raw_kkt_status}"),
-            })?;
-        let role = KKTRole::try_from(raw_kkt_role).map_err(|_| KKTError::FrameDecodingError {
-            info: format!("Header - Invalid KKT Role: {raw_kkt_role}"),
-        })?;
-        let mode = KKTMode::try_from(raw_kkt_mode).map_err(|_| KKTError::FrameDecodingError {
-            info: format!("Header - Invalid KKT Mode: {raw_kkt_mode}"),
+        let status = KKTStatus::try_from(raw_kkt_status).map_err(|_| {
+            KKTContextEncodingError::InvalidStatus {
+                raw: raw_kkt_status,
+            }
         })?;
+        let role = KKTRole::try_from(raw_kkt_role)
+            .map_err(|_| KKTContextEncodingError::InvalidRole { raw: raw_kkt_role })?;
+        let mode = KKTMode::try_from(raw_kkt_mode)
+            .map_err(|_| KKTContextEncodingError::InvalidMode { raw: raw_kkt_mode })?;
 
         // SAFETY: we're taking exactly `CIPHERSUITE_ENCODING_LEN` bytes
         #[allow(clippy::unwrap_used)]
@@ -228,9 +251,8 @@ mod tests {
         let valid_context = KKTContext::new(
             KKTRole::Initiator,
             KKTMode::Mutual,
-            Ciphersuite::decode([255, 1, 0, 0]).unwrap(),
-        )
-        .unwrap();
+            Ciphersuite::decode([1, 1, 0, 0]).unwrap(),
+        );
         let encoded = valid_context.encode().unwrap();
         let decoded = KKTContext::try_decode(encoded).unwrap();
 

common/nym-kkt/Cargo.toml

@@ -7,35 +7,30 @@ license.workspace = true
 publish = false
 
 [dependencies]
-blake3 = { workspace = true }
 thiserror = { workspace = true }
 num_enum = { workspace = true }
 strum = { workspace = true }
 
-
 # internal
-nym-crypto = { path = "../crypto", features = ["asymmetric", "serde"] }
+nym-crypto = { path = "../crypto", features = ["hashing"] }
 nym-kkt-ciphersuite = { workspace = true, features = ["digests"] }
+nym-kkt-context = { path = "../nym-kkt-context" }
+nym-pemstore = { workspace = true }
 
-libcrux-kem = { git = "https://github.com/cryspen/libcrux" }
-libcrux-ecdh = { git = "https://github.com/cryspen/libcrux", features = ["codec"] }
-libcrux-chacha20poly1305 = { git = "https://github.com/cryspen/libcrux" }
+libcrux-kem = { workspace = true }
+libcrux-ecdh = { workspace = true, features = ["codec"] }
+libcrux-chacha20poly1305 = { workspace = true }
 
-# rand 0.9 for libcrux integration (libcrux uses rand 0.9)
 rand09 = { workspace = true }
 zeroize = { workspace = true, features = ["zeroize_derive"] }
-classic-mceliece-rust = { git = "https://github.com/georgio/classic-mceliece-rust", features = ["mceliece460896f", "zeroize"] }
 
+libcrux-psq = { workspace = true, features = ["classic-mceliece"] }
+libcrux-ml-kem = { workspace = true }
 
 [dev-dependencies]
 rand_chacha = "0.9.0"
 anyhow = { workspace = true }
-criterion = { workspace = true }
 
 
-[[bench]]
-name = "benches"
-harness = false
-
 [lints]
 workspace = true

common/nym-kkt/benches/benches.rs

@@ -1,480 +0,0 @@
-// Copyright 2025 - Nym Technologies SA <contact@nymtech.net>
-// SPDX-License-Identifier: Apache-2.0
-
-// fine in benchmarking code
-#![allow(clippy::expect_used)]
-#![allow(clippy::unwrap_used)]
-
-use criterion::{Criterion, criterion_group, criterion_main};
-
-use nym_crypto::asymmetric::ed25519;
-use nym_kkt::{
-    ciphersuite::{Ciphersuite, EncapsulationKey, HashFunction, KEM, SignatureScheme},
-    context::KKTMode,
-    frame::KKTFrame,
-    key_utils::{generate_keypair_libcrux, generate_keypair_mceliece, hash_encapsulation_key},
-    session::{
-        anonymous_initiator_process, initiator_ingest_response, initiator_process,
-        responder_ingest_message, responder_process,
-    },
-};
-use rand09::prelude::*;
-
-pub fn gen_ed25519_keypair(c: &mut Criterion) {
-    c.bench_function("Generate Ed25519 Keypair", |b| {
-        b.iter(|| {
-            let mut s: [u8; 32] = [0u8; 32];
-            rand09::rng().fill_bytes(&mut s);
-            ed25519::KeyPair::from_secret(s, 0)
-        });
-    });
-}
-
-pub fn gen_mlkem768_keypair(c: &mut Criterion) {
-    c.bench_function("Generate MlKem768 Keypair", |b| {
-        b.iter(|| {
-            libcrux_kem::key_gen(libcrux_kem::Algorithm::MlKem768, &mut rand09::rng()).unwrap()
-        });
-    });
-}
-
-pub fn kkt_benchmark(c: &mut Criterion) {
-    let mut rng = rand09::rng();
-
-    // generate ed25519 keys
-    let mut secret_initiator: [u8; 32] = [0u8; 32];
-    rng.fill_bytes(&mut secret_initiator);
-    let initiator_ed25519_keypair = ed25519::KeyPair::from_secret(secret_initiator, 0);
-
-    let mut secret_responder: [u8; 32] = [0u8; 32];
-    rng.fill_bytes(&mut secret_responder);
-
-    let responder_ed25519_keypair = ed25519::KeyPair::from_secret(secret_responder, 1);
-    for kem in [KEM::MlKem768, KEM::XWing, KEM::X25519, KEM::McEliece] {
-        for hash_function in [
-            HashFunction::Blake3,
-            HashFunction::SHA256,
-            HashFunction::Shake128,
-            HashFunction::Shake256,
-        ] {
-            let ciphersuite = Ciphersuite::resolve_ciphersuite(
-                kem,
-                hash_function,
-                SignatureScheme::Ed25519,
-                None,
-            )
-            .unwrap();
-
-            // generate kem public keys
-
-            let (responder_kem_public_key, initiator_kem_public_key) = match kem {
-                KEM::MlKem768 => (
-                    EncapsulationKey::MlKem768(generate_keypair_libcrux(&mut rng, kem).unwrap().1),
-                    EncapsulationKey::MlKem768(generate_keypair_libcrux(&mut rng, kem).unwrap().1),
-                ),
-                KEM::XWing => (
-                    EncapsulationKey::XWing(generate_keypair_libcrux(&mut rng, kem).unwrap().1),
-                    EncapsulationKey::XWing(generate_keypair_libcrux(&mut rng, kem).unwrap().1),
-                ),
-                KEM::X25519 => (
-                    EncapsulationKey::X25519(generate_keypair_libcrux(&mut rng, kem).unwrap().1),
-                    EncapsulationKey::X25519(generate_keypair_libcrux(&mut rng, kem).unwrap().1),
-                ),
-                KEM::McEliece => (
-                    EncapsulationKey::McEliece(generate_keypair_mceliece(&mut rng).1),
-                    EncapsulationKey::McEliece(generate_keypair_mceliece(&mut rng).1),
-                ),
-            };
-
-            let i_kem_key_bytes = initiator_kem_public_key.encode();
-
-            let r_kem_key_bytes = responder_kem_public_key.encode();
-
-            let i_dir_hash = hash_encapsulation_key(
-                &ciphersuite.hash_function(),
-                ciphersuite.hash_len(),
-                &i_kem_key_bytes,
-            );
-
-            let r_dir_hash = hash_encapsulation_key(
-                &ciphersuite.hash_function(),
-                ciphersuite.hash_len(),
-                &r_kem_key_bytes,
-            );
-
-            // Anonymous Initiator, OneWay
-            {
-                c.bench_function(
-                    &format!("{kem}, {hash_function} | Anonymous Initiator: Generate Request",),
-                    |b| {
-                        b.iter(|| anonymous_initiator_process(&mut rng, ciphersuite).unwrap());
-                    },
-                );
-
-                let (i_context, i_frame) =
-                    anonymous_initiator_process(&mut rng, ciphersuite).unwrap();
-
-                c.bench_function(
-                    &format!(
-                        "{kem}, {hash_function} | Anonymous Initiator: Encode Frame - Request",
-                    ),
-                    |b| b.iter(|| i_frame.to_bytes()),
-                );
-
-                let i_frame_bytes = i_frame.to_bytes();
-
-                c.bench_function(
-                    &format!(
-                        "{kem}, {hash_function} | Anonymous Initiator: Decode Frame - Request",
-                    ),
-                    |b| b.iter(|| KKTFrame::from_bytes(&i_frame_bytes).unwrap()),
-                );
-
-                let (i_frame_r, r_context) = KKTFrame::from_bytes(&i_frame_bytes).unwrap();
-
-                c.bench_function(
-                    &format!(
-                        "{kem}, {hash_function} | Anonymous Initiator: Responder Ingest Frame",
-                    ),
-                    |b| {
-                        b.iter(|| {
-                            responder_ingest_message(&r_context, None, None, &i_frame_r).unwrap()
-                        });
-                    },
-                );
-
-                let (r_context, _) =
-                    responder_ingest_message(&r_context, None, None, &i_frame_r).unwrap();
-
-                c.bench_function(
-                    &format!(
-                        "{kem}, {hash_function} | Anonymous Initiator: Responder Generate Response",
-                    ),
-                    |b| {
-                        b.iter(|| {
-                            responder_process(
-                                &r_context,
-                                i_frame_r.session_id(),
-                                responder_ed25519_keypair.private_key(),
-                                &responder_kem_public_key,
-                            )
-                            .unwrap()
-                        });
-                    },
-                );
-                let r_frame = responder_process(
-                    &r_context,
-                    i_frame_r.session_id(),
-                    responder_ed25519_keypair.private_key(),
-                    &responder_kem_public_key,
-                )
-                .unwrap();
-
-                c.bench_function(
-                    &format!(
-                        "{kem}, {hash_function} | Anonymous Initiator: Responder Encode Frame",
-                    ),
-                    |b| b.iter(|| r_frame.to_bytes()),
-                );
-
-                c.bench_function(
-                    &format!(
-                        "{kem}, {hash_function} | Anonymous Initiator: Initiator Ingest Response",
-                    ),
-                    |b| {
-                        b.iter(|| {
-                            initiator_ingest_response(
-                                &i_context,
-                                &r_frame,
-                                &r_frame.context().unwrap(),
-                                responder_ed25519_keypair.public_key(),
-                                &r_dir_hash,
-                            )
-                            .unwrap()
-                        });
-                    },
-                );
-
-                let obtained_key = initiator_ingest_response(
-                    &i_context,
-                    &r_frame,
-                    &r_frame.context().unwrap(),
-                    responder_ed25519_keypair.public_key(),
-                    &r_dir_hash,
-                )
-                .unwrap();
-
-                assert_eq!(obtained_key.encode(), r_kem_key_bytes)
-            }
-            // Initiator, OneWay
-            {
-                let (i_context, i_frame) = initiator_process(
-                    &mut rng,
-                    KKTMode::OneWay,
-                    ciphersuite,
-                    initiator_ed25519_keypair.private_key(),
-                    None,
-                )
-                .unwrap();
-
-                c.bench_function(
-                    &format!("{kem}, {hash_function} | Initiator OneWay: Generate Request",),
-                    |b| {
-                        b.iter(|| {
-                            initiator_process(
-                                &mut rng,
-                                KKTMode::OneWay,
-                                ciphersuite,
-                                initiator_ed25519_keypair.private_key(),
-                                None,
-                            )
-                            .unwrap()
-                        });
-                    },
-                );
-
-                c.bench_function(
-                    &format!("{kem}, {hash_function} | Initiator OneWay: Encode Frame - Request",),
-                    |b| b.iter(|| i_frame.to_bytes()),
-                );
-
-                let i_frame_bytes = i_frame.to_bytes();
-
-                c.bench_function(
-                    &format!("{kem}, {hash_function} | Initiator OneWay: Decode Frame - Request",),
-                    |b| b.iter(|| KKTFrame::from_bytes(&i_frame_bytes).unwrap()),
-                );
-
-                let (i_frame_r, r_context) = KKTFrame::from_bytes(&i_frame_bytes).unwrap();
-
-                c.bench_function(
-                    &format!("{kem}, {hash_function} | Initiator OneWay: Responder Ingest Frame",),
-                    |b| {
-                        b.iter(|| {
-                            responder_ingest_message(
-                                &r_context,
-                                Some(initiator_ed25519_keypair.public_key()),
-                                None,
-                                &i_frame_r,
-                            )
-                            .unwrap()
-                        });
-                    },
-                );
-
-                let (r_context, r_obtained_key) = responder_ingest_message(
-                    &r_context,
-                    Some(initiator_ed25519_keypair.public_key()),
-                    None,
-                    &i_frame_r,
-                )
-                .unwrap();
-
-                assert!(r_obtained_key.is_none());
-
-                c.bench_function(
-                    &format!(
-                        "{kem}, {hash_function} | Initiator OneWay: Responder Generate Response",
-                    ),
-                    |b| {
-                        b.iter(|| {
-                            responder_process(
-                                &r_context,
-                                i_frame_r.session_id(),
-                                responder_ed25519_keypair.private_key(),
-                                &responder_kem_public_key,
-                            )
-                            .unwrap()
-                        });
-                    },
-                );
-
-                let r_frame = responder_process(
-                    &r_context,
-                    i_frame_r.session_id(),
-                    responder_ed25519_keypair.private_key(),
-                    &responder_kem_public_key,
-                )
-                .unwrap();
-
-                c.bench_function(
-                    &format!("{kem}, {hash_function} | Initiator OneWay: Responder Encode Frame",),
-                    |b| {
-                        b.iter(|| r_frame.to_bytes());
-                    },
-                );
-
-                c.bench_function(
-                    &format!(
-                        "{kem}, {hash_function} | Initiator OneWay: Initiator Ingest Response",
-                    ),
-                    |b| {
-                        b.iter(|| {
-                            initiator_ingest_response(
-                                &i_context,
-                                &r_frame,
-                                &r_frame.context().unwrap(),
-                                responder_ed25519_keypair.public_key(),
-                                &r_dir_hash,
-                            )
-                            .unwrap()
-                        });
-                    },
-                );
-
-                let i_obtained_key = initiator_ingest_response(
-                    &i_context,
-                    &r_frame,
-                    &r_frame.context().unwrap(),
-                    responder_ed25519_keypair.public_key(),
-                    &r_dir_hash,
-                )
-                .unwrap();
-
-                assert_eq!(i_obtained_key.encode(), r_kem_key_bytes)
-            }
-
-            // Initiator, Mutual
-            {
-                c.bench_function(
-                    &format!("{kem}, {hash_function} | Initiator Mutual: Generate Request",),
-                    |b| {
-                        b.iter(|| {
-                            initiator_process(
-                                &mut rng,
-                                KKTMode::Mutual,
-                                ciphersuite,
-                                initiator_ed25519_keypair.private_key(),
-                                Some(&initiator_kem_public_key),
-                            )
-                            .unwrap()
-                        });
-                    },
-                );
-
-                let (i_context, i_frame) = initiator_process(
-                    &mut rng,
-                    KKTMode::Mutual,
-                    ciphersuite,
-                    initiator_ed25519_keypair.private_key(),
-                    Some(&initiator_kem_public_key),
-                )
-                .unwrap();
-
-                c.bench_function(
-                    &format!("{kem}, {hash_function} | Initiator Mutual: Encode Frame - Request",),
-                    |b| {
-                        b.iter(|| i_frame.to_bytes());
-                    },
-                );
-
-                let i_frame_bytes = i_frame.to_bytes();
-
-                c.bench_function(
-                    &format!("{kem}, {hash_function} | Initiator Mutual: Decode Frame - Request",),
-                    |b| {
-                        b.iter(|| KKTFrame::from_bytes(&i_frame_bytes).unwrap());
-                    },
-                );
-
-                let (i_frame_r, r_context) = KKTFrame::from_bytes(&i_frame_bytes).unwrap();
-
-                c.bench_function(
-                    &format!("{kem}, {hash_function} | Initiator Mutual: Responder Ingest Frame",),
-                    |b| {
-                        b.iter(|| {
-                            responder_ingest_message(
-                                &r_context,
-                                Some(initiator_ed25519_keypair.public_key()),
-                                Some(&i_dir_hash),
-                                &i_frame_r,
-                            )
-                            .unwrap()
-                        });
-                    },
-                );
-
-                let (r_context, r_obtained_key) = responder_ingest_message(
-                    &r_context,
-                    Some(initiator_ed25519_keypair.public_key()),
-                    Some(&i_dir_hash),
-                    &i_frame_r,
-                )
-                .unwrap();
-
-                assert_eq!(r_obtained_key.unwrap().encode(), i_kem_key_bytes);
-
-                c.bench_function(
-                    &format!(
-                        "{kem}, {hash_function} | Initiator Mutual: Responder Generate Response",
-                    ),
-                    |b| {
-                        b.iter(|| {
-                            responder_process(
-                                &r_context,
-                                i_frame_r.session_id(),
-                                responder_ed25519_keypair.private_key(),
-                                &responder_kem_public_key,
-                            )
-                            .unwrap()
-                        });
-                    },
-                );
-
-                let r_frame = responder_process(
-                    &r_context,
-                    i_frame_r.session_id(),
-                    responder_ed25519_keypair.private_key(),
-                    &responder_kem_public_key,
-                )
-                .unwrap();
-
-                c.bench_function(
-                    &format!("{kem}, {hash_function} | Initiator Mutual: Responder Encode Frame",),
-                    |b| {
-                        b.iter(|| {
-                            r_frame.to_bytes();
-                        });
-                    },
-                );
-
-                c.bench_function(
-                    &format!(
-                        "{kem}, {hash_function} | Initiator Mutual: Initiator Ingest Response",
-                    ),
-                    |b| {
-                        b.iter(|| {
-                            initiator_ingest_response(
-                                &i_context,
-                                &r_frame,
-                                &r_frame.context().unwrap(),
-                                responder_ed25519_keypair.public_key(),
-                                &r_dir_hash,
-                            )
-                            .unwrap()
-                        });
-                    },
-                );
-
-                let obtained_key = initiator_ingest_response(
-                    &i_context,
-                    &r_frame,
-                    &r_frame.context().unwrap(),
-                    responder_ed25519_keypair.public_key(),
-                    &r_dir_hash,
-                )
-                .unwrap();
-
-                assert_eq!(obtained_key.encode(), r_kem_key_bytes)
-            }
-        }
-    }
-}
-
-criterion_group!(
-    benches,
-    gen_ed25519_keypair,
-    gen_mlkem768_keypair,
-    kkt_benchmark
-);
-criterion_main!(benches);

common/nym-kkt/src/carrier.rs

@@ -0,0 +1,188 @@
+use libcrux_chacha20poly1305::TAG_LEN;
+use libcrux_psq::handshake::types::{DHKeyPair, DHPublicKey};
+use nym_crypto::hkdf::blake3::derive_key_blake3;
+use rand09::{CryptoRng, RngCore};
+use zeroize::{Zeroize, ZeroizeOnDrop, Zeroizing};
+
+use crate::error::KKTError;
+
+// This is arbitrary
+pub const MAX_PAYLOAD_LEN: usize = 1_000_000;
+const CARRIER_KDF_INFO_TX: &str = "CARRIER_V1_KDF_TX";
+const CARRIER_KDF_INFO_RX: &str = "CARRIER_V1_KDF_RX";
+
+#[derive(Zeroize, ZeroizeOnDrop)]
+pub struct Carrier {
+    tx_key: [u8; 32],
+    rx_key: [u8; 32],
+    tx_counter: u64,
+    rx_counter: u64,
+}
+
+pub enum CarrierRole {
+    Initiator,
+    Responder,
+}
+
+fn increment_nonce(nonce: &mut u64) -> Result<(), KKTError> {
+    match nonce.checked_add(1) {
+        Some(incremented_nonce) => {
+            *nonce = incremented_nonce;
+            Ok(())
+        }
+        None => Err(KKTError::AEADError {
+            info: "Nonce maxed out.",
+        }),
+    }
+}
+
+fn as_nonce_bytes(nonce: u64) -> [u8; 12] {
+    let mut bytes = [0u8; 12];
+    let nonce_bytes = nonce.to_le_bytes();
+    bytes[4..].clone_from_slice(&nonce_bytes);
+    bytes
+}
+
+impl Carrier {
+    fn init(tx_key: [u8; 32], rx_key: [u8; 32]) -> Self {
+        Self {
+            tx_key,
+            rx_key,
+            tx_counter: 1,
+            rx_counter: 1,
+        }
+    }
+
+    pub fn new<R>(
+        rng: &mut R,
+        remote_public_key: &DHPublicKey,
+        context: &[u8],
+        is_initiator: bool,
+    ) -> Result<(Self, DHPublicKey), KKTError>
+    where
+        R: RngCore + CryptoRng,
+    {
+        let ephemeral_keypair = DHKeyPair::new(rng);
+        let shared_secret = ephemeral_keypair
+            .sk()
+            .diffie_hellman(remote_public_key)
+            .map_err(|_| KKTError::X25519Error {
+                info: "Key Derivation Error",
+            })?;
+
+        Ok((
+            Self::from_secret_slice(shared_secret.as_ref(), context, is_initiator),
+            ephemeral_keypair.pk,
+        ))
+    }
+
+    pub(crate) fn from_secret_slice(secret: &[u8], context: &[u8], is_initiator: bool) -> Self {
+        let (tx_key, rx_key) = if is_initiator {
+            (
+                derive_key_blake3(CARRIER_KDF_INFO_TX, secret, context),
+                derive_key_blake3(CARRIER_KDF_INFO_RX, secret, context),
+            )
+        } else {
+            (
+                derive_key_blake3(CARRIER_KDF_INFO_RX, secret, context),
+                derive_key_blake3(CARRIER_KDF_INFO_TX, secret, context),
+            )
+        };
+
+        Self::init(tx_key, rx_key)
+    }
+
+    pub fn from_secret(secret: [u8; 32], context: &[u8], is_initiator: bool) -> Self {
+        Self::from_secret_slice(Zeroizing::new(secret).as_slice(), context, is_initiator)
+    }
+
+    pub fn encrypt(&mut self, plaintext: &[u8]) -> Result<Vec<u8>, KKTError> {
+        if plaintext.len() > MAX_PAYLOAD_LEN {
+            return Err(KKTError::AEADError {
+                info: "Plaintext too large",
+            });
+        }
+        let mut output_buffer = vec![0; plaintext.len() + TAG_LEN];
+        libcrux_chacha20poly1305::encrypt(
+            &self.tx_key,
+            plaintext,
+            &mut output_buffer,
+            b"kkt-carrier-v1",
+            &as_nonce_bytes(self.tx_counter),
+        )?;
+
+        increment_nonce(&mut self.tx_counter)?;
+
+        Ok(output_buffer)
+    }
+    pub fn decrypt(&mut self, ciphertext: &[u8]) -> Result<Vec<u8>, KKTError> {
+        if ciphertext.len() > MAX_PAYLOAD_LEN + TAG_LEN {
+            return Err(KKTError::AEADError {
+                info: "Ciphertext too large",
+            });
+        }
+        let mut output_buffer = vec![0; ciphertext.len() - TAG_LEN];
+        libcrux_chacha20poly1305::decrypt(
+            &self.rx_key,
+            &mut output_buffer,
+            ciphertext,
+            b"kkt-carrier-v1",
+            &as_nonce_bytes(self.rx_counter),
+        )?;
+
+        increment_nonce(&mut self.rx_counter)?;
+
+        Ok(output_buffer)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::{carrier::Carrier, key_utils::generate_lp_keypair_x25519};
+    use rand09::RngCore;
+
+    #[test]
+    fn test_e2e() {
+        let mut rng = rand09::rng();
+
+        // generate responder x25519 keys
+        let r_x25519 = generate_lp_keypair_x25519(&mut rng);
+
+        let mut context: [u8; 32] = [0u8; 32];
+        rng.fill_bytes(&mut context);
+
+        let ephemeral_keypair = generate_lp_keypair_x25519(&mut rng);
+
+        let i_shared_secret = ephemeral_keypair.sk().diffie_hellman(&r_x25519.pk).unwrap();
+
+        let r_shared_secret = r_x25519.sk().diffie_hellman(&ephemeral_keypair.pk).unwrap();
+
+        let mut i_carrier = Carrier::from_secret_slice(i_shared_secret.as_ref(), &context, true);
+        let mut r_carrier = Carrier::from_secret_slice(r_shared_secret.as_ref(), &context, false);
+
+        let test1 = b"test1: i>r #1";
+        let ct1 = i_carrier.encrypt(test1).unwrap();
+        let pt1 = r_carrier.decrypt(&ct1).unwrap();
+        assert_eq!(pt1, test1);
+
+        let test2 = b"test2: r>i #1";
+        let ct2 = i_carrier.encrypt(test2).unwrap();
+        let pt2 = r_carrier.decrypt(&ct2).unwrap();
+        assert_eq!(pt2, test2);
+        let test3 = b"test3: i>r #2";
+
+        let ct3 = i_carrier.encrypt(test3).unwrap();
+        let pt3 = r_carrier.decrypt(&ct3).unwrap();
+        assert_eq!(pt3, test3);
+
+        let test4 = b"test4: i>r #3";
+        let ct4 = i_carrier.encrypt(test4).unwrap();
+        let pt4 = r_carrier.decrypt(&ct4).unwrap();
+        assert_eq!(pt4, test4);
+
+        let test5 = b"test5: r>i #2";
+        let ct5 = i_carrier.encrypt(test5).unwrap();
+        let pt5 = r_carrier.decrypt(&ct5).unwrap();
+        assert_eq!(pt5, test5);
+    }
+}

common/nym-kkt/src/ciphersuite.rs

@@ -1,74 +0,0 @@
-// Copyright 2025 - Nym Technologies SA <contact@nymtech.net>
-// SPDX-License-Identifier: Apache-2.0
-
-use crate::error::KKTError;
-use libcrux_kem::Algorithm;
-
-pub use nym_kkt_ciphersuite::*;
-
-pub enum EncapsulationKey<'a> {
-    MlKem768(libcrux_kem::PublicKey),
-    XWing(libcrux_kem::PublicKey),
-    X25519(libcrux_kem::PublicKey),
-    McEliece(classic_mceliece_rust::PublicKey<'a>),
-}
-
-pub enum DecapsulationKey<'a> {
-    MlKem768(libcrux_kem::PrivateKey),
-    XWing(libcrux_kem::PrivateKey),
-    X25519(libcrux_kem::PrivateKey),
-    McEliece(classic_mceliece_rust::SecretKey<'a>),
-}
-impl<'a> EncapsulationKey<'a> {
-    pub(crate) fn decode(kem: KEM, bytes: &[u8]) -> Result<Self, KKTError> {
-        match kem {
-            KEM::McEliece => {
-                if bytes.len() != classic_mceliece_rust::CRYPTO_PUBLICKEYBYTES {
-                    Err(KKTError::KEMError {
-                        info: "Received McEliece Encapsulation Key with Invalid Length",
-                    })
-                } else {
-                    let mut public_key_bytes =
-                        Box::new([0u8; classic_mceliece_rust::CRYPTO_PUBLICKEYBYTES]);
-                    // Size must be correct due to KKTFrame::from_bytes(message_bytes)?
-                    public_key_bytes.clone_from_slice(bytes);
-                    Ok(EncapsulationKey::McEliece(
-                        classic_mceliece_rust::PublicKey::from(public_key_bytes),
-                    ))
-                }
-            }
-            KEM::X25519 => Ok(EncapsulationKey::X25519(libcrux_kem::PublicKey::decode(
-                map_kem_to_libcrux_kem(kem)?,
-                bytes,
-            )?)),
-            KEM::MlKem768 => Ok(EncapsulationKey::MlKem768(libcrux_kem::PublicKey::decode(
-                map_kem_to_libcrux_kem(kem)?,
-                bytes,
-            )?)),
-            KEM::XWing => Ok(EncapsulationKey::XWing(libcrux_kem::PublicKey::decode(
-                map_kem_to_libcrux_kem(kem)?,
-                bytes,
-            )?)),
-        }
-    }
-
-    pub fn encode(&self) -> Vec<u8> {
-        match self {
-            EncapsulationKey::XWing(public_key)
-            | EncapsulationKey::MlKem768(public_key)
-            | EncapsulationKey::X25519(public_key) => public_key.encode(),
-            EncapsulationKey::McEliece(public_key) => Vec::from(public_key.as_array()),
-        }
-    }
-}
-
-pub const fn map_kem_to_libcrux_kem(kem: KEM) -> Result<Algorithm, KKTError> {
-    match kem {
-        KEM::MlKem768 => Ok(Algorithm::MlKem768),
-        KEM::XWing => Ok(Algorithm::XWingKemDraft06),
-        KEM::X25519 => Ok(Algorithm::X25519),
-        KEM::McEliece => Err(KKTError::KEMMapping {
-            info: "attempted to map McEliece KEM to libcrux_kem",
-        }),
-    }
-}

common/nym-kkt/src/encryption.rs

@@ -1,253 +0,0 @@
-// Copyright 2025-2026 - Nym Technologies SA <contact@nymtech.net>
-// SPDX-License-Identifier: Apache-2.0
-
-use crate::{KKT_INITIAL_FRAME_AAD, context::KKTContext, error::KKTError, frame::KKTFrame};
-use blake3::Hasher;
-use libcrux_chacha20poly1305::{NONCE_LEN, TAG_LEN};
-use nym_crypto::asymmetric::x25519;
-use rand09::{CryptoRng, RngCore};
-use zeroize::Zeroize;
-
-#[derive(Clone, Copy, Zeroize)]
-pub struct KKTSessionSecret([u8; 32]);
-
-impl KKTSessionSecret {
-    pub fn new<R>(rng: &mut R, remote_public_key: &x25519::PublicKey) -> (Self, x25519::PublicKey)
-    where
-        R: RngCore + CryptoRng,
-    {
-        let mut private_key_bytes = [0u8; x25519::PRIVATE_KEY_SIZE];
-        rng.fill_bytes(&mut private_key_bytes);
-
-        let ephemeral_private_key = x25519::PrivateKey::from_secret(private_key_bytes);
-        let ephemeral_public_key = x25519::PublicKey::from(&ephemeral_private_key);
-
-        (
-            Self::derive(&ephemeral_private_key, remote_public_key),
-            ephemeral_public_key,
-        )
-    }
-    pub fn from_bytes(secret: [u8; 32]) -> Self {
-        Self(secret)
-    }
-
-    fn try_derive(private_key: &x25519::PrivateKey, public_key: &[u8]) -> Result<Self, KKTError> {
-        let mut pub_key: [u8; 32] = [0u8; 32];
-        pub_key.copy_from_slice(&public_key[0..x25519::PUBLIC_KEY_SIZE]);
-
-        // Todo: check validity of pk...
-        let pk = x25519::PublicKey::from(pub_key);
-        Ok(Self::derive(private_key, &pk))
-    }
-
-    pub fn derive(private_key: &x25519::PrivateKey, public_key: &x25519::PublicKey) -> Self {
-        let mut shared_secret = private_key.diffie_hellman(public_key);
-
-        let mut hasher = Hasher::new();
-
-        hasher.update(&shared_secret);
-        shared_secret.zeroize();
-
-        Self(hasher.finalize().as_bytes().to_owned())
-    }
-    pub fn as_bytes(&self) -> &[u8; 32] {
-        &self.0
-    }
-}
-
-pub fn encrypt_initial_kkt_frame<R>(
-    rng: &mut R,
-    remote_public_key: &x25519::PublicKey,
-    kkt_frame: &KKTFrame,
-) -> Result<(KKTSessionSecret, Vec<u8>), KKTError>
-where
-    R: CryptoRng + RngCore,
-{
-    let (session_secret_key, ephemeral_public_key) = KKTSessionSecret::new(rng, remote_public_key);
-
-    let mut encrypted_frame =
-        encrypt_kkt_frame(rng, &session_secret_key, kkt_frame, KKT_INITIAL_FRAME_AAD)?;
-
-    let mut output_buffer = Vec::with_capacity(encrypted_frame.len() + x25519::PUBLIC_KEY_SIZE);
-    output_buffer.extend_from_slice(ephemeral_public_key.as_bytes());
-    output_buffer.append(&mut encrypted_frame);
-
-    // [     32     |  12   | ciphertext | 16];
-    // [eph_pub_key | nonce | ciphertext | tag];
-    Ok((session_secret_key, output_buffer))
-}
-
-pub fn decrypt_initial_kkt_frame(
-    responder_private_key: &x25519::PrivateKey,
-    encrypted_frame_bytes: &[u8],
-) -> Result<(KKTSessionSecret, KKTFrame, KKTContext), KKTError> {
-    if encrypted_frame_bytes.len() < x25519::PUBLIC_KEY_SIZE + TAG_LEN + NONCE_LEN {
-        Err(KKTError::AEADError {
-            info: "Encrypted KKT Frame is too short.",
-        })
-    } else {
-        let shared_secret = KKTSessionSecret::try_derive(
-            responder_private_key,
-            &encrypted_frame_bytes[0..x25519::PUBLIC_KEY_SIZE],
-        )?;
-
-        let (kkt_frame, kkt_context) = decrypt_kkt_frame(
-            &shared_secret,
-            &encrypted_frame_bytes[x25519::PUBLIC_KEY_SIZE..],
-            KKT_INITIAL_FRAME_AAD,
-        )?;
-        Ok((shared_secret, kkt_frame, kkt_context))
-    }
-}
-
-pub fn encrypt_kkt_frame<R>(
-    rng: &mut R,
-    secret_key: &KKTSessionSecret,
-    kkt_frame: &KKTFrame,
-    aad: &[u8],
-) -> Result<Vec<u8>, KKTError>
-where
-    R: CryptoRng + RngCore,
-{
-    let kkt_frame_bytes = kkt_frame.to_bytes();
-
-    // generate nonce
-    let mut nonce: [u8; NONCE_LEN] = [0u8; NONCE_LEN];
-    rng.fill_bytes(&mut nonce);
-
-    let mut ciphertext = encrypt(secret_key.as_bytes(), &kkt_frame_bytes, aad, &nonce)?;
-
-    // [  12  | ciphertext | 16];
-    // [nonce | ciphertext | tag];
-    let mut output_buffer: Vec<u8> =
-        Vec::with_capacity(NONCE_LEN + kkt_frame_bytes.len() + TAG_LEN);
-
-    output_buffer.extend_from_slice(&nonce);
-    output_buffer.append(&mut ciphertext);
-
-    Ok(output_buffer)
-}
-
-// kkt_frame_bytes should look like this
-// [  12  | ciphertext | 16];
-// [nonce | ciphertext | tag];
-pub fn decrypt_kkt_frame(
-    secret_key: &KKTSessionSecret,
-    kkt_frame_bytes: &[u8],
-    aad: &[u8],
-) -> Result<(KKTFrame, KKTContext), KKTError> {
-    let mut nonce: [u8; NONCE_LEN] = [0u8; NONCE_LEN];
-    nonce.copy_from_slice(&kkt_frame_bytes[0..NONCE_LEN]);
-
-    let plaintext = decrypt(
-        secret_key.as_bytes(),
-        &kkt_frame_bytes[NONCE_LEN..],
-        aad,
-        &nonce,
-    )?;
-
-    KKTFrame::from_bytes(&plaintext)
-}
-
-fn encrypt(
-    secret_key: &[u8; 32],
-    plaintext: &[u8],
-    aad: &[u8],
-    nonce: &[u8; NONCE_LEN],
-) -> Result<Vec<u8>, KKTError> {
-    let mut output_buffer = vec![0; plaintext.len() + TAG_LEN];
-    libcrux_chacha20poly1305::encrypt(secret_key, plaintext, &mut output_buffer, aad, nonce)?;
-    Ok(output_buffer)
-}
-
-fn decrypt(
-    secret_key: &[u8; 32],
-    ciphertext: &[u8],
-    aad: &[u8],
-    nonce: &[u8; NONCE_LEN],
-) -> Result<Vec<u8>, KKTError> {
-    let mut output_buffer = vec![0; ciphertext.len() - TAG_LEN];
-    libcrux_chacha20poly1305::decrypt(secret_key, &mut output_buffer, ciphertext, aad, nonce)?;
-    Ok(output_buffer)
-}
-
-#[cfg(test)]
-mod test {
-    use crate::ciphersuite::Ciphersuite;
-    use crate::context::{KKTContext, KKTMode, KKTRole};
-    use crate::encryption::{decrypt_kkt_frame, encrypt_kkt_frame};
-    use crate::frame::{KKT_SESSION_ID_LEN, KKTFrame};
-    use crate::{
-        ciphersuite::DEFAULT_HASH_LEN,
-        encryption::{KKTSessionSecret, decrypt, encrypt},
-        key_utils::generate_keypair_x25519,
-    };
-    use rand09::{RngCore, SeedableRng, rng};
-
-    #[test]
-    fn test_keygen() {
-        let mut rng = rng();
-        let responder_x25519_keypair = generate_keypair_x25519(&mut rng);
-
-        let (session_secret_key, ephemeral_public_key) =
-            KKTSessionSecret::new(&mut rng, responder_x25519_keypair.public_key());
-
-        let shared_secret = KKTSessionSecret::try_derive(
-            responder_x25519_keypair.private_key(),
-            ephemeral_public_key.as_bytes().as_slice(),
-        )
-        .unwrap();
-
-        assert_eq!(shared_secret.as_bytes(), session_secret_key.as_bytes())
-    }
-
-    #[test]
-    fn test_encryption() {
-        let mut rng = rng();
-
-        let mut secret_key = [0u8; DEFAULT_HASH_LEN];
-        rng.fill_bytes(&mut secret_key);
-
-        let mut plaintext = vec![0; 100];
-        rng.fill_bytes(&mut plaintext);
-
-        let mut nonce = [0; 12];
-        rng.fill_bytes(&mut nonce);
-
-        let mut aad = vec![0; 124];
-        rng.fill_bytes(&mut aad);
-
-        let ciphertext = encrypt(&secret_key, &plaintext, &aad, &nonce).unwrap();
-
-        let o_plaintext = decrypt(&secret_key, &ciphertext, &aad, &nonce).unwrap();
-
-        assert_eq!(o_plaintext, plaintext)
-    }
-
-    #[test]
-    fn kkt_frame_encryption() -> anyhow::Result<()> {
-        let mut rng = rand_chacha::ChaCha20Rng::seed_from_u64(42);
-        let session_key = KKTSessionSecret::from_bytes([42u8; 32]);
-        let aad = b"my-amazing-aad";
-
-        let valid_context = KKTContext::new(
-            KKTRole::Initiator,
-            KKTMode::Mutual,
-            Ciphersuite::decode([255, 1, 0, 0])?,
-        )?;
-        let dummy_frame = KKTFrame::new(
-            valid_context.encode()?,
-            &[2u8; 32],
-            [3u8; KKT_SESSION_ID_LEN],
-            &[4u8; 64],
-        );
-
-        let ciphertext = encrypt_kkt_frame(&mut rng, &session_key, &dummy_frame, aad.as_slice())?;
-
-        let (frame, context) = decrypt_kkt_frame(&session_key, &ciphertext, aad.as_slice())?;
-
-        assert_eq!(dummy_frame, frame);
-        assert_eq!(context, valid_context);
-        Ok(())
-    }
-}

common/nym-kkt/src/error.rs

@@ -3,18 +3,18 @@
 
 use crate::context::KKTStatus;
 use nym_kkt_ciphersuite::error::KKTCiphersuiteError;
+use nym_kkt_context::KKTContextEncodingError;
 use std::fmt::Debug;
 use thiserror::Error;
 
 #[derive(Error, Debug)]
 pub enum KKTError {
-    #[error("Signature constructor error")]
-    SigConstructorError,
-    #[error("Signature verification error")]
-    SigVerifError,
     #[error(transparent)]
     CiphersuiteDecodingError(#[from] KKTCiphersuiteError),
 
+    #[error(transparent)]
+    MaskedByteError(#[from] MaskedByteError),
+
     #[error("KEM mapping failure: {}", info)]
     KEMMapping { info: &'static str },
 
@@ -33,9 +33,6 @@ pub enum KKTError {
     #[error("KKT Responder Flagged Error: {}", status)]
     ResponderFlaggedError { status: KKTStatus },
 
-    #[error("KKT Message Count Limit Reached")]
-    MessageCountLimitReached,
-
     #[error("PSQ KEM Error: {}", info)]
     KEMError { info: &'static str },
 
@@ -48,8 +45,40 @@ pub enum KKTError {
     #[error("{}", info)]
     AEADError { info: &'static str },
 
+    #[error("{}", info)]
+    DecodingError { info: &'static str },
+
+    #[error("{}", info)]
+    UnsupportedAlgorithm { info: &'static str },
+
     #[error("Generic libcrux error")]
     LibcruxError,
+
+    #[error("failed to derive shared secret: {inner:?}")]
+    SharedSecretDerivationFailure {
+        inner: libcrux_psq::handshake::HandshakeError,
+    },
+
+    #[error("the received encapsulation key hash does not match the expected value")]
+    MismatchedKEMHash,
+
+    #[error(transparent)]
+    MalformedContext(#[from] KKTContextEncodingError),
+}
+
+impl KKTError {
+    pub fn shared_secret_derivation_failure(inner: libcrux_psq::handshake::HandshakeError) -> Self {
+        KKTError::SharedSecretDerivationFailure { inner }
+    }
+}
+
+#[derive(Error, Debug)]
+pub enum MaskedByteError {
+    #[error("invalid Masked Byte Length: Expected({expected}), Actual({actual})")]
+    InvalidLength { expected: usize, actual: usize },
+
+    #[error("failed to Unmask Byte")]
+    Failure,
 }
 
 impl From<libcrux_kem::Error> for KKTError {

common/nym-kkt/src/frame.rs

@@ -7,90 +7,158 @@
 // [2..=5] => Ciphersuite
 // [6] => Reserved
 
+use crate::context::{KKTMode, KKTRole};
+use crate::message::{
+    DecryptedRequestFrame, KKTRequest, KKTRequestEncryptionResult, KKTRequestPlaintext,
+};
 use crate::{
     context::{KKT_CONTEXT_LEN, KKTContext},
     error::KKTError,
 };
+use libcrux_psq::handshake::types::{DHKeyPair, DHPublicKey};
+use nym_kkt_ciphersuite::KEM;
+use rand09::{CryptoRng, RngCore};
 
-pub const KKT_SESSION_ID_LEN: usize = 16;
-
-pub type KKTSessionId = [u8; KKT_SESSION_ID_LEN];
+pub(crate) const KKT_CARRIER_CONTEXT: &[u8] = b"CARRIER_V1_KKT_V1_KDF";
 
 #[derive(Debug, PartialEq, Clone)]
 pub struct KKTFrame {
-    context: [u8; KKT_CONTEXT_LEN],
-    session_id: KKTSessionId,
+    context: KKTContext,
     body: Vec<u8>,
-    signature: Vec<u8>,
+    payload: Vec<u8>,
 }
 
-// if oneway and message coming from initiator => body is empty, signature contains signature of context + session id (64 bytes).
-// if message coming from anonymous initiator => body is empty, there is no signature.
-// if mutual and message coming from initiator => body has the initiator's kem public key and the signature is over the context + body + session_id.
-// if coming from responder => body has the responder's kem public key and the signature is over the context + body + session_id.
+// if oneway and message coming from initiator => body is empty.
+// if mutual and message coming from initiator => body has the initiator's kem public key.
+// if coming from responder => body has the responder's kem public key.
 
 impl KKTFrame {
-    pub fn new(
-        context: [u8; KKT_CONTEXT_LEN],
-        body: &[u8],
-        session_id: [u8; KKT_SESSION_ID_LEN],
-        signature: &[u8],
-    ) -> Self {
+    pub fn new(context: KKTContext, body: &[u8], payload: Vec<u8>) -> Self {
         Self {
             context,
             body: Vec::from(body),
-            session_id,
-            signature: Vec::from(signature),
+            payload,
         }
     }
-    pub fn context_ref(&self) -> &[u8] {
+
+    pub const fn size_excluding_payload(role: KKTRole, mode: KKTMode, kem: KEM) -> usize {
+        match role {
+            KKTRole::Initiator => {
+                match mode {
+                    KKTMode::OneWay => {
+                        // if oneway and message coming from initiator => body is empty.
+                        KKT_CONTEXT_LEN
+                    }
+                    KKTMode::Mutual => {
+                        // if mutual and message coming from initiator => body has the initiator's kem public key.
+                        KKT_CONTEXT_LEN + kem.encapsulation_key_length()
+                    }
+                }
+            }
+            KKTRole::Responder => {
+                // if coming from responder => body has the responder's kem public key.
+                KKT_CONTEXT_LEN + kem.encapsulation_key_length()
+            }
+        }
+    }
+
+    pub fn size(&self) -> usize {
+        self.payload.len()
+            + Self::size_excluding_payload(
+                self.context.role(),
+                self.context.mode(),
+                self.context.ciphersuite().kem(),
+            )
+    }
+
+    pub fn context(&self) -> &KKTContext {
         &self.context
     }
 
-    pub fn context(&self) -> Result<KKTContext, KKTError> {
-        KKTContext::try_decode(self.context)
+    pub fn payload(&self) -> &[u8] {
+        self.payload.as_ref()
     }
 
-    pub fn signature_ref(&self) -> &[u8] {
-        &self.signature
+    pub fn encrypt_initiator_frame<R>(
+        self,
+        rng: &mut R,
+        responder_public_key: &DHPublicKey,
+        version_byte: u8,
+    ) -> Result<KKTRequestEncryptionResult, KKTError>
+    where
+        R: CryptoRng + RngCore,
+    {
+        let ephemeral_keypair = DHKeyPair::new(rng);
+
+        let plaintext =
+            KKTRequestPlaintext::new(ephemeral_keypair.pk, responder_public_key, version_byte);
+
+        let mut carrier =
+            plaintext.derive_initiator_carrier(ephemeral_keypair.sk(), responder_public_key)?;
+        let full_kkt_message = plaintext.into_request(&mut carrier, self)?;
+
+        Ok(KKTRequestEncryptionResult {
+            carrier,
+            request: full_kkt_message,
+        })
+    }
+
+    pub fn decrypt_initiator_frame(
+        responder_keypair: &DHKeyPair,
+        message: KKTRequest,
+        supported_versions: &[u8],
+        request_payload_len: usize,
+    ) -> Result<DecryptedRequestFrame, KKTError> {
+        let mask = message.plaintext.version_mask(&responder_keypair.pk);
+
+        // check mask
+        // this could be used later when we have multiple versions
+        // if this call fails, it does before the server has to run a DH
+        let outer_protocol_version = message
+            .plaintext
+            .masked_version_bytes
+            .unmask_check_version(&mask, supported_versions)?;
+
+        // after verifying the version, we can perform the DH and continue processing the request
+        let mut carrier = message
+            .plaintext
+            .derive_responder_carrier(responder_keypair)?;
+
+        let decrypted_message = carrier.decrypt(&message.encrypted_frame)?;
+        let frame = KKTFrame::from_bytes(&decrypted_message, request_payload_len)?;
+
+        Ok(DecryptedRequestFrame {
+            carrier,
+            remote_frame: frame,
+            outer_protocol_version,
+        })
     }
 
     pub fn body_ref(&self) -> &[u8] {
         &self.body
     }
 
-    pub fn session_id_ref(&self) -> &[u8] {
-        &self.session_id
-    }
-    pub fn session_id(&self) -> [u8; KKT_SESSION_ID_LEN] {
-        self.session_id
+    pub fn body(self) -> Vec<u8> {
+        self.body
     }
 
-    pub fn signature_mut(&mut self) -> &mut [u8] {
-        &mut self.signature
-    }
     pub fn body_mut(&mut self) -> &mut [u8] {
         &mut self.body
     }
 
-    pub fn session_id_mut(&mut self) -> &mut [u8] {
-        &mut self.session_id
-    }
-
     pub fn frame_length(&self) -> usize {
-        self.context.len() + self.session_id.len() + self.body.len() + self.signature.len()
+        KKT_CONTEXT_LEN + self.body.len()
     }
 
-    pub fn to_bytes(&self) -> Vec<u8> {
+    pub fn try_to_bytes(&self) -> Result<Vec<u8>, KKTError> {
         let mut bytes = Vec::with_capacity(self.frame_length());
-        bytes.extend_from_slice(&self.context);
+        bytes.extend_from_slice(&self.context.encode()?);
         bytes.extend_from_slice(&self.body);
-        bytes.extend_from_slice(&self.session_id);
-        bytes.extend_from_slice(&self.signature);
-        bytes
+        bytes.extend_from_slice(&self.payload);
+        Ok(bytes)
     }
 
-    pub fn from_bytes(bytes: &[u8]) -> Result<(Self, KKTContext), KKTError> {
+    pub fn from_bytes(bytes: &[u8], payload_len: usize) -> Result<Self, KKTError> {
         let len = bytes.len();
         if bytes.len() < KKT_CONTEXT_LEN {
             return Err(KKTError::FrameDecodingError {
@@ -105,7 +173,7 @@ impl KKTFrame {
         let context_bytes = bytes[0..KKT_CONTEXT_LEN].try_into().unwrap();
         let context = KKTContext::try_decode(context_bytes)?;
 
-        if bytes.len() != context.full_message_len() {
+        if bytes.len() != context.full_message_len() + payload_len {
             return Err(KKTError::FrameDecodingError {
                 info: format!(
                     "Frame is shorter than expected: actual {len} != expected {}",
@@ -115,7 +183,6 @@ impl KKTFrame {
         }
 
         let mut body = Vec::new();
-        let mut signature = Vec::new();
 
         // decode body
         if context.body_len() > 0 {
@@ -123,33 +190,9 @@ impl KKTFrame {
             body.extend_from_slice(body_bytes);
         }
 
-        let session_bytes = &bytes[KKT_CONTEXT_LEN + context.body_len()
-            ..KKT_CONTEXT_LEN + context.body_len() + KKT_SESSION_ID_LEN];
-        // SAFETY: we're using exactly KKT_SESSION_ID_LEN bytes and we checked for sufficient bytes
-        #[allow(clippy::unwrap_used)]
-        let session_id = session_bytes.try_into().unwrap();
+        // decode payload. this could be empty.
+        let payload: Vec<u8> = Vec::from(&bytes[KKT_CONTEXT_LEN + context.body_len()..]);
 
-        // // old code left for reference if session id becomes variable in length:
-        // if context.session_id_len() > 0 {
-        //     session_id.extend_from_slice(
-        //         &bytes[KKT_CONTEXT_LEN + context.body_len()
-        //             ..KKT_CONTEXT_LEN + context.body_len() + context.session_id_len()],
-        //     );
-        // }
-
-        // decode signature
-        if context.signature_len() > 0 {
-            let signature_bytes = &bytes[KKT_CONTEXT_LEN + context.body_len() + KKT_SESSION_ID_LEN
-                ..KKT_CONTEXT_LEN
-                    + context.body_len()
-                    + KKT_SESSION_ID_LEN
-                    + context.signature_len()];
-            signature.extend_from_slice(signature_bytes);
-        }
-
-        Ok((
-            KKTFrame::new(context_bytes, &body, session_id, &signature),
-            context,
-        ))
+        Ok(KKTFrame::new(context, &body, payload))
     }
 }

common/nym-kkt/src/initiator.rs

@@ -0,0 +1,188 @@
+// Copyright 2025-2026 - Nym Technologies SA <contact@nymtech.net>
+// SPDX-License-Identifier: Apache-2.0
+
+use libcrux_psq::handshake::types::DHPublicKey;
+use nym_kkt_ciphersuite::Ciphersuite;
+use rand09::{CryptoRng, RngCore};
+use zeroize::{Zeroize, ZeroizeOnDrop};
+
+use crate::keys::EncapsulationKey;
+use crate::message::{KKTRequest, KKTResponse, ProcessedKKTResponse};
+use crate::{
+    carrier::Carrier,
+    context::{KKTContext, KKTMode, KKTRole, KKTStatus},
+    error::KKTError,
+    frame::KKTFrame,
+    key_utils::validate_encapsulation_key,
+};
+
+#[derive(Zeroize, ZeroizeOnDrop)]
+pub struct KKTInitiator<'a> {
+    carrier: Carrier,
+
+    #[zeroize(skip)]
+    context: KKTContext,
+
+    #[zeroize(skip)]
+    expected_hash: &'a [u8],
+}
+
+impl<'a> KKTInitiator<'a> {
+    // to be used by clients
+    pub fn generate_one_way_request<R>(
+        rng: &mut R,
+        ciphersuite: Ciphersuite,
+        responder_dh_public_key: &DHPublicKey,
+        expected_hash: &'a [u8],
+        outer_protocol_version: u8,
+        payload: Option<Vec<u8>>,
+    ) -> Result<(Self, KKTRequest), KKTError>
+    where
+        R: CryptoRng + RngCore,
+    {
+        Self::generate_encrypted_request(
+            rng,
+            KKTMode::OneWay,
+            ciphersuite,
+            None,
+            responder_dh_public_key,
+            expected_hash,
+            outer_protocol_version,
+            payload,
+        )
+    }
+
+    // to be used by nodes
+    pub fn generate_mutual_request<'b, R>(
+        rng: &mut R,
+        ciphersuite: Ciphersuite,
+        local_encapsulation_key: &'b [u8],
+        responder_dh_public_key: &DHPublicKey,
+        expected_hash: &'a [u8],
+        outer_protocol_version: u8,
+        payload: Option<Vec<u8>>,
+    ) -> Result<(Self, KKTRequest), KKTError>
+    where
+        R: CryptoRng + RngCore,
+    {
+        Self::generate_encrypted_request(
+            rng,
+            KKTMode::Mutual,
+            ciphersuite,
+            Some(local_encapsulation_key),
+            responder_dh_public_key,
+            expected_hash,
+            outer_protocol_version,
+            payload,
+        )
+    }
+
+    #[allow(clippy::too_many_arguments)]
+    fn generate_encrypted_request<'b, R>(
+        rng: &mut R,
+        mode: KKTMode,
+        ciphersuite: Ciphersuite,
+        local_encapsulation_key: Option<&'b [u8]>,
+        responder_dh_public_key: &DHPublicKey,
+        expected_hash: &'a [u8],
+        outer_protocol_version: u8,
+        payload: Option<Vec<u8>>,
+    ) -> Result<(Self, KKTRequest), KKTError>
+    where
+        R: CryptoRng + RngCore,
+    {
+        let frame = initiator_process(mode, ciphersuite, local_encapsulation_key, payload)?;
+        let context = *frame.context();
+
+        let request =
+            frame.encrypt_initiator_frame(rng, responder_dh_public_key, outer_protocol_version)?;
+
+        Ok((
+            Self {
+                carrier: request.carrier,
+                context,
+                expected_hash,
+            },
+            request.request,
+        ))
+    }
+
+    pub fn process_response(
+        &mut self,
+        response: KKTResponse,
+        response_payload_len: usize,
+    ) -> Result<ProcessedKKTResponse, KKTError> {
+        let decrypted_response_bytes = self.carrier.decrypt(&response.encrypted_frame)?;
+        let response_frame = KKTFrame::from_bytes(&decrypted_response_bytes, response_payload_len)?;
+        initiator_ingest_response(&self.context, &response_frame, self.expected_hash)
+    }
+}
+
+pub fn initiator_process(
+    mode: KKTMode,
+    ciphersuite: Ciphersuite,
+    own_encapsulation_key: Option<&[u8]>,
+    payload: Option<Vec<u8>>,
+) -> Result<KKTFrame, KKTError> {
+    let context = KKTContext::new(KKTRole::Initiator, mode, ciphersuite);
+
+    let body: &[u8] = match mode {
+        KKTMode::OneWay => &[],
+        KKTMode::Mutual => match own_encapsulation_key {
+            Some(encaps_key) => encaps_key,
+
+            // Missing key
+            None => {
+                return Err(KKTError::FunctionInputError {
+                    info: "KEM Key Not Provided",
+                });
+            }
+        },
+    };
+
+    Ok(KKTFrame::new(
+        context,
+        body,
+        match payload {
+            Some(payload_vec) => payload_vec,
+            None => Vec::with_capacity(0),
+        },
+    ))
+}
+
+pub fn initiator_ingest_response(
+    own_context: &KKTContext,
+    remote_frame: &KKTFrame,
+    expected_hash: &[u8],
+) -> Result<ProcessedKKTResponse, KKTError> {
+    let remote_context = remote_frame.context();
+    let verified_initiator_kem_key = match remote_context.status() {
+        KKTStatus::Ok | KKTStatus::UnverifiedKEMKey => {
+            match validate_encapsulation_key(
+                own_context.ciphersuite().hash_function(),
+                own_context.ciphersuite().hash_len(),
+                remote_frame.body_ref(),
+                expected_hash,
+            ) {
+                true => remote_context.status() != KKTStatus::UnverifiedKEMKey,
+
+                // The key does not match the hash obtained from the directory
+                false => return Err(KKTError::MismatchedKEMHash),
+            }
+        }
+        _ => {
+            return Err(KKTError::ResponderFlaggedError {
+                status: remote_context.status(),
+            });
+        }
+    };
+
+    let kem = own_context.ciphersuite().kem();
+    let kem_bytes = remote_frame.body_ref();
+    let encapsulation_key = EncapsulationKey::try_from_bytes(kem_bytes.to_vec(), kem)?;
+    Ok(ProcessedKKTResponse {
+        encapsulation_key,
+        verified_initiator_kem_key,
+        response_payload: remote_frame.payload().to_vec(),
+    })
+}

common/nym-kkt/src/key_utils.rs

@@ -1,74 +1,35 @@
-use crate::ciphersuite::HashFunction;
-use std::collections::HashMap;
+// Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
+// SPDX-License-Identifier: Apache-2.0
 
-use classic_mceliece_rust::keypair_boxed;
-
-use nym_kkt_ciphersuite::{DEFAULT_HASH_LEN, KeyDigests};
+use libcrux_ml_kem::mlkem768::MlKem768KeyPair;
+use libcrux_psq::handshake::types::DHKeyPair;
+use nym_kkt_ciphersuite::{DEFAULT_HASH_LEN, HashFunction, KEMKeyDigests};
 use rand09::{CryptoRng, RngCore};
+use std::collections::BTreeMap;
 
-pub fn generate_keypair_ed25519<R>(
-    rng: &mut R,
-    index: Option<u32>,
-) -> nym_crypto::asymmetric::ed25519::KeyPair
+pub fn generate_lp_keypair_x25519<R>(rng: &mut R) -> DHKeyPair
 where
     R: RngCore + CryptoRng,
 {
-    let mut secret_initiator: [u8; 32] = [0u8; 32];
-    rng.fill_bytes(&mut secret_initiator);
-    nym_crypto::asymmetric::ed25519::KeyPair::from_secret(secret_initiator, index.unwrap_or(0))
+    DHKeyPair::new(rng)
 }
 
-pub fn generate_keypair_x25519<R>(rng: &mut R) -> nym_crypto::asymmetric::x25519::KeyPair
+pub fn generate_keypair_mlkem<R>(rng: &mut R) -> MlKem768KeyPair
 where
     R: RngCore + CryptoRng,
 {
-    let mut secret_initiator: [u8; 32] = [0u8; 32];
-    rng.fill_bytes(&mut secret_initiator);
-
-    let private_key = nym_crypto::asymmetric::x25519::PrivateKey::from_secret(secret_initiator);
-    private_key.into()
+    libcrux_ml_kem::mlkem768::rand::generate_key_pair(rng)
 }
 
-// (decapsulation_key, encapsulation_key)
-pub fn generate_keypair_libcrux<R>(
-    rng: &mut R,
-    kem: crate::ciphersuite::KEM,
-) -> Result<(libcrux_kem::PrivateKey, libcrux_kem::PublicKey), crate::error::KKTError>
+pub fn generate_keypair_mceliece<R>(rng: &mut R) -> libcrux_psq::classic_mceliece::KeyPair
 where
     R: RngCore + CryptoRng,
 {
-    match kem {
-        crate::ciphersuite::KEM::MlKem768 => {
-            Ok(libcrux_kem::key_gen(libcrux_kem::Algorithm::MlKem768, rng)?)
-        }
-        crate::ciphersuite::KEM::XWing => Ok(libcrux_kem::key_gen(
-            libcrux_kem::Algorithm::XWingKemDraft06,
-            rng,
-        )?),
-        crate::ciphersuite::KEM::X25519 => {
-            Ok(libcrux_kem::key_gen(libcrux_kem::Algorithm::X25519, rng)?)
-        }
-        _ => Err(crate::error::KKTError::KEMError {
-            info: "Key Generation Error: Unsupported Libcrux Algorithm",
-        }),
-    }
-}
-// (decapsulation_key, encapsulation_key)
-pub fn generate_keypair_mceliece<'a, R>(
-    rng: &mut R,
-) -> (
-    classic_mceliece_rust::SecretKey<'a>,
-    classic_mceliece_rust::PublicKey<'a>,
-)
-where
-    R: RngCore + CryptoRng,
-{
-    let (encapsulation_key, decapsulation_key) = keypair_boxed(rng);
-    (decapsulation_key, encapsulation_key)
+    libcrux_psq::classic_mceliece::KeyPair::generate_key_pair(rng)
 }
 
 pub fn hash_key_bytes(
-    hash_function: &HashFunction,
+    hash_function: HashFunction,
     hash_length: usize,
     key_bytes: &[u8],
 ) -> Vec<u8> {
@@ -77,9 +38,9 @@ pub fn hash_key_bytes(
 
 /// attempt to produce digests of the provided key using all known [HashFunction] with a default
 /// hash length where variable output is available
-pub fn produce_key_digests(key_bytes: &[u8]) -> KeyDigests {
+pub fn produce_key_digests(key_bytes: &[u8]) -> KEMKeyDigests {
     use strum::IntoEnumIterator;
-    let mut digests = HashMap::new();
+    let mut digests = BTreeMap::new();
     for hash in HashFunction::iter() {
         digests.insert(hash, hash.digest(key_bytes, DEFAULT_HASH_LEN));
     }
@@ -93,7 +54,7 @@ fn compare_hashes(a: &[u8], b: &[u8]) -> bool {
 }
 
 pub fn validate_encapsulation_key(
-    hash_function: &HashFunction,
+    hash_function: HashFunction,
     hash_length: usize,
     encapsulation_key: &[u8],
     expected_hash_bytes: &[u8],
@@ -104,20 +65,8 @@ pub fn validate_encapsulation_key(
     )
 }
 
-pub fn validate_key_bytes(
-    hash_function: &HashFunction,
-    hash_length: usize,
-    key_bytes: &[u8],
-    expected_hash_bytes: &[u8],
-) -> bool {
-    compare_hashes(
-        &hash_key_bytes(hash_function, hash_length, key_bytes),
-        expected_hash_bytes,
-    )
-}
-
 pub fn hash_encapsulation_key(
-    hash_function: &HashFunction,
+    hash_function: HashFunction,
     hash_length: usize,
     encapsulation_key: &[u8],
 ) -> Vec<u8> {

common/nym-kkt/src/keys.rs

@@ -0,0 +1,440 @@
+// Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
+// SPDX-License-Identifier: Apache-2.0
+
+use crate::error::KKTError;
+use libcrux_psq::handshake::types::PQEncapsulationKey;
+use nym_kkt_ciphersuite::{KEM, KEMKeyDigests};
+use std::collections::BTreeMap;
+use std::fmt::{Debug, Formatter};
+use std::sync::Arc;
+
+use crate::key_utils::produce_key_digests;
+pub use libcrux_ml_kem::mlkem768::{MlKem768KeyPair, MlKem768PrivateKey, MlKem768PublicKey};
+pub use libcrux_psq::classic_mceliece as mceliece;
+pub use libcrux_psq::handshake::types::{DHKeyPair, DHPrivateKey, DHPublicKey};
+
+/// Wrapper around keys used for the KEM exchange
+/// with cheap clones thanks to Arc wrappers
+#[derive(Clone)]
+pub struct KEMKeys {
+    mc_eliece_pk: Arc<mceliece::PublicKey>,
+    mc_eliece_sk: Arc<mceliece::SecretKey>,
+    ml_kem768_pk: Arc<MlKem768PublicKey>,
+    ml_kem768_sk: Arc<MlKem768PrivateKey>,
+}
+
+impl Debug for KEMKeys {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("KEMKeys")
+            .field("mc_eliece", &"<redacted>")
+            .field("ml_kem768", &"<redacted>")
+            .finish()
+    }
+}
+
+impl KEMKeys {
+    pub fn new(mc_eliece: mceliece::KeyPair, ml_kem768: MlKem768KeyPair) -> Self {
+        let (ml_kem768_sk, ml_kem768_pk) = ml_kem768.into_parts();
+        Self {
+            mc_eliece_pk: Arc::new(mc_eliece.pk),
+            mc_eliece_sk: Arc::new(mc_eliece.sk),
+            ml_kem768_pk: Arc::new(ml_kem768_pk),
+            ml_kem768_sk: Arc::new(ml_kem768_sk),
+        }
+    }
+
+    pub fn encapsulation_keys_digests(&self) -> BTreeMap<KEM, KEMKeyDigests> {
+        let mut digests = BTreeMap::new();
+
+        let mlkem_digests = produce_key_digests(self.ml_kem768_pk.as_slice());
+        let mceliece_digests = produce_key_digests(self.mc_eliece_pk.as_ref().as_ref());
+
+        digests.insert(KEM::MlKem768, mlkem_digests);
+        digests.insert(KEM::McEliece, mceliece_digests);
+
+        digests
+    }
+
+    pub fn encoded_encapsulation_key(&self, kem: KEM) -> Option<&[u8]> {
+        match kem {
+            KEM::McEliece => Some(self.mc_eliece_pk.as_ref().as_ref()),
+            KEM::MlKem768 => Some(self.ml_kem768_pk.as_slice()),
+            // _ => None,
+        }
+    }
+
+    pub fn encapsulation_key(&self, kem: KEM) -> Option<EncapsulationKey> {
+        match kem {
+            KEM::McEliece => Some(EncapsulationKey::McEliece(self.mc_eliece_pk.clone())),
+            KEM::MlKem768 => Some(EncapsulationKey::MlKem768(self.ml_kem768_pk.clone())),
+            // _ => None,
+        }
+    }
+
+    pub fn mc_eliece_encapsulation_key(&self) -> &mceliece::PublicKey {
+        &self.mc_eliece_pk
+    }
+
+    pub fn ml_kem768_encapsulation_key(&self) -> &MlKem768PublicKey {
+        self.ml_kem768_pk.as_ref()
+    }
+
+    pub fn mc_eliece_decapsulation_key(&self) -> &mceliece::SecretKey {
+        &self.mc_eliece_sk
+    }
+
+    pub fn ml_kem768_decapsulation_key(&self) -> &MlKem768PrivateKey {
+        &self.ml_kem768_sk
+    }
+}
+
+#[derive(Clone)]
+pub enum EncapsulationKey {
+    McEliece(Arc<mceliece::PublicKey>),
+    MlKem768(Arc<MlKem768PublicKey>),
+}
+
+impl Debug for EncapsulationKey {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        match self {
+            EncapsulationKey::McEliece(_) => write!(f, "EncapsulationKey::McEliece"),
+            EncapsulationKey::MlKem768(_) => write!(f, "EncapsulationKey::MlKem768"),
+        }
+    }
+}
+
+impl EncapsulationKey {
+    pub fn kem(&self) -> KEM {
+        match self {
+            EncapsulationKey::McEliece(_) => KEM::McEliece,
+            EncapsulationKey::MlKem768(_) => KEM::MlKem768,
+        }
+    }
+
+    pub fn as_pq_encapsulation_key(&self) -> PQEncapsulationKey<'_> {
+        match self {
+            EncapsulationKey::McEliece(pk) => PQEncapsulationKey::CMC(pk),
+            EncapsulationKey::MlKem768(pk) => PQEncapsulationKey::MlKem(pk),
+        }
+    }
+
+    pub fn try_from_bytes(bytes: Vec<u8>, kem: KEM) -> Result<EncapsulationKey, KKTError> {
+        match kem {
+            KEM::MlKem768 => Ok(EncapsulationKey::MlKem768(Arc::new(
+                MlKem768PublicKey::try_from(bytes.as_slice()).map_err(|_| KKTError::KEMError {
+                    info: "mlkem768 key of invalid length",
+                })?,
+            ))),
+            KEM::McEliece => {
+                let boxed_array: Box<[u8; nym_kkt_ciphersuite::mceliece::PUBLIC_KEY_LENGTH]> =
+                    bytes
+                        .into_boxed_slice()
+                        .try_into()
+                        .map_err(|_| KKTError::KEMError {
+                            info: "mceliece key of invalid length",
+                        })?;
+
+                Ok(EncapsulationKey::McEliece(Arc::new(
+                    mceliece::PublicKey::from(boxed_array),
+                )))
+            }
+        }
+    }
+
+    pub fn as_bytes(&self) -> &[u8] {
+        match self {
+            EncapsulationKey::McEliece(k) => k.as_ref().as_ref(),
+            EncapsulationKey::MlKem768(k) => k.as_ref().as_ref(),
+        }
+    }
+}
+
+// storage helpers
+pub mod storage_wrappers {
+    use nym_pemstore::traits::PemStorableKey;
+    use thiserror::Error;
+
+    #[derive(Debug, Error)]
+    pub enum MalformedStoredKeyError {
+        #[error("{typ} stored key has an invalid length")]
+        InvalidKeyLength { typ: &'static str },
+
+        #[error("{typ} stored key is malformed: {message}")]
+        MalformedData { typ: &'static str, message: String },
+
+        #[error("attempted to take ownership of a stored {typ} key representation")]
+        IllegalStoredConversion { typ: &'static str },
+    }
+
+    pub trait StorableKey: Sized {
+        type StorableRepresentation<'a>: PemStorableKey
+            + From<&'a Self>
+            + TryInto<Self, Error = MalformedStoredKeyError>
+            + Sized
+        where
+            Self: 'a;
+
+        fn to_storable(&self) -> Self::StorableRepresentation<'_> {
+            self.into()
+        }
+
+        fn from_storable(
+            repr: Self::StorableRepresentation<'_>,
+        ) -> Result<Self, MalformedStoredKeyError> {
+            repr.try_into()
+        }
+    }
+
+    macro_rules! declare_key_wrappers {
+        ($pub_key_type:ty, $private_key_type:ty) => {
+            pub enum StorablePublicKey<'a> {
+                Owned(Box<$pub_key_type>),
+                Borrowed(&'a $pub_key_type),
+            }
+
+            impl AsRef<$pub_key_type> for StorablePublicKey<'_> {
+                fn as_ref(&self) -> &$pub_key_type {
+                    match self {
+                        StorablePublicKey::Owned(k) => k,
+                        StorablePublicKey::Borrowed(k) => k,
+                    }
+                }
+            }
+
+            pub enum StorablePrivateKey<'a> {
+                Owned(Box<$private_key_type>),
+                Borrowed(&'a $private_key_type),
+            }
+
+            impl AsRef<$private_key_type> for StorablePrivateKey<'_> {
+                fn as_ref(&self) -> &$private_key_type {
+                    match self {
+                        StorablePrivateKey::Owned(k) => k,
+                        StorablePrivateKey::Borrowed(k) => k,
+                    }
+                }
+            }
+
+            impl<'a> From<&'a $pub_key_type> for StorablePublicKey<'a> {
+                fn from(value: &'a $pub_key_type) -> Self {
+                    StorablePublicKey::Borrowed(value)
+                }
+            }
+
+            impl<'a> TryFrom<StorablePublicKey<'a>> for $pub_key_type {
+                type Error = MalformedStoredKeyError;
+
+                fn try_from(value: StorablePublicKey<'a>) -> Result<Self, Self::Error> {
+                    match value {
+                        StorablePublicKey::Owned(value) => Ok(*value),
+                        StorablePublicKey::Borrowed(_) => {
+                            Err(MalformedStoredKeyError::IllegalStoredConversion {
+                                typ: <StorablePublicKey as PemStorableKey>::pem_type(),
+                            })
+                        }
+                    }
+                }
+            }
+
+            impl<'a> From<&'a $private_key_type> for StorablePrivateKey<'a> {
+                fn from(value: &'a $private_key_type) -> Self {
+                    StorablePrivateKey::Borrowed(value)
+                }
+            }
+
+            impl<'a> TryFrom<StorablePrivateKey<'a>> for $private_key_type {
+                type Error = MalformedStoredKeyError;
+
+                fn try_from(value: StorablePrivateKey<'a>) -> Result<Self, Self::Error> {
+                    match value {
+                        StorablePrivateKey::Owned(value) => Ok(*value),
+                        StorablePrivateKey::Borrowed(_) => {
+                            Err(MalformedStoredKeyError::IllegalStoredConversion {
+                                typ: <StorablePrivateKey as PemStorableKey>::pem_type(),
+                            })
+                        }
+                    }
+                }
+            }
+
+            impl $crate::keys::storage_wrappers::StorableKey for $pub_key_type {
+                type StorableRepresentation<'a> = StorablePublicKey<'a>;
+            }
+
+            impl $crate::keys::storage_wrappers::StorableKey for $private_key_type {
+                type StorableRepresentation<'a> = StorablePrivateKey<'a>;
+            }
+        };
+    }
+
+    pub mod mceliece {
+        use crate::keys::storage_wrappers::MalformedStoredKeyError;
+        use libcrux_psq::classic_mceliece;
+        use nym_pemstore::traits::PemStorableKey;
+
+        declare_key_wrappers!(classic_mceliece::PublicKey, classic_mceliece::SecretKey);
+
+        impl<'a> PemStorableKey for StorablePrivateKey<'a> {
+            type Error = MalformedStoredKeyError;
+
+            fn pem_type() -> &'static str {
+                "MCELIECE PRIVATE KEY"
+            }
+
+            fn to_bytes(&self) -> Vec<u8> {
+                self.as_ref().as_ref().to_vec()
+            }
+
+            fn from_bytes(bytes: &[u8]) -> Result<Self, Self::Error> {
+                let bytes: Box<[u8; nym_kkt_ciphersuite::mceliece::SECRET_KEY_LENGTH]> =
+                    bytes.to_vec().into_boxed_slice().try_into().map_err(|_| {
+                        MalformedStoredKeyError::InvalidKeyLength {
+                            typ: Self::pem_type(),
+                        }
+                    })?;
+
+                Ok(StorablePrivateKey::Owned(Box::new(
+                    classic_mceliece::SecretKey::from(bytes),
+                )))
+            }
+        }
+
+        impl<'a> PemStorableKey for StorablePublicKey<'a> {
+            type Error = MalformedStoredKeyError;
+
+            fn pem_type() -> &'static str {
+                "MCELIECE PUBLIC KEY"
+            }
+
+            fn to_bytes(&self) -> Vec<u8> {
+                self.as_ref().as_ref().to_vec()
+            }
+
+            fn from_bytes(bytes: &[u8]) -> Result<Self, Self::Error> {
+                let bytes: Box<[u8; nym_kkt_ciphersuite::mceliece::PUBLIC_KEY_LENGTH]> =
+                    bytes.to_vec().into_boxed_slice().try_into().map_err(|_| {
+                        MalformedStoredKeyError::InvalidKeyLength {
+                            typ: Self::pem_type(),
+                        }
+                    })?;
+
+                Ok(StorablePublicKey::Owned(Box::new(
+                    classic_mceliece::PublicKey::from(bytes),
+                )))
+            }
+        }
+    }
+
+    pub mod mlkem768 {
+        use crate::keys::storage_wrappers::MalformedStoredKeyError;
+        use libcrux_ml_kem::mlkem768::{MlKem768PrivateKey, MlKem768PublicKey};
+        use nym_pemstore::traits::PemStorableKey;
+
+        declare_key_wrappers!(MlKem768PublicKey, MlKem768PrivateKey);
+
+        impl<'a> PemStorableKey for StorablePrivateKey<'a> {
+            type Error = MalformedStoredKeyError;
+
+            fn pem_type() -> &'static str {
+                "MLKEM768 PRIVATE KEY"
+            }
+
+            fn to_bytes(&self) -> Vec<u8> {
+                self.as_ref().as_slice().to_vec()
+            }
+
+            fn from_bytes(bytes: &[u8]) -> Result<Self, Self::Error> {
+                let inner = MlKem768PrivateKey::try_from(bytes).map_err(|message| {
+                    MalformedStoredKeyError::MalformedData {
+                        typ: Self::pem_type(),
+                        message: message.to_string(),
+                    }
+                })?;
+                Ok(StorablePrivateKey::Owned(Box::new(inner)))
+            }
+        }
+
+        impl<'a> PemStorableKey for StorablePublicKey<'a> {
+            type Error = MalformedStoredKeyError;
+
+            fn pem_type() -> &'static str {
+                "MLKEM768 PUBLIC KEY"
+            }
+
+            fn to_bytes(&self) -> Vec<u8> {
+                self.as_ref().as_slice().to_vec()
+            }
+
+            fn from_bytes(bytes: &[u8]) -> Result<Self, Self::Error> {
+                let inner = MlKem768PublicKey::try_from(bytes).map_err(|message| {
+                    MalformedStoredKeyError::MalformedData {
+                        typ: Self::pem_type(),
+                        message: message.to_string(),
+                    }
+                })?;
+                Ok(StorablePublicKey::Owned(Box::new(inner)))
+            }
+        }
+    }
+
+    pub mod x25519 {
+        use crate::keys::storage_wrappers::MalformedStoredKeyError;
+        use libcrux_psq::handshake::types::{DHPrivateKey, DHPublicKey};
+        use nym_pemstore::traits::PemStorableKey;
+
+        declare_key_wrappers!(DHPublicKey, DHPrivateKey);
+
+        impl<'a> PemStorableKey for StorablePrivateKey<'a> {
+            type Error = MalformedStoredKeyError;
+
+            fn pem_type() -> &'static str {
+                "LP X25519 PRIVATE KEY"
+            }
+
+            fn to_bytes(&self) -> Vec<u8> {
+                self.as_ref().as_ref().to_vec()
+            }
+
+            fn from_bytes(bytes: &[u8]) -> Result<Self, Self::Error> {
+                let bytes =
+                    bytes
+                        .try_into()
+                        .map_err(|_| MalformedStoredKeyError::InvalidKeyLength {
+                            typ: Self::pem_type(),
+                        })?;
+                Ok(StorablePrivateKey::Owned(Box::new(
+                    DHPrivateKey::from_bytes(&bytes).map_err(|err| {
+                        MalformedStoredKeyError::MalformedData {
+                            typ: Self::pem_type(),
+                            message: format!("{err:?}"),
+                        }
+                    })?,
+                )))
+            }
+        }
+
+        impl<'a> PemStorableKey for StorablePublicKey<'a> {
+            type Error = MalformedStoredKeyError;
+
+            fn pem_type() -> &'static str {
+                "LP X25519 PUBLIC KEY"
+            }
+
+            fn to_bytes(&self) -> Vec<u8> {
+                self.as_ref().as_ref().to_vec()
+            }
+
+            fn from_bytes(bytes: &[u8]) -> Result<Self, Self::Error> {
+                let bytes =
+                    bytes
+                        .try_into()
+                        .map_err(|_| MalformedStoredKeyError::InvalidKeyLength {
+                            typ: Self::pem_type(),
+                        })?;
+                Ok(StorablePublicKey::Owned(Box::new(DHPublicKey::from_bytes(
+                    &bytes,
+                ))))
+            }
+        }
+    }
+}

common/nym-kkt/src/kkt.rs

@@ -1,449 +0,0 @@
-// Copyright 2025 - Nym Technologies SA <contact@nymtech.net>
-// SPDX-License-Identifier: Apache-2.0
-
-//! Convenience wrappers around KKT protocol functions for easier integration.
-//!
-//! This module provides simplified APIs for the common use case of exchanging
-//! KEM public keys between a client (initiator) and gateway (responder).
-//!
-//! The underlying KKT protocol is implemented in the `session` module.
-
-use nym_crypto::asymmetric::{ed25519, x25519};
-use rand09::{CryptoRng, RngCore};
-
-use crate::{
-    ciphersuite::{Ciphersuite, EncapsulationKey},
-    context::{KKTContext, KKTMode},
-    encryption::{decrypt_initial_kkt_frame, decrypt_kkt_frame, encrypt_kkt_frame},
-    error::KKTError,
-};
-
-// Re-export core session functions for advanced use cases
-pub use crate::session::{
-    anonymous_initiator_process, initiator_ingest_response, initiator_process,
-    responder_ingest_message, responder_process,
-};
-
-use crate::encryption::{KKTSessionSecret, encrypt_initial_kkt_frame};
-use crate::frame::KKTFrame;
-
-/// Perform an *Encrypted* request for a KEM public key from a responder (OneWay mode).
-///
-/// This is the client-side operation that initiates a KKT exchange.
-/// The request will be signed with the provided signing key.
-///
-/// # Arguments
-/// * `rng` - random number generator
-/// * `ciphersuite` - Negotiated ciphersuite (KEM, hash, signature algorithms)
-/// * `signing_key` - Client's Ed25519 signing key for authentication
-/// * `responder_dh_public_key` - Responder's long-term x25519 Diffie-Hellman public key
-///
-/// # Returns
-/// * `KKTSessionSecret` - Session Secret Key to use when decrypting responses
-/// * `KKTContext` - Context to use when validating the response
-/// * `Vec<u8>` - Contains the client's ephemeral public key and encrypted and signed bytes to send to responder
-///
-/// # Example
-/// ```ignore
-/// let (session_secret, context, request_frame) = request_kem_key(
-///     &mut rng,
-///     ciphersuite,
-///     client_signing_key,
-///     responder_dh_public_key,
-/// )?;
-/// // Send request_frame to gateway
-/// ```
-pub fn request_kem_key<R: CryptoRng + RngCore>(
-    rng: &mut R,
-    ciphersuite: Ciphersuite,
-    signing_key: &ed25519::PrivateKey,
-    responder_dh_public_key: &x25519::PublicKey,
-) -> Result<(KKTSessionSecret, KKTContext, Vec<u8>), KKTError> {
-    // OneWay mode: client only wants responder's KEM key
-    // None: client doesn't send their own KEM key
-    let (initiator_context, initiator_frame) =
-        initiator_process(rng, KKTMode::OneWay, ciphersuite, signing_key, None)?;
-
-    // Generate the session's shared secret and encrypt the Initiator's request
-    let (session_secret, encrypted_request_bytes) =
-        encrypt_initial_kkt_frame(rng, responder_dh_public_key, &initiator_frame)?;
-
-    Ok((session_secret, initiator_context, encrypted_request_bytes))
-}
-
-/// Decrypt, validate an *Encrypted* KKT response and extract the responder's KEM public key.
-///
-/// This is the client-side operation that processes the gateway's response.
-/// It verifies the signature and validates the key hash against the expected value
-/// (typically retrieved from a directory service).
-///
-/// # Arguments
-/// * `context` - Context from the initial request
-/// * `session_secret` - Session Secret Key (generated with request)
-/// * `responder_vk` - Responder's Ed25519 verification key (from directory)
-/// * `expected_key_hash` - Expected hash of responder's KEM key (from directory)
-/// * `response_bytes` - Serialized response frame from responder
-///
-/// # Returns
-/// * `EncapsulationKey` - Authenticated KEM public key of the responder
-///
-/// # Example
-/// ```ignore
-/// let gateway_kem_key = validate_kem_response(
-///     &context,
-///     &session_secret,
-///     &gateway_verification_key,
-///     &expected_hash_from_directory,
-///     &response_bytes,
-/// )?;
-/// // Use gateway_kem_key for PSQ
-/// ```
-pub fn validate_kem_response<'a>(
-    context: &mut KKTContext,
-    session_secret: &KKTSessionSecret,
-    responder_vk: &ed25519::PublicKey,
-    expected_key_hash: &[u8],
-    encrypted_response_bytes: &[u8],
-) -> Result<EncapsulationKey<'a>, KKTError> {
-    let (responder_frame, responder_context) =
-        decrypt_kkt_response_frame(session_secret, encrypted_response_bytes)?;
-
-    initiator_ingest_response(
-        context,
-        &responder_frame,
-        &responder_context,
-        responder_vk,
-        expected_key_hash,
-    )
-}
-
-/// Decrypts and validates an *Encrypted* KKT response
-///
-/// This is the client-side operation that processes the gateway's response.
-pub fn decrypt_kkt_response_frame(
-    session_secret: &KKTSessionSecret,
-    frame_ciphertext: &[u8],
-) -> Result<(KKTFrame, KKTContext), KKTError> {
-    decrypt_kkt_frame(session_secret, frame_ciphertext, KKT_RESPONSE_AAD)
-}
-
-/// Handle an *Encrypted* KKT request and generate a signed response with the responder's KEM key.
-///
-/// This is the gateway-side operation that processes a client's KKT request.
-/// It validates the request signature (if authenticated) and responds with
-/// the gateway's KEM public key, signed for authenticity.
-///
-/// # Arguments
-/// * `encrypted_request_bytes` - encrypted KEM request
-/// * `initiator_vk` - Initiator's Ed25519 verification key (None for anonymous)
-/// * `responder_signing_key` - Gateway's Ed25519 signing key
-/// * `responder_dh_public_key` - Gateway's long-term x25519 Diffie-Hellman private key
-/// * `responder_kem_key` - Gateway's KEM public key to send
-///
-/// # Returns
-/// * `KKTFrame` - Signed response frame containing the KEM public key
-///
-/// # Example
-/// ```ignore
-/// let response_frame = handle_kem_request(
-///     &request_frame,
-///     Some(client_verification_key),  // or None for anonymous
-///     gateway_signing_key,
-///     &gateway_kem_public_key,
-/// )?;
-/// // Send response_frame back to client
-/// ```
-pub fn handle_kem_request<'a, R>(
-    rng: &mut R,
-    encrypted_request_bytes: &[u8],
-    initiator_vk: Option<&ed25519::PublicKey>,
-    responder_signing_key: &ed25519::PrivateKey,
-    responder_dh_private_key: &x25519::PrivateKey,
-    responder_kem_key: &EncapsulationKey<'a>,
-) -> Result<Vec<u8>, KKTError>
-where
-    R: RngCore + CryptoRng,
-{
-    // Compute the session's shared secret, decrypt and parse context from the request frame
-
-    let (session_secret, request_frame, initiator_context) =
-        decrypt_initial_kkt_frame(responder_dh_private_key, encrypted_request_bytes)?;
-
-    // Validate the request (verifies signature if initiator_vk provided)
-    let (mut response_context, _) = responder_ingest_message(
-        &initiator_context,
-        initiator_vk,
-        None, // Not checking initiator's KEM key in OneWay mode
-        &request_frame,
-    )?;
-
-    // Generate signed response with our KEM public key
-    let responder_frame = responder_process(
-        &mut response_context,
-        request_frame.session_id(),
-        responder_signing_key,
-        responder_kem_key,
-    )?;
-
-    // Encrypt the responder's response with the session's shared secret
-    encrypt_kkt_frame(rng, &session_secret, &responder_frame, KKT_RESPONSE_AAD)
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use crate::{
-        ciphersuite::{HashFunction, KEM, SignatureScheme},
-        key_utils::{generate_keypair_libcrux, hash_encapsulation_key},
-    };
-
-    fn random_x25519_key() -> x25519::PrivateKey {
-        let mut bytes = [0u8; 32];
-        let mut rng = rand09::rng();
-        rng.fill_bytes(&mut bytes);
-        x25519::PrivateKey::from_secret(bytes)
-    }
-
-    #[test]
-    fn test_kkt_wrappers_oneway_authenticated() {
-        let mut rng = rand09::rng();
-
-        // Generate Ed25519 keypairs for both parties
-        let mut initiator_secret = [0u8; 32];
-        rng.fill_bytes(&mut initiator_secret);
-        let ed25519_init = ed25519::KeyPair::from_secret(initiator_secret, 0);
-
-        let mut responder_secret = [0u8; 32];
-        rng.fill_bytes(&mut responder_secret);
-        let ed25519_resp = ed25519::KeyPair::from_secret(responder_secret, 1);
-
-        let x25519_resp_priv = random_x25519_key();
-        let x25519_resp_pub = x25519::PublicKey::from(&x25519_resp_priv);
-
-        // Generate responder's KEM keypair (X25519 for testing)
-        let (_, responder_kem_pk) = generate_keypair_libcrux(&mut rng, KEM::X25519).unwrap();
-        let responder_kem_key = EncapsulationKey::X25519(responder_kem_pk);
-
-        // Create ciphersuite
-        let ciphersuite = Ciphersuite::resolve_ciphersuite(
-            KEM::X25519,
-            HashFunction::Blake3,
-            SignatureScheme::Ed25519,
-            None,
-        )
-        .unwrap();
-
-        // Hash the KEM key (simulating directory storage)
-        let key_hash = hash_encapsulation_key(
-            &ciphersuite.hash_function(),
-            ciphersuite.hash_len(),
-            &responder_kem_key.encode(),
-        );
-
-        // Client: Request KEM key
-        let (session_key, context, request_frame_ciphertext) = request_kem_key(
-            &mut rng,
-            ciphersuite,
-            ed25519_init.private_key(),
-            &x25519_resp_pub,
-        )
-        .unwrap();
-
-        // Gateway: Handle request
-        let response_frame_ciphertext = handle_kem_request(
-            &mut rng,
-            &request_frame_ciphertext,
-            Some(ed25519_init.public_key()), // Authenticated
-            ed25519_resp.private_key(),
-            &x25519_resp_priv,
-            &responder_kem_key,
-        )
-        .unwrap();
-
-        // Client: Validate response
-        let obtained_key = validate_kem_response(
-            &context,
-            &session_key,
-            ed25519_resp.public_key(),
-            &key_hash,
-            &response_frame_ciphertext,
-        )
-        .unwrap();
-
-        // Verify we got the correct KEM key
-        assert_eq!(obtained_key.encode(), responder_kem_key.encode());
-    }
-
-    #[test]
-    fn test_kkt_wrappers_anonymous() {
-        let mut rng = rand09::rng();
-
-        // Only responder has keys
-        let mut responder_secret = [0u8; 32];
-        rng.fill_bytes(&mut responder_secret);
-        let responder_keypair = ed25519::KeyPair::from_secret(responder_secret, 1);
-
-        let (_, responder_kem_pk) = generate_keypair_libcrux(&mut rng, KEM::X25519).unwrap();
-        let responder_kem_key = EncapsulationKey::X25519(responder_kem_pk);
-
-        let x25519_resp_priv = random_x25519_key();
-        let x25519_resp_pub = x25519::PublicKey::from(&x25519_resp_priv);
-
-        let ciphersuite = Ciphersuite::resolve_ciphersuite(
-            KEM::X25519,
-            HashFunction::Blake3,
-            SignatureScheme::Ed25519,
-            None,
-        )
-        .unwrap();
-
-        let key_hash = hash_encapsulation_key(
-            &ciphersuite.hash_function(),
-            ciphersuite.hash_len(),
-            &responder_kem_key.encode(),
-        );
-
-        // Anonymous initiator
-        let (context, request_frame) = anonymous_initiator_process(&mut rng, ciphersuite).unwrap();
-
-        // Generate the session's shared secret and encrypt the Initiator's request
-        let (session_secret, encrypted_request_bytes) =
-            encrypt_initial_kkt_frame(&mut rng, &x25519_resp_pub, &request_frame).unwrap();
-
-        // Gateway: Handle anonymous request
-        let response_frame = handle_kem_request(
-            &mut rng,
-            &encrypted_request_bytes,
-            None, // Anonymous - no verification key
-            responder_keypair.private_key(),
-            &x25519_resp_priv,
-            &responder_kem_key,
-        )
-        .unwrap();
-
-        // Initiator: Validate response
-        let obtained_key = validate_kem_response(
-            &context,
-            &session_secret,
-            responder_keypair.public_key(),
-            &key_hash,
-            &response_frame,
-        )
-        .unwrap();
-
-        assert_eq!(obtained_key.encode(), responder_kem_key.encode());
-    }
-
-    #[test]
-    fn test_invalid_signature_rejected() {
-        let mut rng = rand09::rng();
-
-        let mut initiator_secret = [0u8; 32];
-        rng.fill_bytes(&mut initiator_secret);
-        let initiator_keypair = ed25519::KeyPair::from_secret(initiator_secret, 0);
-
-        let mut responder_secret = [0u8; 32];
-        rng.fill_bytes(&mut responder_secret);
-        let responder_keypair = ed25519::KeyPair::from_secret(responder_secret, 1);
-
-        let x25519_resp_priv = random_x25519_key();
-        let x25519_resp_pub = x25519::PublicKey::from(&x25519_resp_priv);
-
-        // Different keypair for wrong signature
-        let mut wrong_secret = [0u8; 32];
-        rng.fill_bytes(&mut wrong_secret);
-        let wrong_keypair = ed25519::KeyPair::from_secret(wrong_secret, 2);
-
-        let (_, responder_kem_pk) = generate_keypair_libcrux(&mut rng, KEM::X25519).unwrap();
-        let responder_kem_key = EncapsulationKey::X25519(responder_kem_pk);
-
-        let ciphersuite = Ciphersuite::resolve_ciphersuite(
-            KEM::X25519,
-            HashFunction::Blake3,
-            SignatureScheme::Ed25519,
-            None,
-        )
-        .unwrap();
-
-        let (_session_key, _context, request_frame_ciphertext) = request_kem_key(
-            &mut rng,
-            ciphersuite,
-            initiator_keypair.private_key(),
-            &x25519_resp_pub,
-        )
-        .unwrap();
-
-        // Gateway handles request but we provide WRONG verification key
-        let result = handle_kem_request(
-            &mut rng,
-            &request_frame_ciphertext,
-            Some(wrong_keypair.public_key()), // Wrong key!
-            responder_keypair.private_key(),
-            &x25519_resp_priv,
-            &responder_kem_key,
-        );
-
-        // Should fail signature verification
-        assert!(result.is_err());
-    }
-
-    #[test]
-    fn test_hash_mismatch_rejected() {
-        let mut rng = rand09::rng();
-
-        let mut initiator_secret = [0u8; 32];
-        rng.fill_bytes(&mut initiator_secret);
-        let initiator_keypair = ed25519::KeyPair::from_secret(initiator_secret, 0);
-
-        let mut responder_secret = [0u8; 32];
-        rng.fill_bytes(&mut responder_secret);
-        let responder_keypair = ed25519::KeyPair::from_secret(responder_secret, 1);
-
-        let x25519_resp_priv = random_x25519_key();
-        let x25519_resp_pub = x25519::PublicKey::from(&x25519_resp_priv);
-
-        let (_, responder_kem_pk) = generate_keypair_libcrux(&mut rng, KEM::X25519).unwrap();
-        let responder_kem_key = EncapsulationKey::X25519(responder_kem_pk);
-
-        let ciphersuite = Ciphersuite::resolve_ciphersuite(
-            KEM::X25519,
-            HashFunction::Blake3,
-            SignatureScheme::Ed25519,
-            None,
-        )
-        .unwrap();
-
-        // Use WRONG hash
-        let wrong_hash = [0u8; 32];
-
-        let (session_key, context, request_frame) = request_kem_key(
-            &mut rng,
-            ciphersuite,
-            initiator_keypair.private_key(),
-            &x25519_resp_pub,
-        )
-        .unwrap();
-
-        let response_frame = handle_kem_request(
-            &mut rng,
-            &request_frame,
-            Some(initiator_keypair.public_key()),
-            responder_keypair.private_key(),
-            &x25519_resp_priv,
-            &responder_kem_key,
-        )
-        .unwrap();
-
-        // Client validates with WRONG hash
-        let result = validate_kem_response(
-            &context,
-            &session_key,
-            responder_keypair.public_key(),
-            &wrong_hash, // Wrong!
-            &response_frame,
-        );
-
-        // Should fail hash validation
-        assert!(result.is_err());
-    }
-}

common/nym-kkt/src/lib.rs

@@ -1,498 +1,230 @@
 // Copyright 2025 - Nym Technologies SA <contact@nymtech.net>
 // SPDX-License-Identifier: Apache-2.0
 
-pub mod ciphersuite;
-pub mod context;
-pub mod encryption;
+pub mod carrier;
 pub mod error;
 pub mod frame;
+pub mod initiator;
 pub mod key_utils;
-// pub mod kkt;
-pub mod session;
+pub mod keys;
+pub mod masked_byte;
+pub mod message;
+pub mod rekey;
+pub mod responder;
 
-// This must be less than 4 bits
-pub const KKT_VERSION: u8 = 1;
-const _: () = assert!(KKT_VERSION < 1 << 4);
-pub const KKT_RESPONSE_AAD: &[u8] = b"KKT_Response";
-pub(crate) const KKT_INITIAL_FRAME_AAD: &[u8] = b"KKT_INITIAL_FRAME";
+pub use nym_kkt_context as context;
 
 #[cfg(test)]
 mod test {
+    use nym_kkt_ciphersuite::{Ciphersuite, HashFunction, HashLength, KEM, SignatureScheme};
+    use rand09::RngCore;
+
+    use crate::keys::KEMKeys;
     use crate::{
-        KKT_RESPONSE_AAD,
-        ciphersuite::{Ciphersuite, EncapsulationKey, HashFunction, KEM},
-        encryption::{
-            decrypt_initial_kkt_frame, decrypt_kkt_frame, encrypt_initial_kkt_frame,
-            encrypt_kkt_frame,
-        },
-        frame::KKTFrame,
+        initiator::KKTInitiator,
         key_utils::{
-            generate_keypair_ed25519, generate_keypair_libcrux, generate_keypair_mceliece,
-            generate_keypair_x25519, hash_encapsulation_key,
-        },
-        session::{
-            anonymous_initiator_process, initiator_ingest_response, initiator_process,
-            responder_ingest_message, responder_process,
+            generate_keypair_mceliece, generate_keypair_mlkem, generate_lp_keypair_x25519,
+            hash_encapsulation_key,
         },
+        responder::KKTResponder,
     };
 
     #[test]
-    fn test_kkt_psq_e2e_clear() {
+    fn test_kkt_psq_e2e_encrypted_carrier() {
         let mut rng = rand09::rng();
 
-        // generate ed25519 keys
-        let initiator_ed25519_keypair = generate_keypair_ed25519(&mut rng, Some(0));
-        let responder_ed25519_keypair = generate_keypair_ed25519(&mut rng, Some(1));
-
-        for kem in [KEM::MlKem768, KEM::XWing, KEM::X25519, KEM::McEliece] {
-            for hash_function in [
-                HashFunction::Blake3,
-                HashFunction::SHA256,
-                HashFunction::Shake128,
-                HashFunction::Shake256,
-            ] {
-                let ciphersuite = Ciphersuite::resolve_ciphersuite(
-                    kem,
-                    hash_function,
-                    crate::ciphersuite::SignatureScheme::Ed25519,
-                    None,
-                )
-                .unwrap();
-
-                // generate kem public keys
-
-                let (responder_kem_public_key, initiator_kem_public_key) = match kem {
-                    KEM::MlKem768 => (
-                        EncapsulationKey::MlKem768(
-                            generate_keypair_libcrux(&mut rng, kem).unwrap().1,
-                        ),
-                        EncapsulationKey::MlKem768(
-                            generate_keypair_libcrux(&mut rng, kem).unwrap().1,
-                        ),
-                    ),
-                    KEM::XWing => (
-                        EncapsulationKey::XWing(generate_keypair_libcrux(&mut rng, kem).unwrap().1),
-                        EncapsulationKey::XWing(generate_keypair_libcrux(&mut rng, kem).unwrap().1),
-                    ),
-                    KEM::X25519 => (
-                        EncapsulationKey::X25519(
-                            generate_keypair_libcrux(&mut rng, kem).unwrap().1,
-                        ),
-                        EncapsulationKey::X25519(
-                            generate_keypair_libcrux(&mut rng, kem).unwrap().1,
-                        ),
-                    ),
-                    KEM::McEliece => (
-                        EncapsulationKey::McEliece(generate_keypair_mceliece(&mut rng).1),
-                        EncapsulationKey::McEliece(generate_keypair_mceliece(&mut rng).1),
-                    ),
-                };
-
-                let i_kem_key_bytes = initiator_kem_public_key.encode();
-
-                let r_kem_key_bytes = responder_kem_public_key.encode();
-
-                let i_dir_hash = hash_encapsulation_key(
-                    &ciphersuite.hash_function(),
-                    ciphersuite.hash_len(),
-                    &i_kem_key_bytes,
-                );
-
-                let r_dir_hash = hash_encapsulation_key(
-                    &ciphersuite.hash_function(),
-                    ciphersuite.hash_len(),
-                    &r_kem_key_bytes,
-                );
-
-                // Anonymous Initiator, OneWay
-                {
-                    let (i_context, i_frame) =
-                        anonymous_initiator_process(&mut rng, ciphersuite).unwrap();
-
-                    let i_frame_bytes = i_frame.to_bytes();
-
-                    let (i_frame_r, r_context) = KKTFrame::from_bytes(&i_frame_bytes).unwrap();
-
-                    let (r_context, _) =
-                        responder_ingest_message(&r_context, None, None, &i_frame_r).unwrap();
-
-                    let r_frame = responder_process(
-                        &r_context,
-                        i_frame_r.session_id(),
-                        responder_ed25519_keypair.private_key(),
-                        &responder_kem_public_key,
-                    )
-                    .unwrap();
-
-                    let r_bytes = r_frame.to_bytes();
-
-                    let (i_frame_r, i_context_r) = KKTFrame::from_bytes(&r_bytes).unwrap();
-
-                    let i_obtained_key = initiator_ingest_response(
-                        &i_context,
-                        &i_frame_r,
-                        &i_context_r,
-                        responder_ed25519_keypair.public_key(),
-                        &r_dir_hash,
-                    )
-                    .unwrap();
-
-                    assert_eq!(i_obtained_key.encode(), r_kem_key_bytes)
-                }
-                // Initiator, OneWay
-                {
-                    let (i_context, i_frame) = initiator_process(
-                        &mut rng,
-                        crate::context::KKTMode::OneWay,
-                        ciphersuite,
-                        initiator_ed25519_keypair.private_key(),
-                        None,
-                    )
-                    .unwrap();
-
-                    let i_frame_bytes = i_frame.to_bytes();
-
-                    let (i_frame_r, r_context) = KKTFrame::from_bytes(&i_frame_bytes).unwrap();
-
-                    let (r_context, r_obtained_key) = responder_ingest_message(
-                        &r_context,
-                        Some(initiator_ed25519_keypair.public_key()),
-                        None,
-                        &i_frame_r,
-                    )
-                    .unwrap();
-
-                    assert!(r_obtained_key.is_none());
-
-                    let r_frame = responder_process(
-                        &r_context,
-                        i_frame_r.session_id(),
-                        responder_ed25519_keypair.private_key(),
-                        &responder_kem_public_key,
-                    )
-                    .unwrap();
-
-                    let r_bytes = r_frame.to_bytes();
-
-                    let (i_frame_r, i_context_r) = KKTFrame::from_bytes(&r_bytes).unwrap();
-
-                    let i_obtained_key = initiator_ingest_response(
-                        &i_context,
-                        &i_frame_r,
-                        &i_context_r,
-                        responder_ed25519_keypair.public_key(),
-                        &r_dir_hash,
-                    )
-                    .unwrap();
-
-                    assert_eq!(i_obtained_key.encode(), r_kem_key_bytes)
-                }
-
-                // Initiator, Mutual
-                {
-                    let (i_context, i_frame) = initiator_process(
-                        &mut rng,
-                        crate::context::KKTMode::Mutual,
-                        ciphersuite,
-                        initiator_ed25519_keypair.private_key(),
-                        Some(&initiator_kem_public_key),
-                    )
-                    .unwrap();
-
-                    let i_frame_bytes = i_frame.to_bytes();
-
-                    let (i_frame_r, r_context) = KKTFrame::from_bytes(&i_frame_bytes).unwrap();
-
-                    let (r_context, r_obtained_key) = responder_ingest_message(
-                        &r_context,
-                        Some(initiator_ed25519_keypair.public_key()),
-                        Some(&i_dir_hash),
-                        &i_frame_r,
-                    )
-                    .unwrap();
-
-                    assert_eq!(r_obtained_key.unwrap().encode(), i_kem_key_bytes);
-
-                    let r_frame = responder_process(
-                        &r_context,
-                        i_frame_r.session_id(),
-                        responder_ed25519_keypair.private_key(),
-                        &responder_kem_public_key,
-                    )
-                    .unwrap();
-
-                    let r_bytes = r_frame.to_bytes();
-
-                    let (i_frame_r, i_context_r) = KKTFrame::from_bytes(&r_bytes).unwrap();
-
-                    let i_obtained_key = initiator_ingest_response(
-                        &i_context,
-                        &i_frame_r,
-                        &i_context_r,
-                        responder_ed25519_keypair.public_key(),
-                        &r_dir_hash,
-                    )
-                    .unwrap();
-
-                    assert_eq!(i_obtained_key.encode(), r_kem_key_bytes)
-                }
-            }
-        }
-    }
-    #[test]
-    fn test_kkt_psq_e2e_encrypted() {
-        let mut rng = rand09::rng();
-
-        // generate ed25519 keys
-        let initiator_ed25519_keypair = generate_keypair_ed25519(&mut rng, Some(0));
-        let responder_ed25519_keypair = generate_keypair_ed25519(&mut rng, Some(1));
+        let mut payload: Vec<u8> = vec![0u8; 900_000];
+        rng.fill_bytes(&mut payload);
 
         // generate responder x25519 keys
-        let responder_x25519_keypair = generate_keypair_x25519(&mut rng);
+        let responder_x25519_keypair = generate_lp_keypair_x25519(&mut rng);
 
-        for kem in [KEM::MlKem768, KEM::XWing, KEM::X25519, KEM::McEliece] {
-            for hash_function in [
-                HashFunction::Blake3,
-                HashFunction::SHA256,
-                HashFunction::Shake128,
-                HashFunction::Shake256,
-            ] {
+        for hash_function in [
+            HashFunction::Blake3,
+            HashFunction::SHA256,
+            HashFunction::Shake128,
+            HashFunction::Shake256,
+        ] {
+            // generate kem public keys
+
+            let responder_mlkem_keypair = generate_keypair_mlkem(&mut rng);
+            let responder_mceliece_keypair = generate_keypair_mceliece(&mut rng);
+
+            let responder_kem = KEMKeys::new(responder_mceliece_keypair, responder_mlkem_keypair);
+
+            let r_dir_hash_mlkem = hash_encapsulation_key(
+                hash_function,
+                HashLength::Default.value(),
+                responder_kem.ml_kem768_encapsulation_key().as_slice(),
+            );
+
+            let r_dir_hash_mceliece = hash_encapsulation_key(
+                hash_function,
+                HashLength::Default.value(),
+                responder_kem.mc_eliece_encapsulation_key().as_ref(),
+            );
+            let initiator_mlkem_keypair = generate_keypair_mlkem(&mut rng);
+            let initiator_mceliece_keypair = generate_keypair_mceliece(&mut rng);
+
+            let _i_dir_hash_mlkem = hash_encapsulation_key(
+                hash_function,
+                HashLength::Default.value(),
+                initiator_mlkem_keypair.public_key().as_slice(),
+            );
+
+            let _i_dir_hash_mceliece = hash_encapsulation_key(
+                hash_function,
+                HashLength::Default.value(),
+                initiator_mceliece_keypair.pk.as_ref(),
+            );
+
+            let responder = KKTResponder::new(
+                &responder_x25519_keypair,
+                &responder_kem,
+                &[
+                    HashFunction::Blake3,
+                    HashFunction::SHA256,
+                    HashFunction::Shake128,
+                    HashFunction::Shake256,
+                ],
+                &[SignatureScheme::Ed25519],
+                &[1],
+            )
+            .unwrap();
+
+            // OneWay - MlKem
+            {
                 let ciphersuite = Ciphersuite::resolve_ciphersuite(
-                    kem,
+                    KEM::MlKem768,
                     hash_function,
-                    crate::ciphersuite::SignatureScheme::Ed25519,
+                    SignatureScheme::Ed25519,
                     None,
                 )
                 .unwrap();
+                let (mut initiator, request) = KKTInitiator::generate_one_way_request(
+                    &mut rng,
+                    ciphersuite,
+                    &responder_x25519_keypair.pk,
+                    &r_dir_hash_mlkem,
+                    1u8,
+                    Some(payload.clone()),
+                )
+                .unwrap();
 
-                // generate kem public keys
+                let processed_request = responder.process_request(request, payload.len()).unwrap();
 
-                let (responder_kem_public_key, initiator_kem_public_key) = match kem {
-                    KEM::MlKem768 => (
-                        EncapsulationKey::MlKem768(
-                            generate_keypair_libcrux(&mut rng, kem).unwrap().1,
-                        ),
-                        EncapsulationKey::MlKem768(
-                            generate_keypair_libcrux(&mut rng, kem).unwrap().1,
-                        ),
-                    ),
-                    KEM::XWing => (
-                        EncapsulationKey::XWing(generate_keypair_libcrux(&mut rng, kem).unwrap().1),
-                        EncapsulationKey::XWing(generate_keypair_libcrux(&mut rng, kem).unwrap().1),
-                    ),
-                    KEM::X25519 => (
-                        EncapsulationKey::X25519(
-                            generate_keypair_libcrux(&mut rng, kem).unwrap().1,
-                        ),
-                        EncapsulationKey::X25519(
-                            generate_keypair_libcrux(&mut rng, kem).unwrap().1,
-                        ),
-                    ),
-                    KEM::McEliece => (
-                        EncapsulationKey::McEliece(generate_keypair_mceliece(&mut rng).1),
-                        EncapsulationKey::McEliece(generate_keypair_mceliece(&mut rng).1),
-                    ),
-                };
+                assert_eq!(processed_request.request_payload, payload);
 
-                let i_kem_key_bytes = initiator_kem_public_key.encode();
-
-                let r_kem_key_bytes = responder_kem_public_key.encode();
-
-                let i_dir_hash = hash_encapsulation_key(
-                    &ciphersuite.hash_function(),
-                    ciphersuite.hash_len(),
-                    &i_kem_key_bytes,
-                );
-
-                let r_dir_hash = hash_encapsulation_key(
-                    &ciphersuite.hash_function(),
-                    ciphersuite.hash_len(),
-                    &r_kem_key_bytes,
-                );
-
-                // Anonymous Initiator, OneWay
-                {
-                    let (i_context, i_frame) =
-                        anonymous_initiator_process(&mut rng, ciphersuite).unwrap();
-
-                    // encryption - initiator frame
-
-                    let (i_session_secret, i_bytes) = encrypt_initial_kkt_frame(
-                        &mut rng,
-                        responder_x25519_keypair.public_key(),
-                        &i_frame,
-                    )
+                let result = initiator
+                    .process_response(processed_request.response, 0)
                     .unwrap();
 
-                    // decryption - initiator frame
+                assert_eq!(
+                    result.encapsulation_key.as_bytes(),
+                    responder_kem.ml_kem768_encapsulation_key().as_slice(),
+                )
+            }
+            // Mutual - MlKem
+            {
+                let ciphersuite = Ciphersuite::resolve_ciphersuite(
+                    KEM::MlKem768,
+                    hash_function,
+                    SignatureScheme::Ed25519,
+                    None,
+                )
+                .unwrap();
+                let (mut initiator, request) = KKTInitiator::generate_one_way_request(
+                    &mut rng,
+                    ciphersuite,
+                    &responder_x25519_keypair.pk,
+                    &r_dir_hash_mlkem,
+                    1u8,
+                    Some(payload.clone()),
+                )
+                .unwrap();
 
-                    let (r_session_secret, i_frame_r, i_context_r) =
-                        decrypt_initial_kkt_frame(responder_x25519_keypair.private_key(), &i_bytes)
-                            .unwrap();
+                let processed_request = responder.process_request(request, payload.len()).unwrap();
 
-                    let (r_context, _) =
-                        responder_ingest_message(&i_context_r, None, None, &i_frame_r).unwrap();
+                assert_eq!(processed_request.request_payload, payload);
 
-                    let r_frame = responder_process(
-                        &r_context,
-                        i_frame_r.session_id(),
-                        responder_ed25519_keypair.private_key(),
-                        &responder_kem_public_key,
-                    )
+                // if we keep unverified keys, this should change
+                assert!(processed_request.remote_encapsulation_key.is_none());
+
+                let processed_response = initiator
+                    .process_response(processed_request.response, 0)
                     .unwrap();
 
-                    // encryption - responder frame
-                    let r_bytes =
-                        encrypt_kkt_frame(&mut rng, &r_session_secret, &r_frame, KKT_RESPONSE_AAD)
-                            .unwrap();
+                assert_eq!(
+                    processed_response.encapsulation_key.as_bytes(),
+                    responder_kem.ml_kem768_encapsulation_key().as_slice(),
+                )
+            }
 
-                    // decryption - responder frame
+            // OneWay - McEliece
+            {
+                let ciphersuite = Ciphersuite::resolve_ciphersuite(
+                    KEM::McEliece,
+                    hash_function,
+                    SignatureScheme::Ed25519,
+                    None,
+                )
+                .unwrap();
+                let (mut initiator, request) = KKTInitiator::generate_one_way_request(
+                    &mut rng,
+                    ciphersuite,
+                    &responder_x25519_keypair.pk,
+                    &r_dir_hash_mceliece,
+                    1u8,
+                    Some(payload.clone()),
+                )
+                .unwrap();
 
-                    let (i_frame_r, i_context_r) =
-                        decrypt_kkt_frame(&i_session_secret, &r_bytes, KKT_RESPONSE_AAD).unwrap();
+                let processed_request = responder.process_request(request, payload.len()).unwrap();
+                assert_eq!(processed_request.request_payload, payload);
 
-                    let i_obtained_key = initiator_ingest_response(
-                        &i_context,
-                        &i_frame_r,
-                        &i_context_r,
-                        responder_ed25519_keypair.public_key(),
-                        &r_dir_hash,
-                    )
+                let processed_response = initiator
+                    .process_response(processed_request.response, 0)
                     .unwrap();
 
-                    assert_eq!(i_obtained_key.encode(), r_kem_key_bytes)
-                }
-                // Initiator, OneWay
-                {
-                    let (i_context, i_frame) = initiator_process(
-                        &mut rng,
-                        crate::context::KKTMode::OneWay,
-                        ciphersuite,
-                        initiator_ed25519_keypair.private_key(),
-                        None,
-                    )
+                assert_eq!(
+                    processed_response.encapsulation_key.as_bytes(),
+                    responder_kem.mc_eliece_encapsulation_key().as_ref()
+                )
+            }
+            // Mutual - MlKem
+            {
+                let ciphersuite = Ciphersuite::resolve_ciphersuite(
+                    KEM::McEliece,
+                    hash_function,
+                    SignatureScheme::Ed25519,
+                    None,
+                )
+                .unwrap();
+                let (mut initiator, request) = KKTInitiator::generate_one_way_request(
+                    &mut rng,
+                    ciphersuite,
+                    &responder_x25519_keypair.pk,
+                    &r_dir_hash_mceliece,
+                    1u8,
+                    Some(payload.clone()),
+                )
+                .unwrap();
+
+                let processed_request = responder.process_request(request, payload.len()).unwrap();
+
+                assert_eq!(processed_request.request_payload, payload);
+
+                // if we keep unverified keys, this should change
+                assert!(processed_request.remote_encapsulation_key.is_none());
+
+                let processed_response = initiator
+                    .process_response(processed_request.response, 0)
                     .unwrap();
 
-                    // encryption - initiator frame
-
-                    let (i_session_secret, i_bytes) = encrypt_initial_kkt_frame(
-                        &mut rng,
-                        responder_x25519_keypair.public_key(),
-                        &i_frame,
-                    )
-                    .unwrap();
-
-                    // decryption - initiator frame
-
-                    let (r_session_secret, i_frame_r, r_context) =
-                        decrypt_initial_kkt_frame(responder_x25519_keypair.private_key(), &i_bytes)
-                            .unwrap();
-
-                    let (r_context, r_obtained_key) = responder_ingest_message(
-                        &r_context,
-                        Some(initiator_ed25519_keypair.public_key()),
-                        None,
-                        &i_frame_r,
-                    )
-                    .unwrap();
-
-                    assert!(r_obtained_key.is_none());
-
-                    let r_frame = responder_process(
-                        &r_context,
-                        i_frame_r.session_id(),
-                        responder_ed25519_keypair.private_key(),
-                        &responder_kem_public_key,
-                    )
-                    .unwrap();
-
-                    // encryption - responder frame
-                    let r_bytes =
-                        encrypt_kkt_frame(&mut rng, &r_session_secret, &r_frame, KKT_RESPONSE_AAD)
-                            .unwrap();
-
-                    // decryption - responder frame
-
-                    let (i_frame_r, i_context_r) =
-                        decrypt_kkt_frame(&i_session_secret, &r_bytes, KKT_RESPONSE_AAD).unwrap();
-
-                    let i_obtained_key = initiator_ingest_response(
-                        &i_context,
-                        &i_frame_r,
-                        &i_context_r,
-                        responder_ed25519_keypair.public_key(),
-                        &r_dir_hash,
-                    )
-                    .unwrap();
-
-                    assert_eq!(i_obtained_key.encode(), r_kem_key_bytes)
-                }
-
-                // Initiator, Mutual
-                {
-                    let (i_context, i_frame) = initiator_process(
-                        &mut rng,
-                        crate::context::KKTMode::Mutual,
-                        ciphersuite,
-                        initiator_ed25519_keypair.private_key(),
-                        Some(&initiator_kem_public_key),
-                    )
-                    .unwrap();
-
-                    // encryption - initiator frame
-
-                    let (i_session_secret, i_bytes) = encrypt_initial_kkt_frame(
-                        &mut rng,
-                        responder_x25519_keypair.public_key(),
-                        &i_frame,
-                    )
-                    .unwrap();
-
-                    // decryption - initiator frame
-
-                    let (r_session_secret, i_frame_r, i_context_r) =
-                        decrypt_initial_kkt_frame(responder_x25519_keypair.private_key(), &i_bytes)
-                            .unwrap();
-
-                    let (r_context, r_obtained_key) = responder_ingest_message(
-                        &i_context_r,
-                        Some(initiator_ed25519_keypair.public_key()),
-                        Some(&i_dir_hash),
-                        &i_frame_r,
-                    )
-                    .unwrap();
-
-                    assert_eq!(r_obtained_key.unwrap().encode(), i_kem_key_bytes);
-
-                    let r_frame = responder_process(
-                        &r_context,
-                        i_frame_r.session_id(),
-                        responder_ed25519_keypair.private_key(),
-                        &responder_kem_public_key,
-                    )
-                    .unwrap();
-
-                    // encryption - responder frame
-                    let r_bytes =
-                        encrypt_kkt_frame(&mut rng, &r_session_secret, &r_frame, KKT_RESPONSE_AAD)
-                            .unwrap();
-
-                    // decryption - responder frame
-
-                    let (i_frame_r, i_context_r) =
-                        decrypt_kkt_frame(&i_session_secret, &r_bytes, KKT_RESPONSE_AAD).unwrap();
-
-                    let i_obtained_key = initiator_ingest_response(
-                        &i_context,
-                        &i_frame_r,
-                        &i_context_r,
-                        responder_ed25519_keypair.public_key(),
-                        &r_dir_hash,
-                    )
-                    .unwrap();
-
-                    assert_eq!(i_obtained_key.encode(), r_kem_key_bytes)
-                }
+                assert_eq!(
+                    processed_response.encapsulation_key.as_bytes(),
+                    responder_kem.mc_eliece_encapsulation_key().as_ref()
+                )
             }
         }
     }

common/nym-kkt/src/masked_byte.rs

@@ -0,0 +1,189 @@
+use nym_crypto::{blake3, hmac::hmac::digest::ExtendableOutput};
+
+use crate::error::{
+    MaskedByteError,
+    MaskedByteError::{Failure, InvalidLength},
+};
+
+pub const MASKED_BYTE_LEN: usize = 16;
+pub const MASKED_BYTE_CONTEXT_STR: &[u8] = b"NYM_MASKED_BYTE_V1";
+
+const U8_RANGE: [u8; 256] = [
+    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,
+    26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49,
+    50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73,
+    74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97,
+    98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116,
+    117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135,
+    136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154,
+    155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173,
+    174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192,
+    193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211,
+    212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230,
+    231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249,
+    250, 251, 252, 253, 254, 255,
+];
+
+#[derive(Clone, Copy)]
+pub struct MaskedByte([u8; MASKED_BYTE_LEN]);
+
+impl MaskedByte {
+    /// Mask a byte by hashing it with some mask.
+    /// Outputs Blake3_Hash(MASKED_BYTE_CONTEXT_STR || mask || 0xFF || byte)
+    pub fn new(byte: u8, mask: &[u8]) -> Self {
+        let mut output: [u8; MASKED_BYTE_LEN] = [0u8; MASKED_BYTE_LEN];
+        let mut hasher = blake3::Hasher::new();
+        hasher.update(MASKED_BYTE_CONTEXT_STR);
+        hasher.update(mask);
+        // avoid zero update
+        hasher.update(&[0xFF, byte]);
+        hasher.finalize_xof_into(&mut output);
+
+        Self(output)
+    }
+    /// Unmasks a byte by trial hashing.
+    /// This function runs Blake3_Hash(MASKED_BYTE_CONTEXT_STR || mask || 0xFF).
+    /// This Hasher state is then cloned updated with `i: u8` in (0..=u8::max).
+    /// If we find an `i` which yields back the hash input, then we found the masked byte.
+    /// Otherwise, the function returns an error.
+    pub fn unmask(&self, mask: &[u8]) -> Result<u8, MaskedByteError> {
+        self.unmask_check_version(mask, &U8_RANGE)
+    }
+
+    // This could be more efficient than unmask,
+    // because we just could check against a smaller list of supported versions.
+    pub fn unmask_check_version(
+        &self,
+        mask: &[u8],
+        supported_versions: &[u8],
+    ) -> Result<u8, MaskedByteError> {
+        let mut buf: [u8; MASKED_BYTE_LEN] = [0u8; MASKED_BYTE_LEN];
+        let mut hasher = blake3::Hasher::new();
+        hasher.update(MASKED_BYTE_CONTEXT_STR);
+        hasher.update(mask);
+        // avoid zero update
+        hasher.update(&[0xFF]);
+        for i in supported_versions {
+            let mut t_hasher = hasher.clone();
+            t_hasher.update(&[*i]);
+            t_hasher.finalize_xof_into(&mut buf);
+            if buf == self.0 {
+                return Ok(*i);
+            }
+        }
+        Err(Failure)
+    }
+
+    pub fn as_slice(&self) -> &[u8] {
+        &self.0
+    }
+
+    pub fn to_bytes(self) -> [u8; MASKED_BYTE_LEN] {
+        self.0
+    }
+}
+
+impl From<[u8; MASKED_BYTE_LEN]> for MaskedByte {
+    fn from(value: [u8; MASKED_BYTE_LEN]) -> Self {
+        MaskedByte(value)
+    }
+}
+
+impl From<&[u8; MASKED_BYTE_LEN]> for MaskedByte {
+    fn from(value: &[u8; MASKED_BYTE_LEN]) -> Self {
+        MaskedByte(*value)
+    }
+}
+
+impl TryFrom<&[u8]> for MaskedByte {
+    type Error = MaskedByteError;
+
+    fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
+        let Ok(inner) = value.try_into() else {
+            return Err(InvalidLength {
+                expected: MASKED_BYTE_LEN,
+                actual: value.len(),
+            });
+        };
+        Ok(MaskedByte(inner))
+    }
+}
+
+#[cfg(test)]
+mod test {
+
+    use crate::masked_byte::MASKED_BYTE_LEN;
+
+    use super::MaskedByte;
+    use rand09::{Rng, RngCore, rng};
+
+    #[test]
+    fn test_masking() {
+        let mut mask: [u8; 256] = [0u8; 256];
+        let mut wire_bytes: [u8; MASKED_BYTE_LEN];
+
+        // why not
+        for i in 0..=u8::MAX {
+            // gen mask
+            rng().fill_bytes(&mut mask);
+            let masked_byte = MaskedByte::new(i, &mask);
+            wire_bytes = masked_byte.to_bytes();
+
+            let decoded_masked_byte = MaskedByte::from(wire_bytes);
+            let output = decoded_masked_byte.unmask(&mask).unwrap();
+
+            assert_eq!(i, output);
+
+            // flip bit
+            let mut with_flipped_bit = decoded_masked_byte.to_bytes();
+
+            let byte_idx: usize = rng().random_range(0..MASKED_BYTE_LEN);
+            let bit_idx = rng().random_range(0..8);
+            with_flipped_bit[byte_idx] ^= 1 << bit_idx;
+
+            let decoded_masked_byte = MaskedByte::from(with_flipped_bit);
+            assert!(decoded_masked_byte.unmask(&mask).is_err());
+        }
+    }
+
+    #[test]
+    fn test_decoding() {
+        let mut mask: [u8; 256] = [0u8; 256];
+
+        // gen mask
+        rng().fill_bytes(&mut mask);
+        let byte = rng().random();
+        let masked_byte = MaskedByte::new(byte, &mask);
+        let wire_bytes: [u8; MASKED_BYTE_LEN] = masked_byte.to_bytes();
+
+        // should succeed
+        let decoded_masked_byte = MaskedByte::try_from(wire_bytes.as_slice()).unwrap();
+        let output = decoded_masked_byte.unmask(&mask).unwrap();
+
+        assert_eq!(byte, output);
+
+        let empty_slice: &[u8] = &[];
+        // should fail
+        assert!(MaskedByte::try_from(empty_slice).is_err());
+
+        let mut wire_bytes_messy = Vec::from(wire_bytes);
+
+        // add more one more byte
+        wire_bytes_messy.push(0x42);
+        assert_eq!(wire_bytes_messy.len(), MASKED_BYTE_LEN + 1);
+        // should fail
+        assert!(MaskedByte::try_from(wire_bytes_messy.as_slice()).is_err());
+
+        // pop the added byte
+        _ = wire_bytes_messy.pop();
+        assert_eq!(wire_bytes_messy.len(), MASKED_BYTE_LEN);
+        // should succeed
+        assert!(MaskedByte::try_from(wire_bytes_messy.as_slice()).is_ok());
+
+        // pop one more byte
+        _ = wire_bytes_messy.pop();
+        assert_eq!(wire_bytes_messy.len(), MASKED_BYTE_LEN - 1);
+        // should fail
+        assert!(MaskedByte::try_from(wire_bytes_messy.as_slice()).is_err());
+    }
+}

common/nym-kkt/src/message.rs

@@ -0,0 +1,265 @@
+// Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
+// SPDX-License-Identifier: Apache-2.0
+
+use crate::carrier::Carrier;
+use crate::context::{KKTContext, KKTMode, KKTRole};
+use crate::error::KKTError;
+use crate::frame::KKTFrame;
+use crate::keys::EncapsulationKey;
+use crate::masked_byte::{MASKED_BYTE_LEN, MaskedByte};
+use libcrux_chacha20poly1305::TAG_LEN;
+use libcrux_psq::handshake::types::{DHKeyPair, DHPrivateKey, DHPublicKey};
+use nym_kkt_ciphersuite::{KEM, x25519};
+
+pub struct KKTRequest {
+    /// The plaintext part of the request
+    pub(crate) plaintext: KKTRequestPlaintext,
+
+    /// Ciphertext of an initial request `KKTFrame`
+    pub(crate) encrypted_frame: Vec<u8>,
+}
+
+impl KKTRequest {
+    // the size of KKTRequest is the plaintext data followed by the frame and the encryption tag
+    pub const fn size_excluding_payload(mode: KKTMode, kem: KEM) -> usize {
+        KKTRequestPlaintext::SIZE
+            + KKTFrame::size_excluding_payload(KKTRole::Initiator, mode, kem)
+            + TAG_LEN
+    }
+
+    pub fn size(&self) -> usize {
+        self.encrypted_frame.len() + KKTRequestPlaintext::SIZE
+    }
+
+    pub fn into_bytes(mut self) -> Vec<u8> {
+        let mut out = self.plaintext.to_bytes();
+        out.append(&mut self.encrypted_frame);
+        out
+    }
+
+    pub fn try_from_bytes(b: &[u8]) -> Result<Self, KKTError> {
+        if b.len() < x25519::PUBLIC_KEY_LENGTH + MASKED_BYTE_LEN {
+            return Err(KKTError::FrameDecodingError {
+                info: "the KKTRequest frame has invalid length".to_string(),
+            });
+        }
+        let plaintext =
+            KKTRequestPlaintext::try_from_bytes(&b[..x25519::PUBLIC_KEY_LENGTH + MASKED_BYTE_LEN])?;
+
+        Ok(KKTRequest {
+            plaintext,
+            encrypted_frame: b[x25519::PUBLIC_KEY_LENGTH + MASKED_BYTE_LEN..].to_vec(),
+        })
+    }
+}
+
+pub(crate) struct KKTRequestPlaintext {
+    /// Ephemeral Diffie-Hellman public key of the initiator
+    pub(crate) dh_pubkey: DHPublicKey,
+
+    /// Masked bytes representing the outer protocol version information
+    pub(crate) masked_version_bytes: MaskedByte,
+}
+
+impl KKTRequestPlaintext {
+    pub const SIZE: usize = x25519::PUBLIC_KEY_LENGTH + MASKED_BYTE_LEN;
+
+    pub(crate) fn new(
+        initiator_pubkey: DHPublicKey,
+        responder_pubkey: &DHPublicKey,
+        outer_protocol_version: u8,
+    ) -> Self {
+        let mask = Self::create_version_mask(&initiator_pubkey, responder_pubkey);
+        let masked_version_bytes = MaskedByte::new(outer_protocol_version, &mask);
+        KKTRequestPlaintext {
+            dh_pubkey: initiator_pubkey,
+            masked_version_bytes,
+        }
+    }
+
+    pub(crate) fn into_request(
+        self,
+        carrier: &mut Carrier,
+        frame: KKTFrame,
+    ) -> Result<KKTRequest, KKTError> {
+        let frame_bytes = frame.try_to_bytes()?;
+        let frame_ciphertext = carrier.encrypt(&frame_bytes)?;
+        Ok(KKTRequest {
+            plaintext: self,
+            encrypted_frame: frame_ciphertext,
+        })
+    }
+
+    pub(crate) fn create_version_mask(
+        initiator_pubkey: &DHPublicKey,
+        responder_pubkey: &DHPublicKey,
+    ) -> Vec<u8> {
+        let mut mask = Vec::with_capacity(2 * x25519::PUBLIC_KEY_LENGTH);
+        mask.extend_from_slice(initiator_pubkey.as_ref());
+        mask.extend_from_slice(responder_pubkey.as_ref());
+        mask
+    }
+
+    fn create_carrier_ctx(
+        masked_version: &MaskedByte,
+        initiator_pubkey: &DHPublicKey,
+        responder_pubkey: &DHPublicKey,
+    ) -> Vec<u8> {
+        let mut context = Vec::new();
+        context.extend_from_slice(masked_version.as_slice());
+        context.extend_from_slice(crate::frame::KKT_CARRIER_CONTEXT);
+        context.extend_from_slice(initiator_pubkey.as_ref());
+        context.extend_from_slice(responder_pubkey.as_ref());
+        context
+    }
+
+    pub(crate) fn to_bytes(&self) -> Vec<u8> {
+        let mut out = Vec::with_capacity(x25519::PUBLIC_KEY_LENGTH + MASKED_BYTE_LEN);
+        out.extend_from_slice(self.dh_pubkey.as_ref());
+        out.extend_from_slice(self.masked_version_bytes.as_slice());
+        out
+    }
+
+    pub(crate) fn try_from_bytes(b: &[u8]) -> Result<Self, KKTError> {
+        if b.len() != x25519::PUBLIC_KEY_LENGTH + MASKED_BYTE_LEN {
+            return Err(KKTError::FrameDecodingError {
+                info: "the KKTRequest frame has invalid length".to_string(),
+            });
+        }
+        // SAFETY: we're using exactly 32 byte
+        #[allow(clippy::unwrap_used)]
+        let dh_pubkey =
+            DHPublicKey::from_bytes(&b[..x25519::PUBLIC_KEY_LENGTH].try_into().unwrap());
+        let masked_version_bytes = MaskedByte::try_from(&b[x25519::PUBLIC_KEY_LENGTH..])?;
+
+        Ok(KKTRequestPlaintext {
+            dh_pubkey,
+            masked_version_bytes,
+        })
+    }
+
+    pub(crate) fn version_mask(&self, responder_pubkey: &DHPublicKey) -> Vec<u8> {
+        Self::create_version_mask(&self.dh_pubkey, responder_pubkey)
+    }
+
+    pub(crate) fn derive_initiator_carrier(
+        &self,
+        initiator_sk: &DHPrivateKey,
+        responder_pubkey: &DHPublicKey,
+    ) -> Result<Carrier, KKTError> {
+        let ctx = Self::create_carrier_ctx(
+            &self.masked_version_bytes,
+            &self.dh_pubkey,
+            responder_pubkey,
+        );
+
+        let shared_secret = initiator_sk
+            .diffie_hellman(responder_pubkey)
+            .map_err(KKTError::shared_secret_derivation_failure)?;
+
+        Ok(Carrier::from_secret_slice(
+            shared_secret.as_ref(),
+            &ctx,
+            true,
+        ))
+    }
+
+    pub(crate) fn derive_responder_carrier(
+        &self,
+        responder_keys: &DHKeyPair,
+    ) -> Result<Carrier, KKTError> {
+        let ctx = Self::create_carrier_ctx(
+            &self.masked_version_bytes,
+            &self.dh_pubkey,
+            &responder_keys.pk,
+        );
+        let shared_secret = responder_keys
+            .sk()
+            .diffie_hellman(&self.dh_pubkey)
+            .map_err(KKTError::shared_secret_derivation_failure)?;
+        Ok(Carrier::from_secret_slice(
+            shared_secret.as_ref(),
+            &ctx,
+            false,
+        ))
+    }
+}
+
+pub struct KKTRequestEncryptionResult {
+    /// Derived carrier used for decrypting this frame and encrypting the response
+    pub(crate) carrier: Carrier,
+
+    /// The underlying request that is going to get sent to the remote
+    pub(crate) request: KKTRequest,
+}
+
+pub struct DecryptedRequestFrame {
+    /// Derived carrier used for decrypting this frame and encrypting the response
+    pub(crate) carrier: Carrier,
+
+    /// The remote frame sent in the message
+    pub(crate) remote_frame: KKTFrame,
+
+    /// The unmasked byte representing the outer protocol version sent by the initiator
+    pub(crate) outer_protocol_version: u8,
+}
+
+impl DecryptedRequestFrame {
+    pub(crate) fn remote_context(&self) -> &KKTContext {
+        self.remote_frame.context()
+    }
+}
+
+pub struct ProcessedKKTRequest {
+    pub response: KKTResponse,
+
+    /// The obtained encapsulation key of the remote
+    pub remote_encapsulation_key: Option<EncapsulationKey>,
+
+    /// The KEM key requested in the original request
+    pub requested_kem: KEM,
+
+    /// The unmasked byte representing the outer protocol version sent by the initiator
+    pub outer_protocol_version: u8,
+
+    // Request payload data (Could be empty. Contents are unrelated to current KKT execution).
+    pub request_payload: Vec<u8>,
+}
+
+pub struct KKTResponse {
+    /// Encrypted KKT frame that is going to be sent back to the initiator
+    pub encrypted_frame: Vec<u8>,
+}
+
+impl KKTResponse {
+    // the size of KKTRequest is the plaintext data followed by the frame and the encryption tag
+    pub const fn size_excluding_payload(kem: KEM) -> usize {
+        // `KKTMode` argument makes no difference for the Responder role
+        KKTFrame::size_excluding_payload(KKTRole::Responder, KKTMode::OneWay, kem) + TAG_LEN
+    }
+
+    pub fn size(&self) -> usize {
+        self.encrypted_frame.len()
+    }
+
+    pub fn from_bytes(bytes: Vec<u8>) -> KKTResponse {
+        KKTResponse {
+            encrypted_frame: bytes,
+        }
+    }
+
+    pub fn into_bytes(self) -> Vec<u8> {
+        self.encrypted_frame
+    }
+}
+
+pub struct ProcessedKKTResponse {
+    /// The obtained encapsulation key of the remote
+    pub encapsulation_key: EncapsulationKey,
+
+    /// Indicates whether responder was able to verify the initiator's kem key,
+    pub verified_initiator_kem_key: bool,
+
+    /// Optional response payload (Could be empty. Contents are unrelated to current KKT execution).
+    pub response_payload: Vec<u8>,
+}

common/nym-kkt/src/rekey.rs

@@ -0,0 +1,257 @@
+// Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
+// SPDX-License-Identifier: Apache-2.0
+
+//! Post-Quantum Re-Key Protocol
+
+/// This module implements a stateless post-quantum re-keying protocol in one round-trip.
+/// We currently support MlKem768 and XWing.
+///
+/// This protocol is safe if it runs under a trusted secure channel.
+///
+/// Bandwidth costs:
+/// Request (MlKem768): 1216 bytes
+/// Response (MlKem768): 1088 bytes
+/// Request (XWing): 1248 bytes
+/// Response (XWing): 1120 bytes
+use libcrux_kem::*;
+use nym_crypto::hkdf::blake3::derive_key_blake3;
+use nym_kkt_ciphersuite::{KEM, mceliece, ml_kem768, x25519, xwing};
+use rand09::{CryptoRng, RngCore};
+use std::fmt::{Debug, Formatter};
+use zeroize::Zeroize;
+
+use crate::error::KKTError;
+
+/// Context string to be used with the Blake3 KDF.
+const REKEY_CONTEXT: &str = "NYM_PQ_REKEY_v1";
+
+pub struct RekeyInitiator {
+    algorithm: Algorithm,
+    decapsulation_key: PrivateKey,
+    salt: [u8; 32],
+}
+
+impl Debug for RekeyInitiator {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        let key_typ = match self.decapsulation_key {
+            PrivateKey::X25519(_) => "x25519",
+            PrivateKey::P256(_) => "p256",
+            PrivateKey::MlKem512(_) => "ml512",
+            PrivateKey::MlKem768(_) => "mlkem768",
+            PrivateKey::X25519MlKem768Draft00(_) => "x25519-mlkem768",
+            PrivateKey::XWingKemDraft06(_) => "xwing",
+            PrivateKey::MlKem1024(_) => "ml1024",
+        };
+
+        f.debug_struct("RekeyInitiator")
+            .field("algorithm", &self.algorithm)
+            .field("decapsulation_key", &key_typ)
+            .field("salt", &self.salt)
+            .finish()
+    }
+}
+
+impl RekeyInitiator {
+    /// The Initiator generates an ephemeral KEM keypair and a 32-byte salt.
+    /// The Initiator keeps the decapsulation key and generates a request message.
+    /// The request message contains the salt and an encoding of the encapsulation key as follows
+    ///      salt        encapsulation_key
+    /// [0 ........ 32 | 32 .............. ]
+    ///
+    /// Inputs:
+    /// rng: something that implements CryptoRng + RngCore
+    /// kem: a KEM algorithm (we currently support MlKem768 and XWing)
+    ///
+    /// Outputs:
+    /// RekeyInitiator: A struct which contains the decapsulation key, the salt and the kem algorithm in use.
+    /// Vec<u8>: The request message as explained above. This is to be sent to the responder as-is.
+    pub fn generate_request<R>(rng: &mut R, kem: KEM) -> Result<(RekeyInitiator, Vec<u8>), KKTError>
+    where
+        R: CryptoRng + RngCore,
+    {
+        let (algorithm, buffer_size) = match kem {
+            // KEM::XWing => (Algorithm::XWingKemDraft06, 32 + xwing::PUBLIC_KEY_LENGTH),
+            KEM::MlKem768 => (Algorithm::MlKem768, 32 + ml_kem768::PUBLIC_KEY_LENGTH),
+            // We don't support McEliece because the keys are massive.
+            // If this is a deal-breaker, users can start a new session with PSQ which can use McEliece.
+            KEM::McEliece => {
+                return Err(KKTError::UnsupportedAlgorithm {
+                    info: "McEliece is not supported for re-keying",
+                });
+            }
+        };
+
+        // Generate the Initiator's salt
+        let mut salt = [0u8; 32];
+        rng.fill_bytes(&mut salt);
+
+        // Create the buffer for the request message and copy the salt into it.
+        let mut request_buffer = Vec::with_capacity(buffer_size);
+        request_buffer.extend_from_slice(&salt);
+
+        // Generate the ephemeral KEM keypair based on the algorithm from the function's input.
+        let (decapsulation_key, encapsulation_key) = key_gen(algorithm, rng)?;
+
+        // Append the encoding of the KEM encapsulation key to the initiator's randomness.
+        request_buffer.extend(encapsulation_key.encode());
+
+        Ok((
+            // The Initiator should store this until they use `RekeyInitiator::finalize`.
+            RekeyInitiator {
+                algorithm,
+                decapsulation_key,
+                salt,
+            },
+            // This is to be sent to the responder.
+            request_buffer,
+        ))
+    }
+
+    /// The Initiator will attempt to decapsulate the `pre_key` generated by the responder
+    /// secret. This `pre_key` will be combined with the Initiator's previously generated salt
+    /// as input to a Blake3 KDF call to generate the new shared secret.
+    ///
+    /// This function fails if the ciphertext cannot be decoded or decapsulated.
+    ///
+    /// Input:
+    /// response_message: the responder's message which contains an encapsulation of `pre_key`.
+    /// Output:
+    /// [u8; 32]: the new shared secret.
+    pub fn finalize(mut self, response_message: &[u8]) -> Result<[u8; 32], KKTError> {
+        // Decode the responder's ciphertext.
+        let ciphertext = Ct::decode(self.algorithm, response_message)?;
+        // Decapsulate the `pre_key` using the Initiator's decapsulation key.
+        let pre_key = ciphertext.decapsulate(&self.decapsulation_key)?;
+
+        // Encode the `pre_key` into bytes
+        let pre_key_bytes = pre_key.encode();
+
+        let new_secret: [u8; 32] = derive_key_blake3(REKEY_CONTEXT, &pre_key_bytes, &self.salt);
+
+        // Zeroize the Initiator's salt
+        self.salt.zeroize();
+
+        // TODO: zeroize the decapsulation key
+
+        Ok(new_secret)
+    }
+}
+
+/// The responder parses the request message.
+/// The first 32 bytes are the Initiator's salt,
+/// and the remainder is the encoding of the public key.
+/// Given that XWing and MlKem768 have different key lengths,
+/// we could deduce the algorithm from that.
+///
+/// If the message is badly formatted, or the encapsulation received is invalid,
+/// this function will produce an error.
+///
+/// If everything is alright, the responder generates and encapsulates a key `pre_key` to send to the Initiator.
+/// Then, the responder calls a Blake3 KDF over `pre_key` and the Initiator's salt to obtain
+/// the new shared secret.
+///
+/// Inputs:
+/// rng: something that implements CryptoRng + RngCore
+/// request_message: the Initiator's request message (contains the salt and encapsulation key)
+///
+/// Outputs:
+/// [u8; 32]: new shared secret
+/// Vec<u8>: response which contains an encapsulation of a secret value generated by the responder.
+/// This is to be sent back to the Initiator as-is.
+pub fn responder_process<R>(
+    rng: &mut R,
+    mut request_message: Vec<u8>,
+) -> Result<([u8; 32], Vec<u8>), KKTError>
+where
+    R: CryptoRng + RngCore,
+{
+    // Deduce the KEM algorithm from the message length
+    let algorithm = match request_message.len().checked_sub(32) {
+        //
+        Some(num) => match num {
+            // If message length is 1216 (32 + 1184) then the algorithm should be MlKem768
+            ml_kem768::PUBLIC_KEY_LENGTH => Algorithm::MlKem768,
+            // If message length is 1248 (32 + 1216) then the algorithm should be MlKem768
+            xwing::PUBLIC_KEY_LENGTH => Algorithm::XWingKemDraft06,
+            // We don't support McEliece because the keys are massive.
+            // If this is a deal-breaker, users can start a new session with PSQ which can use McEliece.
+            mceliece::PUBLIC_KEY_LENGTH => {
+                return Err(KKTError::UnsupportedAlgorithm {
+                    info: "McEliece is not supported for re-keying",
+                });
+            }
+            // We don't support X25519 because it's not post-quantum secure.
+            x25519::PUBLIC_KEY_LENGTH => {
+                return Err(KKTError::UnsupportedAlgorithm {
+                    info: "McEliece is not supported for re-keying",
+                });
+            }
+            // Reject if the size does not match any of the above.
+            _ => {
+                return Err(KKTError::UnsupportedAlgorithm {
+                    info: "Unknown Algorithm",
+                });
+            }
+        },
+        // Reject if message length is less than 32.
+        None => {
+            return Err(KKTError::DecodingError {
+                info: "Invalid rekey request: size is too small",
+            });
+        }
+    };
+
+    // Split the message to get the Initiator's salt (first 32 bytes)
+    // and the encoding of the Initiator's public key.
+    let (remote_salt, remote_encapsulation_key_bytes) = request_message.split_at_mut(32);
+
+    // Attempt to decode the Initiator's encapsulation key.
+    let remote_encapsulation_key = PublicKey::decode(algorithm, remote_encapsulation_key_bytes)?;
+
+    // Encapsulate a fresh `pre_key` using the Initiator's encapsulation key into `ciphertext`.
+    let (pre_key, ciphertext) = remote_encapsulation_key.encapsulate(rng)?;
+    // Encode the ciphertext into bytes to send back to the initiator.
+    let message = ciphertext.encode();
+
+    // Encode the `pre_key` into bytes
+    let pre_key_bytes = pre_key.encode();
+
+    let new_secret: [u8; 32] = derive_key_blake3(REKEY_CONTEXT, &pre_key_bytes, remote_salt);
+
+    // Zeroize the Initiator's salt
+    remote_salt.zeroize();
+
+    Ok((new_secret, message))
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::error::KKTError;
+    use crate::rekey::{RekeyInitiator, responder_process};
+    use nym_kkt_ciphersuite::KEM;
+
+    #[test]
+    fn rekey_test() {
+        let mut rng = rand09::rng();
+
+        let (rekey_state, request_message) =
+            RekeyInitiator::generate_request(&mut rng, KEM::MlKem768).unwrap();
+
+        let (responder_secret, response_message) =
+            responder_process(&mut rng, request_message).unwrap();
+
+        let initiator_secret = rekey_state.finalize(&response_message).unwrap();
+
+        assert_eq!(initiator_secret, responder_secret);
+
+        // mceliece should fail
+        let err = RekeyInitiator::generate_request(&mut rng, KEM::McEliece).unwrap_err();
+        assert_eq!(
+            err.to_string(),
+            KKTError::UnsupportedAlgorithm {
+                info: "McEliece is not supported for re-keying",
+            }
+            .to_string()
+        )
+    }
+}

common/nym-kkt/src/responder.rs

@@ -0,0 +1,196 @@
+// Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
+// SPDX-License-Identifier: Apache-2.0
+
+use crate::key_utils::validate_encapsulation_key;
+use crate::keys::{EncapsulationKey, KEMKeys};
+use crate::message::{KKTRequest, KKTResponse, ProcessedKKTRequest};
+use crate::{
+    context::{KKTContext, KKTMode, KKTRole, KKTStatus},
+    error::KKTError,
+    frame::KKTFrame,
+};
+use libcrux_psq::handshake::types::DHKeyPair;
+use nym_kkt_ciphersuite::{Ciphersuite, HashFunction, SignatureScheme};
+
+/// Representation of a KKT Responder
+pub struct KKTResponder<'a> {
+    /// Long-term x25519 DH key pair of this Responder
+    x25519_keypair: &'a DHKeyPair,
+
+    /// KEM keys of this responder
+    kem_keys: &'a KEMKeys,
+
+    /// List of supported Hash Functions by this Responder
+    supported_hash_functions: Vec<HashFunction>,
+
+    /// List of supported Signature Schemes by this Responder
+    supported_signature_schemes: Vec<SignatureScheme>,
+
+    /// List of supported outer (LP) protocol version by this Responder
+    supported_outer_protocol_versions: Vec<u8>,
+}
+
+impl<'a> KKTResponder<'a> {
+    pub fn new(
+        x25519_keypair: &'a DHKeyPair,
+        kem_keys: &'a KEMKeys,
+        supported_hash_functions: &[HashFunction],
+        supported_signature_schemes: &[SignatureScheme],
+        supported_outer_protocol_versions: &[u8],
+    ) -> Result<Self, KKTError> {
+        if supported_hash_functions.is_empty() {
+            return Err(KKTError::FunctionInputError {
+                info: "Did not provide a supported HashFunction when instantiating a KKTResponder",
+            });
+        }
+
+        if supported_signature_schemes.is_empty() {
+            return Err(KKTError::FunctionInputError {
+                info: "Did not provide a supported SignatureScheme when instantiating a KKTResponder",
+            });
+        }
+
+        if supported_outer_protocol_versions.is_empty() {
+            return Err(KKTError::FunctionInputError {
+                info: "Did not provide a supported outer protocol version when instantiating a KKTResponder",
+            });
+        }
+
+        Ok(Self {
+            x25519_keypair,
+            kem_keys,
+            supported_hash_functions: supported_hash_functions.to_vec(),
+            supported_signature_schemes: supported_signature_schemes.to_vec(),
+            supported_outer_protocol_versions: supported_outer_protocol_versions.to_vec(),
+        })
+    }
+
+    fn check_ciphersuite_compatiblity(
+        &self,
+        remote_ciphersuite: Ciphersuite,
+    ) -> Result<(), KKTError> {
+        let r_hash = remote_ciphersuite.hash_function();
+        let r_sig = remote_ciphersuite.signature_scheme();
+
+        if !self.supported_hash_functions.contains(&r_hash) {
+            return Err(KKTError::IncompatibilityError {
+                info: "Unsupported HashFunction",
+            });
+        }
+
+        if !self.supported_signature_schemes.contains(&r_sig) {
+            return Err(KKTError::IncompatibilityError {
+                info: "Unsupported SignatureScheme",
+            });
+        }
+
+        Ok(())
+    }
+
+    // When this function fails, we do that silently (i.e. we don't generate a response to the initiator).
+
+    pub fn process_request(
+        &self,
+        request: KKTRequest,
+        request_payload_len: usize,
+    ) -> Result<ProcessedKKTRequest, KKTError> {
+        let processed_req = KKTFrame::decrypt_initiator_frame(
+            self.x25519_keypair,
+            request,
+            &self.supported_outer_protocol_versions,
+            request_payload_len,
+        )?;
+
+        let remote_context = *processed_req.remote_context();
+        let remote_frame = processed_req.remote_frame;
+        let request_payload = remote_frame.payload().to_vec();
+        let mut carrier = processed_req.carrier;
+
+        self.check_ciphersuite_compatiblity(remote_context.ciphersuite())?;
+
+        let (local_context, remote_encapsulation_key) = match remote_context.mode() {
+            KKTMode::OneWay => responder_ingest_message(None, remote_frame)?,
+            KKTMode::Mutual => {
+                // So we can either fetch the remote hash here using some async call to the directory,
+                // which might make registration hang or accept the sent key then verify later.
+
+                // If we choose to not accept, the response's status will be KKTStatus::UnverifiedKEMKey.
+                // The response would still contain the responder's encapsulation key.
+                responder_ingest_message(None, remote_frame)?
+            }
+        };
+
+        let kem = local_context.ciphersuite().kem();
+        let Some(kem_key) = self.kem_keys.encoded_encapsulation_key(kem) else {
+            return Err(KKTError::IncompatibilityError {
+                info: "Unsupported KEM",
+            });
+        };
+
+        // for now the response payload is empty
+        let response_payload = Vec::with_capacity(0);
+
+        let frame = KKTFrame::new(local_context, kem_key, response_payload);
+
+        // encryption - responder frame
+        let encrypted_frame = carrier.encrypt(&frame.try_to_bytes()?)?;
+        Ok(ProcessedKKTRequest {
+            response: KKTResponse { encrypted_frame },
+            remote_encapsulation_key,
+            requested_kem: remote_context.ciphersuite().kem(),
+            outer_protocol_version: processed_req.outer_protocol_version,
+            request_payload,
+        })
+    }
+}
+
+pub fn responder_ingest_message(
+    expected_hash: Option<&[u8]>,
+    remote_frame: KKTFrame,
+) -> Result<(KKTContext, Option<EncapsulationKey>), KKTError> {
+    let remote_context = remote_frame.context();
+    let mut own_context = remote_context.derive_responder_header()?;
+    let cs = own_context.ciphersuite();
+
+    match remote_context.role() {
+        KKTRole::Initiator => {
+            // using own_context here because maybe for whatever reason we want to ignore the remote kem key
+            match own_context.mode() {
+                KKTMode::OneWay => Ok((own_context, None)),
+                KKTMode::Mutual => {
+                    let Some(expected_hash) = expected_hash else {
+                        own_context.update_status(KKTStatus::UnverifiedKEMKey);
+                        // we don't store an unverified key
+                        // changing the status notifies the initiator that we didn't
+
+                        // we could still keep it here and then verify later...
+                        // let received_encapsulation_key = EncapsulationKey::decode(
+                        //     own_context.ciphersuite().kem(),
+                        //     remote_frame.body_ref(),
+                        // )?;
+                        //  Ok((own_context, Some(received_encapsulation_key)))
+                        //
+                        return Ok((own_context, None));
+                    };
+
+                    if !validate_encapsulation_key(
+                        cs.hash_function(),
+                        cs.hash_len(),
+                        remote_frame.body_ref(),
+                        expected_hash,
+                    ) {
+                        // The key does not match the hash obtained from the directory
+                        return Err(KKTError::MismatchedKEMHash);
+                    }
+                    let remote_key =
+                        EncapsulationKey::try_from_bytes(remote_frame.body(), cs.kem())?;
+                    Ok((own_context, Some(remote_key)))
+                }
+            }
+        }
+
+        KKTRole::Responder => Err(KKTError::IncompatibilityError {
+            info: "Responder received a request from another responder.",
+        }),
+    }
+}

common/nym-kkt/src/session.rs

@@ -1,230 +0,0 @@
-use nym_crypto::asymmetric::ed25519::{self, Signature};
-use rand09::{CryptoRng, RngCore};
-
-use crate::frame::KKTSessionId;
-use crate::{
-    ciphersuite::{Ciphersuite, EncapsulationKey},
-    context::{KKTContext, KKTMode, KKTRole, KKTStatus},
-    error::KKTError,
-    frame::{KKT_SESSION_ID_LEN, KKTFrame},
-    key_utils::validate_encapsulation_key,
-};
-
-pub fn initiator_process<'a, R>(
-    rng: &mut R,
-    mode: KKTMode,
-    ciphersuite: Ciphersuite,
-    signing_key: &ed25519::PrivateKey,
-    own_encapsulation_key: Option<&EncapsulationKey<'a>>,
-) -> Result<(KKTContext, KKTFrame), KKTError>
-where
-    R: CryptoRng + RngCore,
-{
-    let context = KKTContext::new(KKTRole::Initiator, mode, ciphersuite)?;
-
-    let context_bytes = context.encode()?;
-
-    let mut session_id = [0; KKT_SESSION_ID_LEN];
-    // Generate Session ID
-    rng.fill_bytes(&mut session_id);
-
-    let body: &[u8] = match mode {
-        KKTMode::OneWay => &[],
-        KKTMode::Mutual => match own_encapsulation_key {
-            Some(encaps_key) => &encaps_key.encode(),
-
-            // Missing key
-            None => {
-                return Err(KKTError::FunctionInputError {
-                    info: "KEM Key Not Provided",
-                });
-            }
-        },
-    };
-
-    let mut bytes_to_sign =
-        Vec::with_capacity(context.full_message_len() - context.signature_len());
-    bytes_to_sign.extend_from_slice(&context_bytes);
-    bytes_to_sign.extend_from_slice(body);
-    bytes_to_sign.extend_from_slice(&session_id);
-
-    let signature = signing_key.sign(bytes_to_sign).to_bytes();
-
-    Ok((
-        context,
-        KKTFrame::new(context_bytes, body, session_id, &signature),
-    ))
-}
-
-pub fn anonymous_initiator_process<R>(
-    rng: &mut R,
-    ciphersuite: Ciphersuite,
-) -> Result<(KKTContext, KKTFrame), KKTError>
-where
-    R: CryptoRng + RngCore,
-{
-    let context = KKTContext::new(KKTRole::AnonymousInitiator, KKTMode::OneWay, ciphersuite)?;
-    let context_bytes = context.encode()?;
-
-    let mut session_id = [0u8; KKT_SESSION_ID_LEN];
-    rng.fill_bytes(&mut session_id);
-
-    Ok((context, KKTFrame::new(context_bytes, &[], session_id, &[])))
-}
-
-pub fn initiator_ingest_response<'a>(
-    own_context: &KKTContext,
-    remote_frame: &KKTFrame,
-    remote_context: &KKTContext,
-    remote_verification_key: &ed25519::PublicKey,
-    expected_hash: &[u8],
-) -> Result<EncapsulationKey<'a>, KKTError> {
-    check_compatibility(own_context, remote_context)?;
-    match remote_context.status() {
-        KKTStatus::Ok => {
-            let mut bytes_to_verify: Vec<u8> = Vec::with_capacity(
-                remote_context.full_message_len() - remote_context.signature_len(),
-            );
-            bytes_to_verify.extend_from_slice(&remote_context.encode()?);
-            bytes_to_verify.extend_from_slice(remote_frame.body_ref());
-            bytes_to_verify.extend_from_slice(remote_frame.session_id_ref());
-
-            match Signature::from_bytes(remote_frame.signature_ref()) {
-                Ok(sig) => match remote_verification_key.verify(bytes_to_verify, &sig) {
-                    Ok(()) => {
-                        let received_encapsulation_key = EncapsulationKey::decode(
-                            own_context.ciphersuite().kem(),
-                            remote_frame.body_ref(),
-                        )?;
-
-                        match validate_encapsulation_key(
-                            &own_context.ciphersuite().hash_function(),
-                            own_context.ciphersuite().hash_len(),
-                            remote_frame.body_ref(),
-                            expected_hash,
-                        ) {
-                            true => Ok(received_encapsulation_key),
-
-                            // The key does not match the hash obtained from the directory
-                            false => Err(KKTError::KEMError {
-                                info: "Hash of received encapsulation key does not match the value stored on the directory.",
-                            }),
-                        }
-                    }
-                    Err(_) => Err(KKTError::SigVerifError),
-                },
-                Err(_) => Err(KKTError::SigConstructorError),
-            }
-        }
-        _ => Err(KKTError::ResponderFlaggedError {
-            status: remote_context.status(),
-        }),
-    }
-}
-
-// todo: figure out how to handle errors using status codes
-
-pub fn responder_ingest_message<'a>(
-    remote_context: &KKTContext,
-    remote_verification_key: Option<&ed25519::PublicKey>,
-    expected_hash: Option<&[u8]>,
-    remote_frame: &KKTFrame,
-) -> Result<(KKTContext, Option<EncapsulationKey<'a>>), KKTError> {
-    let own_context = remote_context.derive_responder_header()?;
-
-    match remote_context.role() {
-        KKTRole::AnonymousInitiator => Ok((own_context, None)),
-
-        KKTRole::Initiator => {
-            match remote_verification_key {
-                Some(remote_verif_key) => {
-                    let mut bytes_to_verify: Vec<u8> = Vec::with_capacity(
-                        own_context.full_message_len() - own_context.signature_len(),
-                    );
-                    bytes_to_verify.extend_from_slice(remote_frame.context_ref());
-                    bytes_to_verify.extend_from_slice(remote_frame.body_ref());
-                    bytes_to_verify.extend_from_slice(remote_frame.session_id_ref());
-
-                    match Signature::from_bytes(remote_frame.signature_ref()) {
-                        Ok(sig) => match remote_verif_key.verify(bytes_to_verify, &sig) {
-                            Ok(()) => {
-                                // using own_context here because maybe for whatever reason we want to ignore the remote kem key
-                                match own_context.mode() {
-                                    KKTMode::OneWay => Ok((own_context, None)),
-                                    KKTMode::Mutual => {
-                                        match expected_hash {
-                                            Some(expected_hash) => {
-                                                let received_encapsulation_key =
-                                                    EncapsulationKey::decode(
-                                                        own_context.ciphersuite().kem(),
-                                                        remote_frame.body_ref(),
-                                                    )?;
-                                                if validate_encapsulation_key(
-                                                    &own_context.ciphersuite().hash_function(),
-                                                    own_context.ciphersuite().hash_len(),
-                                                    remote_frame.body_ref(),
-                                                    expected_hash,
-                                                ) {
-                                                    Ok((
-                                                        own_context,
-                                                        Some(received_encapsulation_key),
-                                                    ))
-                                                }
-                                                // The key does not match the hash obtained from the directory
-                                                else {
-                                                    Err(KKTError::KEMError {
-                                                        info: "Hash of received encapsulation key does not match the value stored on the directory.",
-                                                    })
-                                                }
-                                            }
-                                            None => Err(KKTError::FunctionInputError {
-                                                info: "Expected hash of the remote encapsulation key is not provided.",
-                                            }),
-                                        }
-                                    }
-                                }
-                            }
-                            Err(_) => Err(KKTError::SigVerifError),
-                        },
-                        Err(_) => Err(KKTError::SigConstructorError),
-                    }
-                }
-                None => Err(KKTError::FunctionInputError {
-                    info: "Remote Signature Verification Key Not Provided",
-                }),
-            }
-        }
-        KKTRole::Responder => Err(KKTError::IncompatibilityError {
-            info: "Responder received a request from another responder.",
-        }),
-    }
-}
-
-pub fn responder_process<'a>(
-    own_context: &KKTContext,
-    session_id: KKTSessionId,
-    signing_key: &ed25519::PrivateKey,
-    encapsulation_key: &EncapsulationKey<'a>,
-) -> Result<KKTFrame, KKTError> {
-    let body = encapsulation_key.encode();
-
-    let context_bytes = own_context.encode()?;
-
-    let mut bytes_to_sign =
-        Vec::with_capacity(own_context.full_message_len() - own_context.signature_len());
-    bytes_to_sign.extend_from_slice(&own_context.encode()?);
-    bytes_to_sign.extend_from_slice(&body);
-    bytes_to_sign.extend_from_slice(&session_id);
-
-    let signature = signing_key.sign(bytes_to_sign).to_bytes();
-
-    Ok(KKTFrame::new(context_bytes, &body, session_id, &signature))
-}
-
-fn check_compatibility(
-    _own_context: &KKTContext,
-    _remote_context: &KKTContext,
-) -> Result<(), KKTError> {
-    // todo: check ciphersuite/context compatibility
-    Ok(())
-}

common/nym-lp-common/Cargo.toml

@@ -1,8 +0,0 @@
-[package]
-name = "nym-lp-common"
-version = "0.1.0"
-edition = { workspace = true }
-license = { workspace = true }
-publish = false
-
-[dependencies]

common/nym-lp-transport/src/traits.rs

@@ -1,139 +0,0 @@
-// Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
-// SPDX-License-Identifier: Apache-2.0
-
-#[cfg(feature = "io-mocks")]
-use nym_test_utils::mocks::async_read_write::MockIOStream;
-use std::net::SocketAddr;
-use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
-use tokio::net::TcpStream;
-use tracing::debug;
-
-// only used in internal code (and tests)
-#[allow(async_fn_in_trait)]
-pub trait LpTransport: Sized {
-    async fn connect(endpoint: SocketAddr) -> std::io::Result<Self>;
-
-    fn set_no_delay(&mut self, nodelay: bool) -> std::io::Result<()>;
-
-    /// Sends a serialised (and optionally encrypted) LP packet over the data stream with length-prefixed framing.
-    ///
-    /// Format: 4-byte big-endian u32 length + packet bytes
-    ///
-    /// # Arguments
-    /// * `packet_data` - The serialised LP packet to send
-    ///
-    /// # Errors
-    /// Returns an error on network transmission fails.
-    async fn send_serialised_packet(&mut self, packet_data: &[u8]) -> std::io::Result<()>;
-
-    /// Receives an LP packet from a TCP stream with length-prefixed framing.
-    ///
-    /// Format: 4-byte big-endian u32 length + packet bytes
-    ///
-    /// # Errors
-    /// Returns an error on network transmission fails.
-    async fn receive_raw_packet(&mut self) -> std::io::Result<Vec<u8>>;
-}
-
-async fn send_serialised_packet_async_write<W>(
-    writer: &mut W,
-    packet_data: &[u8],
-) -> std::io::Result<()>
-where
-    W: AsyncWrite + Unpin,
-{
-    // Send 4-byte length prefix (u32 big-endian)
-    let len = packet_data.len() as u32;
-    writer
-        .write_all(&len.to_be_bytes())
-        .await
-        .inspect_err(|e| debug!("Failed to send packet length: {e}"))?;
-
-    // Send the actual packet data
-    writer
-        .write_all(packet_data)
-        .await
-        .inspect_err(|e| debug!("Failed to send packet data: {e}"))?;
-
-    // Flush to ensure data is sent immediately
-    writer
-        .flush()
-        .await
-        .inspect_err(|e| debug!("Failed to flush stream: {e}"))?;
-
-    tracing::trace!(
-        "Sent LP packet ({} bytes + 4 byte header)",
-        packet_data.len()
-    );
-    Ok(())
-}
-
-async fn receive_raw_packet_async_read<R>(reader: &mut R) -> std::io::Result<Vec<u8>>
-where
-    R: AsyncRead + Unpin,
-{
-    // Read 4-byte length prefix (u32 big-endian)
-    let mut len_buf = [0u8; 4];
-    reader
-        .read_exact(&mut len_buf)
-        .await
-        .inspect_err(|e| debug!("Failed to read packet length: {e}"))?;
-
-    let packet_len = u32::from_be_bytes(len_buf) as usize;
-
-    // Sanity check to prevent huge allocations
-    const MAX_PACKET_SIZE: usize = 65536; // 64KB max
-    if packet_len > MAX_PACKET_SIZE {
-        return Err(std::io::Error::other(format!(
-            "Packet size {packet_len} exceeds maximum {MAX_PACKET_SIZE}",
-        )));
-    }
-
-    // Read the actual packet data
-    let mut packet_buf = vec![0u8; packet_len];
-    reader
-        .read_exact(&mut packet_buf)
-        .await
-        .inspect_err(|e| debug!("Failed to read packet data: {e}"))?;
-
-    tracing::trace!("Received LP packet ({packet_len} bytes + 4 byte header)");
-    Ok(packet_buf)
-}
-
-impl LpTransport for TcpStream {
-    async fn connect(endpoint: SocketAddr) -> std::io::Result<Self> {
-        TcpStream::connect(endpoint).await
-    }
-
-    fn set_no_delay(&mut self, nodelay: bool) -> std::io::Result<()> {
-        // Set TCP_NODELAY for low latency
-        self.set_nodelay(nodelay)
-    }
-
-    async fn send_serialised_packet(&mut self, packet_data: &[u8]) -> std::io::Result<()> {
-        send_serialised_packet_async_write(self, packet_data).await
-    }
-
-    async fn receive_raw_packet(&mut self) -> std::io::Result<Vec<u8>> {
-        receive_raw_packet_async_read(self).await
-    }
-}
-
-#[cfg(feature = "io-mocks")]
-impl LpTransport for MockIOStream {
-    async fn connect(_endpoint: SocketAddr) -> std::io::Result<Self> {
-        Ok(MockIOStream::default())
-    }
-
-    fn set_no_delay(&mut self, _nodelay: bool) -> std::io::Result<()> {
-        Ok(())
-    }
-
-    async fn send_serialised_packet(&mut self, packet_data: &[u8]) -> std::io::Result<()> {
-        send_serialised_packet_async_write(self, packet_data).await
-    }
-
-    async fn receive_raw_packet(&mut self) -> std::io::Result<Vec<u8>> {
-        receive_raw_packet_async_read(self).await
-    }
-}

common/nym-lp/Cargo.toml

@@ -7,50 +7,36 @@ publish = false
 
 [dependencies]
 thiserror = { workspace = true }
-parking_lot = { workspace = true }
-snow = { workspace = true }
 bs58 = { workspace = true }
-serde = { workspace = true }
 bytes = { workspace = true }
-dashmap = { workspace = true }
-sha2 = { workspace = true }
 tracing = { workspace = true }
-rand = { workspace = true }
-# rand 0.9 for KKT integration (nym-kkt uses rand 0.9)
 rand09 = { workspace = true }
+tls_codec = { workspace =  true }
+tokio = { workspace = true, features = ["net", "io-util"] }
 
-nym-crypto = { path = "../crypto", features = ["hashing", "asymmetric"] }
+nym-crypto = { path = "../crypto", features = ["hashing"] }
 nym-kkt = { path = "../nym-kkt" }
-nym-lp-common = { path = "../nym-lp-common" }
-nym-lp-transport = { path = "../nym-lp-transport" }
+nym-kkt-ciphersuite = { workspace = true }
 
 # libcrux dependencies for PSQ (Post-Quantum PSK derivation)
-libcrux-psq = { git = "https://github.com/cryspen/libcrux", features = [
-    "test-utils",
-] }
-libcrux-kem = { git = "https://github.com/cryspen/libcrux" }
-libcrux-traits = { git = "https://github.com/cryspen/libcrux" }
-tls_codec = { workspace = true }
+libcrux-psq = { workspace = true, features = ["test-utils"] }
 num_enum = { workspace = true }
-chacha20poly1305 = { workspace = true }
 zeroize = { workspace = true, features = ["zeroize_derive"] }
 
+
 # needed for the 'mock 'feature
 nym-test-utils = { workspace = true, optional = true }
 
 [dev-dependencies]
 criterion = { version = "0.5", features = ["html_reports"] }
-#rand_chacha = "0.3"
-mock_instant = { workspace = true }
-nym-crypto = { path = "../crypto", features = ["rand"] }
 nym-test-utils = { workspace = true }
 anyhow = { workspace = true }
 tokio = { workspace = true, features = ["rt-multi-thread", "macros"] }
-nym-lp-transport = { path = "../nym-lp-transport", features = ["io-mocks"] }
+
 
 [features]
-mock = ["nym-test-utils", "nym-crypto/rand"]
+mock = ["nym-test-utils"]
 
 [[bench]]
 name = "replay_protection"
-harness = false
+harness = false

common/nym-lp/benches/replay_protection.rs

@@ -1,9 +1,8 @@
 use criterion::{BenchmarkId, Criterion, Throughput, black_box, criterion_group, criterion_main};
 use nym_lp::replay::ReceivingKeyCounterValidator;
-use nym_test_utils::helpers::u64_seeded_rng;
-use parking_lot::Mutex;
-use rand::Rng;
-use std::sync::Arc;
+use nym_test_utils::helpers::deterministic_rng_09;
+use rand09::Rng;
+use std::sync::{Arc, Mutex};
 
 fn bench_sequential_counters(c: &mut Criterion) {
     let mut group = c.benchmark_group("replay_sequential");
@@ -47,8 +46,8 @@ fn bench_out_of_order_counters(c: &mut Criterion) {
                 let validator = ReceivingKeyCounterValidator::default();
 
                 // Create random counters within a valid window
-                let mut rng = u64_seeded_rng(42);
-                let counters: Vec<u64> = (0..size).map(|_| rng.gen_range(0..1024)).collect();
+                let mut rng = deterministic_rng_09();
+                let counters: Vec<u64> = (0..size).map(|_| rng.random_range(0..1024)).collect();
 
                 b.iter(|| {
                     let mut validator = validator.clone();
@@ -75,19 +74,15 @@ fn bench_thread_safety(c: &mut Criterion) {
             BenchmarkId::new("thread_safe_validator", size),
             &size,
             |b, &size| {
-                let validator = Arc::new(Mutex::new(ReceivingKeyCounterValidator::default()));
+                let mut validator = ReceivingKeyCounterValidator::default();
                 let counters: Vec<u64> = (0..size).collect();
 
                 b.iter(|| {
                     for &counter in &counters {
-                        let result = {
-                            let guard = validator.lock();
-                            black_box(guard.will_accept_branchless(counter))
-                        };
+                        let result = { black_box(validator.will_accept_branchless(counter)) };
 
                         if result.is_ok() {
-                            let mut guard = validator.lock();
-                            let _ = black_box(guard.mark_did_receive_branchless(counter));
+                            let _ = black_box(validator.mark_did_receive_branchless(counter));
                         }
                     }
                 });
@@ -202,7 +197,7 @@ fn bench_concurrency_scaling(c: &mut Criterion) {
                             let mut success_count = 0;
                             for i in 0..100 {
                                 let counter = t * 1000 + i;
-                                let mut guard = validator_clone.lock();
+                                let mut guard = validator_clone.lock().unwrap();
                                 if guard.mark_did_receive_branchless(counter as u64).is_ok() {
                                     success_count += 1;
                                 }

common/nym-lp/src/config.rs

@@ -18,7 +18,7 @@ pub const DEFAULT_PSK_TTL_SECS: u64 = 3600;
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct LpConfig {
     /// KEM algorithm for PSQ key encapsulation.
-    /// X25519 = classical (testing), MlKem768 = PQ, XWing = hybrid.
+    /// Supported KEMs: MlKem768, McEliece
     #[serde(with = "kem_serde")]
     pub kem_algorithm: KEM,
 
@@ -32,7 +32,7 @@ pub struct LpConfig {
 impl Default for LpConfig {
     fn default() -> Self {
         Self {
-            kem_algorithm: KEM::X25519,
+            kem_algorithm: KEM::MlKem768,
             psk_ttl_secs: DEFAULT_PSK_TTL_SECS,
             enable_kkt: true,
         }
@@ -55,10 +55,10 @@ mod kem_serde {
         S: Serializer,
     {
         match kem {
-            KEM::X25519 => "X25519",
             KEM::MlKem768 => "MlKem768",
-            KEM::XWing => "XWing",
             KEM::McEliece => "McEliece",
+            KEM::X25519 => return Err(serde::ser::Error::custom("Unsupported KEM: X25519")),
+            KEM::XWing => return Err(serde::ser::Error::custom("Unsupported KEM: XWing")),
         }
         .serialize(serializer)
     }
@@ -69,10 +69,10 @@ mod kem_serde {
     {
         let s = String::deserialize(deserializer)?;
         match s.as_str() {
-            "X25519" => Ok(KEM::X25519),
             "MlKem768" => Ok(KEM::MlKem768),
-            "XWing" => Ok(KEM::XWing),
             "McEliece" => Ok(KEM::McEliece),
+            "X25519" => Err(serde::de::Error::custom("Unsupported KEM: X25519")),
+            "XWing" => Err(serde::de::Error::custom("Unsupported KEM: XWing")),
             _ => Err(serde::de::Error::custom(format!("Unknown KEM: {}", s))),
         }
     }

common/nym-lp/src/error.rs

@@ -1,11 +1,16 @@
 // Copyright 2025 - Nym Technologies SA <contact@nymtech.net>
 // SPDX-License-Identifier: Apache-2.0
 
-use crate::message::MessageType;
-use crate::{noise_protocol::NoiseError, replay::ReplayError};
-use nym_crypto::asymmetric::ed25519::Ed25519RecoveryError;
-use nym_kkt::ciphersuite::{HashFunction, KEM};
+use crate::packet::MalformedLpPacketError;
+use crate::peer_config::LpReceiverIndex;
+use crate::replay::ReplayError;
+use crate::transport::LpTransportError;
+use libcrux_psq::handshake::HandshakeError;
+use libcrux_psq::handshake::builders::BuilderError;
+use libcrux_psq::session::SessionError;
+// use nym_crypto::asymmetric::ed25519::Ed25519RecoveryError;
 use nym_kkt::error::KKTError;
+use nym_kkt_ciphersuite::{HashFunction, KEM};
 use thiserror::Error;
 
 #[derive(Error, Debug)]
@@ -13,33 +18,18 @@ pub enum LpError {
     #[error("IO Error: {0}")]
     IoError(#[from] std::io::Error),
 
-    #[error("Snow Error: {0}")]
-    SnowKeyError(#[from] snow::Error),
-
-    #[error("Snow Pattern Error: {0}")]
-    SnowPatternError(String),
-
-    #[error("Noise Protocol Error: {0}")]
-    NoiseError(#[from] NoiseError),
-
     #[error("Replay detected: {0}")]
     Replay(#[from] ReplayError),
 
-    #[error("Invalid packet format: {0}")]
-    InvalidPacketFormat(String),
-
-    #[error("Invalid message type: {0}")]
-    InvalidMessageType(u32),
-
-    #[error("Payload too large: {0}")]
-    PayloadTooLarge(usize),
-
     #[error("Insufficient buffer size provided")]
     InsufficientBufferSize,
 
     #[error("Attempted operation on closed session")]
     SessionClosed,
 
+    #[error("There already exists an LP session with receiver index {0}")]
+    DuplicateSessionId(LpReceiverIndex),
+
     #[error("Internal error: {0}")]
     Internal(String),
 
@@ -52,15 +42,12 @@ pub enum LpError {
     #[error("Deserialization error: {0}")]
     DeserializationError(String),
 
-    #[error("KKT protocol error: {0}")]
-    KKTError(String),
-
     #[error(transparent)]
     InvalidBase58String(#[from] bs58::decode::Error),
 
     /// Session ID from incoming packet does not match any known session.
     #[error("Received packet with unknown session ID: {0}")]
-    UnknownSessionId(u32),
+    UnknownSessionId(LpReceiverIndex),
 
     /// Invalid state transition attempt in the state machine.
     #[error("Invalid input '{input}' for current state '{state}'")]
@@ -75,27 +62,14 @@ pub enum LpError {
     LpSessionProcessing,
 
     /// State machine not found.
-    #[error("State machine not found for lp_id: {lp_id}")]
-    StateMachineNotFound { lp_id: u32 },
+    #[error("State machine not found for lp_id: {0}")]
+    StateMachineNotFound(LpReceiverIndex),
 
-    /// Ed25519 to X25519 conversion error.
-    #[error("Ed25519 key conversion error: {0}")]
-    Ed25519RecoveryError(#[from] Ed25519RecoveryError),
-
-    /// Outer AEAD authentication tag verification failed.
-    #[error("AEAD authentication tag verification failed")]
-    AeadTagMismatch,
-
-    /// Received an LP packet with an incompatible, future, version
-    #[error("incompatible LP packet version. got: {got}, highest supported: {highest_supported}")]
-    IncompatibleFuturePacketVersion { got: u8, highest_supported: u8 },
-
-    /// Received an LP packet with an incompatible, legacy, version
-    #[error("incompatible LP packet version. got: {got}, lowest supported: {lowest_supported}")]
-    IncompatibleLegacyPacketVersion { got: u8, lowest_supported: u8 },
-
-    #[error("attempted to create an LP responder without providing a valid KEM key")]
-    ResponderWithMissingKEMKey,
+    // /// Ed25519 to X25519 conversion error.
+    // #[error("Ed25519 key conversion error: {0}")]
+    // Ed25519RecoveryError(#[from] Ed25519RecoveryError),
+    #[error("attempted to create an LP responder without providing a valid KEM keys")]
+    ResponderWithMissingKEMKeys,
 
     #[error(
         "there are no known digests for remote's KEM key with {kem} KEM and {hash_function} hash function"
@@ -113,16 +87,56 @@ pub enum LpError {
         #[from]
         source: KKTError,
     },
+
+    #[error(transparent)]
+    MalformedPacket(#[from] MalformedLpPacketError),
+
+    #[error("version {version} is not supported")]
+    UnsupportedVersion { version: u8 },
+
+    #[error("failed to build PSQ responder: {inner:?}")]
+    PSQResponderBuilderFailure { inner: BuilderError },
+
+    #[error("failed to build PSQ initiator: {inner:?}")]
+    PSQInitiatorBuilderFailure { inner: BuilderError },
+
+    #[error("failed to complete the PSQ handshake: {inner:?}")]
+    PSQHandshakeFailure { inner: HandshakeError },
+
+    #[error("failed to run the PSQ session: {inner:?}")]
+    PSQSessionFailure { inner: SessionError },
+
+    #[error("failed to derive a transport channel: {inner:?}")]
+    TransportDerivationFailure { inner: SessionError },
+
+    #[error("the initiator authenticator is not available after ingesting PSQ msg1")]
+    MissingInitiatorAuthenticator,
+
+    #[error("transport failure: {0}")]
+    TransportFailure(#[from] LpTransportError),
+
+    #[error("the current session is not in transport state")]
+    NotInTransport,
 }
 
 impl LpError {
     pub fn kkt_psq_handshake(msg: impl Into<String>) -> Self {
         Self::KKTPSQHandshake(msg.into())
     }
+}
 
-    pub fn unexpected_handshake_response(got: MessageType, expected: MessageType) -> LpError {
-        Self::KKTPSQHandshake(format!(
-            "received unexpected response, got: {got:?}, expected: {expected:?}"
-        ))
+impl From<HandshakeError> for LpError {
+    fn from(handshake_error: HandshakeError) -> Self {
+        Self::PSQHandshakeFailure {
+            inner: handshake_error,
+        }
+    }
+}
+
+impl From<SessionError> for LpError {
+    fn from(session_error: SessionError) -> Self {
+        Self::PSQSessionFailure {
+            inner: session_error,
+        }
     }
 }

common/nym-lp/src/kkt_orchestrator.rs

@@ -1,492 +0,0 @@
-// Copyright 2025 - Nym Technologies SA <contact@nymtech.net>
-// SPDX-License-Identifier: Apache-2.0
-
-//! KKT (Key Encapsulation Transport) orchestration for nym-lp sessions.
-//!
-//! This module provides functions to perform KKT key exchange before establishing
-//! an nym-lp session. The KKT protocol allows secure distribution of post-quantum
-//! KEM public keys, which are then used with PSQ to derive a strong pre-shared key
-//! for the Noise protocol.
-//!
-//! # Protocol Flow
-//!
-//! 1. **Client (Initiator)**:
-//!    - Calls `create_request()` to generate a KKT request
-//!    - Sends `LpMessage::KKTRequest` to gateway
-//!    - Receives `LpMessage::KKTResponse` from gateway
-//!    - Calls `process_response()` to validate and extract gateway's KEM key
-//!
-//! 2. **Gateway (Responder)**:
-//!    - Receives `LpMessage::KKTRequest` from client
-//!    - Calls `handle_request()` to validate request and generate response
-//!    - Sends `LpMessage::KKTResponse` to client
-//!
-//! # Example
-//!
-//! ```ignore
-//! use nym_lp::kkt_orchestrator::{create_request, process_response, handle_request};
-//! use nym_lp::message::{KKTRequestData, KKTResponseData};
-//! use nym_kkt::ciphersuite::{Ciphersuite, KEM, HashFunction, SignatureScheme, EncapsulationKey};
-//!
-//! // Setup ciphersuite
-//! let ciphersuite = Ciphersuite::resolve_ciphersuite(
-//!     KEM::X25519,
-//!     HashFunction::Blake3,
-//!     SignatureScheme::Ed25519,
-//!     None,
-//! ).unwrap();
-//!
-//! // Client: Create request
-//! let (session_secret, client_context, request_data) = create_request(
-//!     ciphersuite,
-//!     &client_signing_key,
-//!     &responder_dh_public_key
-//! ).unwrap();
-//!
-//! // Gateway: Handle request
-//! let response_data = handle_request(
-//!     &request_data,
-//!     Some(&client_verification_key),
-//!     &gateway_signing_key,
-//!     &gateway_dh_private_key,
-//!     &gateway_kem_public_key,
-//! ).unwrap();
-//!
-//! // Client: Process response
-//! let gateway_kem_key = process_response(
-//!     client_context,
-//!     &session_secret,
-//!     &gateway_verification_key,
-//!     &expected_key_hash,
-//!     &response_data,
-//! ).unwrap();
-//! ```
-
-use crate::LpError;
-use crate::message::{KKTRequestData, KKTResponseData};
-use nym_crypto::asymmetric::{ed25519, x25519};
-use nym_kkt::ciphersuite::{Ciphersuite, EncapsulationKey};
-use nym_kkt::context::KKTContext;
-use nym_kkt::encryption::KKTSessionSecret;
-use nym_kkt::kkt::{handle_kem_request, request_kem_key, validate_kem_response};
-
-/// Creates a KKT request to obtain the responder's KEM public key.
-///
-/// This is called by the **client (initiator)** to begin the KKT exchange.
-/// The returned context must be used when processing the response.
-///
-/// # Arguments
-/// * `ciphersuite` - Negotiated ciphersuite (KEM, hash, signature algorithms)
-/// * `signing_key` - Client's Ed25519 signing key for authentication
-/// * `responder_dh_public_key` - Gateway's x25519 public key (from directory)
-///
-/// # Returns
-/// * `KKTSessionSecret` - Session secret key to encrypt/decrypt KKT messages for this session
-/// * `KKTContext` - Context to use when validating the response
-/// * `KKTRequestData` - Serialized KKT request frame to send to gateway
-///
-/// # Errors
-/// Returns `LpError::KKTError` if KKT request generation fails.
-pub fn create_request(
-    ciphersuite: Ciphersuite,
-    signing_key: &ed25519::PrivateKey,
-    responder_dh_public_key: &x25519::PublicKey,
-) -> Result<(KKTSessionSecret, KKTContext, KKTRequestData), LpError> {
-    // Note: Uses rand 0.9's thread_rng() to match nym-kkt's rand version
-    let mut rng = rand09::rng();
-    let (session_secret, context, request_bytes) =
-        request_kem_key(&mut rng, ciphersuite, signing_key, responder_dh_public_key)
-            .map_err(|e| LpError::KKTError(e.to_string()))?;
-
-    Ok((session_secret, context, KKTRequestData(request_bytes)))
-}
-
-/// Processes a KKT response and extracts the responder's KEM public key.
-///
-/// This is called by the **client (initiator)** after receiving a KKT response
-/// from the gateway. It verifies the signature and validates the key hash.
-///
-/// # Arguments
-/// * `context` - Context from the initial `create_request()` call
-/// * `session_secret` - The KKT session secret key from the initial `create_request()` call
-/// * `responder_vk` - Responder's Ed25519 verification key (from directory)
-/// * `expected_key_hash` - Expected hash of responder's KEM key (from directory)
-/// * `response_data` - Serialized KKT response frame from responder
-///
-/// # Returns
-/// * `EncapsulationKey` - Authenticated KEM public key of the responder
-///
-/// # Errors
-/// Returns `LpError::KKTError` if:
-/// - Response deserialization fails
-/// - Signature verification fails
-/// - Key hash doesn't match expected value
-pub fn process_response<'a>(
-    mut context: KKTContext,
-    session_secret: &KKTSessionSecret,
-    responder_vk: &ed25519::PublicKey,
-    expected_key_hash: &[u8],
-    response_data: &KKTResponseData,
-) -> Result<EncapsulationKey<'a>, LpError> {
-    validate_kem_response(
-        &mut context,
-        session_secret,
-        responder_vk,
-        expected_key_hash,
-        &response_data.0,
-    )
-    .map_err(|e| LpError::KKTError(e.to_string()))
-}
-
-/// Handles a KKT request and generates a signed response with the responder's KEM key.
-///
-/// This is called by the **gateway (responder)** when receiving a KKT request
-/// from a client. It validates the request signature (if authenticated) and
-/// responds with the gateway's KEM public key, signed for authenticity.
-///
-/// # Arguments
-/// * `request_data` - Serialized KKT request frame from initiator
-/// * `initiator_vk` - Initiator's Ed25519 verification key (None for anonymous)
-/// * `responder_signing_key` - Gateway's Ed25519 signing key
-/// * `responder_dh_private_key` - Gateway's x25519 private key
-/// * `responder_kem_key` - Gateway's KEM public key to send
-///
-/// # Returns
-/// * `KKTResponseData` - Signed response frame containing the KEM public key
-///
-/// # Errors
-/// Returns `LpError::KKTError` if:
-/// - Request deserialization fails
-/// - Signature verification fails (if authenticated)
-/// - Response generation fails
-pub fn handle_request<'a>(
-    request_data: &KKTRequestData,
-    initiator_vk: Option<&ed25519::PublicKey>,
-    responder_signing_key: &ed25519::PrivateKey,
-    responder_dh_private_key: &x25519::PrivateKey,
-    responder_kem_key: &EncapsulationKey<'a>,
-) -> Result<KKTResponseData, LpError> {
-    let mut rng = rand09::rng();
-    // Handle the request and generate response
-    let response_bytes = handle_kem_request(
-        &mut rng,
-        &request_data.0,
-        initiator_vk,
-        responder_signing_key,
-        responder_dh_private_key,
-        responder_kem_key,
-    )
-    .map_err(|e| LpError::KKTError(e.to_string()))?;
-
-    Ok(KKTResponseData(response_bytes))
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use crate::peer::mock_peers;
-    use nym_kkt::ciphersuite::{HashFunction, KEM, SignatureScheme};
-    use nym_kkt::key_utils::{
-        generate_keypair_ed25519, generate_keypair_libcrux, generate_keypair_x25519,
-        hash_encapsulation_key,
-    };
-    use rand09::RngCore;
-
-    #[test]
-    fn test_kkt_roundtrip_authenticated() {
-        let mut rng = rand09::rng();
-
-        // Generate Ed25519 keypairs for both parties
-        let initiator_ed25519_keypair = generate_keypair_ed25519(&mut rng, Some(0));
-        let responder_ed25519_keypair = generate_keypair_ed25519(&mut rng, Some(1));
-
-        let responder_x25519 = generate_keypair_x25519(&mut rng);
-
-        // Generate responder's KEM keypair (X25519 for testing)
-        let (_, responder_kem_pk) = generate_keypair_libcrux(&mut rng, KEM::X25519).unwrap();
-        let responder_kem_key = EncapsulationKey::X25519(responder_kem_pk);
-
-        // Create ciphersuite
-        let ciphersuite = Ciphersuite::resolve_ciphersuite(
-            KEM::X25519,
-            HashFunction::Blake3,
-            SignatureScheme::Ed25519,
-            None,
-        )
-        .unwrap();
-
-        // Hash the KEM key (simulating directory storage)
-        let key_hash = hash_encapsulation_key(
-            &ciphersuite.hash_function(),
-            ciphersuite.hash_len(),
-            &responder_kem_key.encode(),
-        );
-
-        // Client: Create request
-        let (session_secret, context, request_data) = create_request(
-            ciphersuite,
-            initiator_ed25519_keypair.private_key(),
-            responder_x25519.public_key(),
-        )
-        .unwrap();
-
-        // Gateway: Handle request
-        let response_data = handle_request(
-            &request_data,
-            Some(initiator_ed25519_keypair.public_key()),
-            responder_ed25519_keypair.private_key(),
-            responder_x25519.private_key(),
-            &responder_kem_key,
-        )
-        .unwrap();
-
-        // Client: Process response
-        let obtained_key = process_response(
-            context,
-            &session_secret,
-            responder_ed25519_keypair.public_key(),
-            &key_hash,
-            &response_data,
-        )
-        .unwrap();
-
-        // Verify we got the correct KEM key
-        assert_eq!(obtained_key.encode(), responder_kem_key.encode());
-    }
-
-    // #[test]
-    // fn test_kkt_roundtrip_anonymous() {
-    //     let mut rng = rand09::rng();
-
-    //     // Only responder has keys (anonymous initiator)
-    //     // Generate Ed25519 keypairs for both parties
-
-    //     let responder_ed25519_keypair = generate_keypair_ed25519(&mut rng, Some(1));
-
-    //             let responder_x25519 = generate_keypair_x25519(&mut rng);
-
-    //     let (_, responder_kem_pk) = generate_keypair_libcrux(&mut rng, KEM::X25519).unwrap();
-    //     let responder_kem_key = EncapsulationKey::X25519(responder_kem_pk);
-
-    //     let ciphersuite = Ciphersuite::resolve_ciphersuite(
-    //         KEM::X25519,
-    //         HashFunction::Blake3,
-    //         SignatureScheme::Ed25519,
-    //         None,
-    //     )
-    //     .unwrap();
-
-    //     let key_hash = hash_encapsulation_key(
-    //         &ciphersuite.hash_function(),
-    //         ciphersuite.hash_len(),
-    //         &responder_kem_key.encode(),
-    //     );
-
-    //     // Anonymous initiator - use anonymous_initiator_process directly
-    //     use nym_kkt::kkt::anonymous_initiator_process;
-    //     let (mut context, request_frame) =
-    //         anonymous_initiator_process(&mut rng, ciphersuite).unwrap();
-    //     let request_data = KKTRequestData(request_frame.to_bytes());
-
-    //     // Gateway: Handle anonymous request
-    //     let response_data = handle_request(
-    //         &request_data,
-    //         None,
-    //         responder_ed25519_keypair.private_key(),
-    //         &responder_x25519_sk,
-    //         &responder_kem_key,
-    //     )
-    //     .unwrap();
-
-    //     // Initiator: Validate response
-    //     let obtained_key = initiator_ingest_response(
-    //         &mut context,
-    //         responder_ed25519_keypair.public_key(),
-    //         &key_hash,
-    //         &response_data.0,
-    //     )
-    //     .unwrap();
-
-    //     assert_eq!(obtained_key.encode(), responder_kem_key.encode());
-    // }
-
-    #[test]
-    fn test_invalid_signature_rejected() {
-        let mut rng = rand09::rng();
-
-        // Generate Ed25519 keypairs for both parties
-        let initiator_ed25519_keypair = generate_keypair_ed25519(&mut rng, Some(0));
-        let responder_ed25519_keypair = generate_keypair_ed25519(&mut rng, Some(1));
-
-        let responder_x25519 = generate_keypair_x25519(&mut rng);
-
-        // Different keypair for wrong signature
-        let mut wrong_secret = [0u8; 32];
-        rng.fill_bytes(&mut wrong_secret);
-        let wrong_keypair = ed25519::KeyPair::from_secret(wrong_secret, 2);
-
-        let (_, responder_kem_pk) = generate_keypair_libcrux(&mut rng, KEM::X25519).unwrap();
-        let responder_kem_key = EncapsulationKey::X25519(responder_kem_pk);
-
-        let ciphersuite = Ciphersuite::resolve_ciphersuite(
-            KEM::X25519,
-            HashFunction::Blake3,
-            SignatureScheme::Ed25519,
-            None,
-        )
-        .unwrap();
-
-        let (_session_secret, _context, request_data) = create_request(
-            ciphersuite,
-            initiator_ed25519_keypair.private_key(),
-            responder_x25519.public_key(),
-        )
-        .unwrap();
-
-        // Gateway handles request but we provide WRONG verification key
-        let result = handle_request(
-            &request_data,
-            Some(wrong_keypair.public_key()), // Wrong key!
-            responder_ed25519_keypair.private_key(),
-            responder_x25519.private_key(),
-            &responder_kem_key,
-        );
-
-        // Should fail signature verification
-        assert!(result.is_err());
-        if let Err(LpError::KKTError(_)) = result {
-            // Expected
-        } else {
-            panic!("Expected KKTError");
-        }
-    }
-
-    #[test]
-    fn test_hash_mismatch_rejected() {
-        let (init, resp) = mock_peers();
-        let responder_kem_key = resp.encapsulate_kem_key().unwrap();
-
-        let ciphersuite = Ciphersuite::resolve_ciphersuite(
-            KEM::X25519,
-            HashFunction::Blake3,
-            SignatureScheme::Ed25519,
-            None,
-        )
-        .unwrap();
-
-        // Use WRONG hash
-        let wrong_hash = [0u8; 32];
-
-        let (session_secret, context, request_data) = create_request(
-            ciphersuite,
-            init.ed25519.private_key(),
-            resp.x25519.public_key(),
-        )
-        .unwrap();
-
-        let response_data = handle_request(
-            &request_data,
-            Some(init.ed25519.public_key()),
-            resp.ed25519.private_key(),
-            resp.x25519.private_key(),
-            &responder_kem_key,
-        )
-        .unwrap();
-
-        // Client validates with WRONG hash
-        let result = process_response(
-            context,
-            &session_secret,
-            resp.ed25519.public_key(),
-            &wrong_hash, // Wrong!
-            &response_data,
-        );
-
-        // Should fail hash validation
-        assert!(result.is_err());
-        if let Err(LpError::KKTError(_)) = result {
-            // Expected
-        } else {
-            panic!("Expected KKTError");
-        }
-    }
-
-    #[test]
-    fn test_malformed_request_rejected() {
-        let mut rng = rand09::rng();
-
-        let mut responder_secret = [0u8; 32];
-        rng.fill_bytes(&mut responder_secret);
-        let responder_ed25519_keypair = generate_keypair_ed25519(&mut rng, Some(1));
-
-        let responder_x25519 = generate_keypair_x25519(&mut rng);
-
-        let (_, responder_kem_pk) = generate_keypair_libcrux(&mut rng, KEM::X25519).unwrap();
-        let responder_kem_key = EncapsulationKey::X25519(responder_kem_pk);
-
-        // Create malformed request data (invalid bytes)
-        let malformed_request = KKTRequestData(vec![0xFF; 100]);
-
-        let result = handle_request(
-            &malformed_request,
-            None,
-            responder_ed25519_keypair.private_key(),
-            responder_x25519.private_key(),
-            &responder_kem_key,
-        );
-
-        // Should fail to parse
-        assert!(result.is_err());
-        if let Err(LpError::KKTError(_)) = result {
-            // Expected
-        } else {
-            panic!("Expected KKTError");
-        }
-    }
-
-    #[test]
-    fn test_malformed_response_rejected() {
-        let mut rng = rand09::rng();
-
-        // Generate Ed25519 keypairs for both parties
-        let initiator_ed25519_keypair = generate_keypair_ed25519(&mut rng, Some(0));
-        let responder_ed25519_keypair = generate_keypair_ed25519(&mut rng, Some(1));
-
-        let responder_x25519 = generate_keypair_x25519(&mut rng);
-
-        let ciphersuite = Ciphersuite::resolve_ciphersuite(
-            KEM::X25519,
-            HashFunction::Blake3,
-            SignatureScheme::Ed25519,
-            None,
-        )
-        .unwrap();
-
-        let (session_secret, context, _request_data) = create_request(
-            ciphersuite,
-            initiator_ed25519_keypair.private_key(),
-            responder_x25519.public_key(),
-        )
-        .unwrap();
-
-        // Create malformed response data
-        let malformed_response = KKTResponseData(vec![0xFF; 100]);
-        let key_hash = [0u8; 32];
-
-        let result = process_response(
-            context,
-            &session_secret,
-            responder_ed25519_keypair.public_key(),
-            &key_hash,
-            &malformed_response,
-        );
-
-        // Should fail to parse
-        assert!(result.is_err());
-        if let Err(LpError::KKTError(_)) = result {
-            // Expected
-        } else {
-            panic!("Expected KKTError");
-        }
-    }
-}

common/nym-lp/src/lib.rs

@@ -2,32 +2,40 @@
 // SPDX-License-Identifier: Apache-2.0
 
 pub mod codec;
-pub mod config;
 pub mod error;
-// pub mod kkt_orchestrator;
-pub mod message;
-pub mod noise_protocol;
 pub mod packet;
 pub mod peer;
-pub mod psk;
-mod psq;
+pub mod peer_config;
+pub mod psq;
 pub mod replay;
 pub mod session;
 mod session_integration;
 pub mod session_manager;
 pub mod state_machine;
+pub mod transport;
 
-pub use config::LpConfig;
 pub use error::LpError;
-pub use message::{ClientHelloData, LpMessage};
-pub use packet::{BOOTSTRAP_RECEIVER_IDX, LpPacket, OuterHeader};
+pub use nym_kkt_ciphersuite::{
+    Ciphersuite, HashFunction, HashLength, KEM, KEMKeyDigests, SignatureScheme,
+};
+
+#[cfg(any(feature = "mock", test))]
 pub use replay::{ReceivingKeyCounterValidator, ReplayError};
 pub use session::LpSession;
 pub use session_manager::SessionManager;
 pub use state_machine::LpStateMachine;
 
-pub const NOISE_PATTERN: &str = "Noise_XKpsk3_25519_ChaChaPoly_SHA256";
-pub const NOISE_PSK_INDEX: u8 = 3;
+#[cfg(any(feature = "mock", test))]
+use nym_test_utils::helpers::u64_seeded_rng_09;
+
+#[cfg(any(feature = "mock", test))]
+use crate::psq::{PSQ_MSG2_SIZE, initiator, psq_msg1_size, responder};
+
+#[cfg(any(feature = "mock", test))]
+use crate::session::PersistentSessionBinding;
+
+#[cfg(any(feature = "mock", test))]
+use libcrux_psq::{Channel, IntoSession};
 
 #[cfg(any(feature = "mock", test))]
 pub struct SessionsMock {
@@ -37,118 +45,103 @@ pub struct SessionsMock {
 
 #[cfg(any(feature = "mock", test))]
 impl SessionsMock {
-    pub fn mock_post_handshake(session_id: u32) -> SessionsMock {
+    pub fn mock_seeded_post_handshake(seed: u64, kem: KEM) -> SessionsMock {
         use crate::peer::mock_peers;
-        use nym_kkt::ciphersuite::{DecapsulationKey, EncapsulationKey};
+        use crate::peer_config::LpReceiverIndex;
+        use rand09::Rng;
 
         let (init, resp) = mock_peers();
         let resp_remote = resp.as_remote();
-        let init_remote = init.as_remote();
-        let salt = [42u8; 32];
-        let session_id_bytes = session_id.to_le_bytes();
+
+        let mut init_rng = u64_seeded_rng_09(seed);
+        let resp_rng = u64_seeded_rng_09(seed + 1);
+
+        let receiver_index: LpReceiverIndex = init_rng.random();
+
+        let kem_keys = resp.kem_keypairs.as_ref().unwrap();
 
         // skip KKT by just deriving the kem key locally
-        let kem_keys = resp.kem_psq.as_ref().unwrap();
+        let encapsulation_key = kem_keys.encapsulation_key(kem).unwrap();
+        let enc_key = encapsulation_key.clone();
 
-        let libcrux_private_key = libcrux_kem::PrivateKey::decode(
-            libcrux_kem::Algorithm::X25519,
-            kem_keys.private_key().as_bytes(),
-        )
-        .unwrap();
-        let decapsulation_key = DecapsulationKey::X25519(libcrux_private_key);
+        let initiator_ciphersuite =
+            initiator::build_psq_ciphersuite(&init, &resp_remote, &enc_key).unwrap();
+        let mut initiator =
+            initiator::build_psq_principal(init_rng, 1, initiator_ciphersuite).unwrap();
 
-        let libcrux_public_key = libcrux_kem::PublicKey::decode(
-            libcrux_kem::Algorithm::X25519,
-            kem_keys.public_key().as_bytes(),
-        )
-        .unwrap();
-        let encapsulation_key = EncapsulationKey::X25519(libcrux_public_key);
+        let responder_ciphersuite = responder::build_psq_ciphersuite(&resp, kem).unwrap();
+        let mut responder =
+            responder::build_psq_principal(resp_rng, 1, responder_ciphersuite).unwrap();
 
-        // INIT -> RESP: PSQ MSG1
-        let psq_initiator = crate::psk::psq_initiator_create_message(
-            init.x25519.private_key(),
-            &resp_remote.x25519_public,
-            &encapsulation_key,
-            init.ed25519.private_key(),
-            init.ed25519.public_key(),
-            &salt,
-            &session_id_bytes,
-        )
-        .unwrap();
+        // run PSQ
+        let mut payload_buf_responder = vec![0u8; 4096];
+        let mut payload_buf_initiator = vec![0u8; 4096];
 
-        let psk = psq_initiator.psk;
-        let psq_payload = psq_initiator.payload;
-        let outer_aead_key = crate::codec::OuterAeadKey::from_psk(&psk);
+        // Send first message
+        let mut buf = vec![0u8; psq_msg1_size(kem)];
+        let len_i = initiator.write_message(&[], &mut buf).unwrap();
+        assert_eq!(len_i, buf.len());
 
-        let noise_state_init = snow::Builder::new(crate::noise_protocol::NoiseProtocol::params())
-            .local_private_key(init.x25519().private_key().as_bytes())
-            .remote_public_key(resp_remote.x25519_public.as_bytes())
-            .psk(crate::NOISE_PSK_INDEX, &psk)
-            .build_initiator()
+        // Read first message
+        let (_, _) = responder
+            .read_message(&buf, &mut payload_buf_responder)
             .unwrap();
-        let mut noise_protocol_init = crate::noise_protocol::NoiseProtocol::new(noise_state_init);
-        let noise_msg1 = noise_protocol_init.get_bytes_to_send().unwrap().unwrap();
 
-        let psq_responder = crate::psk::psq_responder_process_message(
-            resp.x25519.private_key(),
-            &init_remote.x25519_public,
-            (&decapsulation_key, &encapsulation_key),
-            &init_remote.ed25519_public,
-            &psq_payload,
-            &salt,
-            &session_id_bytes,
-        )
-        .unwrap();
+        // Get the authenticator out here, so we can deserialize the session later.
+        let Some(initiator_authenticator) = responder.initiator_authenticator() else {
+            panic!("No initiator authenticator found")
+        };
 
-        let noise_state_resp = snow::Builder::new(crate::noise_protocol::NoiseProtocol::params())
-            .local_private_key(resp.x25519().private_key().as_bytes())
-            .remote_public_key(init_remote.x25519_public.as_bytes())
-            .psk(crate::NOISE_PSK_INDEX, &psk)
-            .build_responder()
+        // Respond
+        let mut buf = [0u8; PSQ_MSG2_SIZE];
+        let len_r = responder.write_message(&[], &mut buf).unwrap();
+        assert_eq!(len_r, buf.len());
+
+        // Finalize on registration initiator
+        let (_, _) = initiator
+            .read_message(&buf, &mut payload_buf_initiator)
             .unwrap();
-        let mut noise_protocol_resp = crate::noise_protocol::NoiseProtocol::new(noise_state_resp);
-        noise_protocol_resp.read_message(&noise_msg1).unwrap();
 
-        let noise_msg2 = noise_protocol_resp.get_bytes_to_send().unwrap().unwrap();
-        noise_protocol_init.read_message(&noise_msg2).unwrap();
-        let noise_msg3 = noise_protocol_init.get_bytes_to_send().unwrap().unwrap();
+        assert!(initiator.is_handshake_finished());
+        assert!(responder.is_handshake_finished());
 
-        assert!(noise_protocol_init.is_handshake_finished());
-
-        noise_protocol_resp.read_message(&noise_msg3).unwrap();
-        assert!(noise_protocol_resp.is_handshake_finished());
+        let binding = PersistentSessionBinding {
+            initiator_authenticator,
+            responder_ecdh_pk: resp_remote.x25519_public,
+            responder_pq_pk: Some(encapsulation_key),
+        };
 
         SessionsMock {
             initiator: LpSession::new(
-                session_id,
+                initiator.into_session().unwrap(),
+                binding.clone(),
+                receiver_index,
                 1,
-                outer_aead_key.clone(),
-                init,
-                resp_remote,
-                crate::session::PqSharedSecret::new(psq_initiator.pq_shared_secret),
-                noise_protocol_init,
-            ),
+            )
+            .unwrap(),
             responder: LpSession::new(
-                session_id,
+                responder.into_session().unwrap(),
+                binding,
+                receiver_index,
                 1,
-                outer_aead_key,
-                resp,
-                init_remote,
-                crate::session::PqSharedSecret::new(psq_responder.pq_shared_secret),
-                noise_protocol_resp,
-            ),
+            )
+            .unwrap(),
         }
     }
 
+    pub fn mock_post_handshake(kem: KEM) -> SessionsMock {
+        Self::mock_seeded_post_handshake(1, kem)
+    }
+
     // we just need a dummy 'valid' session for simpler tests
     pub fn mock_initiator() -> LpSession {
-        Self::mock_post_handshake(1234).initiator
+        Self::mock_post_handshake(KEM::default()).initiator
     }
 }
 
 #[cfg(any(feature = "mock", test))]
 pub fn sessions_for_tests() -> (LpSession, LpSession) {
-    let sessions = SessionsMock::mock_post_handshake(69);
+    let sessions = SessionsMock::mock_post_handshake(KEM::default());
     (sessions.initiator, sessions.responder)
 }
 
@@ -156,224 +149,3 @@ pub fn sessions_for_tests() -> (LpSession, LpSession) {
 pub fn mock_session_for_test() -> LpSession {
     SessionsMock::mock_initiator()
 }
-
-#[cfg(test)]
-mod tests {
-    use crate::message::LpMessage;
-    use crate::packet::{LpHeader, LpPacket, TRAILER_LEN};
-    use crate::session_manager::SessionManager;
-    use crate::{LpError, SessionsMock, mock_session_for_test};
-    use bytes::BytesMut;
-
-    // Import the new standalone functions
-    use crate::codec::{parse_lp_packet, serialize_lp_packet};
-
-    #[test]
-    fn test_replay_protection_integration() {
-        // Create session
-        let mut session = mock_session_for_test();
-
-        // === Packet 1 (Counter 0 - Should succeed) ===
-        let packet1 = LpPacket {
-            header: LpHeader {
-                protocol_version: 1,
-                reserved: [0u8; 3],
-                receiver_idx: 42, // Matches session's sending_index assumption for this test
-                counter: 0,
-            },
-            message: LpMessage::Busy,
-            trailer: [0u8; TRAILER_LEN],
-        };
-
-        // Serialize packet
-        let mut buf1 = BytesMut::new();
-        serialize_lp_packet(&packet1, &mut buf1, None).unwrap();
-
-        // Parse packet
-        let parsed_packet1 = parse_lp_packet(&buf1, None).unwrap();
-
-        // Perform replay check (should pass)
-        session
-            .receiving_counter_quick_check(parsed_packet1.header.counter)
-            .expect("Initial packet failed replay check");
-
-        // Mark received (simulating successful processing)
-        session
-            .receiving_counter_mark(parsed_packet1.header.counter)
-            .expect("Failed to mark initial packet received");
-
-        // === Packet 2 (Counter 0 - Replay, should fail check) ===
-        let packet2 = LpPacket {
-            header: LpHeader {
-                protocol_version: 1,
-                reserved: [0u8; 3],
-                receiver_idx: 42,
-                counter: 0, // Same counter as before (replay)
-            },
-            message: LpMessage::Busy,
-            trailer: [0u8; TRAILER_LEN],
-        };
-
-        // Serialize packet
-        let mut buf2 = BytesMut::new();
-        serialize_lp_packet(&packet2, &mut buf2, None).unwrap();
-
-        // Parse packet
-        let parsed_packet2 = parse_lp_packet(&buf2, None).unwrap();
-
-        // Perform replay check (should fail)
-        let replay_result = session.receiving_counter_quick_check(parsed_packet2.header.counter);
-        assert!(replay_result.is_err());
-        match replay_result.unwrap_err() {
-            LpError::Replay(e) => {
-                assert!(matches!(e, crate::replay::ReplayError::DuplicateCounter));
-            }
-            e => panic!("Expected replay error, got {:?}", e),
-        }
-        // Do not mark received as it failed validation
-
-        // === Packet 3 (Counter 1 - Should succeed) ===
-        let packet3 = LpPacket {
-            header: LpHeader {
-                protocol_version: 1,
-                reserved: [0u8; 3],
-                receiver_idx: 42,
-                counter: 1, // Incremented counter
-            },
-            message: LpMessage::Busy,
-            trailer: [0u8; TRAILER_LEN],
-        };
-
-        // Serialize packet
-        let mut buf3 = BytesMut::new();
-        serialize_lp_packet(&packet3, &mut buf3, None).unwrap();
-
-        // Parse packet
-        let parsed_packet3 = parse_lp_packet(&buf3, None).unwrap();
-
-        // Perform replay check (should pass)
-        session
-            .receiving_counter_quick_check(parsed_packet3.header.counter)
-            .expect("Packet 3 failed replay check");
-
-        // Mark received
-        session
-            .receiving_counter_mark(parsed_packet3.header.counter)
-            .expect("Failed to mark packet 3 received");
-
-        // Verify validator state directly on the session
-        let state = session.current_packet_cnt();
-        assert_eq!(state.0, 2); // Next expected counter (correct - was 1, now expects 2)
-        assert_eq!(state.1, 2); // Total marked received (correct - packets 1 and 3)
-    }
-
-    #[test]
-    fn test_session_manager_integration() {
-        // Create session manager
-        let mut local_manager = SessionManager::new();
-        let mut remote_manager = SessionManager::new();
-
-        // Use fixed receiver_index for deterministic test
-        let receiver_index: u32 = 54321;
-
-        let sessions = SessionsMock::mock_post_handshake(receiver_index);
-        let local_session = sessions.initiator;
-        let remote_session = sessions.responder;
-
-        // Create a session via manager
-        let _ = local_manager.create_session_state_machine(local_session);
-        let _ = remote_manager.create_session_state_machine(remote_session);
-
-        // === Packet 1 (Counter 0 - Should succeed) ===
-        let packet1 = LpPacket {
-            header: LpHeader {
-                protocol_version: 1,
-                reserved: [0u8; 3],
-                receiver_idx: receiver_index,
-                counter: 0,
-            },
-            message: LpMessage::Busy,
-            trailer: [0u8; TRAILER_LEN],
-        };
-
-        // Serialize
-        let mut buf1 = BytesMut::new();
-        serialize_lp_packet(&packet1, &mut buf1, None).unwrap();
-
-        // Parse
-        let parsed_packet1 = parse_lp_packet(&buf1, None).unwrap();
-
-        // Process via SessionManager method (which should handle checks + marking)
-        // NOTE: We might need a method on SessionManager/LpSession like `process_incoming_packet`
-        //       that encapsulates parse -> check -> process_noise -> mark.
-        //       For now, we simulate the steps using the retrieved session.
-
-        // Perform replay check
-        local_manager
-            .receiving_counter_quick_check(receiver_index, parsed_packet1.header.counter)
-            .expect("Packet 1 check failed");
-        // Mark received
-        local_manager
-            .receiving_counter_mark(receiver_index, parsed_packet1.header.counter)
-            .expect("Packet 1 mark failed");
-
-        // === Packet 2 (Counter 1 - Should succeed on same session) ===
-        let packet2 = LpPacket {
-            header: LpHeader {
-                protocol_version: 1,
-                reserved: [0u8; 3],
-                receiver_idx: receiver_index,
-                counter: 1,
-            },
-            message: LpMessage::Busy,
-            trailer: [0u8; TRAILER_LEN],
-        };
-
-        // Serialize
-        let mut buf2 = BytesMut::new();
-        serialize_lp_packet(&packet2, &mut buf2, None).unwrap();
-
-        // Parse
-        let parsed_packet2 = parse_lp_packet(&buf2, None).unwrap();
-
-        // Perform replay check
-        local_manager
-            .receiving_counter_quick_check(receiver_index, parsed_packet2.header.counter)
-            .expect("Packet 2 check failed");
-        // Mark received
-        local_manager
-            .receiving_counter_mark(receiver_index, parsed_packet2.header.counter)
-            .expect("Packet 2 mark failed");
-
-        // === Packet 3 (Counter 0 - Replay, should fail check) ===
-        let packet3 = LpPacket {
-            header: LpHeader {
-                protocol_version: 1,
-                reserved: [0u8; 3],
-                receiver_idx: receiver_index,
-                counter: 0, // Replay of first packet
-            },
-            message: LpMessage::Busy,
-            trailer: [0u8; TRAILER_LEN],
-        };
-
-        // Serialize
-        let mut buf3 = BytesMut::new();
-        serialize_lp_packet(&packet3, &mut buf3, None).unwrap();
-
-        // Parse
-        let parsed_packet3 = parse_lp_packet(&buf3, None).unwrap();
-
-        // Perform replay check (should fail)
-        let replay_result = local_manager
-            .receiving_counter_quick_check(receiver_index, parsed_packet3.header.counter);
-        assert!(replay_result.is_err());
-        match replay_result.unwrap_err() {
-            LpError::Replay(e) => {
-                assert!(matches!(e, crate::replay::ReplayError::DuplicateCounter));
-            }
-            e => panic!("Expected replay error for packet 3, got {:?}", e),
-        }
-        // Do not mark received
-    }
-}

common/nym-lp/src/message.rs

@@ -1,892 +0,0 @@
-// Copyright 2025 - Nym Technologies SA <contact@nymtech.net>
-// SPDX-License-Identifier: Apache-2.0
-
-use crate::packet::LpHeader;
-use crate::peer::LpRemotePeer;
-use crate::{BOOTSTRAP_RECEIVER_IDX, LpError, LpPacket};
-use bytes::{BufMut, BytesMut};
-use num_enum::{IntoPrimitive, TryFromPrimitive};
-use nym_crypto::asymmetric::{ed25519, x25519};
-use rand::RngCore;
-use serde::{Deserialize, Serialize};
-use std::fmt::{self, Display};
-use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr};
-
-/// Data structure for the ClientHello message
-#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq)]
-pub struct ClientHelloData {
-    /// Client-proposed receiver index for session identification (4 bytes)
-    /// Auto-generated randomly by the client
-    pub receiver_index: u32,
-    /// Client's LP x25519 public key (32 bytes) - derived from Ed25519 key
-    pub client_lp_public_key: x25519::PublicKey,
-    /// Client's Ed25519 public key (32 bytes) - for PSQ authentication
-    pub client_ed25519_public_key: ed25519::PublicKey,
-    /// Salt for PSK derivation (32 bytes: 8-byte timestamp + 24-byte nonce)
-    pub salt: [u8; 32],
-}
-
-impl ClientHelloData {
-    // 4 bytes for receiver index + 32 bytes for client lp key, 32 bytes for client ed25519 key + 32 bytes for salt
-    pub const LEN: usize = 100;
-
-    pub fn into_lp_packet(self, protocol_version: u8) -> LpPacket {
-        LpPacket::new(
-            LpHeader::new(
-                BOOTSTRAP_RECEIVER_IDX, // session_id not yet established
-                0,                      // counter starts at 0
-                protocol_version,
-            ),
-            LpMessage::ClientHello(self),
-        )
-    }
-
-    fn len(&self) -> usize {
-        Self::LEN
-    }
-
-    fn generate_receiver_index() -> u32 {
-        loop {
-            let candidate = rand::random();
-            if candidate != BOOTSTRAP_RECEIVER_IDX {
-                return candidate;
-            }
-        }
-    }
-
-    /// Generates a new ClientHelloData with fresh salt.
-    ///
-    /// Salt format: 8 bytes timestamp (u64 LE) + 24 bytes random nonce
-    ///
-    /// # Arguments
-    /// * `client_lp_public_key` - Client's x25519 public key (derived from Ed25519)
-    /// * `client_ed25519_public_key` - Client's Ed25519 public key (for PSQ authentication)
-    pub fn new_with_fresh_salt(
-        client_lp_public_key: x25519::PublicKey,
-        client_ed25519_public_key: ed25519::PublicKey,
-        timestamp: u64,
-    ) -> Self {
-        // Generate salt: timestamp + nonce
-        let mut salt = [0u8; 32];
-
-        // First 8 bytes: current timestamp as u64 little-endian
-        salt[..8].copy_from_slice(&timestamp.to_le_bytes());
-
-        // Last 24 bytes: random nonce
-        rand::thread_rng().fill_bytes(&mut salt[8..]);
-
-        Self {
-            receiver_index: Self::generate_receiver_index(), // Auto-generate random receiver index
-            client_lp_public_key,
-            client_ed25519_public_key,
-            salt,
-        }
-    }
-
-    /// Extracts the timestamp from the salt.
-    ///
-    /// # Returns
-    /// Unix timestamp in seconds
-    pub fn extract_timestamp(&self) -> u64 {
-        let mut timestamp_bytes = [0u8; 8];
-        timestamp_bytes.copy_from_slice(&self.salt[..8]);
-        u64::from_le_bytes(timestamp_bytes)
-    }
-
-    pub fn encode(&self, dst: &mut BytesMut) {
-        dst.put_u32_le(self.receiver_index);
-        dst.put_slice(self.client_lp_public_key.as_bytes());
-        dst.put_slice(self.client_ed25519_public_key.as_bytes());
-        dst.put_slice(&self.salt);
-    }
-
-    pub fn decode(b: &[u8]) -> Result<Self, LpError> {
-        if b.len() != Self::LEN {
-            return Err(LpError::DeserializationError(format!(
-                "Expected {} bytes to deserialise ClientHelloData. got {}",
-                Self::LEN,
-                b.len()
-            )));
-        }
-
-        // SAFETY: we checked for valid byte lengths
-        #[allow(clippy::unwrap_used)]
-        let client_lp_public_key_bytes = b[4..36].try_into().unwrap();
-        let client_ed25519_public_key_bytes = b[36..68].try_into().unwrap();
-
-        Ok(ClientHelloData {
-            receiver_index: u32::from_le_bytes([b[0], b[1], b[2], b[3]]),
-            client_lp_public_key: x25519::PublicKey::from_byte_array(client_lp_public_key_bytes),
-            client_ed25519_public_key: ed25519::PublicKey::from_byte_array(
-                client_ed25519_public_key_bytes,
-            )?,
-            salt: b[68..].try_into().unwrap(),
-        })
-    }
-
-    /// Attempt to construct remote peer information based on the data provided in this packet.
-    pub fn to_remote_peer(&self) -> LpRemotePeer {
-        LpRemotePeer::new(self.client_ed25519_public_key, self.client_lp_public_key)
-    }
-}
-
-#[derive(Debug, Copy, Clone, PartialEq, Eq, IntoPrimitive, TryFromPrimitive)]
-#[repr(u32)]
-pub enum MessageType {
-    Busy = 0x0000,
-    Handshake = 0x0001,
-    EncryptedData = 0x0002,
-    ClientHello = 0x0003,
-    KKTRequest = 0x0004,
-    KKTResponse = 0x0005,
-    ForwardPacket = 0x0006,
-    /// Receiver index collision - client should retry with new index
-    Collision = 0x0007,
-    /// Acknowledgment - gateway confirms receipt of message
-    Ack = 0x0008,
-    /// Subsession request - client initiates subsession creation
-    SubsessionRequest = 0x0009,
-    /// Subsession KK1 - first message of Noise KK handshake
-    SubsessionKK1 = 0x000A,
-    /// Subsession KK2 - second message of Noise KK handshake
-    SubsessionKK2 = 0x000B,
-    /// Subsession ready - subsession established confirmation
-    SubsessionReady = 0x000C,
-    /// Subsession abort - race winner tells loser to become responder
-    SubsessionAbort = 0x000D,
-    /// General error
-    Error = 0x00FF,
-}
-
-impl MessageType {
-    pub(crate) fn from_u32(value: u32) -> Option<Self> {
-        MessageType::try_from(value).ok()
-    }
-
-    pub fn to_u32(&self) -> u32 {
-        u32::from(*self)
-    }
-}
-
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct HandshakeData(pub Vec<u8>);
-
-impl HandshakeData {
-    pub(crate) fn new(bytes: Vec<u8>) -> Self {
-        Self(bytes)
-    }
-    fn len(&self) -> usize {
-        self.0.len()
-    }
-
-    fn encode(&self, dst: &mut BytesMut) {
-        dst.put_slice(&self.0);
-    }
-
-    fn decode(bytes: &[u8]) -> Result<Self, LpError> {
-        Ok(HandshakeData(bytes.to_vec()))
-    }
-}
-
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct EncryptedDataPayload(pub Vec<u8>);
-
-impl EncryptedDataPayload {
-    #[allow(dead_code)]
-    pub(crate) fn new(bytes: Vec<u8>) -> Self {
-        Self(bytes)
-    }
-
-    fn len(&self) -> usize {
-        self.0.len()
-    }
-
-    fn encode(&self, dst: &mut BytesMut) {
-        dst.put_slice(&self.0);
-    }
-
-    fn decode(bytes: &[u8]) -> Result<Self, LpError> {
-        Ok(EncryptedDataPayload(bytes.to_vec()))
-    }
-}
-
-/// KKT request frame data (serialized KKTFrame bytes)
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct KKTRequestData(pub Vec<u8>);
-
-impl KKTRequestData {
-    pub(crate) fn new(bytes: Vec<u8>) -> Self {
-        Self(bytes)
-    }
-
-    fn len(&self) -> usize {
-        self.0.len()
-    }
-
-    fn encode(&self, dst: &mut BytesMut) {
-        dst.put_slice(&self.0);
-    }
-
-    fn decode(bytes: &[u8]) -> Result<Self, LpError> {
-        Ok(KKTRequestData(bytes.to_vec()))
-    }
-}
-
-/// KKT response frame data (serialized KKTFrame bytes)
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct KKTResponseData(pub Vec<u8>);
-
-impl KKTResponseData {
-    pub(crate) fn new(bytes: Vec<u8>) -> Self {
-        Self(bytes)
-    }
-
-    fn len(&self) -> usize {
-        self.0.len()
-    }
-
-    fn encode(&self, dst: &mut BytesMut) {
-        dst.put_slice(&self.0);
-    }
-
-    fn decode(bytes: &[u8]) -> Result<Self, LpError> {
-        Ok(KKTResponseData(bytes.to_vec()))
-    }
-}
-
-/// General human-readable error message
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct ErrorPacketData {
-    pub message: String,
-}
-
-impl ErrorPacketData {
-    pub(crate) fn new(message: impl Into<String>) -> Self {
-        ErrorPacketData {
-            message: message.into(),
-        }
-    }
-
-    fn len(&self) -> usize {
-        // length-encoding + message
-        4 + self.message.len()
-    }
-
-    fn encode(&self, dst: &mut BytesMut) {
-        dst.put_u32_le(self.message.len() as u32);
-        dst.put_slice(self.message.as_bytes());
-    }
-
-    fn decode(bytes: &[u8]) -> Result<Self, LpError> {
-        if bytes.len() < 4 {
-            return Err(LpError::DeserializationError(format!(
-                "Too few bytes to deserialise ErrorPacketData. got {}",
-                bytes.len()
-            )));
-        }
-
-        let message_len = u32::from_le_bytes([bytes[0], bytes[1], bytes[2], bytes[3]]) as usize;
-        if bytes[4..].len() != message_len {
-            return Err(LpError::DeserializationError(format!(
-                "Wrong number of bytes to deserialise ErrorPacketData. got {}. Expected {}",
-                bytes.len(),
-                4 + message_len
-            )));
-        }
-
-        let message = String::from_utf8_lossy(&bytes[4..]).to_string();
-
-        Ok(ErrorPacketData { message })
-    }
-}
-
-/// Packet forwarding request with embedded inner LP packet
-#[derive(Debug, Clone)]
-pub struct ForwardPacketData {
-    /// Target gateway's Ed25519 identity (32 bytes)
-    pub target_gateway_identity: [u8; 32],
-
-    /// Target gateway's LP address (IP:port string)
-    pub target_lp_address: SocketAddr,
-
-    /// Complete inner LP packet bytes (serialized LpPacket)
-    /// This is the CLIENT→EXIT gateway packet, encrypted for exit
-    pub inner_packet_bytes: Vec<u8>,
-}
-
-impl ForwardPacketData {
-    pub fn new(
-        target_gateway_identity: ed25519::PublicKey,
-        target_lp_address: SocketAddr,
-        inner_packet_bytes: Vec<u8>,
-    ) -> Self {
-        ForwardPacketData {
-            target_gateway_identity: target_gateway_identity.to_bytes(),
-            target_lp_address,
-            inner_packet_bytes,
-        }
-    }
-
-    fn len(&self) -> usize {
-        // 32 bytes target gateway identity
-        // +
-        // 1 byte length of target lp address type
-        // +
-        // {4,16} target_lp_address IPv{4,6}
-        // +
-        // 2 bytes target_lp_address port
-        // +
-        // 4 bytes of length of inner packet bytes
-        // +
-        // inner_packet_bytes.len()
-        match self.target_lp_address {
-            SocketAddr::V4(_) => 32 + 1 + 4 + 2 + 4 + self.inner_packet_bytes.len(),
-            SocketAddr::V6(_) => 32 + 1 + 16 + 2 + 4 + self.inner_packet_bytes.len(),
-        }
-    }
-
-    fn encode(&self, dst: &mut BytesMut) {
-        let (is_ipv6, ip_bytes) = match &self.target_lp_address {
-            SocketAddr::V4(address) => (false, address.ip().octets().to_vec()),
-            SocketAddr::V6(address) => (true, address.ip().octets().to_vec()),
-        };
-
-        dst.put_slice(&self.target_gateway_identity);
-        dst.put_u8(is_ipv6 as u8); // IP type , 0 for ipv4
-        dst.put_slice(&ip_bytes); // IP bytes
-        dst.put_u16_le(self.target_lp_address.port()); // Port
-        dst.put_u32_le(self.inner_packet_bytes.len() as u32);
-        dst.put_slice(&self.inner_packet_bytes);
-    }
-
-    pub fn to_bytes(&self) -> Vec<u8> {
-        let mut buf = BytesMut::new();
-        self.encode(&mut buf);
-        buf.into()
-    }
-
-    pub fn decode(bytes: &[u8]) -> Result<Self, LpError> {
-        // smallest possible packet with ipv4 and empty data
-        if bytes.len() < 43 {
-            // 32 + 1 + 4 + 2 + 4 + 0
-            return Err(LpError::DeserializationError(format!(
-                "Too few bytes to deserialise ForwardPacketData. got {}",
-                bytes.len()
-            )));
-        }
-        // SAFETY: we ensured we have sufficient data
-        #[allow(clippy::unwrap_used)]
-        let target_gateway_identity = bytes[0..32].try_into().unwrap();
-        let target_lp_address_is_ipv6 = bytes[32] != 0;
-
-        let (target_lp_address, next_index) = if target_lp_address_is_ipv6 {
-            // IPv6, first check we have actually enough bytes
-            // smallest possible packet with ipv6 and empty data
-            if bytes.len() < 55 {
-                // 32 + 1 + 16 + 2 + 4 + 0
-                return Err(LpError::DeserializationError(format!(
-                    "Too few bytes to deserialise ipv6 ForwardPacketData. got {}",
-                    bytes.len()
-                )));
-            }
-            // SAFETY: we ensured we have sufficient data, and the length is correct for casting
-            #[allow(clippy::unwrap_used)]
-            let ipv6 = IpAddr::V6(Ipv6Addr::from_octets(bytes[33..49].try_into().unwrap()));
-            let port = u16::from_le_bytes([bytes[49], bytes[50]]);
-            (SocketAddr::new(ipv6, port), 51)
-        } else {
-            // IPv4. Length check done at the start
-            // SAFETY: we ensured we have sufficient data, and the length is correct for casting
-            #[allow(clippy::unwrap_used)]
-            let ipv4 = IpAddr::V4(Ipv4Addr::from_octets(bytes[33..37].try_into().unwrap()));
-            let port = u16::from_le_bytes([bytes[37], bytes[38]]);
-            (SocketAddr::new(ipv4, port), 39)
-        };
-
-        let inner_packet_bytes_len = u32::from_le_bytes([
-            bytes[next_index],
-            bytes[next_index + 1],
-            bytes[next_index + 2],
-            bytes[next_index + 3],
-        ]);
-        if bytes[next_index + 4..].len() != inner_packet_bytes_len as usize {
-            return Err(LpError::DeserializationError(format!(
-                "Expected {inner_packet_bytes_len} bytes to deserialise inner packet bytes of ForwardPacketData. got {}",
-                bytes[next_index + 4..].len()
-            )));
-        }
-        let inner_packet_bytes = bytes[next_index + 4..].to_vec();
-
-        Ok(ForwardPacketData {
-            target_gateway_identity,
-            target_lp_address,
-            inner_packet_bytes,
-        })
-    }
-}
-
-/// Subsession KK1 message - first message of Noise KK handshake
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct SubsessionKK1Data {
-    /// Noise KK first message payload (ephemeral key + encrypted static)
-    pub payload: Vec<u8>,
-}
-
-impl SubsessionKK1Data {
-    fn len(&self) -> usize {
-        self.payload.len()
-    }
-
-    fn encode(&self, dst: &mut BytesMut) {
-        dst.put_slice(&self.payload);
-    }
-
-    fn decode(bytes: &[u8]) -> Result<Self, LpError> {
-        Ok(SubsessionKK1Data {
-            payload: bytes.to_vec(),
-        })
-    }
-}
-
-/// Subsession KK2 message - second message of Noise KK handshake
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct SubsessionKK2Data {
-    /// Noise KK second message payload (ephemeral key + encrypted response)
-    pub payload: Vec<u8>,
-}
-
-impl SubsessionKK2Data {
-    fn len(&self) -> usize {
-        self.payload.len()
-    }
-
-    fn encode(&self, dst: &mut BytesMut) {
-        dst.put_slice(&self.payload);
-    }
-
-    fn decode(bytes: &[u8]) -> Result<Self, LpError> {
-        Ok(SubsessionKK2Data {
-            payload: bytes.to_vec(),
-        })
-    }
-}
-
-/// Subsession ready confirmation with new session index
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct SubsessionReadyData {
-    /// New subsession's receiver index for routing
-    pub receiver_index: u32,
-}
-
-impl SubsessionReadyData {
-    pub const LEN: usize = 4;
-
-    fn len(&self) -> usize {
-        Self::LEN
-    }
-
-    fn encode(&self, dst: &mut BytesMut) {
-        dst.put_u32_le(self.receiver_index);
-    }
-
-    fn decode(bytes: &[u8]) -> Result<Self, LpError> {
-        if bytes.len() != 4 {
-            return Err(LpError::DeserializationError(format!(
-                "Expected 4 bytes to deserialise SubsessionReadyData. got {}",
-                bytes.len()
-            )));
-        }
-        Ok(SubsessionReadyData {
-            receiver_index: u32::from_le_bytes([bytes[0], bytes[1], bytes[2], bytes[3]]),
-        })
-    }
-}
-
-#[derive(Debug, Clone)]
-pub enum LpMessage {
-    Busy,
-    Handshake(HandshakeData),
-    EncryptedData(EncryptedDataPayload),
-    ClientHello(ClientHelloData),
-    KKTRequest(KKTRequestData),
-    KKTResponse(KKTResponseData),
-    ForwardPacket(ForwardPacketData),
-    /// Receiver index collision - client should retry with new receiver_index
-    Collision,
-    /// Acknowledgment - gateway confirms receipt of message
-    Ack,
-    /// Subsession request - client initiates subsession creation (empty, signal only)
-    SubsessionRequest,
-    /// Subsession KK1 - first message of Noise KK handshake
-    SubsessionKK1(SubsessionKK1Data),
-    /// Subsession KK2 - second message of Noise KK handshake
-    SubsessionKK2(SubsessionKK2Data),
-    /// Subsession ready - subsession established confirmation
-    SubsessionReady(SubsessionReadyData),
-    /// Subsession abort - race winner tells loser to become responder (empty, signal only)
-    SubsessionAbort,
-    /// An error has occurred
-    Error(ErrorPacketData),
-}
-
-impl From<HandshakeData> for LpMessage {
-    fn from(value: HandshakeData) -> Self {
-        LpMessage::Handshake(value)
-    }
-}
-
-impl From<EncryptedDataPayload> for LpMessage {
-    fn from(value: EncryptedDataPayload) -> Self {
-        LpMessage::EncryptedData(value)
-    }
-}
-
-impl From<ClientHelloData> for LpMessage {
-    fn from(value: ClientHelloData) -> Self {
-        LpMessage::ClientHello(value)
-    }
-}
-
-impl From<KKTRequestData> for LpMessage {
-    fn from(value: KKTRequestData) -> Self {
-        LpMessage::KKTRequest(value)
-    }
-}
-
-impl From<KKTResponseData> for LpMessage {
-    fn from(value: KKTResponseData) -> Self {
-        LpMessage::KKTResponse(value)
-    }
-}
-
-impl From<ForwardPacketData> for LpMessage {
-    fn from(value: ForwardPacketData) -> Self {
-        LpMessage::ForwardPacket(value)
-    }
-}
-
-impl From<SubsessionKK1Data> for LpMessage {
-    fn from(value: SubsessionKK1Data) -> Self {
-        LpMessage::SubsessionKK1(value)
-    }
-}
-
-impl From<SubsessionKK2Data> for LpMessage {
-    fn from(value: SubsessionKK2Data) -> Self {
-        LpMessage::SubsessionKK2(value)
-    }
-}
-
-impl From<SubsessionReadyData> for LpMessage {
-    fn from(value: SubsessionReadyData) -> Self {
-        LpMessage::SubsessionReady(value)
-    }
-}
-
-impl Display for LpMessage {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
-            LpMessage::Busy => write!(f, "Busy"),
-            LpMessage::Handshake(_) => write!(f, "Handshake"),
-            LpMessage::EncryptedData(_) => write!(f, "EncryptedData"),
-            LpMessage::ClientHello(_) => write!(f, "ClientHello"),
-            LpMessage::KKTRequest(_) => write!(f, "KKTRequest"),
-            LpMessage::KKTResponse(_) => write!(f, "KKTResponse"),
-            LpMessage::ForwardPacket(_) => write!(f, "ForwardPacket"),
-            LpMessage::Collision => write!(f, "Collision"),
-            LpMessage::Ack => write!(f, "Ack"),
-            LpMessage::SubsessionRequest => write!(f, "SubsessionRequest"),
-            LpMessage::SubsessionKK1(_) => write!(f, "SubsessionKK1"),
-            LpMessage::SubsessionKK2(_) => write!(f, "SubsessionKK2"),
-            LpMessage::SubsessionReady(_) => write!(f, "SubsessionReady"),
-            LpMessage::SubsessionAbort => write!(f, "SubsessionAbort"),
-            LpMessage::Error(_) => write!(f, "Error"),
-        }
-    }
-}
-
-impl LpMessage {
-    pub fn payload(&self) -> &[u8] {
-        match self {
-            LpMessage::Busy => &[],
-            LpMessage::Handshake(payload) => payload.0.as_slice(),
-            LpMessage::EncryptedData(payload) => payload.0.as_slice(),
-            LpMessage::ClientHello(_) => &[], // Structured data, serialized in encode_content
-            LpMessage::KKTRequest(payload) => payload.0.as_slice(),
-            LpMessage::KKTResponse(payload) => payload.0.as_slice(),
-            LpMessage::ForwardPacket(_) => &[], // Structured data, serialized in encode_content
-            LpMessage::Collision => &[],
-            LpMessage::Ack => &[],
-            LpMessage::SubsessionRequest => &[],
-            LpMessage::SubsessionKK1(_) => &[], // Structured data, serialized in encode_content
-            LpMessage::SubsessionKK2(_) => &[], // Structured data, serialized in encode_content
-            LpMessage::SubsessionReady(_) => &[], // Structured data, serialized in encode_content
-            LpMessage::SubsessionAbort => &[],
-            LpMessage::Error(_) => &[], // Structured data, serialized in encode_content (?)
-        }
-    }
-
-    pub fn is_empty(&self) -> bool {
-        match self {
-            LpMessage::Busy => true,
-            LpMessage::Handshake(payload) => payload.0.is_empty(),
-            LpMessage::EncryptedData(payload) => payload.0.is_empty(),
-            LpMessage::ClientHello(_) => false, // Always has data
-            LpMessage::KKTRequest(payload) => payload.0.is_empty(),
-            LpMessage::KKTResponse(payload) => payload.0.is_empty(),
-            LpMessage::ForwardPacket(_) => false, // Always has data
-            LpMessage::Collision => true,
-            LpMessage::Ack => true,
-            LpMessage::SubsessionRequest => true, // Empty signal
-            LpMessage::SubsessionKK1(_) => false, // Always has payload
-            LpMessage::SubsessionKK2(_) => false, // Always has payload
-            LpMessage::SubsessionReady(_) => false, // Always has receiver_index
-            LpMessage::SubsessionAbort => true,   // Empty signal
-            LpMessage::Error(_) => false,
-        }
-    }
-
-    pub fn len(&self) -> usize {
-        match self {
-            LpMessage::Busy => 0,
-            LpMessage::Handshake(payload) => payload.len(),
-            LpMessage::EncryptedData(payload) => payload.len(),
-            LpMessage::ClientHello(payload) => payload.len(),
-            LpMessage::KKTRequest(payload) => payload.len(),
-            LpMessage::KKTResponse(payload) => payload.len(),
-            LpMessage::ForwardPacket(payload) => payload.len(),
-            LpMessage::Collision => 0,
-            LpMessage::Ack => 0,
-            LpMessage::SubsessionRequest => 0,
-            LpMessage::SubsessionKK1(payload) => payload.len(),
-            LpMessage::SubsessionKK2(payload) => payload.len(),
-            LpMessage::SubsessionReady(payload) => payload.len(),
-            LpMessage::SubsessionAbort => 0,
-            LpMessage::Error(payload) => payload.len(),
-        }
-    }
-
-    pub fn typ(&self) -> MessageType {
-        match self {
-            LpMessage::Busy => MessageType::Busy,
-            LpMessage::Handshake(_) => MessageType::Handshake,
-            LpMessage::EncryptedData(_) => MessageType::EncryptedData,
-            LpMessage::ClientHello(_) => MessageType::ClientHello,
-            LpMessage::KKTRequest(_) => MessageType::KKTRequest,
-            LpMessage::KKTResponse(_) => MessageType::KKTResponse,
-            LpMessage::ForwardPacket(_) => MessageType::ForwardPacket,
-            LpMessage::Collision => MessageType::Collision,
-            LpMessage::Ack => MessageType::Ack,
-            LpMessage::SubsessionRequest => MessageType::SubsessionRequest,
-            LpMessage::SubsessionKK1(_) => MessageType::SubsessionKK1,
-            LpMessage::SubsessionKK2(_) => MessageType::SubsessionKK2,
-            LpMessage::SubsessionReady(_) => MessageType::SubsessionReady,
-            LpMessage::SubsessionAbort => MessageType::SubsessionAbort,
-            LpMessage::Error(_) => MessageType::Error,
-        }
-    }
-
-    pub fn encode_content(&self, dst: &mut BytesMut) {
-        match self {
-            LpMessage::Busy => { /* No content */ }
-            LpMessage::Handshake(payload) => payload.encode(dst),
-            LpMessage::EncryptedData(payload) => payload.encode(dst),
-            LpMessage::ClientHello(data) => data.encode(dst),
-            LpMessage::KKTRequest(payload) => payload.encode(dst),
-            LpMessage::KKTResponse(payload) => payload.encode(dst),
-            LpMessage::ForwardPacket(data) => data.encode(dst),
-            LpMessage::Collision => { /* No content */ }
-            LpMessage::Ack => { /* No content */ }
-            LpMessage::SubsessionRequest => { /* No content - signal only */ }
-            LpMessage::SubsessionKK1(data) => data.encode(dst),
-            LpMessage::SubsessionKK2(data) => data.encode(dst),
-            LpMessage::SubsessionReady(data) => data.encode(dst),
-            LpMessage::SubsessionAbort => { /* No content - signal only */ }
-            LpMessage::Error(data) => data.encode(dst),
-        }
-    }
-
-    /// Parse message from its type and content bytes.
-    ///
-    /// Used when decrypting outer-encrypted packets where the message type
-    /// was encrypted along with the content.
-    pub fn decode_content(content: &[u8], message_type: MessageType) -> Result<Self, LpError> {
-        match message_type {
-            MessageType::Busy => {
-                content.ensure_empty()?;
-                Ok(LpMessage::Busy)
-            }
-            MessageType::Handshake => Ok(LpMessage::Handshake(HandshakeData::decode(content)?)),
-            MessageType::EncryptedData => Ok(LpMessage::EncryptedData(
-                EncryptedDataPayload::decode(content)?,
-            )),
-            MessageType::ClientHello => {
-                Ok(LpMessage::ClientHello(ClientHelloData::decode(content)?))
-            }
-            MessageType::KKTRequest => Ok(LpMessage::KKTRequest(KKTRequestData::decode(content)?)),
-            MessageType::KKTResponse => {
-                Ok(LpMessage::KKTResponse(KKTResponseData::decode(content)?))
-            }
-            MessageType::ForwardPacket => Ok(LpMessage::ForwardPacket(ForwardPacketData::decode(
-                content,
-            )?)),
-            MessageType::Collision => {
-                content.ensure_empty()?;
-                Ok(LpMessage::Collision)
-            }
-            MessageType::Ack => {
-                content.ensure_empty()?;
-                Ok(LpMessage::Ack)
-            }
-            MessageType::SubsessionRequest => {
-                content.ensure_empty()?;
-                Ok(LpMessage::SubsessionRequest)
-            }
-            MessageType::SubsessionKK1 => Ok(LpMessage::SubsessionKK1(SubsessionKK1Data::decode(
-                content,
-            )?)),
-            MessageType::SubsessionKK2 => Ok(LpMessage::SubsessionKK2(SubsessionKK2Data::decode(
-                content,
-            )?)),
-            MessageType::SubsessionReady => Ok(LpMessage::SubsessionReady(
-                SubsessionReadyData::decode(content)?,
-            )),
-            MessageType::SubsessionAbort => {
-                content.ensure_empty()?;
-                Ok(LpMessage::SubsessionAbort)
-            }
-            MessageType::Error => Ok(LpMessage::Error(ErrorPacketData::decode(content)?)),
-        }
-    }
-}
-
-/// Helper trait for improving readability to return error if bytes content is not empty
-trait EnsureEmptyContent {
-    fn ensure_empty(&self) -> Result<(), LpError>;
-}
-
-impl EnsureEmptyContent for &[u8] {
-    fn ensure_empty(&self) -> Result<(), LpError> {
-        if !self.is_empty() {
-            return Err(LpError::InvalidPayloadSize {
-                expected: 0,
-                actual: self.len(),
-            });
-        }
-        Ok(())
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use std::time::{SystemTime, UNIX_EPOCH};
-
-    use super::*;
-    use crate::LpPacket;
-    use crate::packet::{LpHeader, TRAILER_LEN};
-
-    #[test]
-    fn encoding() {
-        let message = LpMessage::EncryptedData(EncryptedDataPayload(vec![11u8; 124]));
-
-        let resp_header = LpHeader {
-            protocol_version: 1,
-            reserved: [0u8; 3],
-            receiver_idx: 0,
-            counter: 0,
-        };
-
-        let packet = LpPacket {
-            header: resp_header,
-            message,
-            trailer: [80; TRAILER_LEN],
-        };
-
-        // Just print packet for debug, will be captured in test output
-        println!("{packet:?}");
-
-        // Verify message type
-        assert!(matches!(packet.message.typ(), MessageType::EncryptedData));
-
-        // Verify correct data in message
-        match &packet.message {
-            LpMessage::EncryptedData(data) => {
-                assert_eq!(*data, EncryptedDataPayload(vec![11u8; 124]));
-            }
-            _ => panic!("Wrong message type"),
-        }
-    }
-
-    #[test]
-    fn test_client_hello_salt_generation() {
-        let timestamp = SystemTime::now()
-            .duration_since(UNIX_EPOCH)
-            .expect("System time before UNIX epoch")
-            .as_secs();
-
-        let mut rng = rand::thread_rng();
-        let ed25519 = ed25519::KeyPair::new(&mut rng);
-        let x25519 = ed25519.to_x25519();
-
-        let client_key = *x25519.public_key();
-        let client_ed25519_key = *ed25519.public_key();
-        let hello1 =
-            ClientHelloData::new_with_fresh_salt(client_key, client_ed25519_key, timestamp);
-        let hello2 =
-            ClientHelloData::new_with_fresh_salt(client_key, client_ed25519_key, timestamp);
-
-        // Different salts should be generated
-        assert_ne!(hello1.salt, hello2.salt);
-
-        // But timestamps should be very close (within 1 second)
-        let ts1 = hello1.extract_timestamp();
-        let ts2 = hello2.extract_timestamp();
-        assert!((ts1 as i64 - ts2 as i64).abs() <= 1);
-    }
-
-    #[test]
-    fn test_client_hello_timestamp_extraction() {
-        let timestamp = SystemTime::now()
-            .duration_since(UNIX_EPOCH)
-            .expect("System time before UNIX epoch")
-            .as_secs();
-        let mut rng = rand::thread_rng();
-        let ed25519 = ed25519::KeyPair::new(&mut rng);
-        let x25519 = ed25519.to_x25519();
-
-        let client_key = *x25519.public_key();
-        let client_ed25519_key = *ed25519.public_key();
-        let hello = ClientHelloData::new_with_fresh_salt(client_key, client_ed25519_key, timestamp);
-
-        let timestamp = hello.extract_timestamp();
-        let now = std::time::SystemTime::now()
-            .duration_since(std::time::UNIX_EPOCH)
-            .unwrap()
-            .as_secs();
-
-        // Timestamp should be within 1 second of now
-        assert!((timestamp as i64 - now as i64).abs() <= 1);
-    }
-
-    #[test]
-    fn test_client_hello_salt_format() {
-        let timestamp = SystemTime::now()
-            .duration_since(UNIX_EPOCH)
-            .expect("System time before UNIX epoch")
-            .as_secs();
-        let mut rng = rand::thread_rng();
-        let ed25519 = ed25519::KeyPair::new(&mut rng);
-        let x25519 = ed25519.to_x25519();
-
-        let client_key = *x25519.public_key();
-        let client_ed25519_key = *ed25519.public_key();
-        let hello = ClientHelloData::new_with_fresh_salt(client_key, client_ed25519_key, timestamp);
-
-        // First 8 bytes should be non-zero timestamp
-        let timestamp_bytes = &hello.salt[..8];
-        assert_ne!(timestamp_bytes, &[0u8; 8]);
-
-        // Salt should be 32 bytes total
-        assert_eq!(hello.salt.len(), 32);
-    }
-}

common/nym-lp/src/noise_protocol.rs

@@ -1,337 +0,0 @@
-// Copyright 2025 - Nym Technologies SA <contact@nymtech.net>
-// SPDX-License-Identifier: Apache-2.0
-
-//! Sans-IO Noise protocol state machine, adapted from noise-psq.
-
-use snow::{TransportState, params::NoiseParams};
-use thiserror::Error;
-
-// --- Error Definition ---
-
-/// Errors related to the Noise protocol state machine.
-#[derive(Error, Debug)]
-pub enum NoiseError {
-    #[error("encountered a Noise decryption error")]
-    DecryptionError,
-
-    #[error("encountered a Noise Protocol error - {0}")]
-    ProtocolError(snow::Error),
-
-    #[error("operation is invalid in the current protocol state")]
-    IncorrectStateError,
-
-    #[error("attempted transport mode operation without real PSK injection")]
-    PskNotInjected,
-
-    #[error("Other Noise-related error: {0}")]
-    Other(String),
-
-    #[error("session is read-only after demotion")]
-    SessionReadOnly,
-}
-
-impl From<snow::Error> for NoiseError {
-    fn from(err: snow::Error) -> Self {
-        match err {
-            snow::Error::Decrypt => NoiseError::DecryptionError,
-            err => NoiseError::ProtocolError(err),
-        }
-    }
-}
-
-// --- Protocol State and Structs ---
-
-/// Represents the possible states of the Noise protocol machine.
-#[derive(Debug)]
-pub enum NoiseProtocolState {
-    /// The protocol is currently performing the handshake.
-    /// Contains the Snow handshake state.
-    Handshaking(Box<snow::HandshakeState>),
-
-    /// The handshake is complete, and the protocol is in transport mode.
-    /// Contains the Snow transport state.
-    Transport(TransportState),
-
-    /// The protocol has encountered an unrecoverable error.
-    /// Stores the error description.
-    Failed(String),
-}
-
-/// The core sans-io Noise protocol state machine.
-#[derive(Debug)]
-pub struct NoiseProtocol {
-    state: NoiseProtocolState,
-    // We might need buffers for incoming/outgoing data later if we add internal buffering
-    // read_buffer: Vec<u8>,
-    // write_buffer: Vec<u8>,
-}
-
-/// Represents the outcome of processing received bytes via `read_message`.
-#[derive(Debug, PartialEq)]
-pub enum ReadResult {
-    /// A handshake or transport message was successfully processed, but yielded no application data
-    /// and did not complete the handshake.
-    NoOp,
-    /// A complete application data message was decrypted.
-    DecryptedData(Vec<u8>),
-    /// The handshake successfully completed during this read operation.
-    HandshakeComplete,
-    // NOTE: NeedMoreBytes variant removed as read_message expects full frames.
-}
-
-// --- Implementation ---
-
-impl NoiseProtocol {
-    pub fn params() -> NoiseParams {
-        // SAFETY: the hardcoded pattern must be valid
-        // and if for some reason it was not, we MUST fail non-gracefully for there is no possible recovery
-        #[allow(clippy::unwrap_used)]
-        crate::NOISE_PATTERN.parse().unwrap()
-    }
-
-    /// Creates a new `NoiseProtocol` instance in the Handshaking state.
-    ///
-    /// Takes an initialized `snow::HandshakeState` (e.g., from `snow::Builder`).
-    pub fn new(initial_state: snow::HandshakeState) -> Self {
-        NoiseProtocol {
-            state: NoiseProtocolState::Handshaking(Box::new(initial_state)),
-        }
-    }
-
-    fn prepare_handshake_state<'a>(
-        local_private_key: &'a [u8],
-        remote_public_key: &'a [u8],
-        psk: &'a [u8],
-    ) -> snow::Builder<'a> {
-        let psk_index = crate::NOISE_PSK_INDEX;
-        let noise_params = NoiseProtocol::params();
-
-        snow::Builder::new(noise_params)
-            .local_private_key(local_private_key)
-            .remote_public_key(remote_public_key)
-            .psk(psk_index, psk)
-    }
-
-    /// Builds a new `NoiseProtocol` initiator instance with the provided local private key,
-    /// remote public key and psk
-    pub fn build_new_initiator(
-        local_private_key: &[u8],
-        remote_public_key: &[u8],
-        psk: &[u8],
-    ) -> Result<Self, NoiseError> {
-        let handshake_state =
-            Self::prepare_handshake_state(local_private_key, remote_public_key, psk)
-                .build_initiator()?;
-        Ok(Self::new(handshake_state))
-    }
-
-    /// Builds a new `NoiseProtocol` responder instance with the provided local private key,
-    /// remote public key and psk
-    pub fn build_new_responder(
-        local_private_key: &[u8],
-        remote_public_key: &[u8],
-        psk: &[u8],
-    ) -> Result<Self, NoiseError> {
-        let handshake_state =
-            Self::prepare_handshake_state(local_private_key, remote_public_key, psk)
-                .build_responder()?;
-        Ok(Self::new(handshake_state))
-    }
-
-    /// Processes a single, complete incoming Noise message frame.
-    ///
-    /// Assumes the caller handles buffering and framing to provide one full message.
-    /// Returns the result of processing the message.
-    pub fn read_message(&mut self, input: &[u8]) -> Result<ReadResult, NoiseError> {
-        // Allocate a buffer large enough for the maximum possible Noise message size.
-        // TODO: Consider reusing a buffer for efficiency.
-        let mut buffer = vec![0u8; 65535]; // Max Noise message size
-
-        match &mut self.state {
-            NoiseProtocolState::Handshaking(handshake_state) => {
-                match handshake_state.read_message(input, &mut buffer) {
-                    Ok(_) => {
-                        if handshake_state.is_handshake_finished() {
-                            // Transition to Transport state.
-                            let current_state = std::mem::replace(
-                                &mut self.state,
-                                // Temporary placeholder needed for mem::replace
-                                NoiseProtocolState::Failed(
-                                    NoiseError::IncorrectStateError.to_string(),
-                                ),
-                            );
-                            if let NoiseProtocolState::Handshaking(state_to_convert) = current_state
-                            {
-                                match state_to_convert.into_transport_mode() {
-                                    Ok(transport_state) => {
-                                        self.state = NoiseProtocolState::Transport(transport_state);
-                                        Ok(ReadResult::HandshakeComplete)
-                                    }
-                                    Err(e) => {
-                                        let err = NoiseError::from(e);
-                                        self.state = NoiseProtocolState::Failed(err.to_string());
-                                        Err(err)
-                                    }
-                                }
-                            } else {
-                                // Should be unreachable
-                                let err = NoiseError::IncorrectStateError;
-                                self.state = NoiseProtocolState::Failed(err.to_string());
-                                Err(err)
-                            }
-                        } else {
-                            // Handshake continues
-                            Ok(ReadResult::NoOp)
-                        }
-                    }
-                    Err(e) => {
-                        let err = NoiseError::from(e);
-                        self.state = NoiseProtocolState::Failed(err.to_string());
-                        Err(err)
-                    }
-                }
-            }
-            NoiseProtocolState::Transport(transport_state) => {
-                match transport_state.read_message(input, &mut buffer) {
-                    Ok(len) => Ok(ReadResult::DecryptedData(buffer[..len].to_vec())),
-                    Err(e) => {
-                        let err = NoiseError::from(e);
-                        self.state = NoiseProtocolState::Failed(err.to_string());
-                        Err(err)
-                    }
-                }
-            }
-            NoiseProtocolState::Failed(_) => Err(NoiseError::IncorrectStateError),
-        }
-    }
-
-    /// Checks if there are pending handshake messages to send.
-    ///
-    /// If in Handshaking state and it's our turn, generates the message.
-    /// Transitions state to Transport if the handshake completes after this message.
-    /// Returns `None` if not in Handshaking state or not our turn.
-    pub fn get_bytes_to_send(&mut self) -> Option<Result<Vec<u8>, NoiseError>> {
-        match &mut self.state {
-            NoiseProtocolState::Handshaking(handshake_state) => {
-                if handshake_state.is_my_turn() {
-                    let mut buffer = vec![0u8; 65535];
-                    match handshake_state.write_message(&[], &mut buffer) {
-                        // Empty payload for handshake msg
-                        Ok(len) => {
-                            if handshake_state.is_handshake_finished() {
-                                // Transition to Transport state.
-                                let current_state = std::mem::replace(
-                                    &mut self.state,
-                                    NoiseProtocolState::Failed(
-                                        NoiseError::IncorrectStateError.to_string(),
-                                    ),
-                                );
-                                if let NoiseProtocolState::Handshaking(state_to_convert) =
-                                    current_state
-                                {
-                                    match state_to_convert.into_transport_mode() {
-                                        Ok(transport_state) => {
-                                            self.state =
-                                                NoiseProtocolState::Transport(transport_state);
-                                            Some(Ok(buffer[..len].to_vec())) // Return final handshake msg
-                                        }
-                                        Err(e) => {
-                                            let err = NoiseError::from(e);
-                                            self.state =
-                                                NoiseProtocolState::Failed(err.to_string());
-                                            Some(Err(err))
-                                        }
-                                    }
-                                } else {
-                                    // Should be unreachable
-                                    let err = NoiseError::IncorrectStateError;
-                                    self.state = NoiseProtocolState::Failed(err.to_string());
-                                    Some(Err(err))
-                                }
-                            } else {
-                                // Handshake continues
-                                Some(Ok(buffer[..len].to_vec()))
-                            }
-                        }
-                        Err(e) => {
-                            let err = NoiseError::from(e);
-                            self.state = NoiseProtocolState::Failed(err.to_string());
-                            Some(Err(err))
-                        }
-                    }
-                } else {
-                    // Not our turn
-                    None
-                }
-            }
-            NoiseProtocolState::Transport(_) | NoiseProtocolState::Failed(_) => {
-                // No handshake messages to send in these states
-                None
-            }
-        }
-    }
-
-    /// Encrypts an application data payload for sending during the Transport phase.
-    ///
-    /// Returns the ciphertext (payload + 16-byte tag).
-    /// Errors if not in Transport state or encryption fails.
-    pub fn write_message(&mut self, payload: &[u8]) -> Result<Vec<u8>, NoiseError> {
-        match &mut self.state {
-            NoiseProtocolState::Transport(transport_state) => {
-                let mut buffer = vec![0u8; payload.len() + 16]; // Payload + tag
-                match transport_state.write_message(payload, &mut buffer) {
-                    Ok(len) => Ok(buffer[..len].to_vec()),
-                    Err(e) => {
-                        let err = NoiseError::from(e);
-                        self.state = NoiseProtocolState::Failed(err.to_string());
-                        Err(err)
-                    }
-                }
-            }
-            NoiseProtocolState::Handshaking(_) | NoiseProtocolState::Failed(_) => {
-                Err(NoiseError::IncorrectStateError)
-            }
-        }
-    }
-
-    /// Returns true if the protocol is in the transport phase (handshake complete).
-    pub fn is_transport(&self) -> bool {
-        matches!(self.state, NoiseProtocolState::Transport(_))
-    }
-
-    /// Returns true if the protocol has failed.
-    pub fn is_failed(&self) -> bool {
-        matches!(self.state, NoiseProtocolState::Failed(_))
-    }
-
-    /// Check if the handshake has finished and the protocol is in transport mode.
-    pub fn is_handshake_finished(&self) -> bool {
-        matches!(self.state, NoiseProtocolState::Transport(_))
-    }
-
-    /// Inject a PSK into the Noise HandshakeState.
-    ///
-    /// This allows dynamic PSK injection after HandshakeState construction,
-    /// which is required for PSQ (Post-Quantum Secure PSK) integration where
-    /// the PSK is derived during the handshake process.
-    ///
-    /// # Arguments
-    /// * `index` - PSK index (typically 3 for XKpsk3 pattern)
-    /// * `psk` - The pre-shared key bytes to inject
-    ///
-    /// # Errors
-    /// Returns an error if:
-    /// - Not in handshake state
-    /// - The underlying snow library rejects the PSK
-    pub fn set_psk(&mut self, index: u8, psk: &[u8]) -> Result<(), NoiseError> {
-        match &mut self.state {
-            NoiseProtocolState::Handshaking(handshake_state) => {
-                handshake_state
-                    .set_psk(index as usize, psk)
-                    .map_err(NoiseError::ProtocolError)?;
-                Ok(())
-            }
-            _ => Err(NoiseError::IncorrectStateError),
-        }
-    }
-}

common/nym-lp/src/packet.rs

@@ -1,289 +0,0 @@
-// Copyright 2025 - Nym Technologies SA <contact@nymtech.net>
-// SPDX-License-Identifier: Apache-2.0
-
-use crate::LpError;
-use crate::message::{LpMessage, MessageType};
-use crate::replay::ReceivingKeyCounterValidator;
-use bytes::{BufMut, BytesMut};
-use nym_lp_common::format_debug_bytes;
-use parking_lot::Mutex;
-use std::fmt::Write;
-use std::fmt::{Debug, Formatter};
-use std::sync::Arc;
-use tracing::warn;
-
-#[allow(dead_code)]
-pub(crate) const UDP_HEADER_LEN: usize = 8;
-#[allow(dead_code)]
-pub(crate) const IP_HEADER_LEN: usize = 40; // v4 - 20, v6 - 40
-#[allow(dead_code)]
-pub(crate) const MTU: usize = 1500;
-#[allow(dead_code)]
-pub(crate) const UDP_OVERHEAD: usize = UDP_HEADER_LEN + IP_HEADER_LEN;
-
-#[allow(dead_code)]
-pub const TRAILER_LEN: usize = 16;
-#[allow(dead_code)]
-pub(crate) const UDP_PAYLOAD_SIZE: usize = MTU - UDP_OVERHEAD - TRAILER_LEN;
-
-pub mod version {
-    /// The current version of the Lewes Protocol that is put into each new constructed header.
-    pub const CURRENT: u8 = 1;
-}
-
-#[derive(Clone)]
-pub struct LpPacket {
-    pub(crate) header: LpHeader,
-    pub(crate) message: LpMessage,
-    pub(crate) trailer: [u8; TRAILER_LEN],
-}
-
-impl Debug for LpPacket {
-    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
-        write!(f, "{}", format_debug_bytes(&self.debug_bytes())?)
-    }
-}
-
-impl LpPacket {
-    pub fn new(header: LpHeader, message: LpMessage) -> Self {
-        Self {
-            header,
-            message,
-            trailer: [0; TRAILER_LEN],
-        }
-    }
-
-    pub fn typ(&self) -> MessageType {
-        self.message.typ()
-    }
-
-    /// Compute a hash of the message payload
-    ///
-    /// This can be used for message integrity verification or deduplication
-    pub fn hash_payload(&self) -> [u8; 32] {
-        use sha2::{Digest, Sha256};
-
-        let mut hasher = Sha256::new();
-        let mut buffer = BytesMut::new();
-
-        // Include message type and content in the hash
-        buffer.put_slice(&(self.message.typ() as u16).to_le_bytes());
-        self.message.encode_content(&mut buffer);
-
-        hasher.update(&buffer);
-        hasher.finalize().into()
-    }
-
-    pub fn hash_payload_hex(&self) -> String {
-        let hash = self.hash_payload();
-        hash.iter()
-            .fold(String::with_capacity(hash.len() * 2), |mut acc, byte| {
-                let _ = write!(acc, "{:02x}", byte);
-                acc
-            })
-    }
-
-    pub fn message(&self) -> &LpMessage {
-        &self.message
-    }
-
-    pub fn header(&self) -> &LpHeader {
-        &self.header
-    }
-
-    pub(crate) fn debug_bytes(&self) -> Vec<u8> {
-        let mut bytes = BytesMut::new();
-        self.encode(&mut bytes);
-        bytes.freeze().to_vec()
-    }
-
-    pub(crate) fn encode(&self, dst: &mut BytesMut) {
-        self.header.encode(dst);
-
-        dst.put_slice(&(self.message.typ() as u16).to_le_bytes());
-        self.message.encode_content(dst);
-
-        dst.put_slice(&self.trailer)
-    }
-
-    /// Validate packet counter against a replay protection validator
-    ///
-    /// This performs a quick check to see if the packet counter is valid before
-    /// any expensive processing is done.
-    pub fn validate_counter(
-        &self,
-        validator: &Arc<Mutex<ReceivingKeyCounterValidator>>,
-    ) -> Result<(), LpError> {
-        let guard = validator.lock();
-        guard.will_accept_branchless(self.header.counter)?;
-        Ok(())
-    }
-
-    /// Mark packet as received in the replay protection validator
-    ///
-    /// This should be called after a packet has been successfully processed.
-    pub fn mark_received(
-        &self,
-        validator: &Arc<Mutex<ReceivingKeyCounterValidator>>,
-    ) -> Result<(), LpError> {
-        let mut guard = validator.lock();
-        guard.mark_did_receive_branchless(self.header.counter)?;
-        Ok(())
-    }
-}
-
-/// Session ID used for ClientHello bootstrap packets before session is established.
-///
-/// When a client first connects, it sends a ClientHello packet with receiver_idx=0
-/// because neither side can compute the deterministic session ID yet (requires
-/// both parties' X25519 keys). After ClientHello is processed, both sides derive
-/// the same session ID from their keys, and all subsequent packets use that ID.
-pub const BOOTSTRAP_RECEIVER_IDX: u32 = 0;
-
-/// Outer header (12 bytes) - always cleartext, used for routing.
-///
-/// This is the first 12 bytes of every LP packet, containing only the fields
-/// needed for session lookup (receiver_idx) and replay protection (counter).
-/// For encrypted packets, this is the AAD (additional authenticated data).
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub struct OuterHeader {
-    pub receiver_idx: u32,
-    pub counter: u64,
-}
-
-impl OuterHeader {
-    pub const SIZE: usize = 12; // receiver_idx(4) + counter(8)
-
-    pub fn new(receiver_idx: u32, counter: u64) -> Self {
-        Self {
-            receiver_idx,
-            counter,
-        }
-    }
-
-    pub fn parse(src: &[u8]) -> Result<Self, LpError> {
-        if src.len() < Self::SIZE {
-            return Err(LpError::InsufficientBufferSize);
-        }
-        Ok(Self {
-            receiver_idx: u32::from_le_bytes(src[0..4].try_into().unwrap()),
-            counter: u64::from_le_bytes(src[4..12].try_into().unwrap()),
-        })
-    }
-
-    pub fn encode(&self) -> [u8; Self::SIZE] {
-        let mut buf = [0u8; Self::SIZE];
-        buf[0..4].copy_from_slice(&self.receiver_idx.to_le_bytes());
-        buf[4..12].copy_from_slice(&self.counter.to_le_bytes());
-        buf
-    }
-
-    /// Encode directly into a BytesMut buffer
-    pub fn encode_into(&self, dst: &mut BytesMut) {
-        dst.put_slice(&self.receiver_idx.to_le_bytes());
-        dst.put_slice(&self.counter.to_le_bytes());
-    }
-}
-
-/// Internal LP header representation containing all logical header fields.
-///
-/// **Note**: This struct represents the LOGICAL header, not the wire format.
-/// On the wire, packets use the unified format where:
-/// - `OuterHeader` (receiver_idx + counter) always comes first (12 bytes, cleartext)
-/// - Inner content (version + reserved + payload) follows (cleartext or encrypted)
-///
-/// The `LpHeader::encode()` method outputs the old logical format for debug purposes only.
-/// Use `serialize_lp_packet()` in codec.rs for actual wire serialization.
-#[derive(Debug, Clone)]
-pub struct LpHeader {
-    pub protocol_version: u8,
-    pub reserved: [u8; 3],
-    pub receiver_idx: u32,
-    pub counter: u64,
-}
-
-impl LpHeader {
-    pub const SIZE: usize = 16;
-}
-
-impl LpHeader {
-    pub fn new(receiver_idx: u32, counter: u64, protocol_version: u8) -> Self {
-        Self {
-            protocol_version,
-            reserved: [0u8; 3],
-            receiver_idx,
-            counter,
-        }
-    }
-
-    pub fn encode(&self, dst: &mut BytesMut) {
-        // protocol version
-        dst.put_u8(self.protocol_version);
-
-        // reserved
-        dst.put_slice(&self.reserved);
-
-        // sender index
-        dst.put_slice(&self.receiver_idx.to_le_bytes());
-
-        // counter
-        dst.put_slice(&self.counter.to_le_bytes());
-    }
-
-    pub fn parse(src: &[u8]) -> Result<Self, LpError> {
-        if src.len() < Self::SIZE {
-            return Err(LpError::InsufficientBufferSize);
-        }
-
-        let protocol_version = src[0];
-
-        // Ensure we are using compatible protocol
-        // right now only support a single version
-        if protocol_version > version::CURRENT {
-            return Err(LpError::IncompatibleFuturePacketVersion {
-                got: protocol_version,
-                highest_supported: version::CURRENT,
-            });
-        }
-
-        if protocol_version < version::CURRENT {
-            return Err(LpError::IncompatibleLegacyPacketVersion {
-                got: protocol_version,
-                lowest_supported: version::CURRENT,
-            });
-        }
-
-        // skip reserved bytes, but log if they're different from the expected zeroes
-        let reserved = [src[1], src[2], src[3]];
-        if reserved != [0u8; 3] {
-            warn!("received non-zero reserved bytes. got: {reserved:?}");
-        }
-
-        let mut receiver_idx_bytes = [0u8; 4];
-        receiver_idx_bytes.copy_from_slice(&src[4..8]);
-        let receiver_idx = u32::from_le_bytes(receiver_idx_bytes);
-
-        let mut counter_bytes = [0u8; 8];
-        counter_bytes.copy_from_slice(&src[8..16]);
-        let counter = u64::from_le_bytes(counter_bytes);
-
-        Ok(LpHeader {
-            protocol_version,
-            reserved,
-            receiver_idx,
-            counter,
-        })
-    }
-
-    /// Get the counter value from the header
-    pub fn counter(&self) -> u64 {
-        self.counter
-    }
-
-    /// Get the sender index from the header
-    pub fn receiver_idx(&self) -> u32 {
-        self.receiver_idx
-    }
-}
-
-// subsequent data: MessageType || Data

common/nym-lp/src/packet/error.rs

@@ -0,0 +1,33 @@
+// Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
+// SPDX-License-Identifier: Apache-2.0
+
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum MalformedLpPacketError {
+    #[error("failed to deserialise received data: {0}")]
+    DeserialisationFailure(String),
+
+    #[error("provided insufficient data to fully deserialise the struct")]
+    InsufficientData,
+
+    #[error("{0} is not a valid LpDataKind")]
+    InvalidLpDataKind(u16),
+
+    #[error("invalid payload size: expected {expected}, got {actual}")]
+    InvalidPayloadSize { expected: usize, actual: usize },
+
+    /// Received an LP packet with an incompatible, future, version
+    #[error("incompatible LP packet version. got: {got}, highest supported: {highest_supported}")]
+    IncompatibleFuturePacketVersion { got: u8, highest_supported: u8 },
+
+    /// Received an LP packet with an incompatible, legacy, version
+    #[error("incompatible LP packet version. got: {got}, lowest supported: {lowest_supported}")]
+    IncompatibleLegacyPacketVersion { got: u8, lowest_supported: u8 },
+}
+
+impl MalformedLpPacketError {
+    pub fn invalid_data_kind(message_type: u16) -> Self {
+        MalformedLpPacketError::InvalidLpDataKind(message_type)
+    }
+}

common/nym-lp/src/packet/header.rs

@@ -0,0 +1,148 @@
+// Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
+// SPDX-License-Identifier: Apache-2.0
+
+use crate::packet::version;
+use crate::{packet::error::MalformedLpPacketError, peer_config::LpReceiverIndex};
+use bytes::{BufMut, BytesMut};
+use tracing::warn;
+
+/// Outer header (12 bytes) - always cleartext, used for routing.
+///
+/// This is the first 12 bytes of every LP packet, containing only the fields
+/// needed for session lookup (receiver_idx) and replay protection (counter).
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct OuterHeader {
+    pub receiver_idx: LpReceiverIndex,
+    pub counter: u64,
+}
+
+impl OuterHeader {
+    pub const SIZE: usize = 12; // receiver_idx(4) + counter(8)
+
+    pub fn new(receiver_idx: LpReceiverIndex, counter: u64) -> Self {
+        Self {
+            receiver_idx,
+            counter,
+        }
+    }
+
+    pub fn parse(src: &[u8]) -> Result<Self, MalformedLpPacketError> {
+        if src.len() < Self::SIZE {
+            return Err(MalformedLpPacketError::InsufficientData);
+        }
+        #[allow(clippy::unwrap_used)]
+        Ok(Self {
+            receiver_idx: LpReceiverIndex::from_le_bytes(src[0..4].try_into().unwrap()),
+            counter: u64::from_le_bytes(src[4..12].try_into().unwrap()),
+        })
+    }
+
+    pub fn to_bytes(&self) -> [u8; Self::SIZE] {
+        let mut bytes = [0u8; Self::SIZE];
+        bytes[0..4].copy_from_slice(&self.receiver_idx.to_le_bytes());
+        bytes[4..12].copy_from_slice(&self.counter.to_le_bytes());
+        bytes
+    }
+
+    /// Encode directly into a BytesMut buffer
+    pub fn encode(&self, dst: &mut BytesMut) {
+        dst.put_slice(&self.receiver_idx.to_le_bytes());
+        dst.put_slice(&self.counter.to_le_bytes());
+    }
+}
+
+/// InnerHeader header (8 bytes) - encrypted, used for message parsing
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct InnerHeader {
+    pub protocol_version: u8,
+    pub reserved: [u8; 3],
+}
+
+impl InnerHeader {
+    pub const SIZE: usize = 4; // protocol_version(1) + reserved(3)
+
+    pub fn encode(&self, dst: &mut BytesMut) {
+        // protocol version
+        dst.put_u8(self.protocol_version);
+
+        // reserved
+        dst.put_slice(&self.reserved);
+    }
+
+    pub fn parse(src: &[u8]) -> Result<Self, MalformedLpPacketError> {
+        if src.len() < Self::SIZE {
+            return Err(MalformedLpPacketError::InsufficientData);
+        }
+
+        let protocol_version = src[0];
+
+        // Ensure we are using compatible protocol
+        // right now only support a single version
+        if protocol_version > version::CURRENT {
+            return Err(MalformedLpPacketError::IncompatibleFuturePacketVersion {
+                got: protocol_version,
+                highest_supported: version::CURRENT,
+            });
+        }
+
+        if protocol_version < version::CURRENT {
+            return Err(MalformedLpPacketError::IncompatibleLegacyPacketVersion {
+                got: protocol_version,
+                lowest_supported: version::CURRENT,
+            });
+        }
+
+        // skip reserved bytes, but log if they're different from the expected zeroes
+        let reserved = [src[1], src[2], src[3]];
+        if reserved != [0u8; 3] {
+            warn!("received non-zero reserved bytes. got: {reserved:?}");
+        }
+
+        Ok(InnerHeader {
+            protocol_version,
+            reserved,
+        })
+    }
+}
+
+/// Internal LP header representation containing all logical header fields.
+///
+/// **Note**: This struct represents the LOGICAL header, not the wire format.
+/// On the wire, packets use the unified format where:
+/// - `OuterHeader` (receiver_idx + counter) always comes first (12 bytes, cleartext)
+/// - Inner content (version + reserved + payload) follows (cleartext or encrypted)
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct LpHeader {
+    pub outer: OuterHeader,
+    pub inner: InnerHeader,
+}
+
+impl LpHeader {
+    pub fn new(receiver_idx: LpReceiverIndex, counter: u64, protocol_version: u8) -> Self {
+        Self {
+            outer: OuterHeader {
+                receiver_idx,
+                counter,
+            },
+            inner: InnerHeader {
+                protocol_version,
+                reserved: [0u8; 3],
+            },
+        }
+    }
+
+    pub(crate) fn dbg_encode(&self, dst: &mut BytesMut) {
+        self.outer.encode(dst);
+        self.inner.encode(dst);
+    }
+
+    /// Get the counter value from the header
+    pub fn counter(&self) -> u64 {
+        self.outer.counter
+    }
+
+    /// Get the sender index from the header
+    pub fn receiver_idx(&self) -> LpReceiverIndex {
+        self.outer.receiver_idx
+    }
+}

common/nym-lp/src/packet/message.rs

@@ -0,0 +1,255 @@
+// Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
+// SPDX-License-Identifier: Apache-2.0
+
+use crate::packet::error::MalformedLpPacketError;
+use bytes::{BufMut, Bytes, BytesMut};
+use num_enum::{IntoPrimitive, TryFromPrimitive};
+use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr};
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct LpMessageHeader {
+    pub kind: LpMessageType,
+    pub message_attributes: [u8; 14],
+}
+
+impl LpMessageHeader {
+    pub const SIZE: usize = 16; // message_kind(2) + message_attributes(14)
+
+    pub fn new(kind: LpMessageType, message_attributes: [u8; 14]) -> Self {
+        Self {
+            kind,
+            message_attributes,
+        }
+    }
+
+    pub fn new_no_attributes(kind: LpMessageType) -> Self {
+        Self {
+            kind,
+            message_attributes: [0; 14],
+        }
+    }
+
+    /// Encode directly into a BytesMut buffer
+    pub fn encode(&self, dst: &mut BytesMut) {
+        dst.put_u16_le(self.kind as u16);
+        dst.put_slice(&self.message_attributes);
+    }
+
+    pub fn parse(src: &[u8]) -> Result<Self, MalformedLpPacketError> {
+        if src.len() < Self::SIZE {
+            return Err(MalformedLpPacketError::InsufficientData);
+        }
+        let raw_kind = u16::from_le_bytes([src[0], src[1]]);
+
+        let kind = LpMessageType::try_from(raw_kind)
+            .map_err(|_| MalformedLpPacketError::invalid_data_kind(raw_kind))?;
+
+        #[allow(clippy::unwrap_used)]
+        let message_attributes = src[2..16].try_into().unwrap();
+        Ok(Self {
+            kind,
+            message_attributes,
+        })
+    }
+}
+
+/// Represent application data being sent in Transport mode
+#[derive(Debug, Clone, PartialEq)]
+pub struct LpMessage {
+    pub header: LpMessageHeader,
+    pub content: Bytes,
+}
+
+impl AsRef<[u8]> for LpMessage {
+    fn as_ref(&self) -> &[u8] {
+        &self.content
+    }
+}
+
+impl LpMessage {
+    pub fn new(kind: LpMessageType, content: impl Into<Bytes>) -> Self {
+        Self {
+            header: LpMessageHeader::new_no_attributes(kind),
+            content: content.into(),
+        }
+    }
+
+    pub fn encode(&self, dst: &mut BytesMut) {
+        self.header.encode(dst);
+
+        dst.put_slice(&self.content);
+    }
+
+    pub fn decode(src: &[u8]) -> Result<Self, MalformedLpPacketError> {
+        let header = LpMessageHeader::parse(src)?;
+        let content = src[LpMessageHeader::SIZE..].to_vec().into();
+
+        Ok(Self { header, content })
+    }
+
+    pub fn kind(&self) -> LpMessageType {
+        self.header.kind
+    }
+
+    pub fn new_opaque(content: impl Into<Bytes>) -> Self {
+        Self::new(LpMessageType::Opaque, content)
+    }
+
+    pub fn new_registration(data: impl Into<Bytes>) -> Self {
+        Self::new(LpMessageType::Registration, data)
+    }
+
+    pub fn new_forward(data: impl Into<Bytes>) -> Self {
+        Self::new(LpMessageType::Forward, data)
+    }
+
+    pub(crate) fn len(&self) -> usize {
+        LpMessageHeader::SIZE + self.content.len()
+    }
+}
+
+/// Represent kind of application data being sent in Transport mode
+#[derive(Clone, Copy, PartialEq, Eq, Debug, IntoPrimitive, TryFromPrimitive)]
+#[repr(u16)]
+pub enum LpMessageType {
+    Opaque = 0,
+    Registration = 1,
+    Forward = 2,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ExpectedResponseSize {
+    /// We've sent a handshake message and expect response of predefined size
+    Handshake(u32),
+
+    /// We've sent a transport message and the response is length-prefixed
+    Transport,
+}
+
+impl ExpectedResponseSize {
+    pub fn to_bytes(&self) -> [u8; 4] {
+        // there are no empty handshake messages, so we use 0 bytes to indicate Transport variant
+        match self {
+            ExpectedResponseSize::Handshake(size) => size.to_le_bytes(),
+            ExpectedResponseSize::Transport => [0u8; 4],
+        }
+    }
+
+    pub fn from_bytes(b: [u8; 4]) -> Self {
+        let size = u32::from_le_bytes(b);
+        if size == 0 {
+            ExpectedResponseSize::Transport
+        } else {
+            ExpectedResponseSize::Handshake(size)
+        }
+    }
+}
+
+/// Packet forwarding request with embedded inner LP packet
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ForwardPacketData {
+    /// Target gateway's LP address (IP:port string)
+    pub target_lp_address: SocketAddr,
+
+    /// Indication of the expected size of the response
+    /// to allow the proxy to read correct data from the stream
+    pub expected_response_size: ExpectedResponseSize,
+
+    /// Complete inner LP packet bytes (serialized LpPacket)
+    /// This is the CLIENT→EXIT gateway packet, encrypted for exit
+    pub inner_packet_bytes: Vec<u8>,
+}
+
+impl ForwardPacketData {
+    pub fn new(
+        target_lp_address: SocketAddr,
+        expected_response_size: ExpectedResponseSize,
+        inner_packet_bytes: Vec<u8>,
+    ) -> Self {
+        ForwardPacketData {
+            target_lp_address,
+            expected_response_size,
+            inner_packet_bytes,
+        }
+    }
+
+    // 0 || [4B ipv4]  || [2B port] || [4B res size] || [4B plen] || payload
+    // 1 || [16B ipv6] || [2B port] || [4B res size] || [4B plen] || payload
+    fn encode(&self, dst: &mut BytesMut) {
+        let (is_ipv6, ip_bytes) = match &self.target_lp_address {
+            SocketAddr::V4(address) => (false, address.ip().octets().to_vec()),
+            SocketAddr::V6(address) => (true, address.ip().octets().to_vec()),
+        };
+
+        dst.put_u8(is_ipv6 as u8); // IP type , 0 for ipv4
+        dst.put_slice(&ip_bytes); // IP bytes
+        dst.put_u16_le(self.target_lp_address.port()); // Port
+        dst.put_slice(&self.expected_response_size.to_bytes());
+        dst.put_u32_le(self.inner_packet_bytes.len() as u32);
+        dst.put_slice(&self.inner_packet_bytes);
+    }
+
+    pub fn to_bytes(&self) -> Vec<u8> {
+        let mut buf = BytesMut::new();
+        self.encode(&mut buf);
+        buf.into()
+    }
+
+    pub fn decode(b: &[u8]) -> Result<Self, MalformedLpPacketError> {
+        // smallest possible packet with ipv4 and empty data
+        if b.len() < 15 {
+            // 1 + 4 + 2 + 4 + 4 + 0
+            return Err(MalformedLpPacketError::DeserialisationFailure(format!(
+                "Too few bytes to deserialise ForwardPacketData. got {}",
+                b.len()
+            )));
+        }
+
+        let target_lp_address_is_ipv6 = b[0] != 0;
+
+        let (target_lp_address, i) = if target_lp_address_is_ipv6 {
+            // IPv6, first check we have actually enough bytes
+            // smallest possible packet with ipv6 and empty data
+            if b.len() < 27 {
+                // 1 + 16 + 2 + 4 + 4+ 0
+                return Err(MalformedLpPacketError::DeserialisationFailure(format!(
+                    "Too few bytes to deserialise ipv6 ForwardPacketData. got {}",
+                    b.len()
+                )));
+            }
+            // Ipv6Addr::from_octets is not available until 1.91 so we have to use
+            // the slightly less obvious u128 conversion
+            // SAFETY: we ensured we have sufficient data, and the length is correct for casting
+            #[allow(clippy::unwrap_used)]
+            let ipv6 = IpAddr::V6(Ipv6Addr::from_bits(u128::from_be_bytes(
+                b[1..17].try_into().unwrap(),
+            )));
+            let port = u16::from_le_bytes([b[17], b[18]]);
+            (SocketAddr::new(ipv6, port), 19)
+        } else {
+            // IPv4. Length check done at the start
+
+            // Ipv4Addr::from_octets is not available until 1.91
+            let ipv4 = IpAddr::V4(Ipv4Addr::new(b[1], b[2], b[3], b[4]));
+            let port = u16::from_le_bytes([b[5], b[6]]);
+            (SocketAddr::new(ipv4, port), 7)
+        };
+
+        let expected_response_size_bytes = [b[i], b[i + 1], b[i + 2], b[i + 3]];
+        let inner_packet_bytes_len = u32::from_le_bytes([b[i + 4], b[i + 5], b[i + 6], b[i + 7]]);
+
+        if b[i + 8..].len() != inner_packet_bytes_len as usize {
+            return Err(MalformedLpPacketError::DeserialisationFailure(format!(
+                "Expected {inner_packet_bytes_len} bytes to deserialise inner packet bytes of ForwardPacketData. got {}",
+                b[i + 8..].len()
+            )));
+        }
+        let inner_packet_bytes = b[i + 8..].to_vec();
+
+        Ok(ForwardPacketData {
+            target_lp_address,
+            expected_response_size: ExpectedResponseSize::from_bytes(expected_response_size_bytes),
+            inner_packet_bytes,
+        })
+    }
+}

common/nym-lp/src/packet/mod.rs

@@ -0,0 +1,120 @@
+// Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
+// SPDX-License-Identifier: Apache-2.0
+
+use crate::packet::utils::format_debug_bytes;
+use bytes::{BufMut, BytesMut};
+use std::fmt::{Debug, Formatter};
+
+pub use error::MalformedLpPacketError;
+pub use header::{InnerHeader, LpHeader, OuterHeader};
+pub use message::{ForwardPacketData, LpMessage};
+
+pub mod error;
+pub mod header;
+pub mod message;
+pub mod replay;
+pub mod utils;
+
+pub mod version {
+    /// The current version of the Lewes Protocol that is put into each new constructed header.
+    pub const CURRENT: u8 = 1;
+}
+
+#[allow(dead_code)]
+pub(crate) const UDP_HEADER_LEN: usize = 8;
+#[allow(dead_code)]
+pub(crate) const IP_HEADER_LEN: usize = 40; // v4 - 20, v6 - 40
+#[allow(dead_code)]
+pub(crate) const MTU: usize = 1500;
+#[allow(dead_code)]
+pub(crate) const UDP_OVERHEAD: usize = UDP_HEADER_LEN + IP_HEADER_LEN;
+#[allow(dead_code)]
+pub(crate) const UDP_PAYLOAD_SIZE: usize = MTU - UDP_OVERHEAD;
+
+#[derive(Clone)]
+pub struct EncryptedLpPacket {
+    // The outer header that's sent in plaintext
+    pub(crate) outer_header: OuterHeader,
+
+    // The ciphertext containing the inner header and the payload
+    pub(crate) ciphertext: Vec<u8>,
+}
+
+impl std::fmt::Debug for EncryptedLpPacket {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", format_debug_bytes(&self.debug_bytes())?)
+    }
+}
+
+impl EncryptedLpPacket {
+    pub fn new(outer_header: OuterHeader, ciphertext: Vec<u8>) -> EncryptedLpPacket {
+        EncryptedLpPacket {
+            outer_header,
+            ciphertext,
+        }
+    }
+
+    pub fn encoded_length(&self) -> usize {
+        OuterHeader::SIZE + self.ciphertext.len()
+    }
+
+    pub(crate) fn debug_bytes(&self) -> Vec<u8> {
+        let mut bytes = BytesMut::new();
+        self.encode(&mut bytes);
+        bytes.freeze().to_vec()
+    }
+
+    pub fn encode(&self, dst: &mut BytesMut) {
+        self.outer_header.encode(dst);
+        dst.put_slice(&self.ciphertext)
+    }
+
+    pub fn ciphertext(&self) -> &[u8] {
+        &self.ciphertext
+    }
+
+    pub fn outer_header(&self) -> OuterHeader {
+        self.outer_header
+    }
+}
+
+#[derive(Clone, PartialEq)]
+pub struct LpPacket {
+    pub(crate) header: LpHeader,
+    pub(crate) message: LpMessage,
+}
+
+impl Debug for LpPacket {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", format_debug_bytes(&self.debug_bytes())?)
+    }
+}
+
+impl LpPacket {
+    pub fn new(header: LpHeader, message: LpMessage) -> Self {
+        Self { header, message }
+    }
+
+    pub fn message(&self) -> &LpMessage {
+        &self.message
+    }
+
+    pub fn into_message(self) -> LpMessage {
+        self.message
+    }
+
+    pub fn header(&self) -> &LpHeader {
+        &self.header
+    }
+
+    pub(crate) fn debug_bytes(&self) -> Vec<u8> {
+        let mut bytes = BytesMut::new();
+        self.dbg_encode(&mut bytes);
+        bytes.freeze().to_vec()
+    }
+
+    pub(crate) fn dbg_encode(&self, dst: &mut BytesMut) {
+        self.header.dbg_encode(dst);
+        self.message.encode(dst)
+    }
+}

common/nym-lp/src/packet/replay.rs

@@ -0,0 +1,33 @@
+use crate::{LpError, packet::LpPacket, replay::ReceivingKeyCounterValidator};
+
+pub trait LpPacketReplayExt {
+    /// Validate packet counter against a replay protection validator
+    ///
+    /// This performs a quick check to see if the packet counter is valid before
+    /// any expensive processing is done.
+    fn validate_counter(&self, validator: &ReceivingKeyCounterValidator) -> Result<(), LpError>;
+
+    /// Mark packet as received in the replay protection validator
+    ///
+    /// This should be called after a packet has been successfully processed.
+    fn mark_received(&self, validator: &mut ReceivingKeyCounterValidator) -> Result<(), LpError>;
+}
+
+impl LpPacketReplayExt for LpPacket {
+    /// Validate packet counter against a replay protection validator
+    ///
+    /// This performs a quick check to see if the packet counter is valid before
+    /// any expensive processing is done.
+    fn validate_counter(&self, validator: &ReceivingKeyCounterValidator) -> Result<(), LpError> {
+        validator.will_accept_branchless(self.header().outer.counter)?;
+        Ok(())
+    }
+
+    /// Mark packet as received in the replay protection validator
+    ///
+    /// This should be called after a packet has been successfully processed.
+    fn mark_received(&self, validator: &mut ReceivingKeyCounterValidator) -> Result<(), LpError> {
+        validator.mark_did_receive_branchless(self.header().outer.counter)?;
+        Ok(())
+    }
+}

common/nym-lp/src/packet/utils.rs

@@ -1,8 +1,4 @@
-// Copyright 2025 - Nym Technologies SA <contact@nymtech.net>
-// SPDX-License-Identifier: Apache-2.0
-
-use std::fmt;
-use std::fmt::Write;
+use std::fmt::{self, Write};
 
 pub fn format_debug_bytes(bytes: &[u8]) -> Result<String, fmt::Error> {
     let mut out = String::new();

common/nym-lp/src/peer.rs

@@ -1,102 +1,77 @@
 // Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
 // SPDX-License-Identifier: Apache-2.0
 
-use crate::{ClientHelloData, LpError};
-use nym_crypto::asymmetric::{ed25519, x25519};
-use nym_kkt::ciphersuite::{Ciphersuite, KEM, KEMKeyDigests, SignatureScheme, SigningKeyDigests};
-use std::collections::HashMap;
+use crate::LpError;
+use nym_kkt_ciphersuite::{Ciphersuite, KEM, KEMKeyDigests};
+use std::collections::BTreeMap;
+use std::fmt::Debug;
 use std::sync::Arc;
 
+pub use libcrux_psq::handshake::types::{DHKeyPair, DHPublicKey};
+pub use nym_kkt::key_utils::{
+    generate_keypair_mceliece, generate_keypair_mlkem, generate_lp_keypair_x25519,
+};
+pub use nym_kkt::keys::KEMKeys;
+
 /// Representation of a local Lewes Protocol peer
 /// encapsulating all the known information and keys.
-#[derive(Debug, Clone)]
+#[derive(Clone)]
 pub struct LpLocalPeer {
-    /// Local Ed25519 keys for PSQ authentication
-    pub(crate) ed25519: Arc<ed25519::KeyPair>,
+    pub(crate) ciphersuite: Ciphersuite,
 
     /// Local x25519 keys (Noise static key)
-    pub(crate) x25519: Arc<x25519::KeyPair>,
+    pub(crate) x25519: Arc<DHKeyPair>,
 
-    /// Local KEM key used for PSQ
-    pub(crate) kem_psq: Option<Arc<x25519::KeyPair>>,
+    /// Local KEM keys used for PSQ
+    pub(crate) kem_keypairs: Option<KEMKeys>,
 }
 
 impl LpLocalPeer {
-    pub fn new(ed25519: Arc<ed25519::KeyPair>, x25519: Arc<x25519::KeyPair>) -> Self {
+    pub fn new(ciphersuite: Ciphersuite, x25519: Arc<DHKeyPair>) -> Self {
         LpLocalPeer {
-            ed25519,
+            ciphersuite,
             x25519,
-            kem_psq: None,
+            kem_keypairs: Default::default(),
         }
     }
 
-    pub fn build_client_hello_data(&self, timestamp: u64) -> ClientHelloData {
-        ClientHelloData::new_with_fresh_salt(
-            *self.x25519().public_key(),
-            *self.ed25519().public_key(),
-            timestamp,
-        )
-    }
-
     #[must_use]
-    pub fn with_kem_psq_key(mut self, key: Arc<x25519::KeyPair>) -> Self {
-        self.kem_psq = Some(key);
+    pub fn with_kem_keys(mut self, kem_keys: KEMKeys) -> Self {
+        self.kem_keypairs = Some(kem_keys);
         self
     }
 
-    pub fn ed25519(&self) -> &Arc<ed25519::KeyPair> {
-        &self.ed25519
-    }
-
-    pub fn x25519(&self) -> &Arc<x25519::KeyPair> {
+    pub fn x25519(&self) -> &Arc<DHKeyPair> {
         &self.x25519
     }
 
-    /// Returns the reference to the KEM Public key of the peer (if available).
-    pub fn get_kem_key_handle(&self) -> Result<&x25519::PublicKey, LpError> {
-        self.kem_psq
-            .as_ref()
-            .map(|kp| kp.public_key())
-            .ok_or(LpError::ResponderWithMissingKEMKey)
-    }
-
     /// Convert this `LpLocalPeer` into a valid `LpRemotePeer` that can be used within tests
     #[doc(hidden)]
     pub fn as_remote(&self) -> LpRemotePeer {
-        let expected_kem_key_digests = match &self.kem_psq {
-            None => HashMap::new(),
-            Some(kem_keys) => {
-                let mut digests = HashMap::new();
-                digests.insert(
-                    KEM::X25519,
-                    nym_kkt::key_utils::produce_key_digests(kem_keys.public_key().as_bytes()),
-                );
-                digests
-            }
-        };
-
-        let mut expected_signing_key_digests = HashMap::new();
-        expected_signing_key_digests.insert(
-            SignatureScheme::Ed25519,
-            nym_kkt::key_utils::produce_key_digests(self.ed25519.public_key().as_bytes()),
-        );
+        let expected_kem_key_digests = self
+            .kem_keypairs
+            .as_ref()
+            .map(|k| k.encapsulation_keys_digests())
+            .unwrap_or_default();
 
         LpRemotePeer {
-            ed25519_public: *self.ed25519.public_key(),
-            x25519_public: *self.x25519.public_key(),
+            x25519_public: self.x25519.pk,
             expected_kem_key_digests,
-            expected_signing_key_digests,
         }
     }
 
-    // this is only exposed in tests as ideally we should be storing the proper types to begin with
-    #[cfg(test)]
-    pub fn encapsulate_kem_key(&self) -> Option<nym_kkt::ciphersuite::EncapsulationKey<'_>> {
-        let pk_bytes = self.kem_psq.as_ref()?.public_key().to_bytes();
-        let libcrux_pk =
-            libcrux_kem::PublicKey::decode(libcrux_kem::Algorithm::X25519, &pk_bytes).ok()?;
+    pub fn ciphersuite(&self) -> Ciphersuite {
+        self.ciphersuite
+    }
+}
 
-        Some(nym_kkt::ciphersuite::EncapsulationKey::X25519(libcrux_pk))
+impl Debug for LpLocalPeer {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("LpLocalPeer")
+            .field("ciphersuite", &self.ciphersuite)
+            .field("x25519", &self.x25519.pk)
+            .field("kem_keypairs", &self.kem_keypairs)
+            .finish()
     }
 }
 
@@ -104,45 +79,31 @@ impl LpLocalPeer {
 /// encapsulating all the known information and keys.
 #[derive(Debug, Clone)]
 pub struct LpRemotePeer {
-    /// Remote Ed25519 public key for PSQ authentication
-    pub(crate) ed25519_public: ed25519::PublicKey,
-
     /// Remote X25519 public key (Noise static key)
-    pub(crate) x25519_public: x25519::PublicKey,
+    pub(crate) x25519_public: DHPublicKey,
 
     /// Expected digests of the remote's KEM key
-    pub(crate) expected_kem_key_digests: HashMap<KEM, KEMKeyDigests>,
-
-    /// Expected digests of the remote's signing key
-    pub(crate) expected_signing_key_digests: HashMap<SignatureScheme, SigningKeyDigests>,
+    pub(crate) expected_kem_key_digests: BTreeMap<KEM, KEMKeyDigests>,
 }
 
 impl LpRemotePeer {
-    pub fn new(ed25519_public: ed25519::PublicKey, x25519_public: x25519::PublicKey) -> Self {
+    pub fn new(x25519_public: DHPublicKey) -> Self {
         LpRemotePeer {
-            ed25519_public,
             x25519_public,
             expected_kem_key_digests: Default::default(),
-            expected_signing_key_digests: Default::default(),
         }
     }
 
-    pub fn ed25519(&self) -> ed25519::PublicKey {
-        self.ed25519_public
-    }
-
-    pub fn x25519(&self) -> x25519::PublicKey {
-        self.x25519_public
+    pub fn x25519(&self) -> &DHPublicKey {
+        &self.x25519_public
     }
 
     #[must_use]
     pub fn with_key_digests(
         mut self,
-        expected_kem_key_digests: HashMap<KEM, KEMKeyDigests>,
-        expected_signing_key_digests: HashMap<SignatureScheme, SigningKeyDigests>,
+        expected_kem_key_digests: BTreeMap<KEM, KEMKeyDigests>,
     ) -> Self {
         self.expected_kem_key_digests = expected_kem_key_digests;
-        self.expected_signing_key_digests = expected_signing_key_digests;
         self
     }
 
@@ -168,30 +129,40 @@ impl LpRemotePeer {
     }
 }
 
+impl From<DHPublicKey> for LpRemotePeer {
+    fn from(value: DHPublicKey) -> Self {
+        LpRemotePeer {
+            x25519_public: value,
+            expected_kem_key_digests: Default::default(),
+        }
+    }
+}
+
 #[cfg(any(feature = "mock", test))]
 pub fn mock_peer() -> LpLocalPeer {
     // use deterministic rng
-    let mut rng = nym_test_utils::helpers::deterministic_rng();
+    let mut rng = nym_test_utils::helpers::deterministic_rng_09();
     random_peer(&mut rng)
 }
 
 #[cfg(any(feature = "mock", test))]
-pub fn random_peer<R: rand::CryptoRng + rand::RngCore>(rng: &mut R) -> LpLocalPeer {
-    let ed25519 = Arc::new(ed25519::KeyPair::new(rng));
-    let x25519 = Arc::new(ed25519.to_x25519());
-    let kem_psq = Some(x25519.clone());
+pub fn random_peer<R: rand09::CryptoRng + rand09::RngCore>(rng: &mut R) -> LpLocalPeer {
+    let x25519 = Arc::new(nym_kkt::key_utils::generate_lp_keypair_x25519(rng));
 
     LpLocalPeer {
-        ed25519,
+        ciphersuite: Ciphersuite::default(),
+
         x25519,
-        kem_psq,
+        kem_keypairs: Some(KEMKeys::new(
+            nym_kkt::key_utils::generate_keypair_mceliece(rng),
+            nym_kkt::key_utils::generate_keypair_mlkem(rng),
+        )),
     }
 }
 
 #[cfg(any(feature = "mock", test))]
 pub fn mock_peers() -> (LpLocalPeer, LpLocalPeer) {
-    // use deterministic rng
-    let mut rng = nym_test_utils::helpers::deterministic_rng();
+    let mut rng = nym_test_utils::helpers::deterministic_rng_09();
 
     (random_peer(&mut rng), random_peer(&mut rng))
 }

common/nym-lp/src/peer_config.rs

@@ -0,0 +1,482 @@
+// Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
+// SPDX-License-Identifier: Apache-2.0
+
+use crate::LpError;
+use libcrux_psq::handshake::types::Authenticator;
+
+use nym_crypto::hkdf::blake3::derive_key_blake3_multi_input;
+use nym_kkt::keys::EncapsulationKey;
+use rand09::{self, CryptoRng, Rng};
+use tls_codec::Serialize;
+use zeroize::Zeroize;
+
+pub type LpReceiverIndex = u32;
+
+pub const MAX_HOPS: u8 = 16;
+pub const LP_PEER_CONFIG_SIZE: usize = 20;
+
+const SEED_LEN: usize = 16;
+const CONFIG_LEN: usize = 1;
+const FILLER_LEN: usize = LP_PEER_CONFIG_SIZE - SEED_LEN - CONFIG_LEN;
+
+const RECEIVER_INDEX_DERIVATION_CONTEXT: &str = "LP_PEER_CONFIG_RECEIVER_INDEX_DERIVATION_V1";
+
+// 20 bytes
+#[derive(PartialEq)]
+pub struct LpPeerConfig {
+    // The first 4 fields will be packed in one u8
+    // with 1 bit left at the end
+
+    // Determine the hop id.
+    // Should be 0 if node_initiator is true
+    // Should be > 1 if is_exit is true
+    hop_id: u8,
+
+    // Determine if the recipient should be an exit node
+    is_exit: bool,
+
+    // Determine if we are establishing a node<>node connection
+    // Should be false if is_exit is true
+    node_initiator: bool,
+
+    // Enable censorship resistance countermeasures
+    censorship_resistance: bool,
+
+    // If we add more config params later, we can use this
+    filler: [u8; FILLER_LEN],
+
+    seed: [u8; SEED_LEN],
+}
+
+impl LpPeerConfig {
+    /// Creates a new client to entry config.
+    /// Sets `hop_id` to 0.
+    /// Input: censorship_resistance flag to enable censorship resistance features.
+    pub fn new_client_to_entry<R>(rng: &mut R, censorship_resistance: bool) -> Self
+    where
+        R: Rng + CryptoRng,
+    {
+        Self::build(
+            0,
+            false,
+            false,
+            censorship_resistance,
+            rng.random(),
+            rng.random(),
+        )
+    }
+    /// Creates a new client to exit config.
+    /// Inputs:
+    /// hop_id: this value must be in the range (1..=15). This function returns an error if this is not the case.
+    /// censorship_resistance flag to enable censorship resistance features.
+    pub fn new_client_to_exit<R>(
+        rng: &mut R,
+        hop_id: u8,
+        censorship_resistance: bool,
+    ) -> Result<Self, LpError>
+    where
+        R: Rng + CryptoRng,
+    {
+        Self::new(rng, hop_id, true, false, censorship_resistance)
+    }
+    /// Creates a new client to an intermediate node config.
+    /// Inputs:
+    /// hop_id: this value must be in the range (1..=14). This function returns an error if this is not the case.
+    /// censorship_resistance flag to enable censorship resistance features.
+    pub fn new_client_to_intermediate<R>(
+        rng: &mut R,
+        hop_id: u8,
+        censorship_resistance: bool,
+    ) -> Result<Self, LpError>
+    where
+        R: Rng + CryptoRng,
+    {
+        if hop_id == 0 || hop_id == 15 {
+            Err(LpError::Internal(format!(
+                "An intermediate hop cannot be the first or last hop. Requested hop id {hop_id}"
+            )))
+        } else {
+            Self::new(rng, hop_id, false, false, censorship_resistance)
+        }
+    }
+
+    /// Creates a new node to node config.
+    /// Censorship resistance features are disabled by default between nodes.
+    pub fn new_node_to_node<R>(rng: &mut R) -> Result<Self, LpError>
+    where
+        R: Rng + CryptoRng,
+    {
+        // no need for censorship resistance between nodes (for now)
+        // hop_id between nodes is 0
+        Self::new(rng, 0, false, true, false)
+    }
+
+    pub fn new<R>(
+        rng: &mut R,
+        hop_id: u8,
+        is_exit: bool,
+        node_initiator: bool,
+        censorship_resistance: bool,
+    ) -> Result<Self, LpError>
+    where
+        R: Rng + CryptoRng,
+    {
+        Self::build_checked(
+            hop_id,
+            is_exit,
+            node_initiator,
+            censorship_resistance,
+            rng.random(),
+            rng.random(),
+        )
+    }
+    fn build(
+        hop_id: u8,
+        is_exit: bool,
+        node_initiator: bool,
+        censorship_resistance: bool,
+        seed: [u8; SEED_LEN],
+        filler: [u8; FILLER_LEN],
+    ) -> Self {
+        Self {
+            hop_id,
+            is_exit,
+            node_initiator,
+            censorship_resistance,
+            filler,
+            seed,
+        }
+    }
+    fn build_checked(
+        hop_id: u8,
+        is_exit: bool,
+        node_initiator: bool,
+        censorship_resistance: bool,
+        seed: [u8; SEED_LEN],
+        filler: [u8; FILLER_LEN],
+    ) -> Result<Self, LpError> {
+        if node_initiator && is_exit {
+            Err(LpError::Internal(
+                "A node cannot establish an exit node for itself.".into(),
+            ))
+        } else if node_initiator && hop_id != 0 {
+            Err(LpError::Internal(
+                "Hop id in node to node connections must be zero.".into(),
+            ))
+        } else if !node_initiator && hop_id >= MAX_HOPS {
+            Err(LpError::Internal(format!(
+                "Requested hop index ({}) is greater than the allowed maximum {}.",
+                hop_id,
+                MAX_HOPS - 1
+            )))
+        } else if !node_initiator && is_exit && hop_id == 0 {
+            Err(LpError::Internal(
+                "Hop id for exit node cannot be zero.".into(),
+            ))
+        } else if !node_initiator && !is_exit && hop_id == 15 {
+            Err(LpError::Internal(
+                "The hop with id 15 must be an exit node.".into(),
+            ))
+        } else {
+            Ok(Self::build(
+                hop_id,
+                is_exit,
+                node_initiator,
+                censorship_resistance,
+                seed,
+                filler,
+            ))
+        }
+    }
+
+    pub fn hop_id(&self) -> u8 {
+        self.hop_id
+    }
+
+    pub fn seed(&self) -> &[u8; SEED_LEN] {
+        &self.seed
+    }
+
+    pub fn serialize(&self) -> [u8; LP_PEER_CONFIG_SIZE] {
+        let mut output_bytes: [u8; LP_PEER_CONFIG_SIZE] = [0u8; LP_PEER_CONFIG_SIZE];
+        output_bytes[0..4].copy_from_slice(self.pack_config().as_slice());
+        output_bytes[4..].copy_from_slice(&self.seed);
+        output_bytes
+    }
+    pub fn deserialize(bytes: &[u8]) -> Result<Self, LpError> {
+        if bytes.len() != LP_PEER_CONFIG_SIZE {
+            Err(LpError::DeserializationError(format!(
+                "Invalid Lp Config Length ({}), expected ({})",
+                bytes.len(),
+                LP_PEER_CONFIG_SIZE
+            )))
+        } else {
+            let (hop_id, is_exit, node_initiator, censorship_resistance) =
+                Self::unpack_first_byte(bytes[0]);
+
+            let mut filler: [u8; FILLER_LEN] = [0u8; FILLER_LEN];
+            filler.copy_from_slice(&bytes[CONFIG_LEN..CONFIG_LEN + FILLER_LEN]);
+
+            let mut seed: [u8; SEED_LEN] = [0u8; SEED_LEN];
+            seed.copy_from_slice(&bytes[CONFIG_LEN + FILLER_LEN..LP_PEER_CONFIG_SIZE]);
+
+            Self::build_checked(
+                hop_id,
+                is_exit,
+                node_initiator,
+                censorship_resistance,
+                seed,
+                filler,
+            )
+        }
+    }
+
+    fn pack_config(&self) -> [u8; 4] {
+        [
+            self.pack_first_byte(),
+            self.filler[0],
+            self.filler[1],
+            self.filler[2],
+        ]
+    }
+
+    fn pack_first_byte(&self) -> u8 {
+        let mut byte = self.hop_id;
+
+        // Set the 5th bit to determine if the node is an exit node
+        if self.is_exit {
+            byte |= 0b0001_0000;
+        }
+        // Set the 6th bit to determine if we're establishing a node to node connection
+        if self.node_initiator {
+            byte |= 0b0010_0000;
+        }
+        // Set the 7th bit to determine if we should use censorship resistance measures
+        if self.censorship_resistance {
+            byte |= 0b0100_0000;
+        }
+
+        // There will be 1 free bit at the end
+
+        byte
+    }
+
+    fn unpack_first_byte(byte: u8) -> (u8, bool, bool, bool) {
+        // extract 4 bits
+        let hop_id = byte & 0b0000_1111;
+
+        // extract 5th bit
+        let is_exit = (byte & 0b0001_0000) >> 4 == 1;
+        // extract 6th bit
+        let node_initiator = (byte & 0b0010_0000) >> 5 == 1;
+        // extract 7th bit
+        let censorship_resistance = (byte & 0b0100_0000) >> 6 == 1;
+
+        // If we need to use the last bit, we can add something here
+        (hop_id, is_exit, node_initiator, censorship_resistance)
+    }
+
+    pub fn is_client_entry(&self) -> bool {
+        self.hop_id == 0 && !self.is_exit && !self.node_initiator
+    }
+
+    pub fn is_client_intermediate_node(&self) -> bool {
+        self.hop_id > 0 && !self.is_exit && !self.node_initiator
+    }
+
+    pub fn is_client_exit(&self) -> bool {
+        self.hop_id > 0 && self.is_exit && !self.node_initiator
+    }
+
+    pub fn is_node_to_node(&self) -> bool {
+        self.hop_id == 0 && !self.is_exit && self.node_initiator
+    }
+
+    // This returns a LpReceiverIndex made out of the first 4 bytes from
+    // KDF(RECEIVER_INDEX_DERIVATION_CONTEXT, initiator_pub_key || responder_kem_key, seed)
+    pub fn derive_receiver_index(
+        &self,
+        initiator_public_key: &Authenticator,
+        responder_kem_pk: &EncapsulationKey,
+    ) -> Result<LpReceiverIndex, LpError> {
+        let initiator_public_key = initiator_public_key.tls_serialize_detached().map_err(|_| {
+            LpError::Internal(
+                "Failed to serialize initiator public key when computing receiver index".into(),
+            )
+        })?;
+        let mut h = derive_key_blake3_multi_input(
+            RECEIVER_INDEX_DERIVATION_CONTEXT,
+            &[initiator_public_key.as_slice(), responder_kem_pk.as_bytes()],
+            self.seed(),
+        );
+        let index = LpReceiverIndex::from_le_bytes([h[0], h[1], h[2], h[3]]);
+        h.zeroize();
+        Ok(index)
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::peer_config::LpPeerConfig;
+
+    #[test]
+    fn test_pack_config() {
+        let mut rng = rand09::rng();
+
+        // Node to node, no censorship resistance
+        {
+            let expected_conf = 0b0010_0000;
+            let conf = LpPeerConfig::new(&mut rng, 0, false, true, false).unwrap();
+            let conf_bytes = conf.serialize();
+            let deserialized_conf_first_byte = LpPeerConfig::deserialize(&conf_bytes)
+                .unwrap()
+                .pack_config()[0];
+
+            assert_eq!(expected_conf, conf_bytes[0]);
+            assert_eq!(expected_conf, deserialized_conf_first_byte);
+            assert_eq!(
+                conf_bytes[0],
+                LpPeerConfig::new_node_to_node(&mut rng)
+                    .unwrap()
+                    .serialize()[0]
+            );
+            assert!(conf.is_node_to_node());
+        }
+
+        // Node to node, with censorship resistance
+        {
+            let expected_conf = 0b0110_0000;
+            let conf = LpPeerConfig::new(&mut rng, 0, false, true, true).unwrap();
+            let conf_bytes = conf.serialize();
+            let deserialized_conf_first_byte = LpPeerConfig::deserialize(&conf_bytes)
+                .unwrap()
+                .pack_config()[0];
+
+            assert_eq!(expected_conf, conf_bytes[0]);
+            assert_eq!(expected_conf, deserialized_conf_first_byte);
+            assert!(conf.is_node_to_node());
+        }
+
+        // Client to Entry, no censorship resistance
+        {
+            let expected_conf = 0b0000_0000;
+            let conf = LpPeerConfig::new(&mut rng, 0, false, false, false).unwrap();
+            let conf_bytes = conf.serialize();
+            let deserialized_conf_first_byte = LpPeerConfig::deserialize(&conf_bytes)
+                .unwrap()
+                .pack_config()[0];
+            let conf_alt_first_byte =
+                LpPeerConfig::new_client_to_entry(&mut rng, false).serialize()[0];
+
+            assert_eq!(expected_conf, conf_bytes[0]);
+            assert_eq!(expected_conf, deserialized_conf_first_byte);
+            assert_eq!(conf_bytes[0], conf_alt_first_byte);
+            assert!(conf.is_client_entry())
+        }
+
+        // Client to Entry, with censorship resistance
+        {
+            let expected_conf = 0b0100_0000;
+            let conf = LpPeerConfig::new(&mut rng, 0, false, false, true).unwrap();
+            let conf_bytes = conf.serialize();
+            let deserialized_conf_first_byte = LpPeerConfig::deserialize(&conf_bytes)
+                .unwrap()
+                .pack_config()[0];
+            let conf_alt_first_byte =
+                LpPeerConfig::new_client_to_entry(&mut rng, true).serialize()[0];
+
+            assert_eq!(expected_conf, conf_bytes[0]);
+            assert_eq!(expected_conf, deserialized_conf_first_byte);
+            assert_eq!(conf_bytes[0], conf_alt_first_byte);
+            assert!(conf.is_client_entry());
+        }
+
+        // Client to Exit(exit hop = 1), with censorship resistance
+        {
+            let expected_conf = 0b0101_0001;
+            let conf = LpPeerConfig::new(&mut rng, 1, true, false, true).unwrap();
+            let conf_bytes = conf.serialize();
+            let deserialized_conf_first_byte = LpPeerConfig::deserialize(&conf_bytes)
+                .unwrap()
+                .pack_config()[0];
+            let conf_alt_first_byte = LpPeerConfig::new_client_to_exit(&mut rng, 1, true)
+                .unwrap()
+                .serialize()[0];
+
+            assert_eq!(expected_conf, conf_bytes[0]);
+            assert_eq!(expected_conf, deserialized_conf_first_byte);
+            assert_eq!(conf_bytes[0], conf_alt_first_byte);
+            assert!(conf.is_client_exit());
+        }
+
+        // Client to Exit(exit hop = 2), without censorship resistance
+        {
+            let expected_conf = 0b0001_0010;
+            let conf = LpPeerConfig::new(&mut rng, 2, true, false, false).unwrap();
+            let conf_bytes = conf.serialize();
+            let deserialized_conf_first_byte = LpPeerConfig::deserialize(&conf_bytes)
+                .unwrap()
+                .pack_config()[0];
+            let conf_alt_first_byte = LpPeerConfig::new_client_to_exit(&mut rng, 2, false)
+                .unwrap()
+                .serialize()[0];
+
+            assert_eq!(expected_conf, conf_bytes[0]);
+            assert_eq!(expected_conf, deserialized_conf_first_byte);
+            assert_eq!(conf_bytes[0], conf_alt_first_byte);
+            assert!(conf.is_client_exit());
+        }
+        // Client to Intermediate (hop_id = 14), without censorship resistance
+        {
+            let expected_conf = 0b0000_1110;
+            let conf = LpPeerConfig::new(&mut rng, 14, false, false, false).unwrap();
+            let conf_bytes = conf.serialize();
+            let deserialized_conf_first_byte = LpPeerConfig::deserialize(&conf_bytes)
+                .unwrap()
+                .pack_config()[0];
+            let conf_alt_first_byte = LpPeerConfig::new_client_to_intermediate(&mut rng, 14, false)
+                .unwrap()
+                .serialize()[0];
+
+            assert_eq!(expected_conf, conf_bytes[0]);
+            assert_eq!(expected_conf, deserialized_conf_first_byte);
+            assert_eq!(conf_bytes[0], conf_alt_first_byte);
+            assert!(conf.is_client_intermediate_node());
+        }
+    }
+
+    #[test]
+    fn test_failures() {
+        let mut rng = rand09::rng();
+        // Hop with id 15 must be an exit node
+        assert!(LpPeerConfig::new(&mut rng, 15, false, false, false).is_err());
+
+        // intermediate hop cannot be the first hop
+        assert!(LpPeerConfig::new_client_to_intermediate(&mut rng, 0, false).is_err());
+        // intermediate hop cannot be the last hop
+        assert!(LpPeerConfig::new_client_to_intermediate(&mut rng, 15, false).is_err());
+
+        // Hop with id 0 must be an entry node
+        assert!(LpPeerConfig::new_client_to_intermediate(&mut rng, 0, false).is_err());
+        assert!(LpPeerConfig::new_client_to_exit(&mut rng, 0, false).is_err());
+        assert!(LpPeerConfig::new(&mut rng, 0, true, false, false).is_err());
+
+        // cannot be node to node with hop_id > 0
+        assert!(LpPeerConfig::new(&mut rng, 1, false, true, false).is_err());
+
+        // cannot be node to node and exit at the same time
+        assert!(LpPeerConfig::new(&mut rng, 0, true, true, false).is_err());
+
+        // cannot have hop_id greater than 15
+        // this is a valid config
+        assert!(LpPeerConfig::new(&mut rng, 0, false, false, false).is_ok());
+        // this is a valid config
+        assert!(LpPeerConfig::new(&mut rng, 14, false, false, false).is_ok());
+        // this is a valid config
+        assert!(LpPeerConfig::new(&mut rng, 15, true, false, false).is_ok());
+        // these are not valid configs
+        assert!(LpPeerConfig::new(&mut rng, 16, false, false, false).is_err());
+        assert!(LpPeerConfig::new(&mut rng, 16, true, false, false).is_err());
+        assert!(LpPeerConfig::new(&mut rng, 240, false, false, false).is_err());
+    }
+}

common/nym-lp/src/psk.rs

@@ -1,792 +0,0 @@
-// Copyright 2025 - Nym Technologies SA <contact@nymtech.net>
-// SPDX-License-Identifier: Apache-2.0
-
-//! PSK (Pre-Shared Key) derivation for LP sessions using Blake3 KDF.
-//!
-//! This module implements identity-bound PSK derivation where both client and gateway
-//! derive the same PSK from their LP keypairs.
-//!
-//! PSQ is embedded in Noise (not separate protocol) because:
-//! 1. Single round-trip: PSQ ciphertext piggybacks on Noise handshake messages
-//! 2. PSK binding: Noise XKpsk3 pattern authenticates both ECDH and PSQ-derived PSK
-//! 3. Simpler state machine: No separate PSQ negotiation phase needed
-//! 4. Atomic security: Session establishment either succeeds fully or fails completely
-//!
-//! Two approaches are supported:
-//! - **Legacy ECDH-only** (`derive_psk`) - Simple but no post-quantum security
-//! - **PSQ-enhanced** (`derive_psk_with_psq_*`) - Combines ECDH with post-quantum KEM
-//!
-//! ## Error Handling Strategy
-//!
-//! **PSQ failures always abort the handshake cleanly with no retry or fallback.**
-//!
-//! ### Rationale
-//!
-//! PSQ errors indicate:
-//! - **Authentication failures** (CredError) - Potential attack or misconfiguration
-//! - **Timing failures** (TimestampElapsed) - Replay attacks or clock skew
-//! - **Crypto failures** (CryptoError) - Library bugs or hardware faults
-//! - **Serialization failures** (Serialization) - Protocol violations or corruption
-//!
-//! None of these are transient errors that benefit from retry. Falling back to
-//! ECDH-only PSK would silently degrade post-quantum security.
-//!
-//! ### Error Recovery Behavior
-//!
-//! On any PSQ error:
-//! 1. Function returns `Err(LpError)` immediately
-//! 2. Session state remains unchanged (dummy PSK, clean Noise state)
-//! 3. Handshake aborts - caller must start fresh connection
-//! 4. Error is logged with diagnostic context
-//!
-//! ### State Guarantees on Error
-//!
-//! - **`psq_state`**: Remains in `NotStarted` (initiator) or `ResponderWaiting` (responder)
-//! - **Noise `HandshakeState`**: PSK slot 3 = dummy `[0u8; 32]` (not modified on error)
-//! - **No partial data**: All allocations are stack-local to failed function
-//! - **No cleanup needed**: No state was mutated
-
-use crate::LpError;
-use libcrux_psq::v1::cred::{Authenticator, Ed25519};
-use libcrux_psq::v1::impls::X25519 as PsqX25519;
-use libcrux_psq::v1::psk_registration::{Initiator, InitiatorMsg, Responder};
-use libcrux_psq::v1::traits::{Ciphertext as PsqCiphertext, PSQ};
-use nym_crypto::asymmetric::{ed25519, x25519};
-use nym_kkt::ciphersuite::{DecapsulationKey, EncapsulationKey};
-use std::time::Duration;
-use tls_codec::{Deserialize as TlsDeserializeTrait, Serialize as TlsSerializeTrait};
-
-/// Context string for Blake3 KDF domain separation (PSQ-enhanced).
-const PSK_PSQ_CONTEXT: &str = "nym-lp-psk-psq-v1";
-
-/// Session context for PSQ protocol.
-const PSQ_SESSION_CONTEXT: &[u8] = b"nym-lp-psq-session";
-
-/// Context string for subsession PSK derivation.
-const SUBSESSION_PSK_CONTEXT: &str = "lp-subsession-psk-v1";
-
-/// Result from PSQ initiator message creation.
-///
-/// Contains all outputs needed for session establishment:
-/// - `psk`: Final derived PSK for Noise handshake (ECDH || K_pq || salt → Blake3)
-/// - `payload`: Serialized PSQ message to send to responder
-/// - `pq_shared_secret`: Raw K_pq from KEM encapsulation (for subsession derivation)
-#[derive(Debug)]
-pub struct PsqInitiatorResult {
-    /// Final PSK for Noise XKpsk3 handshake
-    pub psk: [u8; 32],
-    /// Serialized PSQ payload to embed in handshake message
-    pub payload: Vec<u8>,
-    /// Raw PQ shared secret (K_pq) before KDF combination.
-    /// Used for deriving subsession PSKs to preserve PQ protection.
-    pub pq_shared_secret: [u8; 32],
-}
-
-/// Result from PSQ responder message processing.
-///
-/// Contains all outputs needed for session establishment:
-/// - `psk`: Final derived PSK for Noise handshake (matches initiator's)
-/// - `psk_handle`: Encrypted PSK handle (ctxt_B) to send back to initiator
-/// - `pq_shared_secret`: Raw K_pq from KEM decapsulation (for subsession derivation)
-#[derive(Debug)]
-pub struct PsqResponderResult {
-    /// Final PSK for Noise XKpsk3 handshake
-    pub psk: [u8; 32],
-    /// Encrypted PSK handle (ctxt_B) from PSQ responder message
-    pub psk_handle: Vec<u8>,
-    /// Raw PQ shared secret (K_pq) before KDF combination.
-    /// Used for deriving subsession PSKs to preserve PQ protection.
-    pub pq_shared_secret: [u8; 32],
-}
-
-/// Derives a PSK using PSQ (Post-Quantum Secure PSK) protocol - Initiator side.
-///
-/// This function combines classical ECDH with post-quantum KEM to provide forward secrecy
-/// and HNDL (Harvest-Now, Decrypt-Later) resistance.
-///
-/// # Formula
-/// ```text
-/// ecdh_secret = ECDH(local_x25519_private, remote_x25519_public)
-/// (psq_psk, ct) = PSQ_Encapsulate(remote_kem_public, session_context)
-/// psk = Blake3_derive_key(
-///     context="nym-lp-psk-psq-v1",
-///     input=ecdh_secret || psq_psk || salt
-/// )
-/// ```
-///
-/// # Arguments
-/// * `local_x25519_private` - Initiator's X25519 private key (for Noise)
-/// * `remote_x25519_public` - Responder's X25519 public key (for Noise)
-/// * `remote_kem_public` - Responder's KEM public key (obtained via KKT)
-/// * `salt` - 32-byte salt for session binding
-///
-/// # Returns
-/// * `Ok((psk, ciphertext))` - PSK and ciphertext to send to responder
-/// * `Err(LpError)` - If PSQ encapsulation fails
-///
-/// # Example
-/// ```ignore
-/// // Client side (after KKT exchange)
-/// let (psk, ciphertext) = derive_psk_with_psq_initiator(
-///     client_x25519_private,
-///     gateway_x25519_public,
-///     &gateway_kem_key,  // from KKT
-///     &salt
-/// )?;
-/// // Send ciphertext to gateway
-/// ```
-pub fn derive_psk_with_psq_initiator(
-    local_x25519_private: &x25519::PrivateKey,
-    remote_x25519_public: &x25519::PublicKey,
-    remote_kem_public: &EncapsulationKey,
-    salt: &[u8; 32],
-) -> Result<([u8; 32], Vec<u8>), LpError> {
-    // Step 1: Classical ECDH for baseline security
-    let ecdh_secret = local_x25519_private.diffie_hellman(remote_x25519_public);
-
-    // Step 2: PSQ encapsulation for post-quantum security
-    // KEM algorithm migration path:
-    // - X25519: Current default for testing/compatibility (no HNDL resistance)
-    // - MlKem768: Future production default (NIST PQ Level 3, HNDL resistant)
-    // - XWing: Maximum security option (hybrid X25519 + ML-KEM)
-    // Migration: Update LpConfig.kem_algorithm, no protocol changes needed.
-    // KKT protocol adapts automatically to different KEM key sizes.
-    let kem_pk = match remote_kem_public {
-        EncapsulationKey::X25519(pk) => pk,
-        _ => {
-            return Err(LpError::KKTError(
-                "Only X25519 KEM is currently supported for PSQ".to_string(),
-            ));
-        }
-    };
-
-    let mut rng = rand09::rng();
-    let (psq_psk, ciphertext) =
-        PsqX25519::encapsulate_psq(kem_pk, PSQ_SESSION_CONTEXT, &mut rng)
-            .map_err(|e| LpError::Internal(format!("PSQ encapsulation failed: {:?}", e)))?;
-
-    // Step 3: Combine ECDH + PSQ via Blake3 KDF
-    let mut combined = Vec::with_capacity(64 + psq_psk.len());
-    combined.extend_from_slice(&ecdh_secret);
-    combined.extend_from_slice(&psq_psk); // psq_psk is [u8; 32], need &
-    combined.extend_from_slice(salt);
-
-    let final_psk = nym_crypto::kdf::derive_key_blake3(PSK_PSQ_CONTEXT, &combined, &[]);
-
-    // Serialize ciphertext using TLS encoding for transport
-    let ct_bytes = ciphertext
-        .tls_serialize_detached()
-        .map_err(|e| LpError::Internal(format!("Ciphertext serialization failed: {:?}", e)))?;
-
-    Ok((final_psk, ct_bytes))
-}
-
-/// Derives a PSK using PSQ (Post-Quantum Secure PSK) protocol - Responder side.
-///
-/// This function decapsulates the ciphertext from the initiator and combines it with
-/// ECDH to derive the same PSK.
-///
-/// # Formula
-/// ```text
-/// ecdh_secret = ECDH(local_x25519_private, remote_x25519_public)
-/// psq_psk = PSQ_Decapsulate(local_kem_keypair, ciphertext, session_context)
-/// psk = Blake3_derive_key(
-///     context="nym-lp-psk-psq-v1",
-///     input=ecdh_secret || psq_psk || salt
-/// )
-/// ```
-///
-/// # Arguments
-/// * `local_x25519_private` - Responder's X25519 private key (for Noise)
-/// * `remote_x25519_public` - Initiator's X25519 public key (for Noise)
-/// * `local_kem_keypair` - Responder's KEM keypair (decapsulation key, public key)
-/// * `ciphertext` - PSQ ciphertext from initiator
-/// * `salt` - 32-byte salt for session binding
-///
-/// # Returns
-/// * `Ok(psk)` - Derived PSK
-/// * `Err(LpError)` - If PSQ decapsulation fails
-///
-/// # Example
-/// ```ignore
-/// // Gateway side (after receiving ciphertext)
-/// let psk = derive_psk_with_psq_responder(
-///     gateway_x25519_private,
-///     client_x25519_public,
-///     (&gateway_kem_sk, &gateway_kem_pk),
-///     &ciphertext,  // from client
-///     &salt
-/// )?;
-/// ```
-pub fn derive_psk_with_psq_responder(
-    local_x25519_private: &x25519::PrivateKey,
-    remote_x25519_public: &x25519::PublicKey,
-    local_kem_keypair: (&DecapsulationKey, &EncapsulationKey),
-    ciphertext: &[u8],
-    salt: &[u8; 32],
-) -> Result<[u8; 32], LpError> {
-    // Step 1: Classical ECDH for baseline security
-    let ecdh_secret = local_x25519_private.diffie_hellman(remote_x25519_public);
-
-    // Step 2: Extract X25519 keypair from DecapsulationKey/EncapsulationKey
-    let (kem_sk, kem_pk) = match (local_kem_keypair.0, local_kem_keypair.1) {
-        (DecapsulationKey::X25519(sk), EncapsulationKey::X25519(pk)) => (sk, pk),
-        _ => {
-            return Err(LpError::KKTError(
-                "Only X25519 KEM is currently supported for PSQ".to_string(),
-            ));
-        }
-    };
-
-    // Step 3: Deserialize ciphertext using TLS decoding
-    let ct = PsqCiphertext::<PsqX25519>::tls_deserialize(&mut &ciphertext[..])
-        .map_err(|e| LpError::Internal(format!("Ciphertext deserialization failed: {:?}", e)))?;
-
-    // Step 4: PSQ decapsulation for post-quantum security
-    let psq_psk = PsqX25519::decapsulate_psq(kem_sk, kem_pk, &ct, PSQ_SESSION_CONTEXT)
-        .map_err(|e| LpError::Internal(format!("PSQ decapsulation failed: {:?}", e)))?;
-
-    // Step 5: Combine ECDH + PSQ via Blake3 KDF (same formula as initiator)
-    let mut combined = Vec::with_capacity(64 + psq_psk.len());
-    combined.extend_from_slice(&ecdh_secret);
-    combined.extend_from_slice(&psq_psk); // psq_psk is [u8; 32], need &
-    combined.extend_from_slice(salt);
-
-    let final_psk = nym_crypto::kdf::derive_key_blake3(PSK_PSQ_CONTEXT, &combined, &[]);
-
-    Ok(final_psk)
-}
-
-/// PSQ protocol wrapper for initiator (client) side.
-///
-/// Creates a PSQ initiator message with Ed25519 authentication, following the protocol:
-/// 1. Encapsulate PSK using responder's KEM key
-/// 2. Derive PSK and AEAD keys from K_pq
-/// 3. Sign the encapsulation with Ed25519
-/// 4. AEAD encrypt (timestamp || signature || public_key)
-///
-/// Returns (PSK, serialized_payload) where payload includes enc_pq and encrypted auth data.
-///
-/// # Arguments
-/// * `local_x25519_private` - Client's X25519 private key (for hybrid ECDH)
-/// * `remote_x25519_public` - Gateway's X25519 public key (for hybrid ECDH)
-/// * `remote_kem_public` - Gateway's PQ KEM public key (from KKT)
-/// * `client_ed25519_sk` - Client's Ed25519 signing key
-/// * `client_ed25519_pk` - Client's Ed25519 public key (credential)
-/// * `salt` - Session salt
-/// * `session_context` - Context bytes for PSQ (e.g., b"nym-lp-psq-session")
-///
-/// # Returns
-/// `PsqInitiatorResult` containing PSK, payload, and raw PQ shared secret
-pub fn psq_initiator_create_message(
-    local_x25519_private: &x25519::PrivateKey,
-    remote_x25519_public: &x25519::PublicKey,
-    remote_kem_public: &EncapsulationKey,
-    client_ed25519_sk: &ed25519::PrivateKey,
-    client_ed25519_pk: &ed25519::PublicKey,
-    salt: &[u8; 32],
-    session_context: &[u8],
-) -> Result<PsqInitiatorResult, LpError> {
-    // Step 1: Classical ECDH for baseline security
-    let ecdh_secret = local_x25519_private.diffie_hellman(remote_x25519_public);
-
-    // Step 2: PSQ v1 with Ed25519 authentication
-    // Extract X25519 KEM key from EncapsulationKey
-    let kem_pk = match remote_kem_public {
-        EncapsulationKey::X25519(pk) => pk,
-        _ => {
-            return Err(LpError::KKTError(
-                "Only X25519 KEM is currently supported for PSQ".to_string(),
-            ));
-        }
-    };
-
-    // Convert nym Ed25519 keys to libcrux format
-    type Ed25519VerificationKey = <Ed25519 as Authenticator>::VerificationKey;
-    let ed25519_sk_bytes = client_ed25519_sk.to_bytes();
-    let ed25519_pk_bytes = client_ed25519_pk.to_bytes();
-    let ed25519_verification_key = Ed25519VerificationKey::from_bytes(ed25519_pk_bytes);
-
-    // Use PSQ v1 API with Ed25519 authentication
-    let mut rng = rand09::rng();
-    let (state, initiator_msg) = Initiator::send_initial_message::<Ed25519, PsqX25519>(
-        session_context,
-        Duration::from_secs(3600), // 1 hour expiry
-        kem_pk,
-        &ed25519_sk_bytes,
-        &ed25519_verification_key,
-        &mut rng,
-    )
-    .map_err(|e| {
-        tracing::error!(
-            "PSQ initiator failed - KEM encapsulation or signing error: {:?}",
-            e
-        );
-        LpError::Internal(format!("PSQ v1 send_initial_message failed: {:?}", e))
-    })?;
-
-    // Extract PSQ shared secret (unregistered PSK) - this is K_pq
-    let psq_psk = state.unregistered_psk();
-
-    // pq_shared_secret is the raw K_pq from KEM encapsulation.
-    // Store it for subsession derivation before it's combined with ECDH.
-    let pq_shared_secret: [u8; 32] = *psq_psk;
-
-    // Step 3: Combine ECDH + PSQ via Blake3 KDF
-    let mut combined = Vec::with_capacity(64 + psq_psk.len());
-    combined.extend_from_slice(&ecdh_secret);
-    combined.extend_from_slice(psq_psk); // psq_psk is already a &[u8; 32]
-    combined.extend_from_slice(salt);
-
-    let final_psk = nym_crypto::kdf::derive_key_blake3(PSK_PSQ_CONTEXT, &combined, &[]);
-
-    // Serialize InitiatorMsg with TLS encoding for transport
-    let msg_bytes = initiator_msg
-        .tls_serialize_detached()
-        .map_err(|e| LpError::Internal(format!("InitiatorMsg serialization failed: {:?}", e)))?;
-
-    Ok(PsqInitiatorResult {
-        psk: final_psk,
-        payload: msg_bytes,
-        pq_shared_secret,
-    })
-}
-
-/// PSQ protocol wrapper for responder (gateway) side.
-///
-/// Processes a PSQ initiator message, verifies authentication, and derives PSK.
-/// Follows the protocol:
-/// 1. Decapsulate to get K_pq
-/// 2. Derive AEAD keys and verify encrypted auth data
-/// 3. Verify Ed25519 signature
-/// 4. Check timestamp validity
-/// 5. Derive PSK
-///
-/// # Arguments
-/// * `local_x25519_private` - Gateway's X25519 private key (for hybrid ECDH)
-/// * `remote_x25519_public` - Client's X25519 public key (for hybrid ECDH)
-/// * `local_kem_keypair` - Gateway's PQ KEM keypair
-/// * `initiator_ed25519_pk` - Client's Ed25519 public key (for signature verification)
-/// * `psq_payload` - Serialized PSQ payload from initiator
-/// * `salt` - Session salt (must match initiator's)
-/// * `session_context` - Context bytes for PSQ
-///
-/// # Returns
-/// `PsqResponderResult` containing PSK, PSK handle, and raw PQ shared secret
-pub fn psq_responder_process_message(
-    local_x25519_private: &x25519::PrivateKey,
-    remote_x25519_public: &x25519::PublicKey,
-    local_kem_keypair: (&DecapsulationKey, &EncapsulationKey),
-    initiator_ed25519_pk: &ed25519::PublicKey,
-    psq_payload: &[u8],
-    salt: &[u8; 32],
-    session_context: &[u8],
-) -> Result<PsqResponderResult, LpError> {
-    // Step 1: Classical ECDH for baseline security
-    let ecdh_secret = local_x25519_private.diffie_hellman(remote_x25519_public);
-
-    // Step 2: Extract X25519 keypair from DecapsulationKey/EncapsulationKey
-    let (kem_sk, kem_pk) = match (local_kem_keypair.0, local_kem_keypair.1) {
-        (DecapsulationKey::X25519(sk), EncapsulationKey::X25519(pk)) => (sk, pk),
-        _ => {
-            return Err(LpError::KKTError(
-                "Only X25519 KEM is currently supported for PSQ".to_string(),
-            ));
-        }
-    };
-
-    // Step 3: Deserialize InitiatorMsg using TLS decoding
-    let initiator_msg = InitiatorMsg::<PsqX25519>::tls_deserialize(&mut &psq_payload[..])
-        .map_err(|e| LpError::Internal(format!("InitiatorMsg deserialization failed: {:?}", e)))?;
-
-    // Step 4: Convert nym Ed25519 public key to libcrux VerificationKey format
-    type Ed25519VerificationKey = <Ed25519 as Authenticator>::VerificationKey;
-    let initiator_ed25519_pk_bytes = initiator_ed25519_pk.to_bytes();
-    let initiator_verification_key = Ed25519VerificationKey::from_bytes(initiator_ed25519_pk_bytes);
-
-    // Step 5: PSQ v1 responder processing with Ed25519 verification
-    let (registered_psk, responder_msg) = Responder::send::<Ed25519, PsqX25519>(
-        b"nym-lp-handle",            // PSK storage handle
-        Duration::from_secs(3600),   // 1 hour expiry (must match initiator)
-        session_context,             // Must match initiator's session_context
-        kem_pk,                      // Responder's public key
-        kem_sk,                      // Responder's secret key
-        &initiator_verification_key, // Initiator's Ed25519 public key for verification
-        &initiator_msg,              // InitiatorMsg to verify and process
-    )
-    .map_err(|e| {
-        use libcrux_psq::v1::Error as PsqError;
-        match e {
-            PsqError::CredError => {
-                tracing::warn!(
-                    "PSQ responder auth failure - invalid Ed25519 signature (potential attack)"
-                );
-            }
-            PsqError::TimestampElapsed | PsqError::RegistrationError => {
-                tracing::warn!(
-                    "PSQ responder timing failure - TTL expired (potential replay attack)"
-                );
-            }
-            _ => {
-                tracing::error!("PSQ responder failed - {:?}", e);
-            }
-        }
-        LpError::Internal(format!("PSQ v1 responder send failed: {:?}", e))
-    })?;
-
-    // Extract the PSQ PSK from the registered PSK - this is K_pq
-    let psq_psk = registered_psk.psk;
-
-    // pq_shared_secret is the raw K_pq from KEM decapsulation.
-    // Store it for subsession derivation before it's combined with ECDH.
-    let pq_shared_secret: [u8; 32] = psq_psk;
-
-    // Step 6: Combine ECDH + PSQ via Blake3 KDF (same formula as initiator)
-    let mut combined = Vec::with_capacity(64 + psq_psk.len());
-    combined.extend_from_slice(&ecdh_secret);
-    combined.extend_from_slice(&psq_psk); // psq_psk is [u8; 32], need &
-    combined.extend_from_slice(salt);
-
-    let final_psk = nym_crypto::kdf::derive_key_blake3(PSK_PSQ_CONTEXT, &combined, &[]);
-
-    // Step 7: Serialize ResponderMsg (contains ctxt_B - encrypted PSK handle)
-    use tls_codec::Serialize;
-    let responder_msg_bytes = responder_msg
-        .tls_serialize_detached()
-        .map_err(|e| LpError::Internal(format!("ResponderMsg serialization failed: {:?}", e)))?;
-
-    Ok(PsqResponderResult {
-        psk: final_psk,
-        psk_handle: responder_msg_bytes,
-        pq_shared_secret,
-    })
-}
-
-/// Derive subsession PSK from parent's PQ shared secret.
-///
-/// Uses Blake3 KDF with domain separation to derive unique PSK for each subsession.
-/// This preserves PQ protection: subsession keys inherit quantum resistance from
-/// parent's KEM shared secret (K_pq).
-///
-/// # Security Model
-///
-/// Subsessions use Noise KKpsk0 pattern where:
-/// - Both parties already know each other's static X25519 keys (from parent session)
-/// - PSK provides PQ protection by deriving from parent's K_pq
-/// - Each subsession gets unique PSK via index parameter (prevents key reuse)
-///
-/// # Arguments
-/// * `pq_shared_secret` - Parent session's K_pq (32 bytes from KEM)
-/// * `subsession_index` - Monotonic index for this subsession (prevents reuse)
-///
-/// # Returns
-/// 32-byte PSK for Noise KKpsk0 handshake
-pub fn derive_subsession_psk(pq_shared_secret: &[u8; 32], subsession_index: u64) -> [u8; 32] {
-    nym_crypto::kdf::derive_key_blake3(
-        SUBSESSION_PSK_CONTEXT,
-        pq_shared_secret,
-        &subsession_index.to_le_bytes(),
-    )
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use rand::thread_rng;
-
-    fn generate_x25519_keypair() -> x25519::KeyPair {
-        x25519::KeyPair::new(&mut thread_rng())
-    }
-
-    #[test]
-    fn test_psk_derivation_is_symmetric() {
-        let keypair_1 = generate_x25519_keypair();
-        let keypair_2 = generate_x25519_keypair();
-        let salt = [2u8; 32];
-
-        let mut rng = &mut rand09::rng();
-        let (_kem_sk, kem_pk) = generate_keypair_libcrux(&mut rng, KEM::X25519).unwrap();
-        let enc_key = EncapsulationKey::X25519(kem_pk);
-        let dec_key = DecapsulationKey::X25519(_kem_sk);
-
-        // Client derives PSK
-        let (client_psk, ciphertext) = derive_psk_with_psq_initiator(
-            keypair_1.private_key(),
-            keypair_2.public_key(),
-            &enc_key,
-            &salt,
-        )
-        .unwrap();
-
-        // Gateway derives PSK from their perspective
-        let gateway_psk = derive_psk_with_psq_responder(
-            keypair_2.private_key(),
-            keypair_1.public_key(),
-            (&dec_key, &enc_key),
-            &ciphertext,
-            &salt,
-        )
-        .unwrap();
-
-        assert_eq!(
-            client_psk, gateway_psk,
-            "Both sides should derive identical PSK"
-        );
-    }
-
-    #[test]
-    fn test_different_salts_produce_different_psks() {
-        let keypair_1 = generate_x25519_keypair();
-        let keypair_2 = generate_x25519_keypair();
-
-        let salt1 = [1u8; 32];
-        let salt2 = [2u8; 32];
-        let mut rng = &mut rand09::rng();
-        let (_kem_sk, kem_pk) = generate_keypair_libcrux(&mut rng, KEM::X25519).unwrap();
-        let enc_key = EncapsulationKey::X25519(kem_pk);
-
-        let psk1 = derive_psk_with_psq_initiator(
-            keypair_1.private_key(),
-            keypair_2.public_key(),
-            &enc_key,
-            &salt1,
-        )
-        .unwrap();
-        let psk2 = derive_psk_with_psq_initiator(
-            keypair_1.private_key(),
-            keypair_2.public_key(),
-            &enc_key,
-            &salt2,
-        )
-        .unwrap();
-
-        assert_ne!(psk1, psk2, "Different salts should produce different PSKs");
-    }
-
-    #[test]
-    fn test_different_keys_produce_different_psks() {
-        let keypair_1 = generate_x25519_keypair();
-        let keypair_2 = generate_x25519_keypair();
-        let keypair_3 = generate_x25519_keypair();
-        let salt = [3u8; 32];
-
-        let mut rng = &mut rand09::rng();
-        let (_kem_sk, kem_pk) = generate_keypair_libcrux(&mut rng, KEM::X25519).unwrap();
-        let enc_key = EncapsulationKey::X25519(kem_pk);
-
-        let psk1 = derive_psk_with_psq_initiator(
-            keypair_1.private_key(),
-            keypair_2.public_key(),
-            &enc_key,
-            &salt,
-        )
-        .unwrap();
-        let psk2 = derive_psk_with_psq_initiator(
-            keypair_1.private_key(),
-            keypair_3.public_key(),
-            &enc_key,
-            &salt,
-        )
-        .unwrap();
-
-        assert_ne!(
-            psk1, psk2,
-            "Different remote keys should produce different PSKs"
-        );
-    }
-
-    // PSQ-enhanced PSK tests
-    use nym_kkt::ciphersuite::{DecapsulationKey, EncapsulationKey, KEM};
-    use nym_kkt::key_utils::generate_keypair_libcrux;
-
-    #[test]
-    fn test_psq_derivation_deterministic() {
-        let mut rng = rand09::rng();
-
-        // Generate X25519 keypairs for Noise
-        let client_keypair = generate_x25519_keypair();
-        let gateway_keypair = generate_x25519_keypair();
-
-        // Generate KEM keypair for PSQ
-        let (kem_sk, kem_pk) = generate_keypair_libcrux(&mut rng, KEM::X25519).unwrap();
-        let enc_key = EncapsulationKey::X25519(kem_pk);
-        let dec_key = DecapsulationKey::X25519(kem_sk);
-
-        let salt = [1u8; 32];
-
-        // Derive PSK twice with same inputs (initiator side)
-        let (_psk1, ct1) = derive_psk_with_psq_initiator(
-            client_keypair.private_key(),
-            gateway_keypair.public_key(),
-            &enc_key,
-            &salt,
-        )
-        .unwrap();
-
-        let (_psk2, _ct2) = derive_psk_with_psq_initiator(
-            client_keypair.private_key(),
-            gateway_keypair.public_key(),
-            &enc_key,
-            &salt,
-        )
-        .unwrap();
-
-        // PSKs will be different due to randomness in PSQ, but ciphertexts too
-        // This test verifies the function is deterministic given the SAME ciphertext
-        let psk_responder1 = derive_psk_with_psq_responder(
-            gateway_keypair.private_key(),
-            client_keypair.public_key(),
-            (&dec_key, &enc_key),
-            &ct1,
-            &salt,
-        )
-        .unwrap();
-
-        let psk_responder2 = derive_psk_with_psq_responder(
-            gateway_keypair.private_key(),
-            client_keypair.public_key(),
-            (&dec_key, &enc_key),
-            &ct1, // Same ciphertext
-            &salt,
-        )
-        .unwrap();
-
-        assert_eq!(
-            psk_responder1, psk_responder2,
-            "Same ciphertext should produce same PSK"
-        );
-    }
-
-    #[test]
-    fn test_psq_derivation_symmetric() {
-        let mut rng = rand09::rng();
-
-        // Generate X25519 keypairs for Noise
-        let client_keypair = generate_x25519_keypair();
-        let gateway_keypair = generate_x25519_keypair();
-
-        // Generate KEM keypair for PSQ
-        let (kem_sk, kem_pk) = generate_keypair_libcrux(&mut rng, KEM::X25519).unwrap();
-        let enc_key = EncapsulationKey::X25519(kem_pk);
-        let dec_key = DecapsulationKey::X25519(kem_sk);
-
-        let salt = [2u8; 32];
-
-        // Client derives PSK (initiator)
-        let (client_psk, ciphertext) = derive_psk_with_psq_initiator(
-            client_keypair.private_key(),
-            gateway_keypair.public_key(),
-            &enc_key,
-            &salt,
-        )
-        .unwrap();
-
-        // Gateway derives PSK from ciphertext (responder)
-        let gateway_psk = derive_psk_with_psq_responder(
-            gateway_keypair.private_key(),
-            client_keypair.public_key(),
-            (&dec_key, &enc_key),
-            &ciphertext,
-            &salt,
-        )
-        .unwrap();
-
-        assert_eq!(
-            client_psk, gateway_psk,
-            "Both sides should derive identical PSK via PSQ"
-        );
-    }
-
-    #[test]
-    fn test_different_kem_keys_different_psk() {
-        let mut rng = rand09::rng();
-
-        let client_keypair = generate_x25519_keypair();
-        let gateway_keypair = generate_x25519_keypair();
-
-        // Two different KEM keypairs
-        let (_, kem_pk1) = generate_keypair_libcrux(&mut rng, KEM::X25519).unwrap();
-        let (_, kem_pk2) = generate_keypair_libcrux(&mut rng, KEM::X25519).unwrap();
-
-        let enc_key1 = EncapsulationKey::X25519(kem_pk1);
-        let enc_key2 = EncapsulationKey::X25519(kem_pk2);
-
-        let salt = [3u8; 32];
-
-        let (psk1, _) = derive_psk_with_psq_initiator(
-            client_keypair.private_key(),
-            gateway_keypair.public_key(),
-            &enc_key1,
-            &salt,
-        )
-        .unwrap();
-
-        let (psk2, _) = derive_psk_with_psq_initiator(
-            client_keypair.private_key(),
-            gateway_keypair.public_key(),
-            &enc_key2,
-            &salt,
-        )
-        .unwrap();
-
-        assert_ne!(
-            psk1, psk2,
-            "Different KEM keys should produce different PSKs"
-        );
-    }
-
-    #[test]
-    fn test_psq_psk_output_length() {
-        let mut rng = rand09::rng();
-
-        let client_keypair = generate_x25519_keypair();
-        let gateway_keypair = generate_x25519_keypair();
-
-        let (_, kem_pk) = generate_keypair_libcrux(&mut rng, KEM::X25519).unwrap();
-        let enc_key = EncapsulationKey::X25519(kem_pk);
-
-        let salt = [4u8; 32];
-
-        let (psk, _) = derive_psk_with_psq_initiator(
-            client_keypair.private_key(),
-            gateway_keypair.public_key(),
-            &enc_key,
-            &salt,
-        )
-        .unwrap();
-
-        assert_eq!(psk.len(), 32, "PSQ PSK should be exactly 32 bytes");
-    }
-
-    #[test]
-    fn test_psq_different_salts_different_psks() {
-        let mut rng = rand09::rng();
-
-        let client_keypair = generate_x25519_keypair();
-        let gateway_keypair = generate_x25519_keypair();
-
-        let (_, kem_pk) = generate_keypair_libcrux(&mut rng, KEM::X25519).unwrap();
-        let enc_key = EncapsulationKey::X25519(kem_pk);
-
-        let salt1 = [1u8; 32];
-        let salt2 = [2u8; 32];
-
-        let (psk1, _) = derive_psk_with_psq_initiator(
-            client_keypair.private_key(),
-            gateway_keypair.public_key(),
-            &enc_key,
-            &salt1,
-        )
-        .unwrap();
-
-        let (psk2, _) = derive_psk_with_psq_initiator(
-            client_keypair.private_key(),
-            gateway_keypair.public_key(),
-            &enc_key,
-            &salt2,
-        )
-        .unwrap();
-
-        assert_ne!(psk1, psk2, "Different salts should produce different PSKs");
-    }
-}

common/nym-lp/src/psq/handshake_message.rs

@@ -0,0 +1,145 @@
+// Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
+// SPDX-License-Identifier: Apache-2.0
+
+use crate::psq::{PSQ_MSG2_SIZE, psq_msg1_size};
+use crate::transport::{LpTransportError, traits::HandshakeMessage};
+use nym_kkt::context::KKTMode;
+use nym_kkt_ciphersuite::KEM;
+use std::ops::Deref;
+
+pub struct KKTRequest(nym_kkt::message::KKTRequest);
+
+impl From<nym_kkt::message::KKTRequest> for KKTRequest {
+    fn from(request: nym_kkt::message::KKTRequest) -> Self {
+        KKTRequest(request)
+    }
+}
+
+impl From<KKTRequest> for nym_kkt::message::KKTRequest {
+    fn from(request: KKTRequest) -> Self {
+        request.0
+    }
+}
+
+impl HandshakeMessage for KKTRequest {
+    fn into_bytes(self) -> Vec<u8> {
+        self.0.into_bytes()
+    }
+
+    fn try_from_bytes(bytes: Vec<u8>) -> Result<Self, LpTransportError> {
+        Ok(KKTRequest(
+            nym_kkt::message::KKTRequest::try_from_bytes(&bytes)
+                .map_err(|err| LpTransportError::MalformedPacket(err.to_string()))?,
+        ))
+    }
+
+    fn expected_size(mode: KKTMode, expected_kem: KEM, payload_size: usize) -> usize {
+        nym_kkt::message::KKTRequest::size_excluding_payload(mode, expected_kem) + payload_size
+    }
+
+    fn response_size(&self, expected_kem: KEM) -> Option<usize> {
+        Some(nym_kkt::message::KKTResponse::size_excluding_payload(
+            expected_kem,
+        ))
+    }
+}
+
+pub struct KKTResponse(nym_kkt::message::KKTResponse);
+
+impl From<nym_kkt::message::KKTResponse> for KKTResponse {
+    fn from(request: nym_kkt::message::KKTResponse) -> Self {
+        KKTResponse(request)
+    }
+}
+
+impl From<KKTResponse> for nym_kkt::message::KKTResponse {
+    fn from(request: KKTResponse) -> Self {
+        request.0
+    }
+}
+
+impl HandshakeMessage for KKTResponse {
+    fn into_bytes(self) -> Vec<u8> {
+        self.0.into_bytes()
+    }
+
+    fn try_from_bytes(bytes: Vec<u8>) -> Result<Self, LpTransportError> {
+        Ok(KKTResponse(nym_kkt::message::KKTResponse::from_bytes(
+            bytes,
+        )))
+    }
+
+    fn expected_size(_: KKTMode, expected_kem: KEM, payload_size: usize) -> usize {
+        nym_kkt::message::KKTResponse::size_excluding_payload(expected_kem) + payload_size
+    }
+
+    fn response_size(&self, expected_kem: KEM) -> Option<usize> {
+        Some(psq_msg1_size(expected_kem))
+    }
+}
+
+pub struct PSQMsg1(Vec<u8>);
+
+impl Deref for PSQMsg1 {
+    type Target = Vec<u8>;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl PSQMsg1 {
+    pub fn new(bytes: Vec<u8>) -> Self {
+        PSQMsg1(bytes)
+    }
+}
+
+impl HandshakeMessage for PSQMsg1 {
+    fn into_bytes(self) -> Vec<u8> {
+        self.0
+    }
+
+    fn try_from_bytes(bytes: Vec<u8>) -> Result<Self, LpTransportError> {
+        Ok(PSQMsg1(bytes))
+    }
+
+    fn expected_size(_: KKTMode, expected_kem: KEM, payload_size: usize) -> usize {
+        psq_msg1_size(expected_kem) + payload_size
+    }
+
+    fn response_size(&self, _: KEM) -> Option<usize> {
+        Some(PSQ_MSG2_SIZE)
+    }
+}
+
+pub struct PSQMsg2(Vec<u8>);
+
+impl Deref for PSQMsg2 {
+    type Target = Vec<u8>;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl PSQMsg2 {
+    pub fn new(bytes: Vec<u8>) -> Self {
+        PSQMsg2(bytes)
+    }
+}
+
+impl HandshakeMessage for PSQMsg2 {
+    fn into_bytes(self) -> Vec<u8> {
+        self.0
+    }
+
+    fn try_from_bytes(bytes: Vec<u8>) -> Result<Self, LpTransportError> {
+        Ok(PSQMsg2(bytes))
+    }
+
+    fn expected_size(_: KKTMode, _: KEM, payload_size: usize) -> usize {
+        PSQ_MSG2_SIZE + payload_size
+    }
+
+    fn response_size(&self, _: KEM) -> Option<usize> {
+        None
+    }
+}

common/nym-lp/src/psq/helpers.rs

@@ -1,52 +1,12 @@
 // Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
 // SPDX-License-Identifier: Apache-2.0
 
-use crate::codec::{OuterAeadKey, parse_lp_packet, serialize_lp_packet};
-use crate::{LpError, LpPacket};
-use bytes::BytesMut;
-use nym_lp_transport::traits::LpTransport;
+use libcrux_psq::handshake::ciphersuites::CiphersuiteName;
+use nym_kkt_ciphersuite::KEM;
 
-#[cfg(test)]
-use mock_instant::thread_local::{SystemTime, UNIX_EPOCH};
-#[cfg(not(test))]
-use std::time::{SystemTime, UNIX_EPOCH};
-
-pub(crate) fn current_timestamp() -> Result<u64, LpError> {
-    SystemTime::now()
-        .duration_since(UNIX_EPOCH)
-        .map_err(|_| LpError::Internal("System time before UNIX epoch".into()))
-        .map(|d| d.as_secs())
-}
-
-// only used in internal code (and tests)
-#[allow(async_fn_in_trait)]
-pub trait LpTransportHandshakeExt: LpTransport {
-    // the outer key is temporary until the algorithm is changed with psqv2
-    async fn receive_packet(
-        &mut self,
-        outer_key: Option<&OuterAeadKey>,
-    ) -> Result<LpPacket, LpError>
-    where
-        Self: Unpin,
-    {
-        let raw = self.receive_raw_packet().await?;
-        parse_lp_packet(&raw, outer_key)
-    }
-
-    async fn send_packet(
-        &mut self,
-        packet: LpPacket,
-        outer_key: Option<&OuterAeadKey>,
-    ) -> Result<(), LpError>
-    where
-        Self: Unpin,
-    {
-        let mut packet_buf = BytesMut::new();
-
-        serialize_lp_packet(&packet, &mut packet_buf, outer_key)?;
-        self.send_serialised_packet(&packet_buf).await?;
-        Ok(())
+pub(crate) fn kem_to_ciphersuite(kem: KEM) -> CiphersuiteName {
+    match kem {
+        KEM::MlKem768 => CiphersuiteName::X25519_MLKEM768_X25519_AESGCM128_HKDFSHA256,
+        KEM::McEliece => CiphersuiteName::X25519_CLASSICMCELIECE_X25519_AESGCM128_HKDFSHA256,
     }
 }
-
-impl<T> LpTransportHandshakeExt for T where T: LpTransport {}

common/nym-lp/src/psq/initiator.rs

@@ -1,391 +1,340 @@
 // Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
 // SPDX-License-Identifier: Apache-2.0
 
-use crate::codec::OuterAeadKey;
-use crate::message::{HandshakeData, KKTRequestData, MessageType};
-use crate::noise_protocol::NoiseProtocol;
-use crate::peer::LpRemotePeer;
-use crate::psk::psq_initiator_create_message;
-use crate::psq::helpers::{LpTransportHandshakeExt, current_timestamp};
-use crate::psq::{IntermediateHandshakeFailure, PSQHandshakeState};
-use crate::session::PqSharedSecret;
-use crate::{ClientHelloData, LpError, LpMessage, LpSession};
-use nym_kkt::KKT_RESPONSE_AAD;
-use nym_kkt::ciphersuite::EncapsulationKey;
-use nym_kkt::context::KKTContext;
-use nym_kkt::encryption::{KKTSessionSecret, decrypt_kkt_frame, encrypt_initial_kkt_frame};
-use nym_kkt::session::{anonymous_initiator_process, initiator_ingest_response};
-use nym_lp_transport::traits::LpTransport;
-use rand09::rng;
+use crate::peer::{LpLocalPeer, LpRemotePeer};
+use crate::peer_config::LpPeerConfig;
+use crate::psq::handshake_message::{PSQMsg1, PSQMsg2};
+use crate::psq::helpers::kem_to_ciphersuite;
+use crate::psq::{
+    AAD_INITIATOR_INNER_V1, AAD_INITIATOR_OUTER_V1, InitiatorData, PSQ_MSG2_SIZE,
+    PSQHandshakeState, SESSION_CONTEXT_V1, handshake_message, psq_msg1_size,
+};
+use crate::session::PersistentSessionBinding;
+use crate::transport::traits::LpHandshakeChannel;
+use crate::{LpError, LpSession};
+use libcrux_psq::handshake::RegistrationInitiator;
+use libcrux_psq::handshake::builders::{
+    CiphersuiteBuilder, InitiatorCiphersuite, PrincipalBuilder,
+};
+use libcrux_psq::handshake::types::Authenticator;
+use libcrux_psq::{Channel, IntoSession};
+use nym_kkt::initiator::KKTInitiator;
+use nym_kkt::keys::EncapsulationKey;
+use nym_kkt::message::{KKTRequest, KKTResponse};
+use rand09::SeedableRng;
 use tracing::debug;
 
-impl<'a, S> PSQHandshakeState<'a, S>
+pub struct PSQHandshakeStateInitiator<'a, S> {
+    pub(super) inner_state: PSQHandshakeState<'a, S>,
+    pub(super) initiator_data: InitiatorData,
+}
+
+pub(crate) fn build_psq_principal<R>(
+    rng: R,
+    version: u8,
+    ciphersuite: InitiatorCiphersuite,
+) -> Result<RegistrationInitiator<R>, LpError>
 where
-    S: LpTransport + Unpin,
+    R: rand09::CryptoRng,
 {
-    /// Generate and send client hello to the responder
-    pub(crate) async fn send_client_hello(&mut self) -> Result<ClientHelloData, LpError> {
-        let protocol = self.protocol_version()?;
+    let (ctx, inner_aad, outer_aad) = match version {
+        1 => (
+            SESSION_CONTEXT_V1,
+            AAD_INITIATOR_INNER_V1,
+            AAD_INITIATOR_OUTER_V1,
+        ),
+        other => return Err(LpError::UnsupportedVersion { version: other }),
+    };
 
-        // 1. Generate and send ClientHelloData with fresh salt and both public keys
-        let timestamp = current_timestamp()?;
+    PrincipalBuilder::new(rng)
+        .outer_aad(outer_aad)
+        .inner_aad(inner_aad)
+        .context(ctx)
+        .build_registration_initiator(ciphersuite)
+        .map_err(|inner| LpError::PSQInitiatorBuilderFailure { inner })
+}
 
-        let client_hello_data = self.local_peer.build_client_hello_data(timestamp);
-        self.connection
-            .send_packet(client_hello_data.into_lp_packet(protocol), None)
-            .await?;
-        Ok(client_hello_data)
-    }
-
-    /// Attempt to receive an ack to sent client hello. returns a boolean indicating
-    /// whether the request has been successful or whether there has been a collision in receiver
-    /// index requiring a retry
-    pub(crate) async fn receive_client_hello_ack(&mut self) -> Result<bool, LpError> {
-        match self.receive_non_error(None).await?.message {
-            LpMessage::Ack => Ok(true),
-            LpMessage::Collision => Ok(false),
-            other => {
-                // TODO: retry on collision
-                Err(LpError::unexpected_handshake_response(
-                    other.typ(),
-                    MessageType::Ack,
-                ))
-            }
-        }
+pub(crate) fn build_psq_ciphersuite<'a>(
+    init: &'a LpLocalPeer,
+    responder: &'a LpRemotePeer,
+    kem_key: &'a EncapsulationKey,
+) -> Result<InitiatorCiphersuite<'a>, LpError> {
+    let psq_ciphersuite = kem_to_ciphersuite(kem_key.kem());
+
+    let builder = CiphersuiteBuilder::new(psq_ciphersuite)
+        .longterm_x25519_keys(init.x25519())
+        .peer_longterm_x25519_pk(responder.x25519());
+
+    match kem_key {
+        EncapsulationKey::McEliece(kem_key) => builder.peer_longterm_cmc_pk(kem_key),
+        EncapsulationKey::MlKem768(kem_key) => builder.peer_longterm_mlkem_pk(kem_key),
     }
+    .build_initiator_ciphersuite()
+    .map_err(|inner| LpError::PSQInitiatorBuilderFailure { inner })
+}
 
+impl<'a, S> PSQHandshakeStateInitiator<'a, S>
+where
+    S: LpHandshakeChannel + Unpin,
+{
     /// Attempt to send KKT request to begin the handshake
-    pub(crate) async fn send_kkt_request(
-        &mut self,
-        session_id: u32,
-        remote_peer: &LpRemotePeer,
-    ) -> Result<(KKTContext, KKTSessionSecret), LpError> {
-        let protocol = self.protocol_version()?;
+    async fn send_kkt_request(&mut self, request: KKTRequest) -> Result<(), LpError> {
+        let kem = self.inner_state.local_peer.ciphersuite.kem();
 
-        let (kkt_context, kkt_frame) = anonymous_initiator_process(&mut rng(), self.ciphersuite)?;
-        let (session_secret, encrypted_frame) =
-            encrypt_initial_kkt_frame(&mut rng(), &remote_peer.x25519_public, &kkt_frame)?;
-        let lp_message = KKTRequestData::new(encrypted_frame).into();
-        let lp_packet = self.next_packet(session_id, protocol, lp_message);
-        self.connection.send_packet(lp_packet, None).await?;
-        Ok((kkt_context, session_secret))
-    }
-
-    /// Attempt to receive a KKT response to the previously sent request and extract (and validate)
-    /// the received encapsulation key
-    pub(crate) async fn receive_kkt_response(
-        &mut self,
-        (kkt_context, session_secret): (KKTContext, KKTSessionSecret),
-        remote_peer: &LpRemotePeer,
-    ) -> Result<EncapsulationKey<'static>, LpError> {
-        let kkt_response = match self.receive_non_error(None).await?.message {
-            LpMessage::KKTResponse(response) => response,
-            other => {
-                return Err(LpError::unexpected_handshake_response(
-                    other.typ(),
-                    MessageType::KKTResponse,
-                ));
-            }
-        };
-        debug!("received KKT response");
-        let expected_kem_key_digest = remote_peer.expected_kem_key_hash(self.ciphersuite)?;
-
-        let (response_frame, remote_context) =
-            decrypt_kkt_frame(&session_secret, &kkt_response.0, KKT_RESPONSE_AAD)?;
-        let encapsulation_key = initiator_ingest_response(
-            &kkt_context,
-            &response_frame,
-            &remote_context,
-            &remote_peer.ed25519_public,
-            &expected_kem_key_digest,
-        )?;
-        Ok(encapsulation_key)
-    }
-
-    /// Attempt to prepare and send initial PSQ msg1
-    pub(crate) async fn send_psq_initiator_message(
-        &mut self,
-        remote_peer: &LpRemotePeer,
-        encapsulation_key: &EncapsulationKey<'_>,
-        salt: &[u8; 32],
-        session_id_bytes: &[u8; 4],
-    ) -> Result<(OuterAeadKey, NoiseProtocol, PqSharedSecret), LpError> {
-        let protocol = self.protocol_version()?;
-        let session_id = u32::from_le_bytes(*session_id_bytes);
-
-        let psq_initiator = psq_initiator_create_message(
-            self.local_peer.x25519.private_key(),
-            &remote_peer.x25519_public,
-            encapsulation_key,
-            self.local_peer.ed25519.private_key(),
-            self.local_peer.ed25519.public_key(),
-            salt,
-            session_id_bytes,
-        )?;
-        let psk = psq_initiator.psk;
-        let psq_payload = psq_initiator.payload;
-
-        // TEMP \/
-        let outer_aead_key = OuterAeadKey::from_psk(&psk);
-        // TEMP /\
-
-        // prepare noise state and msg1
-        let mut noise_protocol = NoiseProtocol::build_new_initiator(
-            self.local_peer.x25519().private_key().as_bytes(),
-            remote_peer.x25519_public.as_bytes(),
-            &psk,
-        )?;
-
-        // prepare noise msg1
-        let noise_msg1 = noise_protocol
-            .get_bytes_to_send()
-            .ok_or_else(|| LpError::kkt_psq_handshake("failed to generate noise msg1"))??;
-        let psq_len = psq_payload.len() as u16;
-        let mut combined = Vec::with_capacity(2 + psq_payload.len() + noise_msg1.len());
-        combined.extend_from_slice(&psq_len.to_le_bytes());
-        combined.extend_from_slice(&psq_payload);
-        combined.extend_from_slice(&noise_msg1);
-
-        let lp_message = HandshakeData::new(combined).into();
-        let lp_packet = self.next_packet(session_id, protocol, lp_message);
-
-        self.connection.send_packet(lp_packet, None).await?;
-        Ok((
-            outer_aead_key,
-            noise_protocol,
-            PqSharedSecret::new(psq_initiator.pq_shared_secret),
-        ))
-    }
-
-    /// Attempt to receive and validate received PSQ msg2
-    pub(crate) async fn receive_psq_responder_message(
-        &mut self,
-        outer_aead_key: &OuterAeadKey,
-        noise_protocol: &mut NoiseProtocol,
-    ) -> Result<(), LpError> {
-        let psq_msg2 = match self
+        self.inner_state
             .connection
-            .receive_packet(Some(outer_aead_key))
-            .await?
-            .message
-        {
-            LpMessage::Handshake(response) => response.0,
-            other => {
-                return Err(LpError::unexpected_handshake_response(
-                    other.typ(),
-                    MessageType::Handshake,
-                ));
-            }
-        };
-
-        // Extract PSK handle: [u16 handle_len][handle_bytes][noise_msg]
-        if psq_msg2.len() < 2 {
-            return Err(LpError::kkt_psq_handshake("too short msg2 received"));
-        }
-        let handle_len = u16::from_le_bytes([psq_msg2[0], psq_msg2[1]]) as usize;
-        if psq_msg2.len() < 2 + handle_len {
-            return Err(LpError::kkt_psq_handshake("too short msg2 received"));
-        }
-        // Extract and "store" the PSK handle
-        let _psq_handle_bytes = &psq_msg2[2..2 + handle_len];
-        let noise_payload = &psq_msg2[2 + handle_len..];
-
-        // *sigh* ignore the message
-        let _noise_msg2 = noise_protocol.read_message(noise_payload)?;
+            .send_handshake_message::<handshake_message::KKTRequest>(request.into(), kem)
+            .await?;
         Ok(())
     }
 
-    /// Attempt to prepare and send final PSQ msg3
-    pub(crate) async fn send_final_psq_message(
-        &mut self,
-        session_id: u32,
-        outer_aead_key: &OuterAeadKey,
-        noise_protocol: &mut NoiseProtocol,
-    ) -> Result<(), LpError> {
-        let protocol = self.protocol_version()?;
+    /// Attempt to receive a KKT response to the previously sent request
+    async fn receive_kkt_response(&mut self) -> Result<KKTResponse, LpError> {
+        // no response payload
+        let packet_len =
+            KKTResponse::size_excluding_payload(self.inner_state.local_peer.ciphersuite.kem());
 
-        let noise_msg3 = noise_protocol
-            .get_bytes_to_send()
-            .ok_or_else(|| LpError::kkt_psq_handshake("failed to generate noise msg3"))??;
-
-        let lp_message = HandshakeData::new(noise_msg3).into();
-        let lp_packet = self.next_packet(session_id, protocol, lp_message);
-        self.connection
-            .send_packet(lp_packet, Some(outer_aead_key))
+        let resp = self
+            .inner_state
+            .connection
+            .receive_handshake_message::<handshake_message::KKTResponse>(packet_len)
             .await?;
 
-        if !noise_protocol.is_handshake_finished() {
-            return Err(LpError::kkt_psq_handshake(
-                "noise handshake not finished after msg3",
-            ));
-        }
-
-        Ok(())
+        Ok(resp.into())
     }
 
-    /// Receive final ACK that indicates finalisation of the handshake
-    pub(crate) async fn receive_final_ack(
-        &mut self,
-        outer_aead_key: &OuterAeadKey,
-    ) -> Result<(), LpError> {
-        match self
-            .connection
-            .receive_packet(Some(outer_aead_key))
-            .await?
-            .message
-        {
-            LpMessage::Ack => Ok(()),
-            other => Err(LpError::unexpected_handshake_response(
-                other.typ(),
-                MessageType::Ack,
-            )),
-        }
-    }
-
-    async fn complete_as_initiator_inner(
-        &mut self,
-    ) -> Result<LpSession, IntermediateHandshakeFailure>
+    pub async fn complete_handshake(self) -> Result<LpSession, LpError>
     where
-        S: LpTransport + Unpin,
+        S: LpHandshakeChannel + Unpin,
     {
-        // 0. retrieve the expected kem key hash. if we don't know it,
-        // there's no point in even trying to start the handshake
-        let Some(remote_peer) = self.remote_peer.take() else {
-            return Err(IntermediateHandshakeFailure::plain(
-                LpError::kkt_psq_handshake("initiator can't proceed without remote information"),
-            ));
-        };
+        let mut rng = rand09::rngs::StdRng::from_os_rng();
+        self.complete_handshake_with_rng(&mut rng).await
+    }
 
-        // 1. Generate and send ClientHelloData with fresh salt and both public keys
-        // and keep retrying until we manage to establish a receiver index without collisions
-        let mut attempt = 0;
-        let client_hello_data = loop {
-            attempt += 1;
+    pub async fn complete_handshake_with_rng<R>(mut self, rng: &mut R) -> Result<LpSession, LpError>
+    where
+        S: LpHandshakeChannel + Unpin,
+        R: rand09::CryptoRng,
+    {
+        let ciphersuite = self.inner_state.local_peer.ciphersuite();
+        let kem = ciphersuite.kem();
 
-            debug!("sending client hello");
-            let client_hello = self
-                .send_client_hello()
-                .await
-                .map_err(IntermediateHandshakeFailure::plain)?;
-            if self
-                .receive_client_hello_ack()
-                .await
-                .map_err(IntermediateHandshakeFailure::plain)?
-            {
-                debug!("received client hello ACK");
-                break client_hello;
-            }
-            debug!("received client hello collision");
+        let lp_peer_config = LpPeerConfig::new_client_to_entry(rng, false);
 
-            // TODO: make it configurable
-            if attempt > 3 {
-                return Err(IntermediateHandshakeFailure::plain(
-                    LpError::kkt_psq_handshake(
-                        "failed to establish receiver index without collision",
-                    ),
-                ));
-            }
-        };
-        let session_id = client_hello_data.receiver_index;
-        let session_id_bytes = session_id.to_le_bytes();
-        let salt = client_hello_data.salt;
+        // 1. retrieve the expected kem key hash. if we don't know it,
+        let dir_hash = self
+            .initiator_data
+            .remote_peer
+            .expected_kem_key_hash(ciphersuite)?;
+
+        // 2. prepare and send KKT request
+        let (mut initiator, kkt_request) = KKTInitiator::generate_one_way_request(
+            rng,
+            ciphersuite,
+            self.initiator_data.remote_peer.x25519(),
+            &dir_hash,
+            self.initiator_data.protocol_version,
+            Some(Vec::from(lp_peer_config.serialize())),
+        )?;
+        // derive the receiver index from the request
+        // let receiver_index = kkt_request
 
-        // 3. prepare and send KKT request
         debug!("sending KKT request");
-        let kkt_data = self
-            .send_kkt_request(session_id, &remote_peer)
-            .await
-            .map_err(|source| IntermediateHandshakeFailure {
-                session_id: Some(session_id),
-                protocol_version: self.protocol_version,
-                outer_aead_key: None,
-                source,
-            })?;
+        self.send_kkt_request(kkt_request).await?;
 
-        // 4. receive and process KKT response
-        let encapsulation_key = self
-            .receive_kkt_response(kkt_data, &remote_peer)
-            .await
-            .map_err(|source| IntermediateHandshakeFailure {
-                session_id: Some(session_id),
-                protocol_version: self.protocol_version,
-                outer_aead_key: None,
-                source,
-            })?;
+        // 3. receive and process KKT response
+        let raw_response = self.receive_kkt_response().await?;
         debug!("received KKT response");
 
-        // 5. prepare and send PSQ msg1
-        debug!("sending PSQ msg1");
-        let (outer_aead_key, mut noise_protocol, pq_shared_secret) = self
-            .send_psq_initiator_message(&remote_peer, &encapsulation_key, &salt, &session_id_bytes)
-            .await
-            .map_err(|source| IntermediateHandshakeFailure {
-                session_id: Some(session_id),
-                protocol_version: self.protocol_version,
-                outer_aead_key: None,
-                source,
-            })?;
+        // the responder does not send a payload
+        let response = initiator.process_response(raw_response, 0)?;
 
-        // 6. receive and process PSQ msg2
-        debug!("received PSQ msg2");
-        if let Err(source) = self
-            .receive_psq_responder_message(&outer_aead_key, &mut noise_protocol)
-            .await
-        {
-            return Err(IntermediateHandshakeFailure {
-                session_id: Some(session_id),
-                protocol_version: self.protocol_version,
-                outer_aead_key: Some(outer_aead_key),
-                source,
-            });
+        // 4. generate and send PSQ request
+        let protocol = self.initiator_data.protocol_version;
+        let conn = self.inner_state.connection;
+
+        // note: the clone is cheap due to internal Arcs
+        let encapsulation_key = response.encapsulation_key.clone();
+
+        // build the PSQ initiator
+        let initiator_ciphersuite = build_psq_ciphersuite(
+            &self.inner_state.local_peer,
+            &self.initiator_data.remote_peer,
+            &response.encapsulation_key,
+        )?;
+
+        let mut psq_initiator = build_psq_principal(rng, protocol, initiator_ciphersuite)?;
+
+        // PSQ msg 1 send
+        let mut buf = vec![0u8; psq_msg1_size(kem)];
+        // annoyingly `RegistrationInitiator` has to write into unresizable `&mut [u8]`...
+        let n = psq_initiator.write_message(&[], &mut buf)?;
+        debug!("sending PSQ handshake msg");
+        if n != buf.len() {
+            return Err(LpError::Internal(
+                "unexpected changes in PSQ msg1 size".to_string(),
+            ));
+        }
+        let msg = PSQMsg1::new(buf);
+        conn.send_handshake_message(msg, kem).await?;
+
+        // 5. receive and process PSQ response
+        let psq_msg: PSQMsg2 = conn.receive_handshake_message(PSQ_MSG2_SIZE).await?;
+        debug!("received PSQ handshake msg");
+        psq_initiator.read_message(&psq_msg, &mut [])?;
+
+        if !psq_initiator.is_handshake_finished() {
+            return Err(LpError::kkt_psq_handshake(
+                "handshake not finished after receiving psq response",
+            ));
         }
 
-        // 7. prepare and send PSQ msg3
-        debug!("sending PSQ msg3");
-        if let Err(source) = self
-            .send_final_psq_message(session_id, &outer_aead_key, &mut noise_protocol)
-            .await
-        {
-            return Err(IntermediateHandshakeFailure {
-                session_id: Some(session_id),
-                protocol_version: self.protocol_version,
-                outer_aead_key: Some(outer_aead_key),
-                source,
-            });
-        }
+        let initiator_authenticator = Authenticator::Dh(self.inner_state.local_peer.x25519().pk);
 
-        // 8. receive final ACK and finalise
-        debug!("received final ACK");
-        if let Err(source) = self.receive_final_ack(&outer_aead_key).await {
-            return Err(IntermediateHandshakeFailure {
-                session_id: Some(session_id),
-                protocol_version: self.protocol_version,
-                outer_aead_key: Some(outer_aead_key),
-                source,
-            });
-        }
+        let receiver_index =
+            lp_peer_config.derive_receiver_index(&initiator_authenticator, &encapsulation_key)?;
 
-        #[allow(clippy::expect_used)]
-        Ok(LpSession::new(
-            session_id,
-            self.protocol_version()
-                .expect("protocol version is known at this point"),
-            outer_aead_key,
-            self.local_peer.clone(),
-            remote_peer,
-            pq_shared_secret,
-            noise_protocol,
-        ))
-    }
+        let binding = PersistentSessionBinding {
+            initiator_authenticator,
+            responder_ecdh_pk: self.initiator_data.remote_peer.x25519_public,
+            responder_pq_pk: Some(encapsulation_key),
+        };
 
-    // TODO: missing: receive counter check
-    pub async fn complete_as_initiator(mut self) -> Result<LpSession, LpError>
-    where
-        S: LpTransport + Unpin,
-    {
-        match self.complete_as_initiator_inner().await {
-            Ok(res) => Ok(res),
-            Err(err) => Err(self.try_send_error_packet(err).await),
-        }
+        let psq_session = psq_initiator.into_session()?;
+        LpSession::new(psq_session, binding, receiver_index, protocol)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::codec::{decrypt_data, encrypt_data};
+    use crate::peer::mock_peers;
+    use crate::peer_config::LP_PEER_CONFIG_SIZE;
+    use crate::psq::{PSQ_MSG2_SIZE, psq_msg1_size, responder};
+    use nym_kkt::context::KKTMode;
+    use nym_kkt::responder::KKTResponder;
+    use nym_kkt_ciphersuite::{Ciphersuite, HashFunction, IntoEnumIterator, KEM, SignatureScheme};
+    use nym_test_utils::helpers::{DeterministicRng09Send, u64_seeded_rng_09};
+    use nym_test_utils::mocks::async_read_write::MockIOStream;
+    use nym_test_utils::traits::{Leak, Timeboxed};
+
+    #[tokio::test]
+    async fn initiator_test_plain() -> anyhow::Result<()> {
+        for kem in KEM::iter() {
+            let conn_init = MockIOStream::default();
+            let conn_resp = conn_init.try_get_remote_handle();
+
+            // leak the connections (JUST FOR THE PURPOSE OF THIS TEST!)
+            // so they'd get 'static lifetime
+            let conn_init = conn_init.leak();
+            let conn_resp = conn_resp.leak();
+
+            let (mut init, mut resp) = mock_peers();
+            let resp_remote = resp.as_remote();
+
+            let ciphersuite = Ciphersuite::default().with_kem(kem);
+            init.ciphersuite = ciphersuite;
+            resp.ciphersuite = ciphersuite;
+            let initiator_data = InitiatorData::new(1, resp_remote);
+
+            let handshake_init =
+                PSQHandshakeState::new(conn_init, init).as_initiator(initiator_data);
+
+            let mut init_rng = DeterministicRng09Send::new(u64_seeded_rng_09(1));
+
+            let init_fut = tokio::spawn(async move {
+                handshake_init
+                    .complete_handshake_with_rng(&mut init_rng)
+                    .timeboxed()
+                    .await
+            });
+
+            // responder:
+            let supported_sigs = [SignatureScheme::Ed25519];
+            let supported_hash = [
+                HashFunction::Blake3,
+                HashFunction::Shake256,
+                HashFunction::Shake128,
+                HashFunction::SHA256,
+            ];
+            let resp_keys = resp.kem_keypairs.as_ref().unwrap();
+            let responder_x25519_keypair = resp.x25519();
+
+            let kkt_responder = KKTResponder::new(
+                responder_x25519_keypair,
+                resp_keys,
+                &supported_hash,
+                &supported_sigs,
+                &[1],
+            )?;
+
+            // 1. read KKT request
+            let raw_kkt_req: handshake_message::KKTRequest = conn_resp
+                .receive_handshake_message(
+                    KKTRequest::size_excluding_payload(KKTMode::OneWay, kem) + LP_PEER_CONFIG_SIZE,
+                )
+                .timeboxed()
+                .await??;
+            let req = raw_kkt_req.into();
+
+            // 2. process
+            let processed_req = kkt_responder.process_request(req, LP_PEER_CONFIG_SIZE)?;
+            conn_resp
+                .send_handshake_message::<handshake_message::KKTResponse>(
+                    processed_req.response.into(),
+                    kem,
+                )
+                .timeboxed()
+                .await??;
+
+            // 3. read PSQ req
+            let responder_ciphersuite = responder::build_psq_ciphersuite(&resp, kem)?;
+            let mut responder =
+                responder::build_psq_principal(rand09::rng(), 1, responder_ciphersuite)?;
+            let response_len = psq_msg1_size(kem);
+
+            let msg: PSQMsg1 = conn_resp
+                .receive_handshake_message(response_len)
+                .timeboxed()
+                .await??;
+            responder.read_message(&msg, &mut []).unwrap();
+
+            // 4 send PSQ response
+            let mut buf = vec![0u8; PSQ_MSG2_SIZE];
+            let n = responder.write_message(&[], &mut buf).unwrap();
+            assert_eq!(n, buf.len());
+            let msg = PSQMsg2::new(buf);
+            conn_resp
+                .send_handshake_message(msg, kem)
+                .timeboxed()
+                .await??;
+
+            assert!(responder.is_handshake_finished());
+
+            let mut session_init = init_fut.await???;
+
+            let mut r_transport = responder.into_session().unwrap();
+
+            // test serialization, deserialization
+            let channel_i = session_init.active_transport();
+            let mut channel_r = r_transport.transport_channel().unwrap();
+
+            assert_eq!(channel_i.identifier(), channel_r.identifier());
+
+            let app_data_i = b"Derived session hey".as_slice();
+            let app_data_r = b"Derived session ho".as_slice();
+
+            let ct_i = encrypt_data(app_data_i, channel_i)?;
+            let pt_r = decrypt_data(&ct_i, &mut channel_r)?;
+
+            assert_eq!(app_data_i, pt_r);
+
+            let ct_r = encrypt_data(app_data_r, &mut channel_r)?;
+            let pt_i = decrypt_data(&ct_r, channel_i)?;
+
+            assert_eq!(app_data_r, pt_i);
+        }
+        Ok(())
     }
 }

common/nym-lp/src/psq/mod.rs

@@ -1,172 +1,108 @@
 // Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
 // SPDX-License-Identifier: Apache-2.0
 
-use crate::codec::OuterAeadKey;
-use crate::message::ErrorPacketData;
-use crate::packet::LpHeader;
+use crate::packet::version;
 use crate::peer::{LpLocalPeer, LpRemotePeer};
-use crate::psq::helpers::LpTransportHandshakeExt;
-use crate::{LpError, LpMessage, LpPacket};
-use nym_kkt::ciphersuite::Ciphersuite;
-use nym_lp_transport::traits::LpTransport;
-use tracing::debug;
+use crate::transport::traits::LpHandshakeChannel;
+use nym_kkt_ciphersuite::{HashFunction, IntoEnumIterator, KEM, SignatureScheme};
 
+pub(crate) mod handshake_message;
 mod helpers;
-mod initiator;
-mod responder;
+pub mod initiator;
+pub mod responder;
 
-pub(crate) struct IntermediateHandshakeFailure {
-    /// Session id established during exchange if we managed to derive it
-    session_id: Option<u32>,
+pub use initiator::PSQHandshakeStateInitiator;
+pub use responder::PSQHandshakeStateResponder;
 
-    /// Protocol version established during the exchange
-    protocol_version: Option<u8>,
+pub(crate) const AAD_INITIATOR_OUTER_V1: &[u8] = b"NYM-PQ-AAD-INIT-OUTER-V1";
+pub(crate) const AAD_INITIATOR_INNER_V1: &[u8] = b"NYM-PQ-AAD-INIT-INNER-V1";
+pub(crate) const AAD_RESPONDER_V1: &[u8] = b"NYM-PQ-AAD-RESP-V1";
+pub(crate) const SESSION_CONTEXT_V1: &[u8] = b"NYM-PQ-SESSION-CONTEXT-V1";
 
-    /// Outer aead key established during exchange if we managed to derive it
-    outer_aead_key: Option<OuterAeadKey>,
-
-    /// The error source
-    source: LpError,
-}
-
-impl IntermediateHandshakeFailure {
-    fn plain(source: LpError) -> IntermediateHandshakeFailure {
-        IntermediateHandshakeFailure {
-            session_id: None,
-            protocol_version: None,
-            outer_aead_key: None,
-            source,
-        }
+/// Size of the first (initiator) PSQ message including all serialisation overheads if no additional payload has been attached
+pub(crate) fn psq_msg1_size(kem: KEM) -> usize {
+    match kem {
+        KEM::MlKem768 => 1247,
+        KEM::McEliece => 315,
     }
 }
 
+/// Size of the second (responder) PSQ message including all serialisation overheads if no additional payload has been attached
+pub(crate) const PSQ_MSG2_SIZE: usize = 70;
+
 pub struct PSQHandshakeState<'a, S> {
     /// The underlying connection established for the handshake
     connection: &'a mut S,
 
-    /// Protocol version used for the exchange.
-    /// either known implicitly through the directory (initiator)
-    /// or established through client hello (responder)
-    protocol_version: Option<u8>,
-
-    /// Ciphersuite selected for the KKT/PSQ exchange
-    ciphersuite: Ciphersuite,
-
     /// Representation of a local Lewes Protocol peer
     /// encapsulating all the known information and keys.
     local_peer: LpLocalPeer,
+}
+
+#[derive(Debug)]
+pub struct InitiatorData {
+    /// Protocol version used for the exchange known implicitly through the directory
+    pub protocol_version: u8,
 
     /// Representation of a remote Lewes Protocol peer
     /// encapsulating all the known information and keys.
-    remote_peer: Option<LpRemotePeer>,
+    pub remote_peer: LpRemotePeer,
+}
 
-    /// Counter for outgoing packets
-    sending_counter: u64,
+impl InitiatorData {
+    pub fn new(protocol_version: u8, remote_peer: LpRemotePeer) -> Self {
+        InitiatorData {
+            protocol_version,
+            remote_peer,
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct ResponderData {
+    /// List of supported Hash Functions by this Responder
+    pub supported_hash_functions: Vec<HashFunction>,
+
+    /// List of supported Signature Schemes by this Responder
+    pub supported_signature_schemes: Vec<SignatureScheme>,
+
+    /// List of supported outer (LP) protocol version by this Responder
+    pub supported_outer_protocol_versions: Vec<u8>,
+}
+
+impl Default for ResponderData {
+    fn default() -> Self {
+        // by default all schemes are supported
+        ResponderData {
+            supported_hash_functions: HashFunction::iter().collect(),
+            supported_signature_schemes: SignatureScheme::iter().collect(),
+            supported_outer_protocol_versions: vec![version::CURRENT],
+        }
+    }
 }
 
 impl<'a, S> PSQHandshakeState<'a, S>
 where
-    S: LpTransport + Unpin,
+    S: LpHandshakeChannel + Unpin,
 {
-    pub fn new(connection: &'a mut S, ciphersuite: Ciphersuite, local_peer: LpLocalPeer) -> Self {
+    pub fn new(connection: &'a mut S, local_peer: LpLocalPeer) -> Self {
         PSQHandshakeState {
             connection,
-            protocol_version: None,
-            ciphersuite,
             local_peer,
-            remote_peer: None,
-            sending_counter: 0,
         }
     }
 
-    #[must_use]
-    pub fn with_protocol_version(mut self, protocol_version: u8) -> Self {
-        self.protocol_version = Some(protocol_version);
-        self
-    }
-
-    #[must_use]
-    pub fn with_remote_peer(mut self, remote_peer: LpRemotePeer) -> Self {
-        self.remote_peer = Some(remote_peer);
-        self
-    }
-
-    fn protocol_version(&self) -> Result<u8, LpError> {
-        self.protocol_version
-            .ok_or_else(|| LpError::kkt_psq_handshake("unknown protocol version"))
-    }
-
-    /// Generates the next counter value for outgoing packets.
-    pub fn next_counter(&mut self) -> u64 {
-        let counter = self.sending_counter;
-        self.sending_counter += 1;
-        counter
-    }
-
-    pub fn next_packet(
-        &mut self,
-        session_id: u32,
-        protocol_version: u8,
-        message: LpMessage,
-    ) -> LpPacket {
-        let counter = self.next_counter();
-        let header = LpHeader::new(session_id, counter, protocol_version);
-        LpPacket::new(header, message)
-    }
-
-    pub(crate) async fn try_send_error_packet(
-        &mut self,
-        err: IntermediateHandshakeFailure,
-    ) -> LpError {
-        // if session_id is not known, we can't send the packet back (with the current design)
-        let (Some(session_id), Some(protocol)) = (err.session_id, err.protocol_version) else {
-            return err.source;
-        };
-        if let Err(err) = self
-            .send_error_packet(
-                session_id,
-                protocol,
-                err.source.to_string(),
-                err.outer_aead_key.as_ref(),
-            )
-            .await
-        {
-            debug!("failed to send back error response: {err}")
+    pub fn as_initiator(self, initiator_data: InitiatorData) -> PSQHandshakeStateInitiator<'a, S> {
+        PSQHandshakeStateInitiator {
+            initiator_data,
+            inner_state: self,
         }
-        err.source
     }
 
-    /// Attempt to send an error packet
-    pub(crate) async fn send_error_packet(
-        &mut self,
-        session_id: u32,
-        protocol_version: u8,
-        msg: impl Into<String>,
-        outer_aead_key: Option<&OuterAeadKey>,
-    ) -> Result<(), LpError> {
-        let packet = self.next_packet(
-            session_id,
-            protocol_version,
-            LpMessage::Error(ErrorPacketData::new(msg)),
-        );
-        self.connection.send_packet(packet, outer_aead_key).await?;
-        Ok(())
-    }
-
-    /// Attempt to receive a packet from connection, explicitly checking for an error response
-    /// and returning corresponding message if received
-    pub(crate) async fn receive_non_error(
-        &mut self,
-        outer_aead_key: Option<&OuterAeadKey>,
-    ) -> Result<LpPacket, LpError> {
-        let packet = self.connection.receive_packet(outer_aead_key).await?;
-
-        match &packet.message {
-            LpMessage::Error(error_packet) => Err(LpError::kkt_psq_handshake(format!(
-                "remote error: {}",
-                error_packet.message
-            ))),
-            _ => Ok(packet),
+    pub fn as_responder(self, responder_data: ResponderData) -> PSQHandshakeStateResponder<'a, S> {
+        PSQHandshakeStateResponder {
+            responder_data,
+            inner_state: self,
         }
     }
 }
@@ -174,167 +110,263 @@ where
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::codec::{decrypt_data, encrypt_data};
     use crate::peer::mock_peers;
-    use crate::psq::helpers::LpTransportHandshakeExt;
-    use crate::psq::responder::DEFAULT_TIMESTAMP_TOLERANCE;
-    use mock_instant::thread_local::MockClock;
-    use nym_kkt::ciphersuite::{HashFunction, HashLength, KEM, SignatureScheme};
+    use crate::peer_config::{LP_PEER_CONFIG_SIZE, LpPeerConfig};
+    use libcrux_psq::handshake::types::Authenticator;
+    use libcrux_psq::session::{Session, SessionBinding};
+    use libcrux_psq::{Channel, IntoSession};
+    use nym_kkt::initiator::KKTInitiator;
+    use nym_kkt::responder::KKTResponder;
+    use nym_kkt_ciphersuite::{Ciphersuite, HashFunction, KEM, SignatureScheme};
+    use nym_test_utils::helpers::{
+        DeterministicRng09Send, deterministic_rng_09, u64_seeded_rng_09,
+    };
     use nym_test_utils::mocks::async_read_write::MockIOStream;
     use nym_test_utils::traits::{Leak, TimeboxedSpawnable};
-    use std::time::Duration;
     use tokio::join;
 
-    #[allow(dead_code)]
-    async fn extract_error(conn: &mut MockIOStream) -> String {
-        let packet = conn.receive_packet(None).await.unwrap();
-        match packet.message {
-            LpMessage::Error(error) => error.message,
-            _ => panic!("non error packet"),
-        }
-    }
-
     #[tokio::test]
     async fn e2e_psq_handshake() -> anyhow::Result<()> {
-        let conn_init = MockIOStream::default();
-        let conn_resp = conn_init.try_get_remote_handle();
+        for kem in KEM::iter() {
+            let conn_init = MockIOStream::default();
+            let conn_resp = conn_init.try_get_remote_handle();
 
-        // leak the connections (JUST FOR THE PURPOSE OF THIS TEST!)
-        // so they'd get 'static lifetime
-        let conn_init = conn_init.leak();
-        let conn_resp = conn_resp.leak();
+            // leak the connections (JUST FOR THE PURPOSE OF THIS TEST!)
+            // so they'd get 'static lifetime
+            let conn_init = conn_init.leak();
+            let conn_resp = conn_resp.leak();
+            let ciphersuite = Ciphersuite::default().with_kem(kem);
 
-        let ciphersuite = Ciphersuite::new(
-            KEM::X25519,
-            HashFunction::Blake3,
-            SignatureScheme::Ed25519,
-            HashLength::Default,
-        );
+            let (mut init, mut resp) = mock_peers();
+            init.ciphersuite = ciphersuite;
+            resp.ciphersuite = ciphersuite;
+            let resp_remote = resp.as_remote();
 
-        let (init, resp) = mock_peers();
-        let resp_remote = resp.as_remote();
+            let handshake_init = PSQHandshakeState::new(conn_init, init)
+                .as_initiator(InitiatorData::new(1, resp_remote));
+            let handshake_resp =
+                PSQHandshakeState::new(conn_resp, resp).as_responder(ResponderData::default());
 
-        let handshake_init = PSQHandshakeState::new(conn_init, ciphersuite, init)
-            .with_protocol_version(1)
-            .with_remote_peer(resp_remote);
-        let handshake_resp = PSQHandshakeState::new(conn_resp, ciphersuite, resp);
+            let init_rng = DeterministicRng09Send::new(u64_seeded_rng_09(1));
+            let resp_rng = DeterministicRng09Send::new(u64_seeded_rng_09(2));
 
-        let resp_fut = handshake_resp.complete_as_responder().spawn_timeboxed();
-        let init_fut = handshake_init.complete_as_initiator().spawn_timeboxed();
+            // similarly leak the rngs to get the static lifetimes
+            let init_rng = init_rng.leak();
+            let resp_rng = resp_rng.leak();
 
-        let (session_init, session_resp) = join!(init_fut, resp_fut);
+            let init_fut = handshake_init
+                .complete_handshake_with_rng(init_rng)
+                .spawn_timeboxed();
+            let resp_fut = handshake_resp
+                .complete_handshake_with_rng(resp_rng)
+                .spawn_timeboxed();
 
-        let session_init = session_init???;
-        let session_resp = session_resp???;
+            let (session_init, session_resp) = join!(init_fut, resp_fut);
 
-        assert_eq!(session_init.id(), session_resp.id());
-        assert_eq!(
-            session_init.outer_aead_key().as_bytes(),
-            session_resp.outer_aead_key().as_bytes()
-        );
-        assert_eq!(
-            session_init.pq_shared_secret().as_bytes(),
-            session_resp.pq_shared_secret().as_bytes()
-        );
+            let mut session_init = session_init???;
+            let mut session_resp = session_resp???;
+
+            assert_eq!(session_init.receiver_index(), session_resp.receiver_index());
+
+            assert_eq!(
+                session_init.session_identifier(),
+                session_resp.session_identifier()
+            );
+
+            // test serialization, deserialization
+            let channel_i = session_init.active_transport();
+            let channel_r = session_resp.active_transport();
+
+            assert_eq!(channel_i.identifier(), channel_r.identifier());
+
+            let app_data_i = b"Derived session hey".as_slice();
+            let app_data_r = b"Derived session ho".as_slice();
+
+            let ct_i = encrypt_data(app_data_i, channel_i)?;
+            let pt_r = decrypt_data(&ct_i, channel_r)?;
+
+            assert_eq!(app_data_i, pt_r);
+
+            let ct_r = encrypt_data(app_data_r, channel_r)?;
+            let pt_i = decrypt_data(&ct_r, channel_i)?;
+
+            assert_eq!(app_data_r, pt_i);
+        }
 
         Ok(())
     }
 
-    #[tokio::test]
-    async fn preparing_client_hello_initiator() -> anyhow::Result<()> {
-        let mut conn_init = MockIOStream::default();
-        let mut conn_resp = conn_init.try_get_remote_handle();
+    // plain test without any wrappers
+    #[test]
+    fn e2e_test_plain() {
+        let mut rng = deterministic_rng_09();
 
-        let ciphersuite = Ciphersuite::new(
-            KEM::X25519,
-            HashFunction::Blake3,
-            SignatureScheme::Ed25519,
-            HashLength::Default,
-        );
-        let (init, resp) = mock_peers();
-        let resp_remote = resp.as_remote();
+        for kem in KEM::iter() {
+            // SETUP START:
+            let protocol_version = 1;
+            let (mut init, resp) = mock_peers();
+            init.ciphersuite = Ciphersuite::default().with_kem(kem);
+            let resp_remote = resp.as_remote();
+            let dir_hash = resp_remote.expected_kem_key_hash(init.ciphersuite).unwrap();
 
-        // as initiator
-        let mut handshake_init = PSQHandshakeState::new(&mut conn_init, ciphersuite, init)
-            .with_protocol_version(1)
-            .with_remote_peer(resp_remote);
+            let resp_keys = resp.kem_keypairs.as_ref().unwrap();
+            let responder_x25519_keypair = resp.x25519();
 
-        // you can generate and send (valid) client hello as initiator
-        let client_hello = handshake_init.send_client_hello().await?;
-        let LpMessage::ClientHello(received_client_hello) =
-            conn_resp.receive_packet(None).await?.message
-        else {
-            panic!("wrong message type");
-        };
-        assert_eq!(client_hello, received_client_hello);
-        Ok(())
-    }
+            let supported_sigs = [SignatureScheme::Ed25519];
+            let supported_hash = [
+                HashFunction::Blake3,
+                HashFunction::Shake256,
+                HashFunction::Shake128,
+                HashFunction::SHA256,
+            ];
+            let kkt_responder = KKTResponder::new(
+                responder_x25519_keypair,
+                resp_keys,
+                &supported_hash,
+                &supported_sigs,
+                &[protocol_version],
+            )
+            .unwrap();
 
-    // essentially make sure you can't accidentally trigger the handshake as the responder
-    #[tokio::test]
-    async fn preparing_client_hello_responder() -> anyhow::Result<()> {
-        let conn_init = MockIOStream::default();
-        let mut conn_resp = conn_init.try_get_remote_handle();
+            // SETUP END
 
-        let ciphersuite = Ciphersuite::new(
-            KEM::X25519,
-            HashFunction::Blake3,
-            SignatureScheme::Ed25519,
-            HashLength::Default,
-        );
-        let (_, resp) = mock_peers();
+            let lp_peer_config = LpPeerConfig::new_client_to_entry(&mut rng, false);
 
-        // as initiator
-        let mut handshake_resp = PSQHandshakeState::new(&mut conn_resp, ciphersuite, resp);
+            // OneWay - MlKem
+            let (mut initiator, request) = KKTInitiator::generate_one_way_request(
+                &mut rng,
+                init.ciphersuite,
+                &responder_x25519_keypair.pk,
+                &dir_hash,
+                protocol_version,
+                Some(Vec::from(lp_peer_config.serialize())),
+            )
+            .unwrap();
 
-        // you can generate and send (valid) client hello as initiator
-        let sending_res = handshake_resp.send_client_hello().await;
-        assert!(sending_res.is_err());
-        Ok(())
-    }
+            let processed_req = kkt_responder
+                .process_request(request, LP_PEER_CONFIG_SIZE)
+                .unwrap();
 
-    #[tokio::test]
-    async fn test_receive_client_hello_timestamp_too_skewed() -> anyhow::Result<()> {
-        let current_time = Duration::from_secs(10000);
-        MockClock::set_system_time(current_time);
+            let response = initiator
+                .process_response(processed_req.response, 0)
+                .unwrap();
+            let encapsulation_key = response.encapsulation_key;
 
-        let too_old = current_time - DEFAULT_TIMESTAMP_TOLERANCE - Duration::from_secs(1);
-        let too_recent = current_time + DEFAULT_TIMESTAMP_TOLERANCE + Duration::from_secs(1);
+            let mut payload_buf_responder = vec![0u8; 4096];
+            let mut payload_buf_initiator = vec![0u8; 4096];
 
-        let ciphersuite = Ciphersuite::new(
-            KEM::X25519,
-            HashFunction::Blake3,
-            SignatureScheme::Ed25519,
-            HashLength::Default,
-        );
+            let initiator_ciphersuite =
+                initiator::build_psq_ciphersuite(&init, &resp_remote, &encapsulation_key).unwrap();
+            let mut initiator = initiator::build_psq_principal(
+                rand09::rng(),
+                protocol_version,
+                initiator_ciphersuite,
+            )
+            .unwrap();
 
-        // TOO OLD
-        let mut conn_init = MockIOStream::default();
-        let mut conn_resp = conn_init.try_get_remote_handle();
-        let (init, resp) = mock_peers();
+            let responder_ciphersuite = responder::build_psq_ciphersuite(&resp, kem).unwrap();
+            let mut responder = responder::build_psq_principal(
+                rand09::rng(),
+                protocol_version,
+                responder_ciphersuite,
+            )
+            .unwrap();
 
-        let mut handshake_resp = PSQHandshakeState::new(&mut conn_resp, ciphersuite, resp);
-        let client_hello_too_old = init.build_client_hello_data(too_old.as_secs());
+            // Send first message
+            let mut buf = vec![0u8; psq_msg1_size(kem)];
+            let len_i = initiator.write_message(&[], &mut buf).unwrap();
+            assert_eq!(len_i, buf.len());
 
-        conn_init
-            .send_packet(client_hello_too_old.into_lp_packet(1), None)
-            .await?;
-        let err = handshake_resp.receive_client_hello().await.unwrap_err();
-        assert!(err.to_string().contains("too old"));
+            // Read first message
+            let (_, _) = responder
+                .read_message(&buf, &mut payload_buf_responder)
+                .unwrap();
 
-        // TOO RECENT
-        let mut conn_init = MockIOStream::default();
-        let mut conn_resp = conn_init.try_get_remote_handle();
-        let (init, resp) = mock_peers();
+            // Get the authenticator out here, so we can deserialize the session later.
+            let Some(initiator_authenticator) = responder.initiator_authenticator() else {
+                panic!("No initiator authenticator found")
+            };
 
-        let mut handshake_resp = PSQHandshakeState::new(&mut conn_resp, ciphersuite, resp);
-        let client_hello_too_recent = init.build_client_hello_data(too_recent.as_secs());
+            // Respond
+            let mut buf = [0u8; PSQ_MSG2_SIZE];
+            let len_r = responder.write_message(&[], &mut buf).unwrap();
+            assert_eq!(len_r, buf.len());
 
-        conn_init
-            .send_packet(client_hello_too_recent.into_lp_packet(1), None)
-            .await?;
-        let err = handshake_resp.receive_client_hello().await.unwrap_err();
+            // Finalize on registration initiator
+            let (len_i_deserialized, _) = initiator
+                .read_message(&buf, &mut payload_buf_initiator)
+                .unwrap();
 
-        assert!(err.to_string().contains("too future"));
-        Ok(())
+            // We read the same amount of data.
+            assert_eq!(len_r, len_i_deserialized);
+
+            // Ready for transport mode
+            assert!(initiator.is_handshake_finished());
+            assert!(responder.is_handshake_finished());
+
+            let i_transport = initiator.into_session().unwrap();
+            let r_transport = responder.into_session().unwrap();
+
+            // test serialization, deserialization
+            let mut session_storage = vec![0u8; 4096];
+            i_transport
+                .serialize(
+                    &mut session_storage,
+                    SessionBinding {
+                        initiator_authenticator: &Authenticator::Dh(init.x25519().pk),
+                        responder_ecdh_pk: &responder_x25519_keypair.pk,
+                        responder_pq_pk: Some(encapsulation_key.as_pq_encapsulation_key()),
+                    },
+                )
+                .unwrap();
+            let mut i_transport = Session::deserialize(
+                &session_storage,
+                SessionBinding {
+                    initiator_authenticator: &Authenticator::Dh(init.x25519().pk),
+                    responder_ecdh_pk: &responder_x25519_keypair.pk,
+                    responder_pq_pk: Some(encapsulation_key.as_pq_encapsulation_key()),
+                },
+            )
+            .unwrap();
+
+            r_transport
+                .serialize(
+                    &mut session_storage,
+                    SessionBinding {
+                        initiator_authenticator: &initiator_authenticator,
+                        responder_ecdh_pk: &responder_x25519_keypair.pk,
+                        responder_pq_pk: Some(encapsulation_key.as_pq_encapsulation_key()),
+                    },
+                )
+                .unwrap();
+            let mut r_transport = Session::deserialize(
+                &session_storage,
+                SessionBinding {
+                    initiator_authenticator: &initiator_authenticator,
+                    responder_ecdh_pk: &responder_x25519_keypair.pk,
+                    responder_pq_pk: Some(encapsulation_key.as_pq_encapsulation_key()),
+                },
+            )
+            .unwrap();
+
+            let mut channel_i = i_transport.transport_channel().unwrap();
+            let mut channel_r = r_transport.transport_channel().unwrap();
+
+            assert_eq!(channel_i.identifier(), channel_r.identifier());
+
+            let app_data_i = b"Derived session hey".as_slice();
+            let app_data_r = b"Derived session ho".as_slice();
+
+            let ct_i = encrypt_data(app_data_i, &mut channel_i).unwrap();
+            let pt_r = decrypt_data(&ct_i, &mut channel_r).unwrap();
+
+            assert_eq!(app_data_i, pt_r);
+
+            let ct_r = encrypt_data(app_data_r, &mut channel_r).unwrap();
+            let pt_i = decrypt_data(&ct_r, &mut channel_i).unwrap();
+
+            assert_eq!(app_data_r, pt_i);
+        }
     }
 }

common/nym-lp/src/psq/responder.rs

@@ -1,461 +1,351 @@
 // Copyright 2026 - Nym Technologies SA <contact@nymtech.net>
 // SPDX-License-Identifier: Apache-2.0
 
-use crate::codec::OuterAeadKey;
-use crate::message::{HandshakeData, KKTResponseData, MessageType};
-use crate::noise_protocol::NoiseProtocol;
-use crate::peer::LpRemotePeer;
-use crate::psk::psq_responder_process_message;
-use crate::psq::helpers::{LpTransportHandshakeExt, current_timestamp};
-use crate::psq::{IntermediateHandshakeFailure, PSQHandshakeState};
-use crate::session::PqSharedSecret;
-use crate::{ClientHelloData, LpError, LpMessage, LpSession};
-use nym_kkt::KKT_RESPONSE_AAD;
-use nym_kkt::ciphersuite::{DecapsulationKey, EncapsulationKey};
-use nym_kkt::context::KKTContext;
-use nym_kkt::encryption::{KKTSessionSecret, decrypt_initial_kkt_frame, encrypt_kkt_frame};
-use nym_kkt::frame::KKTSessionId;
-use nym_kkt::session::{responder_ingest_message, responder_process};
-use nym_lp_transport::traits::LpTransport;
-use rand09::rng;
-use std::time::Duration;
+use crate::peer::LpLocalPeer;
+use crate::peer_config::{LP_PEER_CONFIG_SIZE, LpPeerConfig};
+use crate::psq::handshake_message::{PSQMsg1, PSQMsg2};
+use crate::psq::helpers::kem_to_ciphersuite;
+use crate::psq::{
+    AAD_RESPONDER_V1, PSQ_MSG2_SIZE, PSQHandshakeState, ResponderData, SESSION_CONTEXT_V1,
+    handshake_message, psq_msg1_size,
+};
+use crate::session::PersistentSessionBinding;
+use crate::transport::traits::{HandshakeMessage, LpHandshakeChannel};
+use crate::{LpError, LpSession};
+use libcrux_psq::handshake::Responder;
+use libcrux_psq::handshake::builders::{
+    CiphersuiteBuilder, PrincipalBuilder, ResponderCiphersuite,
+};
+use libcrux_psq::{Channel, IntoSession};
+use nym_kkt::context::KKTMode;
+use nym_kkt::message::{KKTRequest, KKTResponse, ProcessedKKTRequest};
+use nym_kkt::responder::KKTResponder;
+use nym_kkt_ciphersuite::KEM;
+use rand09::SeedableRng;
 use tracing::debug;
 
-pub const DEFAULT_TIMESTAMP_TOLERANCE: Duration = Duration::from_secs(30);
-
-// this will be removed anyway, so no point in doing anything more than a hardcoded placeholder
-fn validate_client_hello_timestamp(
-    client_timestamp: u64,
-    tolerance: Duration,
-) -> Result<(), LpError> {
-    let now = current_timestamp()?;
-
-    let age = now.abs_diff(client_timestamp);
-    if age > tolerance.as_secs() {
-        let direction = if now >= client_timestamp {
-            "old"
-        } else {
-            "future"
-        };
-
-        return Err(LpError::kkt_psq_handshake(format!(
-            "ClientHello timestamp is too {direction} (age: {age}s, tolerance: {}s)",
-            tolerance.as_secs()
-        )));
-    }
-
-    Ok(())
+pub struct PSQHandshakeStateResponder<'a, S> {
+    pub(super) inner_state: PSQHandshakeState<'a, S>,
+    pub(super) responder_data: ResponderData,
 }
 
-impl<'a, S> PSQHandshakeState<'a, S>
+pub(crate) fn build_psq_principal<R>(
+    rng: R,
+    version: u8,
+    ciphersuite: ResponderCiphersuite,
+) -> Result<Responder<R>, LpError>
 where
-    S: LpTransport + Unpin,
+    R: rand09::CryptoRng,
 {
-    pub(crate) fn encapsulated_kem_keys(
-        &self,
-    ) -> Result<(DecapsulationKey<'static>, EncapsulationKey<'static>), LpError> {
-        let kem_keys = self
+    let (ctx, aad) = match version {
+        1 => (SESSION_CONTEXT_V1, AAD_RESPONDER_V1),
+        other => return Err(LpError::UnsupportedVersion { version: other }),
+    };
+
+    PrincipalBuilder::new(rng)
+        .context(ctx)
+        .outer_aad(aad)
+        .recent_keys_upper_bound(30)
+        .build_responder(ciphersuite)
+        .map_err(|inner| LpError::PSQResponderBuilderFailure { inner })
+}
+
+pub(crate) fn build_psq_ciphersuite(
+    peer: &LpLocalPeer,
+    kem: KEM,
+) -> Result<ResponderCiphersuite<'_>, LpError> {
+    let Some(kem_keys) = peer.kem_keypairs.as_ref() else {
+        return Err(LpError::ResponderWithMissingKEMKeys);
+    };
+
+    let psq_ciphersuite = kem_to_ciphersuite(kem);
+    let builder = CiphersuiteBuilder::new(psq_ciphersuite).longterm_x25519_keys(peer.x25519());
+
+    match kem {
+        KEM::MlKem768 => builder
+            .longterm_mlkem_encapsulation_key(kem_keys.ml_kem768_encapsulation_key())
+            .longterm_mlkem_decapsulation_key(kem_keys.ml_kem768_decapsulation_key()),
+        KEM::McEliece => builder
+            .longterm_cmc_encapsulation_key(kem_keys.mc_eliece_encapsulation_key())
+            .longterm_cmc_decapsulation_key(kem_keys.mc_eliece_decapsulation_key()),
+    }
+    .build_responder_ciphersuite()
+    .map_err(|inner| LpError::PSQResponderBuilderFailure { inner })
+}
+
+impl<'a, S> PSQHandshakeStateResponder<'a, S>
+where
+    S: LpHandshakeChannel + Unpin,
+{
+    /// Attempt to receive a KKT request from a one-way client
+    async fn receive_one_way_kkt_request(&mut self) -> Result<KKTRequest, LpError> {
+        let packet_len = KKTRequest::size_excluding_payload(
+            KKTMode::OneWay,
+            self.inner_state.local_peer.ciphersuite.kem(),
+        ) + LP_PEER_CONFIG_SIZE;
+
+        let req = self
+            .inner_state
+            .connection
+            .receive_handshake_message::<handshake_message::KKTRequest>(packet_len)
+            .await?;
+
+        Ok(req.into())
+    }
+
+    /// Attempt to process the received KKT request
+    fn process_kkt_request(&self, kkt_request: KKTRequest) -> Result<ProcessedKKTRequest, LpError> {
+        let kem_keys = &self
+            .inner_state
             .local_peer
-            .kem_psq
+            .kem_keypairs
             .as_ref()
-            .ok_or(LpError::ResponderWithMissingKEMKey)?;
+            .ok_or(LpError::ResponderWithMissingKEMKeys)?;
 
-        let libcrux_private_key = libcrux_kem::PrivateKey::decode(
-            libcrux_kem::Algorithm::X25519,
-            kem_keys.private_key().as_bytes(),
-        )
-        .map_err(|e| {
-            LpError::KKTError(format!(
-                "Failed to convert X25519 private key to libcrux PrivateKey: {e:?}",
-            ))
-        })?;
-        let dec_key = DecapsulationKey::X25519(libcrux_private_key);
-
-        let libcrux_public_key = libcrux_kem::PublicKey::decode(
-            libcrux_kem::Algorithm::X25519,
-            kem_keys.public_key().as_bytes(),
-        )
-        .map_err(|e| {
-            LpError::KKTError(format!(
-                "Failed to convert X25519 public key to libcrux PublicKey: {e:?}",
-            ))
-        })?;
-        let enc_key = EncapsulationKey::X25519(libcrux_public_key);
-        Ok((dec_key, enc_key))
-    }
-
-    /// Attempt to receive and validate ClientHello
-    pub(crate) async fn receive_client_hello(
-        &mut self,
-    ) -> Result<(ClientHelloData, LpRemotePeer), LpError> {
-        let client_hello_packet = self.receive_non_error(None).await?;
-        let client_hello = match client_hello_packet.message {
-            LpMessage::ClientHello(client_hello) => client_hello,
-            other => {
-                return Err(LpError::unexpected_handshake_response(
-                    other.typ(),
-                    MessageType::ClientHello,
-                ));
-            }
-        };
-
-        validate_client_hello_timestamp(
-            client_hello.extract_timestamp(),
-            DEFAULT_TIMESTAMP_TOLERANCE,
-        )?;
-
-        // TODO: somehow check for collision
-
-        // set version and remote peer information
-        self.protocol_version = Some(client_hello_packet.header.protocol_version);
-        let remote_peer = LpRemotePeer::new(
-            client_hello.client_ed25519_public_key,
-            client_hello.client_lp_public_key,
-        );
-
-        Ok((client_hello, remote_peer))
-    }
-
-    /// Send client hello ACK
-    pub(crate) async fn send_client_hello_ack(&mut self, session_id: u32) -> Result<(), LpError> {
-        let protocol = self.protocol_version()?;
-
-        let ack = self.next_packet(session_id, protocol, LpMessage::Ack);
-        self.connection.send_packet(ack, None).await?;
-        Ok(())
-    }
-
-    /// Attempt to receive and process a KKT request
-    pub(crate) async fn receive_kkt_request(
-        &mut self,
-    ) -> Result<(KKTContext, KKTSessionSecret, KKTSessionId), LpError> {
-        let kkt_request = match self.receive_non_error(None).await?.message {
-            LpMessage::KKTRequest(request) => request.0,
-            other => {
-                return Err(LpError::unexpected_handshake_response(
-                    other.typ(),
-                    MessageType::KKTRequest,
-                ));
-            }
-        };
-
-        let (session_secret, request_frame, remote_context) =
-            decrypt_initial_kkt_frame(self.local_peer.x25519.private_key(), &kkt_request)?;
-        let (context, _) = responder_ingest_message(&remote_context, None, None, &request_frame)?;
-
-        Ok((context, session_secret, request_frame.session_id()))
+        let processed_req = KKTResponder::new(
+            &self.inner_state.local_peer.x25519,
+            kem_keys,
+            &self.responder_data.supported_hash_functions,
+            &self.responder_data.supported_signature_schemes,
+            &self.responder_data.supported_outer_protocol_versions,
+        )?
+        .process_request(kkt_request, LP_PEER_CONFIG_SIZE)?;
+        Ok(processed_req)
     }
 
     /// Attempt to send KKT response to the previously received request
-    pub(crate) async fn send_kkt_response(
-        &mut self,
-        session_id: u32,
-        (kkt_context, session_secret, kkt_session_id): (KKTContext, KKTSessionSecret, KKTSessionId),
-        encapsulation_key: &EncapsulationKey<'_>,
-    ) -> Result<(), LpError> {
-        let protocol = self.protocol_version()?;
-
-        let response_frame = responder_process(
-            &kkt_context,
-            kkt_session_id,
-            self.local_peer.ed25519().private_key(),
-            encapsulation_key,
-        )?;
-        let encrypted_frame = encrypt_kkt_frame(
-            &mut rng(),
-            &session_secret,
-            &response_frame,
-            KKT_RESPONSE_AAD,
-        )?;
-        let lp_message = KKTResponseData::new(encrypted_frame).into();
-        let lp_packet = self.next_packet(session_id, protocol, lp_message);
-
-        self.connection.send_packet(lp_packet, None).await?;
+    async fn send_kkt_response(&mut self, response: KKTResponse, kem: KEM) -> Result<(), LpError> {
+        self.inner_state
+            .connection
+            .send_handshake_message::<handshake_message::KKTResponse>(response.into(), kem)
+            .await?;
         Ok(())
     }
 
     /// Attempt to receive and process a PSQ msg1 request
-    pub(crate) async fn receive_psq_initiator_message(
-        &mut self,
-        remote_peer: &LpRemotePeer,
-        local_kem_keypair: (&DecapsulationKey<'_>, &EncapsulationKey<'_>),
-        salt: &[u8; 32],
-        session_id_bytes: &[u8; 4],
-    ) -> Result<(OuterAeadKey, NoiseProtocol, PqSharedSecret, Vec<u8>), LpError> {
-        let psq_msg1 = match self.receive_non_error(None).await?.message {
-            LpMessage::Handshake(response) => response.0,
-            other => {
-                return Err(LpError::unexpected_handshake_response(
-                    other.typ(),
-                    MessageType::Handshake,
-                ));
-            }
-        };
-
-        // Extract PSQ payload: [u16 psq_len][psq_payload][noise_msg]
-        if psq_msg1.len() < 2 {
-            return Err(LpError::kkt_psq_handshake("too short msg1 received"));
-        }
-        let handle_len = u16::from_le_bytes([psq_msg1[0], psq_msg1[1]]) as usize;
-        if psq_msg1.len() < 2 + handle_len {
-            return Err(LpError::kkt_psq_handshake("too short msg1 received"));
-        }
-        let psq_payload = &psq_msg1[2..2 + handle_len];
-        let noise_payload = &psq_msg1[2 + handle_len..];
-
-        // Decapsulate PSK from PSQ payload using X25519 as DHKEM
-        let psq_responder = psq_responder_process_message(
-            self.local_peer.x25519.private_key(),
-            &remote_peer.x25519_public,
-            local_kem_keypair,
-            &remote_peer.ed25519_public,
-            psq_payload,
-            salt,
-            session_id_bytes,
-        )?;
-
-        let psk = psq_responder.psk;
-        let psk_handle = psq_responder.psk_handle;
-
-        // TEMP \/
-        let outer_aead_key = OuterAeadKey::from_psk(&psk);
-        // TEMP /\
-
-        let mut noise_protocol = NoiseProtocol::build_new_responder(
-            self.local_peer.x25519().private_key().as_bytes(),
-            remote_peer.x25519_public.as_bytes(),
-            &psk,
-        )?;
-        noise_protocol.read_message(noise_payload)?;
-
-        Ok((
-            outer_aead_key,
-            noise_protocol,
-            PqSharedSecret::new(psq_responder.pq_shared_secret),
-            psk_handle,
-        ))
-    }
-
-    /// Attempt to prepare and generate a responder PSQ msg2
-    pub(crate) async fn send_psq_responder_message(
-        &mut self,
-        session_id: u32,
-        psk_handle: &[u8],
-        outer_aead_key: &OuterAeadKey,
-        noise_protocol: &mut NoiseProtocol,
-    ) -> Result<(), LpError> {
-        let protocol = self.protocol_version()?;
-
-        let msg2 = noise_protocol
-            .get_bytes_to_send()
-            .ok_or_else(|| LpError::kkt_psq_handshake("failed to generate noise msg2"))??;
-        // Embed PSK handle in message: [u16 handle_len][handle_bytes][noise_msg]
-        let handle_len = psk_handle.len() as u16;
-        let mut combined = Vec::with_capacity(2 + psk_handle.len() + msg2.len());
-        combined.extend_from_slice(&handle_len.to_le_bytes());
-        combined.extend_from_slice(psk_handle);
-        combined.extend_from_slice(&msg2);
-
-        let lp_message = HandshakeData::new(combined).into();
-        let lp_packet = self.next_packet(session_id, protocol, lp_message);
-        self.connection
-            .send_packet(lp_packet, Some(outer_aead_key))
-            .await?;
-        Ok(())
-    }
-
-    /// Attempt to receive and process final PSQ msg3
-    pub(crate) async fn receive_final_psq_message(
-        &mut self,
-        outer_aead_key: &OuterAeadKey,
-        noise_protocol: &mut NoiseProtocol,
-    ) -> Result<(), LpError> {
-        let psq_msg3 = match self
+    async fn receive_psq_initiator_message(&mut self, kem: KEM) -> Result<Vec<u8>, LpError> {
+        let packet_len = psq_msg1_size(kem);
+        let msg: PSQMsg1 = self
+            .inner_state
             .connection
-            .receive_packet(Some(outer_aead_key))
-            .await?
-            .message
-        {
-            LpMessage::Handshake(response) => response.0,
-            other => {
-                return Err(LpError::unexpected_handshake_response(
-                    other.typ(),
-                    MessageType::Handshake,
-                ));
-            }
-        };
-
-        noise_protocol.read_message(&psq_msg3)?;
-        if !noise_protocol.is_handshake_finished() {
-            return Err(LpError::kkt_psq_handshake(
-                "noise handshake not finished after msg3",
-            ));
-        }
-        Ok(())
-    }
-
-    /// Send final ACK to indicate finalisation of the handshake
-    pub(crate) async fn send_final_ack(
-        &mut self,
-        session_id: u32,
-        outer_aead_key: &OuterAeadKey,
-    ) -> Result<(), LpError> {
-        let protocol = self.protocol_version()?;
-
-        let ack = self.next_packet(session_id, protocol, LpMessage::Ack);
-        self.connection
-            .send_packet(ack, Some(outer_aead_key))
+            .receive_handshake_message(packet_len)
             .await?;
-        Ok(())
+        Ok(msg.into_bytes())
     }
 
-    async fn complete_as_responder_inner(
-        &mut self,
-    ) -> Result<LpSession, IntermediateHandshakeFailure>
+    pub async fn complete_handshake(self) -> Result<LpSession, LpError>
     where
-        S: LpTransport + Unpin,
+        S: LpHandshakeChannel + Unpin,
     {
-        // 1. receive and validate ClientHello
-        let (client_hello_data, remote_peer) =
-            self.receive_client_hello()
-                .await
-                .map_err(|source| IntermediateHandshakeFailure {
-                    session_id: None,
-                    protocol_version: self.protocol_version,
-                    outer_aead_key: None,
-                    source,
-                })?;
-        debug!("received client hello");
+        let mut rng = rand09::rngs::StdRng::from_os_rng();
+        self.complete_handshake_with_rng(&mut rng).await
+    }
 
-        let session_id = client_hello_data.receiver_index;
-        let session_id_bytes = session_id.to_le_bytes();
-        let salt = client_hello_data.salt;
-
-        // 2. send ack
-        debug!("sending client hello ACK");
-        self.send_client_hello_ack(session_id)
-            .await
-            .map_err(|source| IntermediateHandshakeFailure {
-                session_id: Some(session_id),
-                protocol_version: self.protocol_version,
-                outer_aead_key: None,
-                source,
-            })?;
-
-        // 3. receive and process KKT request
-        let kkt_data =
-            self.receive_kkt_request()
-                .await
-                .map_err(|source| IntermediateHandshakeFailure {
-                    session_id: Some(session_id),
-                    protocol_version: self.protocol_version,
-                    outer_aead_key: None,
-                    source,
-                })?;
+    pub async fn complete_handshake_with_rng<R>(mut self, rng: &mut R) -> Result<LpSession, LpError>
+    where
+        S: LpHandshakeChannel + Unpin,
+        R: rand09::CryptoRng,
+    {
+        // 1. receive and process KKTRequest
+        let kkt_request = self.receive_one_way_kkt_request().await?;
         debug!("received KKT request");
 
-        // TEMP: 'derive' KEM keys
-        let (dec_key, enc_key) =
-            self.encapsulated_kem_keys()
-                .map_err(|source| IntermediateHandshakeFailure {
-                    session_id: Some(session_id),
-                    protocol_version: self.protocol_version,
-                    outer_aead_key: None,
-                    source,
-                })?;
+        let processed_req = self.process_kkt_request(kkt_request)?;
+        let kem = processed_req.requested_kem;
 
-        // 4. prepare and send KKT response
+        let lp_peer_config = LpPeerConfig::deserialize(&processed_req.request_payload)?;
+
+        // 2. send back the KKTResponse
         debug!("sending KKT response");
-        self.send_kkt_response(session_id, kkt_data, &enc_key)
-            .await
-            .map_err(|source| IntermediateHandshakeFailure {
-                session_id: Some(session_id),
-                protocol_version: self.protocol_version,
-                outer_aead_key: None,
-                source,
-            })?;
+        self.send_kkt_response(processed_req.response, kem).await?;
 
-        // 5. receive and process PSQ msg1
-        debug!("received PSQ msg1");
-        let (outer_aead_key, mut noise_protocol, pq_shared_secret, psk_handle) = self
-            .receive_psq_initiator_message(
-                &remote_peer,
-                (&dec_key, &enc_key),
-                &salt,
-                &session_id_bytes,
-            )
-            .await
-            .map_err(|source| IntermediateHandshakeFailure {
-                session_id: Some(session_id),
-                protocol_version: self.protocol_version,
-                outer_aead_key: None,
-                source,
-            })?;
+        // 3. receive and process PSQ request
+        let raw_psq1 = self.receive_psq_initiator_message(kem).await?;
+        debug!("received PSQ handshake msg");
 
-        // 6. prepare and send PSQ msg2
-        debug!("sending PSQ msg2");
-        if let Err(source) = self
-            .send_psq_responder_message(
-                session_id,
-                &psk_handle,
-                &outer_aead_key,
-                &mut noise_protocol,
-            )
-            .await
-        {
-            return Err(IntermediateHandshakeFailure {
-                session_id: Some(session_id),
-                protocol_version: self.protocol_version,
-                outer_aead_key: Some(outer_aead_key),
-                source,
-            });
+        // construct the responder and process the message
+        let responder_ciphersuite = build_psq_ciphersuite(&self.inner_state.local_peer, kem)?;
+        let version = processed_req.outer_protocol_version;
+        let mut psq_responder = build_psq_principal(rng, version, responder_ciphersuite)?;
+        psq_responder.read_message(&raw_psq1, &mut [])?;
+
+        let initiator_authenticator = psq_responder
+            .initiator_authenticator()
+            .ok_or(LpError::MissingInitiatorAuthenticator)?;
+
+        // 4. send PSQ response
+        let conn = self.inner_state.connection;
+
+        let mut buf = vec![0u8; PSQ_MSG2_SIZE];
+        psq_responder.write_message(&[], &mut buf)?;
+        debug!("sending PSQ handshake msg");
+        conn.send_handshake_message(PSQMsg2::new(buf), kem).await?;
+
+        if !psq_responder.is_handshake_finished() {
+            return Err(LpError::kkt_psq_handshake(
+                "handshake not finished after receiving psq response",
+            ));
         }
 
-        // 7. receive and process PSQ msg3
-        debug!("received PSQ msg3");
-        if let Err(source) = self
-            .receive_final_psq_message(&outer_aead_key, &mut noise_protocol)
-            .await
-        {
-            return Err(IntermediateHandshakeFailure {
-                session_id: Some(session_id),
-                protocol_version: self.protocol_version,
-                outer_aead_key: Some(outer_aead_key),
-                source,
-            });
-        }
+        // SAFETY: we have completed the exchange so this key MUST HAVE been present
+        #[allow(clippy::unwrap_used)]
+        let kem_key = self
+            .inner_state
+            .local_peer
+            .kem_keypairs
+            .as_ref()
+            .unwrap()
+            .encapsulation_key(kem)
+            .unwrap();
 
-        // 8. [optionally] send ACK to finalise
-        debug!("sending final ACK");
-        if let Err(source) = self.send_final_ack(session_id, &outer_aead_key).await {
-            return Err(IntermediateHandshakeFailure {
-                session_id: Some(session_id),
-                protocol_version: self.protocol_version,
-                outer_aead_key: Some(outer_aead_key),
-                source,
-            });
-        }
+        let receiver_index =
+            lp_peer_config.derive_receiver_index(&initiator_authenticator, &kem_key)?;
 
-        #[allow(clippy::expect_used)]
-        Ok(LpSession::new(
-            session_id,
-            self.protocol_version()
-                .expect("protocol version is known at this point"),
-            outer_aead_key,
-            self.local_peer.clone(),
-            remote_peer,
-            pq_shared_secret,
-            noise_protocol,
-        ))
-    }
+        let binding = PersistentSessionBinding {
+            initiator_authenticator,
+            responder_ecdh_pk: self.inner_state.local_peer.x25519().pk,
+            responder_pq_pk: Some(kem_key),
+        };
 
-    pub async fn complete_as_responder(mut self) -> Result<LpSession, LpError>
-    where
-        S: LpTransport + Unpin,
-    {
-        match self.complete_as_responder_inner().await {
-            Ok(res) => Ok(res),
-            Err(err) => Err(self.try_send_error_packet(err).await),
-        }
+        let psq_session = psq_responder.into_session()?;
+        LpSession::new(
+            psq_session,
+            binding,
+            receiver_index,
+            processed_req.outer_protocol_version,
+        )
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::codec::{decrypt_data, encrypt_data};
+    use crate::peer::mock_peers;
+    use crate::peer_config::LpPeerConfig;
+    use crate::psq::initiator;
+    use nym_kkt::initiator::KKTInitiator;
+    use nym_kkt_ciphersuite::{Ciphersuite, IntoEnumIterator};
+    use nym_test_utils::helpers::{
+        DeterministicRng09Send, deterministic_rng_09, u64_seeded_rng_09,
+    };
+    use nym_test_utils::mocks::async_read_write::MockIOStream;
+    use nym_test_utils::traits::{Leak, Timeboxed};
+
+    #[tokio::test]
+    async fn responder_test_plain() -> anyhow::Result<()> {
+        for kem in KEM::iter() {
+            let conn_init = MockIOStream::default();
+            let conn_resp = conn_init.try_get_remote_handle();
+
+            // SETUP START:
+            // leak the connections (JUST FOR THE PURPOSE OF THIS TEST!)
+            // so they'd get 'static lifetime
+            let conn_init = conn_init.leak();
+            let conn_resp = conn_resp.leak();
+
+            let (mut init, mut resp) = mock_peers();
+            let resp_remote = resp.as_remote();
+
+            let ciphersuite = Ciphersuite::default().with_kem(kem);
+            init.ciphersuite = ciphersuite;
+            resp.ciphersuite = ciphersuite;
+
+            let responder_data = ResponderData::default();
+            let handshake_resp =
+                PSQHandshakeState::new(conn_resp, resp).as_responder(responder_data);
+
+            let mut resp_rng = DeterministicRng09Send::new(u64_seeded_rng_09(2));
+            let resp_fut = tokio::spawn(async move {
+                handshake_resp
+                    .complete_handshake_with_rng(&mut resp_rng)
+                    .timeboxed()
+                    .await
+            });
+
+            // initiator:
+
+            let mut rng = deterministic_rng_09();
+            let dir_hash = resp_remote.expected_kem_key_hash(init.ciphersuite)?;
+
+            let lp_peer_config = LpPeerConfig::new_client_to_entry(&mut rng, false);
+
+            // OneWay - MlKem
+            let (mut initiator, request) = KKTInitiator::generate_one_way_request(
+                &mut rng,
+                init.ciphersuite,
+                &resp_remote.x25519_public,
+                &dir_hash,
+                1,
+                Some(Vec::from(lp_peer_config.serialize())),
+            )?;
+
+            // 1. send kkt request
+            conn_init
+                .send_handshake_message::<handshake_message::KKTRequest>(request.into(), kem)
+                .timeboxed()
+                .await??;
+
+            // 2. receive KKT response
+            let response_len = KKTResponse::size_excluding_payload(kem);
+            let resp: handshake_message::KKTResponse = conn_init
+                .receive_handshake_message(response_len)
+                .timeboxed()
+                .await??;
+            let kkt_response = resp.into();
+
+            let response = initiator.process_response(kkt_response, 0)?;
+            let encapsulation_key = response.encapsulation_key;
+
+            let initiator_ciphersuite =
+                initiator::build_psq_ciphersuite(&init, &resp_remote, &encapsulation_key)?;
+            let mut initiator =
+                initiator::build_psq_principal(rand09::rng(), 1, initiator_ciphersuite)?;
+
+            // 3. send PSQ msg1
+            // Send first message
+            let mut buf = vec![0u8; psq_msg1_size(kem)];
+            let n = initiator.write_message(&[], &mut buf).unwrap();
+            assert_eq!(n, buf.len());
+            let msg = PSQMsg1::new(buf);
+            conn_init
+                .send_handshake_message(msg, kem)
+                .timeboxed()
+                .await??;
+
+            // 4. receive PSQ msg2
+            let msg: PSQMsg2 = conn_init
+                .receive_handshake_message(PSQ_MSG2_SIZE)
+                .timeboxed()
+                .await??;
+            initiator.read_message(&msg, &mut []).unwrap();
+
+            assert!(initiator.is_handshake_finished());
+
+            let mut session_resp = resp_fut.await???;
+
+            let mut i_transport = initiator.into_session().unwrap();
+
+            // test serialization, deserialization
+            let mut channel_i = i_transport.transport_channel().unwrap();
+            let channel_r = session_resp.active_transport();
+
+            assert_eq!(channel_i.identifier(), channel_r.identifier());
+
+            let app_data_i = b"Derived session hey".as_slice();
+            let app_data_r = b"Derived session ho".as_slice();
+
+            let ct_i = encrypt_data(app_data_i, &mut channel_i)?;
+            let pt_r = decrypt_data(&ct_i, channel_r)?;
+
+            assert_eq!(app_data_i, pt_r);
+
+            let ct_r = encrypt_data(app_data_r, channel_r)?;
+            let pt_i = decrypt_data(&ct_r, &mut channel_i)?;
+
+            assert_eq!(app_data_r, pt_i);
+        }
+
+        Ok(())
     }
 }

common/nym-lp/src/replay/validator.rs

@@ -38,6 +38,16 @@ const N_WORDS: usize = 16;
 /// Total number of bits in the bitmap
 const N_BITS: usize = WORD_SIZE * N_WORDS;
 
+/// Current packet count statistics
+#[derive(Copy, Clone, Debug, PartialEq)]
+pub struct PacketCount {
+    /// the next expected counter value
+    pub next: u64,
+
+    /// the total number of received packets
+    pub received: u64,
+}
+
 /// Validator for receiving key counters to prevent replay attacks.
 ///
 /// This structure maintains a bitmap of received packets and validates
@@ -205,11 +215,14 @@ impl ReceivingKeyCounterValidator {
 
     /// Returns the current packet count statistics.
     ///
-    /// Returns a tuple of `(next, receive_cnt)` where:
+    /// Returns a struct consisting of `(next, receive_cnt)` where:
     /// - `next` is the next expected counter value
     /// - `receive_cnt` is the total number of received packets
-    pub fn current_packet_cnt(&self) -> (u64, u64) {
-        (self.next, self.receive_cnt)
+    pub fn current_packet_cnt(&self) -> PacketCount {
+        PacketCount {
+            next: self.next,
+            received: self.receive_cnt,
+        }
     }
 
     #[inline(always)]
@@ -481,7 +494,10 @@ mod tests {
         let mut validator = ReceivingKeyCounterValidator::default();
 
         // Initial state
-        let (next, count) = validator.current_packet_cnt();
+        let PacketCount {
+            next,
+            received: count,
+        } = validator.current_packet_cnt();
         assert_eq!(next, 0);
         assert_eq!(count, 0);
 
@@ -490,21 +506,30 @@ mod tests {
         assert!(validator.mark_did_receive_branchless(1).is_ok());
         assert!(validator.mark_did_receive_branchless(2).is_ok());
 
-        let (next, count) = validator.current_packet_cnt();
+        let PacketCount {
+            next,
+            received: count,
+        } = validator.current_packet_cnt();
         assert_eq!(next, 3);
         assert_eq!(count, 3);
 
         // After an out of order packet
         assert!(validator.mark_did_receive_branchless(10).is_ok());
 
-        let (next, count) = validator.current_packet_cnt();
+        let PacketCount {
+            next,
+            received: count,
+        } = validator.current_packet_cnt();
         assert_eq!(next, 11);
         assert_eq!(count, 4);
 
         // After a packet from the past (within window)
         assert!(validator.mark_did_receive_branchless(5).is_ok());
 
-        let (next, count) = validator.current_packet_cnt();
+        let PacketCount {
+            next,
+            received: count,
+        } = validator.current_packet_cnt();
         assert_eq!(next, 11); // Next doesn't change
         assert_eq!(count, 5); // Count increases
     }
@@ -553,7 +578,7 @@ mod tests {
         assert!(validator.mark_did_receive_branchless(first_jump).is_ok());
 
         // Verify next counter is updated
-        let (next, _) = validator.current_packet_cnt();
+        let PacketCount { next, .. } = validator.current_packet_cnt();
         assert_eq!(next, first_jump + 1);
 
         // Second large jump, even further ahead
@@ -561,7 +586,7 @@ mod tests {
         assert!(validator.mark_did_receive_branchless(second_jump).is_ok());
 
         // Verify next counter is updated again
-        let (next, _) = validator.current_packet_cnt();
+        let PacketCount { next, .. } = validator.current_packet_cnt();
         assert_eq!(next, second_jump + 1);
 
         // Test packets within the new window
@@ -726,10 +751,10 @@ mod tests {
 
         // Check final state of the validator
         let final_state = validator.lock().unwrap();
-        let (_next, receive_cnt) = final_state.current_packet_cnt();
+        let count = final_state.current_packet_cnt();
 
         // Verify that the received count matches our successful operations
-        assert_eq!(receive_cnt, total_successes as u64);
+        assert_eq!(count.received, total_successes as u64);
     }
 
     #[test]

common/nym-lp/src/session.rs

@@ -4,218 +4,177 @@
 //! Session management for the Lewes Protocol.
 //!
 //! This module implements session management functionality, including replay protection
-//! and Noise protocol state handling.
 
-use crate::codec::OuterAeadKey;
-use crate::message::EncryptedDataPayload;
-// noiserm
-use crate::noise_protocol::{NoiseError, NoiseProtocol, ReadResult};
-use crate::packet::LpHeader;
+use crate::codec::{decrypt_lp_packet, encrypt_lp_packet};
+use crate::packet::{EncryptedLpPacket, LpHeader, LpMessage, LpPacket};
 use crate::peer::{LpLocalPeer, LpRemotePeer};
-use crate::psk::derive_subsession_psk;
-use crate::psq::PSQHandshakeState;
-use crate::replay::ReceivingKeyCounterValidator;
-use crate::{LpError, LpMessage, LpPacket};
-use nym_crypto::asymmetric::{ed25519, x25519};
-use nym_kkt::ciphersuite::{Ciphersuite, HashFunction, HashLength, KEM, SignatureScheme};
-use nym_lp_transport::traits::LpTransport;
-use parking_lot::Mutex;
-use snow::Builder;
-use zeroize::{Zeroize, ZeroizeOnDrop};
+use crate::peer_config::LpReceiverIndex;
+use crate::psq::{
+    InitiatorData, PSQHandshakeState, PSQHandshakeStateInitiator, PSQHandshakeStateResponder,
+    ResponderData,
+};
+use crate::replay::validator::PacketCount;
+use crate::transport::LpHandshakeChannel;
+use crate::{LpError, replay::ReceivingKeyCounterValidator};
+use libcrux_psq::handshake::types::{Authenticator, DHPublicKey};
+use libcrux_psq::session::{Session, SessionBinding};
+use nym_kkt::keys::EncapsulationKey;
+use std::fmt::{Debug, Formatter};
 
-/// PQ shared secret wrapper with automatic memory zeroization.
-/// Ensures K_pq is cleared from memory when dropped.
-#[derive(Clone, Zeroize, ZeroizeOnDrop)]
-pub struct PqSharedSecret([u8; 32]);
-
-impl PqSharedSecret {
-    pub fn new(secret: [u8; 32]) -> Self {
-        Self(secret)
-    }
-
-    pub fn as_bytes(&self) -> &[u8; 32] {
-        &self.0
-    }
-}
-
-impl std::fmt::Debug for PqSharedSecret {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.debug_struct("PqSharedSecret")
-            .field("secret", &"<redacted>")
-            .finish()
-    }
-}
+pub type SessionId = [u8; 32];
 
 /// A session in the Lewes Protocol, handling connection state with Noise.
 ///
 /// Sessions manage connection state, including LP replay protection.
 /// Each session has a unique receiving index and sending index for connection identification.
-#[derive(Debug)]
 pub struct LpSession {
-    /// Id of the established session
-    session_id: u32,
+    /// The underlying established session
+    psq_session: Session,
+
+    /// The public key material bound to the underlying session. Used for serialisation.
+    session_binding: PersistentSessionBinding,
+
+    /// The current active transport channel
+    // In the future it might get split between UDP and TCP transports
+    active_transport: libcrux_psq::session::Transport,
+
+    /// Look-up index established during the initial KKT exchange
+    receiver_index: LpReceiverIndex,
 
     /// Negotiated protocol version from handshake.
-    /// Set during handshake completion from the ClientHello/ServerHello packet header.
-    /// Used for future version negotiation and compatibility checks.
-    version: u8,
-
-    /// Outer AEAD key for packet encryption (derived from PSK after PSQ handshake).
-    outer_aead_key: OuterAeadKey,
-
-    /// Representation of a local Lewes Protocol peer
-    /// encapsulating all the known information and keys.
-    local_peer: LpLocalPeer,
-
-    /// Representation of a remote Lewes Protocol peer
-    /// encapsulating all the known information and keys.
-    remote_peer: LpRemotePeer,
-
-    // TODO: ALL BELOW maybe not needed after all?
-    /// Raw PQ shared secret (K_pq) from PSQ KEM encapsulation/decapsulation.
-    /// Stored after PSQ handshake completes for subsession PSK derivation.
-    pq_shared_secret: PqSharedSecret,
-
-    /// Noise protocol state machine
-    noise_state: NoiseProtocol,
+    protocol_version: u8,
 
     /// Counter for outgoing packets
     sending_counter: u64,
 
     /// Validator for incoming packet counters to prevent replay attacks
     receiving_counter: ReceivingKeyCounterValidator,
+}
 
-    /// Monotonically increasing counter for subsession indices.
-    /// Each subsession gets a unique index to ensure unique PSK derivation.
-    /// Uses u64 to make overflow practically impossible (~585k years at 1M/sec).
-    subsession_counter: u64,
+/// Wraps public key material that is bound to a session.
+#[derive(Clone)]
+pub struct PersistentSessionBinding {
+    /// The initiator's authenticator value, i.e. a long-term DH public value or signature verification key.
+    pub initiator_authenticator: Authenticator,
 
-    /// True if this session has been demoted to read-only mode.
-    /// Demoted sessions can still receive/decrypt but cannot send/encrypt.
-    read_only: bool,
+    /// The responder's long term DH public value.
+    pub responder_ecdh_pk: DHPublicKey,
 
-    /// ID of the successor session that replaced this one.
-    /// Set when demote() is called.
-    successor_session_id: Option<u32>,
+    /// The responder's long term PQ-KEM public key (if any).
+    pub responder_pq_pk: Option<EncapsulationKey>,
+}
+
+impl Debug for PersistentSessionBinding {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("PersistentSessionBinding")
+            .field("initiator_authenticator", &"<initiator_authenticator>")
+            .field("responder_ecdh_pk", &self.responder_ecdh_pk)
+            .field("responder_pq_pk", &self.responder_pq_pk)
+            .finish()
+    }
+}
+
+impl<'a> From<&'a PersistentSessionBinding> for SessionBinding<'a> {
+    fn from(value: &'a PersistentSessionBinding) -> Self {
+        SessionBinding {
+            initiator_authenticator: &value.initiator_authenticator,
+            responder_ecdh_pk: &value.responder_ecdh_pk,
+            responder_pq_pk: value
+                .responder_pq_pk
+                .as_ref()
+                .map(|k| k.as_pq_encapsulation_key()),
+        }
+    }
+}
+
+impl Debug for LpSession {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("LpSession")
+            .field("session_id", &self.psq_session.identifier())
+            .field("session_binding", &self.session_binding)
+            .field("active_transport_id", &self.active_transport.identifier())
+            .field("protocol_version", &self.protocol_version)
+            .field("sending_counter", &self.sending_counter)
+            .field("receiving_counter", &self.receiving_counter)
+            .finish()
+    }
 }
 
 impl LpSession {
     /// Creates a new session after completed KTT/PSQ exchange
-    ///
-    /// # Arguments
-    ///
-    /// * `session_id` - Session identifier
-    /// * `version` - Protocol version to attach in all `LpPacket`s
-    /// * `outer_aead_key` - Outer AEAD key for packet encryption
-    /// * `local_peer` - This side's LP peer's keys
-    /// * `remote_peer` - The remote's LP peer's keys
-    /// * `pq_shared_secret` - Raw PQ shared secret (K_pq) from PSQ KEM encapsulation/decapsulation.
-    /// * `noise_state` - Noise protocol state machine
     pub fn new(
-        session_id: u32,
-        version: u8,
-        outer_aead_key: OuterAeadKey,
-        local_peer: LpLocalPeer,
-        remote_peer: LpRemotePeer,
-        pq_shared_secret: PqSharedSecret,
-        noise_state: NoiseProtocol,
-    ) -> Self {
-        LpSession {
-            session_id,
-            version,
-            outer_aead_key,
-            local_peer,
-            remote_peer,
-            pq_shared_secret,
-            noise_state,
+        mut psq_session: Session,
+        session_binding: PersistentSessionBinding,
+        receiver_index: LpReceiverIndex,
+        protocol_version: u8,
+    ) -> Result<Self, LpError> {
+        // attempt to derive initial transport
+        let transport = psq_session
+            .transport_channel()
+            .map_err(|inner| LpError::TransportDerivationFailure { inner })?;
+
+        Ok(LpSession {
+            psq_session,
+            session_binding,
+            active_transport: transport,
+            receiver_index,
+            protocol_version,
             sending_counter: 0,
             receiving_counter: Default::default(),
-            subsession_counter: 0,
-            read_only: false,
-            successor_session_id: None,
-        }
-    }
-
-    /// Create an instance of `Ciphersuite` using hardcoded defaults.
-    /// This is a temporary workaround until values can be properly inferred
-    /// from reported version
-    pub fn default_ciphersuite() -> Ciphersuite {
-        Ciphersuite::new(
-            KEM::X25519,
-            HashFunction::Blake3,
-            SignatureScheme::Ed25519,
-            HashLength::Default,
-        )
+        })
     }
 
     /// Helper function to create `PSQHandshakeState` for the handshake initiator
-    pub fn complete_as_initiator<S>(
+    pub fn psq_handshake_initiator<S>(
         connection: &'_ mut S,
-        ciphersuite: Ciphersuite,
         local_peer: LpLocalPeer,
         remote_peer: LpRemotePeer,
         remote_protocol_version: u8,
-    ) -> PSQHandshakeState<'_, S>
+    ) -> PSQHandshakeStateInitiator<'_, S>
     where
-        S: LpTransport + Unpin,
+        S: LpHandshakeChannel + Unpin,
     {
-        PSQHandshakeState::new(connection, ciphersuite, local_peer)
-            .with_protocol_version(remote_protocol_version)
-            .with_remote_peer(remote_peer)
+        PSQHandshakeState::new(connection, local_peer)
+            .as_initiator(InitiatorData::new(remote_protocol_version, remote_peer))
     }
 
     /// Helper function to create `PSQHandshakeState` for the handshake responder
     pub fn psq_handshake_responder<S>(
         connection: &'_ mut S,
-        ciphersuite: Ciphersuite,
         local_peer: LpLocalPeer,
-    ) -> PSQHandshakeState<'_, S>
+    ) -> PSQHandshakeStateResponder<'_, S>
     where
-        S: LpTransport + Unpin,
+        S: LpHandshakeChannel + Unpin,
     {
-        PSQHandshakeState::new(connection, ciphersuite, local_peer)
+        PSQHandshakeState::new(connection, local_peer).as_responder(ResponderData::default())
     }
 
-    pub fn id(&self) -> u32 {
-        self.session_id
+    pub fn session_binding(&self) -> &PersistentSessionBinding {
+        &self.session_binding
+    }
+
+    pub fn active_transport(&mut self) -> &mut libcrux_psq::session::Transport {
+        &mut self.active_transport
+    }
+
+    pub fn session_identifier(&self) -> &[u8; 32] {
+        self.psq_session.identifier()
+    }
+
+    pub fn receiver_index(&self) -> LpReceiverIndex {
+        self.receiver_index
     }
 
     /// Returns the negotiated protocol version from the handshake.
     ///
     /// Set during `LpSession` creation after sending / receiving `ClientHelloData`
     pub fn negotiated_version(&self) -> u8 {
-        self.version
-    }
-
-    /// Returns the local X25519 public key.
-    ///
-    /// This is used for KKT protocol when the responder needs to send their
-    /// KEM public key in the KKT response.
-    pub fn local_x25519_public(&self) -> x25519::PublicKey {
-        *self.local_peer.x25519.public_key()
-    }
-
-    /// Returns the remote ed25519 public key.
-    pub fn remote_ed25519_public(&self) -> ed25519::PublicKey {
-        self.remote_peer.ed25519_public
-    }
-
-    /// Returns the remote X25519 public key.
-    ///
-    /// Used for tie-breaking in simultaneous subsession initiation.
-    /// Lower key loses and becomes responder.
-    pub fn remote_x25519_public(&self) -> &x25519::PublicKey {
-        &self.remote_peer.x25519_public
-    }
-
-    /// Returns the outer AEAD key for packet encryption/decryption.
-    pub fn outer_aead_key(&self) -> &OuterAeadKey {
-        &self.outer_aead_key
+        self.protocol_version
     }
 
     pub fn next_packet(&mut self, message: LpMessage) -> Result<LpPacket, LpError> {
         let counter = self.next_counter();
-        let header = LpHeader::new(self.id(), counter, self.version);
+        let header = LpHeader::new(self.receiver_index(), counter, self.protocol_version);
         let packet = LpPacket::new(header, message);
         Ok(packet)
     }
@@ -274,508 +233,132 @@ impl LpSession {
     /// A tuple containing:
     /// * The next expected counter value for incoming packets
     /// * The total number of received packets
-    pub fn current_packet_cnt(&self) -> (u64, u64) {
+    pub fn current_packet_cnt(&self) -> PacketCount {
         self.receiving_counter.current_packet_cnt()
     }
 
-    /// Returns the PQ shared secret (K_pq).
-    ///
-    /// This is the raw KEM output from PSQ before Blake3 KDF combination.
-    /// Used for deriving subsession PSKs to maintain PQ protection.
-    pub fn pq_shared_secret(&self) -> &PqSharedSecret {
-        &self.pq_shared_secret
-    }
-
-    /// Gets the next subsession index and increments the counter.
-    ///
-    /// Each subsession requires a unique index to ensure unique PSK derivation.
-    /// The index is monotonically increasing per session.
-    pub fn next_subsession_index(&mut self) -> u64 {
-        let next = self.subsession_counter;
-        self.subsession_counter += 1;
-        next
-    }
-
-    /// Returns true if this session is in read-only mode.
-    ///
-    /// Read-only sessions have been demoted after a subsession was promoted.
-    /// They can still decrypt incoming messages but cannot encrypt outgoing ones.
-    pub fn is_read_only(&self) -> bool {
-        self.read_only
-    }
-
-    /// Demotes this session to read-only mode after a subsession replaces it.
-    ///
-    /// After demotion:
-    /// - `encrypt_data()` will return `NoiseError::SessionReadOnly`
-    /// - `decrypt_data()` still works (to drain in-flight messages)
-    /// - Session should be cleaned up after TTL expires
-    ///
-    /// # Arguments
-    /// * `successor_idx` - The receiver index of the session that replaced this one
-    pub fn demote(&mut self, successor_idx: u32) {
-        self.successor_session_id = Some(successor_idx);
-        self.read_only = true;
-    }
-
-    /// Returns the successor session ID if this session was demoted.
-    pub fn successor_session_id(&self) -> Option<u32> {
-        self.successor_session_id
-    }
-
-    /// Encrypts application data payload using the established Noise transport session.
+    /// Encrypts a produced application using the established transport session
+    /// and produce an `EncryptedLpPacket`
     ///
     /// # Arguments
     ///
-    /// * `payload` - The application data to encrypt.
+    /// * `data` - plaintext data to encrypt
     ///
     /// # Returns
     ///
-    /// * `Ok(Vec<u8>)` containing the encrypted Noise message ciphertext.
-    /// * `Err(NoiseError)` if the session is not in transport mode or encryption fails.
-    pub fn encrypt_data(&mut self, payload: &[u8]) -> Result<LpMessage, NoiseError> {
-        // Check if session is read-only (demoted)
-        if self.read_only {
-            return Err(NoiseError::SessionReadOnly);
-        }
-
-        let payload = self.noise_state.write_message(payload)?;
-        Ok(LpMessage::EncryptedData(EncryptedDataPayload(payload)))
+    /// * `Ok(EncryptedLpPacket)` containing the encrypted message ciphertext.
+    /// * `Err(LpError)` if the session is not in transport mode or encryption fails.
+    pub(crate) fn encrypt_application_data(
+        &mut self,
+        data: LpMessage,
+    ) -> Result<EncryptedLpPacket, LpError> {
+        let packet = self.next_packet(data)?;
+        encrypt_lp_packet(packet, &mut self.active_transport)
     }
 
-    /// Decrypts an incoming Noise message containing application data.
+    /// Decrypts an incoming LpPacket
     ///
     /// # Arguments
     ///
-    /// * `noise_ciphertext` - The encrypted Noise message received from the peer.
+    /// * `ciphertext` - The encrypted packet
     ///
     /// # Returns
     ///
-    /// * `Ok(Vec<u8>)` containing the decrypted application data payload.
-    /// * `Err(NoiseError)` if the session is not in transport mode, decryption fails, or the message is not data.
-    pub fn decrypt_data(&mut self, noise_ciphertext: &LpMessage) -> Result<Vec<u8>, NoiseError> {
-        let payload = noise_ciphertext.payload();
-
-        match self.noise_state.read_message(payload)? {
-            ReadResult::DecryptedData(data) => Ok(data),
-            _ => Err(NoiseError::IncorrectStateError),
-        }
-    }
-
-    /// Creates a new subsession using Noise KKpsk0 pattern.
-    ///
-    /// KKpsk0 reuses parent's static X25519 keys (both parties know each other from parent session).
-    /// PSK is derived from parent's PQ shared secret, preserving quantum resistance.
-    ///
-    /// # Arguments
-    /// * `subsession_index` - Unique index for this subsession (use `next_subsession_index()`)
-    /// * `is_initiator` - True if this side initiates the subsession handshake
-    ///
-    /// # Returns
-    /// `SubsessionHandshake` ready for KK1/KK2 message exchange
-    ///
-    /// # Errors
-    /// * Returns error if parent handshake not complete
-    /// * Returns error if PQ shared secret not available
-    pub fn create_subsession(
-        &self,
-        subsession_index: u64,
-        is_initiator: bool,
-    ) -> Result<SubsessionHandshake, LpError> {
-        // Get PQ shared secret
-        let pq_secret = self.pq_shared_secret();
-
-        // Derive subsession PSK from parent's PQ shared secret
-        let subsession_psk = derive_subsession_psk(pq_secret.as_bytes(), subsession_index);
-
-        // Build KKpsk0 handshake
-        // Pattern: Noise_KKpsk0_25519_ChaChaPoly_SHA256
-        // Both parties already know each other's static keys from parent session
-        let pattern_name = "Noise_KKpsk0_25519_ChaChaPoly_SHA256";
-        let params = pattern_name.parse()?;
-
-        let local_key_bytes = self.local_peer.x25519.private_key().to_bytes();
-        let remote_key_bytes = self.remote_x25519_public().to_bytes();
-
-        let builder = Builder::new(params)
-            .local_private_key(&local_key_bytes)
-            .remote_public_key(&remote_key_bytes)
-            .psk(0, &subsession_psk); // PSK at position 0 for KKpsk0
-
-        let handshake_state = if is_initiator {
-            builder.build_initiator().map_err(LpError::SnowKeyError)?
-        } else {
-            builder.build_responder().map_err(LpError::SnowKeyError)?
-        };
-
-        Ok(SubsessionHandshake {
-            index: subsession_index,
-            noise_state: Mutex::new(NoiseProtocol::new(handshake_state)),
-            is_initiator,
-            local_peer: self.local_peer.clone(),
-            remote_peer: self.remote_peer.clone(),
-            pq_shared_secret: self.pq_shared_secret.clone(),
-            subsession_psk,
-            negotiated_version: self.version,
-        })
-    }
-}
-
-/// Subsession created via Noise KKpsk0 handshake tunneled through parent session.
-///
-/// Subsessions provide fresh session keys while inheriting PQ protection from parent's
-/// ML-KEM shared secret. After handshake completes, the subsession can be promoted
-/// to replace the parent session.
-///
-/// # Lifecycle
-/// 1. Parent calls `create_subsession()` to get `SubsessionHandshake`
-/// 2. Initiator calls `prepare_message()` to get KK1
-/// 3. KK1 sent through parent session (encrypted tunnel)
-/// 4. Responder calls `process_message(kk1)` to process KK1
-/// 5. Responder calls `prepare_message()` to get KK2
-/// 6. KK2 sent through parent session
-/// 7. Initiator calls `process_message(kk2)` to complete handshake
-/// 8. Both call `is_complete()` to verify
-#[derive(Debug)]
-pub struct SubsessionHandshake {
-    /// Subsession index (unique per parent session)
-    pub index: u64,
-    /// Noise KKpsk0 handshake state
-    noise_state: Mutex<NoiseProtocol>,
-    /// Is this side the initiator?
-    is_initiator: bool,
-
-    // Key material inherited from parent session for into_session() conversion
-    /// Representation of a local Lewes Protocol peer
-    /// encapsulating all the known information and keys.
-    local_peer: LpLocalPeer,
-
-    /// Representation of a remote Lewes Protocol peer
-    /// encapsulating all the known information and keys.
-    remote_peer: LpRemotePeer,
-
-    /// PQ shared secret inherited from parent (for creating further subsessions)
-    pq_shared_secret: PqSharedSecret,
-
-    /// Subsession PSK (for deriving outer AEAD key)
-    subsession_psk: [u8; 32],
-
-    /// Negotiated protocol version from handshake.
-    negotiated_version: u8,
-}
-
-impl SubsessionHandshake {
-    /// Prepares the next KK handshake message (KK1 or KK2 depending on role/state).
-    ///
-    /// # Returns
-    /// Noise handshake message bytes to send through parent session tunnel.
-    pub fn prepare_message(&self) -> Result<Vec<u8>, LpError> {
-        let mut noise_state = self.noise_state.lock();
-        noise_state
-            .get_bytes_to_send()
-            .ok_or_else(|| LpError::Internal("Not our turn to send".into()))?
-            .map_err(LpError::NoiseError)
-    }
-
-    /// Processes a received KK handshake message (KK1 or KK2).
-    ///
-    /// # Arguments
-    /// * `message` - Noise handshake message received through parent session tunnel.
-    ///
-    /// # Returns
-    /// Any payload embedded in the handshake message (usually empty for KK).
-    pub fn process_message(&self, message: &[u8]) -> Result<Vec<u8>, LpError> {
-        let mut noise_state = self.noise_state.lock();
-        let result = noise_state
-            .read_message(message)
-            .map_err(LpError::NoiseError)?;
-        match result {
-            ReadResult::HandshakeComplete | ReadResult::NoOp => Ok(vec![]),
-            ReadResult::DecryptedData(data) => Ok(data),
-        }
-    }
-
-    /// Checks if the handshake is complete (ready for transport mode).
-    pub fn is_complete(&self) -> bool {
-        self.noise_state.lock().is_handshake_finished()
-    }
-
-    /// Returns whether this side is the initiator.
-    pub fn is_initiator(&self) -> bool {
-        self.is_initiator
-    }
-
-    /// Returns the subsession index.
-    pub fn subsession_index(&self) -> u64 {
-        self.index
-    }
-
-    /// Convert completed subsession handshake into a full LpSession.
-    ///
-    /// This consumes the SubsessionHandshake and creates a new LpSession
-    /// that can be used as a replacement for the parent session.
-    ///
-    /// # Arguments
-    /// * `receiver_index` - New receiver index for the promoted session
-    ///
-    /// # Errors
-    /// Returns error if handshake is not complete
-    pub fn into_session(self, receiver_index: u32) -> Result<LpSession, LpError> {
-        if !self.is_complete() {
-            return Err(LpError::Internal(
-                "Cannot convert incomplete subsession to session".to_string(),
-            ));
-        }
-
-        // Extract the noise state (now in transport mode)
-        let noise_state = self.noise_state.into_inner();
-
-        // Derive outer AEAD key from the subsession PSK
-        let outer_key = OuterAeadKey::from_psk(&self.subsession_psk);
-
-        Ok(LpSession {
-            // noiserm
-            session_id: receiver_index,
-            noise_state,
-            sending_counter: 0,
-            receiving_counter: ReceivingKeyCounterValidator::new(0),
-            local_peer: self.local_peer,
-            remote_peer: self.remote_peer,
-            outer_aead_key: outer_key,
-            pq_shared_secret: self.pq_shared_secret,
-            subsession_counter: 0,
-            read_only: false,
-            successor_session_id: None,
-            version: self.negotiated_version,
-        })
+    /// * `Ok(LpPacket)` containing the decrypted application data payload.
+    /// * `Err(LpError)` if the session is not in transport mode, decryption fails, or the message is not data.
+    pub(crate) fn decrypt_packet(
+        &mut self,
+        packet: EncryptedLpPacket,
+    ) -> Result<LpPacket, LpError> {
+        decrypt_lp_packet(packet, &mut self.active_transport)
     }
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{SessionsMock, replay::ReplayError, sessions_for_tests};
-    use rand::thread_rng;
-
-    // Helper function to generate keypairs for tests
-    fn generate_x25519_keypair() -> x25519::KeyPair {
-        x25519::KeyPair::new(&mut thread_rng())
-    }
+    use crate::{ReplayError, SessionsMock};
+    use nym_kkt_ciphersuite::{IntoEnumIterator, KEM};
 
     #[test]
     fn test_session_creation() {
-        let mut session = sessions_for_tests().0;
+        for kem in KEM::iter() {
+            let mut session = SessionsMock::mock_post_handshake(kem).responder;
 
-        // Initial counter should be zero
-        let counter = session.next_counter();
-        assert_eq!(counter, 0);
+            // Initial counter should be zero
+            let counter = session.next_counter();
+            assert_eq!(counter, 0);
 
-        // Counter should increment
-        let counter = session.next_counter();
-        assert_eq!(counter, 1);
+            // Counter should increment
+            let counter = session.next_counter();
+            assert_eq!(counter, 1);
+        }
     }
 
-    // NOTE: These tests are obsolete after removing optional KEM parameters.
-    // PSQ now always runs using X25519 keys internally converted to KEM format.
-    // The new tests at the end of this file (test_psq_*) cover PSQ integration.
-    /*
-    #[test]
-    fn test_session_creation_with_psq_state_initiator() {
-        // OLD API - REMOVED
-    }
-
-    #[test]
-    fn test_session_creation_with_psq_state_responder() {
-        // OLD API - REMOVED
-    }
-    */
-
     #[test]
     fn test_replay_protection_sequential() {
-        let mut session = sessions_for_tests().1;
+        for kem in KEM::iter() {
+            let mut session = SessionsMock::mock_post_handshake(kem).responder;
 
-        // Sequential counters should be accepted
-        assert!(session.receiving_counter_quick_check(0).is_ok());
-        assert!(session.receiving_counter_mark(0).is_ok());
+            // Sequential counters should be accepted
+            assert!(session.receiving_counter_quick_check(0).is_ok());
+            assert!(session.receiving_counter_mark(0).is_ok());
 
-        assert!(session.receiving_counter_quick_check(1).is_ok());
-        assert!(session.receiving_counter_mark(1).is_ok());
+            assert!(session.receiving_counter_quick_check(1).is_ok());
+            assert!(session.receiving_counter_mark(1).is_ok());
 
-        // Duplicates should be rejected
-        assert!(session.receiving_counter_quick_check(0).is_err());
-        let err = session.receiving_counter_mark(0).unwrap_err();
-        match err {
-            LpError::Replay(replay_error) => {
-                assert!(matches!(replay_error, ReplayError::DuplicateCounter));
+            // Duplicates should be rejected
+            assert!(session.receiving_counter_quick_check(0).is_err());
+            let err = session.receiving_counter_mark(0).unwrap_err();
+            match err {
+                LpError::Replay(replay_error) => {
+                    assert!(matches!(replay_error, ReplayError::DuplicateCounter));
+                }
+                _ => panic!("Expected replay error"),
             }
-            _ => panic!("Expected replay error"),
         }
     }
 
     #[test]
     fn test_replay_protection_out_of_order() {
-        let mut session = sessions_for_tests().1;
+        for kem in KEM::iter() {
+            let mut session = SessionsMock::mock_post_handshake(kem).responder;
 
-        // Receive packets in order
-        assert!(session.receiving_counter_mark(0).is_ok());
-        assert!(session.receiving_counter_mark(1).is_ok());
-        assert!(session.receiving_counter_mark(2).is_ok());
+            // Receive packets in order
+            assert!(session.receiving_counter_mark(0).is_ok());
+            assert!(session.receiving_counter_mark(1).is_ok());
+            assert!(session.receiving_counter_mark(2).is_ok());
 
-        // Skip ahead
-        assert!(session.receiving_counter_mark(10).is_ok());
+            // Skip ahead
+            assert!(session.receiving_counter_mark(10).is_ok());
 
-        // Can still receive out-of-order packets within window
-        assert!(session.receiving_counter_quick_check(5).is_ok());
-        assert!(session.receiving_counter_mark(5).is_ok());
+            // Can still receive out-of-order packets within window
+            assert!(session.receiving_counter_quick_check(5).is_ok());
+            assert!(session.receiving_counter_mark(5).is_ok());
 
-        // But duplicates are still rejected
-        assert!(session.receiving_counter_quick_check(5).is_err());
-        assert!(session.receiving_counter_mark(5).is_err());
-    }
-
-    #[test]
-    fn test_packet_stats() {
-        let mut session = sessions_for_tests().1;
-
-        // Initial stats
-        let (next, received) = session.current_packet_cnt();
-        assert_eq!(next, 0);
-        assert_eq!(received, 0);
-
-        // After receiving packets
-        assert!(session.receiving_counter_mark(0).is_ok());
-        assert!(session.receiving_counter_mark(1).is_ok());
-
-        let (next, received) = session.current_packet_cnt();
-        assert_eq!(next, 2);
-        assert_eq!(received, 2);
-    }
-
-    /*
-    // These tests remain commented as they rely on the old mock crypto functions
-    #[test]
-    fn test_mock_crypto() {
-        let mut session = create_test_session(true);
-        let data = [1, 2, 3, 4, 5];
-        let mut encrypted = [0; 5];
-        let mut decrypted = [0; 5];
-
-        // Mock encrypt should copy the data
-        // let encrypted_len = session.encrypt_packet(&data, &mut encrypted).unwrap(); // Removed method
-        // assert_eq!(encrypted_len, 5);
-        // assert_eq!(encrypted, data);
-
-        // Mock decrypt should copy the data
-        // let decrypted_len = session.decrypt_packet(&encrypted, &mut decrypted).unwrap(); // Removed method
-        // assert_eq!(decrypted_len, 5);
-        // assert_eq!(decrypted, data);
-    }
-
-    #[test]
-    fn test_mock_crypto_buffer_too_small() {
-        let mut session = create_test_session(true);
-        let data = [1, 2, 3, 4, 5];
-        let mut too_small = [0; 3];
-
-        // Should fail with buffer too small
-        // let result = session.encrypt_packet(&data, &mut too_small); // Removed method
-        // assert!(result.is_err());
-        // match result.unwrap_err() {
-        //     LpError::InsufficientBufferSize => {} // Error type might change
-        //     _ => panic!("Expected InsufficientBufferSize error"),
-        // }
-    }
-    */
-
-    /// Test that X25519 keys are correctly converted to KEM format
-    #[test]
-    fn test_x25519_to_kem_conversion() {
-        use nym_kkt::ciphersuite::EncapsulationKey;
-
-        let initiator_keys = generate_x25519_keypair();
-        let responder_keys = generate_x25519_keypair();
-
-        // Verify we can convert X25519 public key to KEM format (as done in session.rs)
-        let x25519_public_bytes = responder_keys.public_key().as_bytes();
-        let libcrux_public_key =
-            libcrux_kem::PublicKey::decode(libcrux_kem::Algorithm::X25519, x25519_public_bytes)
-                .expect("X25519 public key should convert to libcrux PublicKey");
-
-        let _kem_key = EncapsulationKey::X25519(libcrux_public_key);
-
-        // Verify we can convert X25519 private key to KEM format
-        let x25519_private_bytes = initiator_keys.private_key().to_bytes();
-        let _libcrux_private_key =
-            libcrux_kem::PrivateKey::decode(libcrux_kem::Algorithm::X25519, &x25519_private_bytes)
-                .expect("X25519 private key should convert to libcrux PrivateKey");
-
-        // Successful conversion is sufficient - actual encapsulation is tested in psk.rs
-        // (libcrux_kem::PrivateKey is an enum with no len() method, conversion success is enough)
-    }
-
-    #[test]
-    fn test_demote_sets_read_only() {
-        let sessions = SessionsMock::mock_post_handshake(12345);
-        let mut session = sessions.initiator;
-
-        // Initially not read-only
-        assert!(!session.is_read_only());
-        assert!(session.successor_session_id().is_none());
-
-        // Demote the session
-        session.demote(99999);
-
-        // Now read-only with successor
-        assert!(session.is_read_only());
-        assert_eq!(session.successor_session_id(), Some(99999));
-    }
-
-    #[test]
-    fn test_encrypt_fails_after_demotion() {
-        let receiver_index = 12345;
-        let sessions = SessionsMock::mock_post_handshake(receiver_index);
-        let mut initiator_session = sessions.initiator;
-
-        // Encryption works before demotion
-        let plaintext = b"Hello before demotion";
-        assert!(initiator_session.encrypt_data(plaintext).is_ok());
-
-        // Demote the session
-        initiator_session.demote(99999);
-
-        // Encryption fails after demotion
-        let result = initiator_session.encrypt_data(plaintext);
-        assert!(result.is_err());
-        match result.unwrap_err() {
-            NoiseError::SessionReadOnly => {
-                // Expected
-            }
-            e => panic!("Expected SessionReadOnly error, got: {:?}", e),
+            // But duplicates are still rejected
+            assert!(session.receiving_counter_quick_check(5).is_err());
+            assert!(session.receiving_counter_mark(5).is_err());
         }
     }
 
     #[test]
-    fn test_decrypt_works_after_demotion() {
-        // --- Setup Handshake ---
-        let receiver_index = 12345;
-        let sessions = SessionsMock::mock_post_handshake(receiver_index);
-        let mut initiator_session = sessions.initiator;
-        let mut responder_session = sessions.responder;
+    fn test_packet_stats() {
+        for kem in KEM::iter() {
+            let mut session = SessionsMock::mock_post_handshake(kem).responder;
 
-        // Responder encrypts a message
-        let plaintext = b"Message to demoted initiator";
-        let ciphertext = responder_session
-            .encrypt_data(plaintext)
-            .expect("Encryption failed");
+            // Initial stats
+            let packet_count = session.current_packet_cnt();
+            assert_eq!(packet_count.next, 0);
+            assert_eq!(packet_count.received, 0);
 
-        // Demote the initiator session
-        initiator_session.demote(99999);
-        assert!(initiator_session.is_read_only());
+            // After receiving packets
+            assert!(session.receiving_counter_mark(0).is_ok());
+            assert!(session.receiving_counter_mark(1).is_ok());
 
-        // Decryption still works on demoted session (drain in-flight)
-        let decrypted = initiator_session
-            .decrypt_data(&ciphertext)
-            .expect("Decryption should work on demoted session");
-        assert_eq!(decrypted, plaintext);
+            let packet_count = session.current_packet_cnt();
+            assert_eq!(packet_count.next, 2);
+            assert_eq!(packet_count.received, 2);
+        }
     }
 }

common/nym-lp/src/session_manager.rs

@@ -6,17 +6,20 @@
 //! This module implements session lifecycle management functionality, handling
 //! creation, retrieval, and storage of sessions.
 
+use crate::packet::{EncryptedLpPacket, LpMessage};
+use crate::peer_config::LpReceiverIndex;
 use crate::state_machine::{LpAction, LpInput, LpStateBare};
-use crate::{LpError, LpMessage, LpSession, LpStateMachine};
+use crate::{LpError, LpSession, LpStateMachine};
 use std::collections::HashMap;
 
+pub use crate::replay::validator::PacketCount;
+
 /// Manages the lifecycle of Lewes Protocol sessions.
 ///
-/// The SessionManager is responsible for creating, storing, and retrieving sessions,
-/// ensuring proper thread-safety for concurrent access.
+/// The SessionManager is responsible for creating, storing, and retrieving sessions
 pub struct SessionManager {
     /// Manages state machines directly, keyed by lp_id
-    state_machines: HashMap<u32, LpStateMachine>,
+    state_machines: HashMap<LpReceiverIndex, LpStateMachine>,
 }
 
 impl Default for SessionManager {
@@ -35,62 +38,47 @@ impl SessionManager {
 
     pub fn process_input(
         &mut self,
-        lp_id: u32,
+        lp_id: LpReceiverIndex,
         input: LpInput,
     ) -> Result<Option<LpAction>, LpError> {
         self.with_state_machine_mut(lp_id, |sm| sm.process_input(input).transpose())?
     }
 
-    pub fn closed(&self, lp_id: u32) -> Result<bool, LpError> {
+    pub fn send_data(
+        &mut self,
+        lp_id: LpReceiverIndex,
+        data: LpMessage,
+    ) -> Result<LpAction, LpError> {
+        self.process_input(lp_id, LpInput::SendData(data))?
+            .ok_or(LpError::NotInTransport)
+    }
+
+    pub fn receive_packet(
+        &mut self,
+        lp_id: LpReceiverIndex,
+        packet: EncryptedLpPacket,
+    ) -> Result<Option<LpAction>, LpError> {
+        self.process_input(lp_id, LpInput::ReceivePacket(packet))
+    }
+
+    pub fn closed(&self, lp_id: LpReceiverIndex) -> Result<bool, LpError> {
         Ok(self.get_state(lp_id)? == LpStateBare::Closed)
     }
 
-    pub fn transport(&self, lp_id: u32) -> Result<bool, LpError> {
+    pub fn transport(&self, lp_id: LpReceiverIndex) -> Result<bool, LpError> {
         Ok(self.get_state(lp_id)? == LpStateBare::Transport)
     }
 
     #[cfg(test)]
-    fn get_state_machine_id(&self, lp_id: u32) -> Result<u32, LpError> {
-        self.with_state_machine(lp_id, |sm| sm.id())?
+    fn get_state_machine_id(&self, lp_id: LpReceiverIndex) -> Result<LpReceiverIndex, LpError> {
+        self.with_state_machine(lp_id, |sm| sm.receiver_index())?
     }
 
-    pub fn get_state(&self, lp_id: u32) -> Result<LpStateBare, LpError> {
+    pub fn get_state(&self, lp_id: LpReceiverIndex) -> Result<LpStateBare, LpError> {
         self.with_state_machine(lp_id, |sm| Ok(sm.bare_state()))?
     }
 
-    pub fn receiving_counter_quick_check(&self, lp_id: u32, counter: u64) -> Result<(), LpError> {
-        self.with_state_machine(lp_id, |sm| {
-            sm.session()?.receiving_counter_quick_check(counter)
-        })?
-    }
-
-    pub fn receiving_counter_mark(&mut self, lp_id: u32, counter: u64) -> Result<(), LpError> {
-        self.with_state_machine_mut(lp_id, |sm| {
-            sm.session_mut()?.receiving_counter_mark(counter)
-        })?
-    }
-
-    pub fn next_counter(&mut self, lp_id: u32) -> Result<u64, LpError> {
-        self.with_state_machine_mut(lp_id, |sm| Ok(sm.session_mut()?.next_counter()))?
-    }
-
-    pub fn decrypt_data(&mut self, lp_id: u32, message: &LpMessage) -> Result<Vec<u8>, LpError> {
-        self.with_state_machine_mut(lp_id, |sm| {
-            sm.session_mut()?
-                .decrypt_data(message)
-                .map_err(LpError::NoiseError)
-        })?
-    }
-
-    pub fn encrypt_data(&mut self, lp_id: u32, message: &[u8]) -> Result<LpMessage, LpError> {
-        self.with_state_machine_mut(lp_id, |sm| {
-            sm.session_mut()?
-                .encrypt_data(message)
-                .map_err(LpError::NoiseError)
-        })?
-    }
-
-    pub fn current_packet_cnt(&self, lp_id: u32) -> Result<(u64, u64), LpError> {
+    pub fn current_packet_cnt(&self, lp_id: LpReceiverIndex) -> Result<PacketCount, LpError> {
         self.with_state_machine(lp_id, |sm| Ok(sm.session()?.current_packet_cnt()))?
     }
 
@@ -98,43 +86,54 @@ impl SessionManager {
         self.state_machines.len()
     }
 
-    pub fn state_machine_exists(&self, lp_id: u32) -> bool {
+    pub fn state_machine_exists(&self, lp_id: LpReceiverIndex) -> bool {
         self.state_machines.contains_key(&lp_id)
     }
 
-    pub fn with_state_machine<F, R>(&self, lp_id: u32, f: F) -> Result<R, LpError>
+    pub fn with_state_machine<F, R>(&self, lp_id: LpReceiverIndex, f: F) -> Result<R, LpError>
     where
         F: FnOnce(&LpStateMachine) -> R,
     {
         if let Some(sm) = self.state_machines.get(&lp_id) {
             Ok(f(sm))
         } else {
-            Err(LpError::StateMachineNotFound { lp_id })
+            Err(LpError::StateMachineNotFound(lp_id))
         }
-        // self.state_machines.get(&lp_id).map(|sm_ref| f(&*sm_ref)) // Lock held only during closure execution
     }
 
     // For mutable access (like running process_input)
-    pub fn with_state_machine_mut<F, R>(&mut self, lp_id: u32, f: F) -> Result<R, LpError>
+    pub fn with_state_machine_mut<F, R>(
+        &mut self,
+        lp_id: LpReceiverIndex,
+        f: F,
+    ) -> Result<R, LpError>
     where
         F: FnOnce(&mut LpStateMachine) -> R, // Closure takes mutable ref
     {
         if let Some(sm) = self.state_machines.get_mut(&lp_id) {
             Ok(f(sm))
         } else {
-            Err(LpError::StateMachineNotFound { lp_id })
+            Err(LpError::StateMachineNotFound(lp_id))
         }
     }
 
-    pub fn create_session_state_machine(&mut self, lp_session: LpSession) -> u32 {
-        let receiver_index = lp_session.id();
+    pub fn create_session_state_machine(
+        &mut self,
+        lp_session: LpSession,
+    ) -> Result<LpReceiverIndex, LpError> {
+        let session_id = lp_session.receiver_index();
+
+        if self.state_machines.contains_key(&session_id) {
+            return Err(LpError::DuplicateSessionId(session_id));
+        }
+
         let sm = LpStateMachine::new(lp_session);
-        self.state_machines.insert(receiver_index, sm);
-        receiver_index
+        self.state_machines.insert(session_id, sm);
+        Ok(session_id)
     }
 
     /// Method to remove a state machine
-    pub fn remove_state_machine(&mut self, lp_id: u32) -> bool {
+    pub fn remove_state_machine(&mut self, lp_id: LpReceiverIndex) -> bool {
         let removed = self.state_machines.remove(&lp_id);
 
         removed.is_some()
@@ -145,21 +144,21 @@ impl SessionManager {
 mod tests {
     use super::*;
     use crate::{SessionsMock, mock_session_for_test};
+    use nym_kkt_ciphersuite::{IntoEnumIterator, KEM};
 
     #[test]
     fn test_session_manager_get() {
         let mut manager = SessionManager::new();
-
         let local_session = mock_session_for_test();
-        let id = local_session.id();
+        let id = local_session.receiver_index();
 
-        let sm_1_id = manager.create_session_state_machine(local_session);
+        let sm_1_id = manager.create_session_state_machine(local_session).unwrap();
         assert_eq!(sm_1_id, id);
 
         let retrieved = manager.state_machine_exists(id);
         assert!(retrieved);
 
-        let not_found = manager.state_machine_exists(99);
+        let not_found = manager.state_machine_exists(123);
         assert!(!not_found);
     }
 
@@ -167,8 +166,7 @@ mod tests {
     fn test_session_manager_remove() {
         let mut manager = SessionManager::new();
         let local_session = mock_session_for_test();
-
-        let sm_1_id = manager.create_session_state_machine(local_session);
+        let sm_1_id = manager.create_session_state_machine(local_session).unwrap();
 
         let removed = manager.remove_state_machine(sm_1_id);
         assert!(removed);
@@ -180,24 +178,26 @@ mod tests {
 
     #[test]
     fn test_multiple_sessions() {
-        let mut manager = SessionManager::new();
-        let session1 = SessionsMock::mock_post_handshake(123).initiator;
-        let session2 = SessionsMock::mock_post_handshake(124).initiator;
-        let session3 = SessionsMock::mock_post_handshake(125).initiator;
+        for kem in KEM::iter() {
+            let mut manager = SessionManager::new();
+            let session1 = SessionsMock::mock_seeded_post_handshake(123, kem).initiator;
+            let session2 = SessionsMock::mock_seeded_post_handshake(124, kem).initiator;
+            let session3 = SessionsMock::mock_seeded_post_handshake(125, kem).initiator;
 
-        let sm_1 = manager.create_session_state_machine(session1);
-        let sm_2 = manager.create_session_state_machine(session2);
-        let sm_3 = manager.create_session_state_machine(session3);
+            let sm_1 = manager.create_session_state_machine(session1).unwrap();
+            let sm_2 = manager.create_session_state_machine(session2).unwrap();
+            let sm_3 = manager.create_session_state_machine(session3).unwrap();
 
-        assert_eq!(manager.session_count(), 3);
+            assert_eq!(manager.session_count(), 3);
 
-        let retrieved1 = manager.get_state_machine_id(sm_1).unwrap();
-        let retrieved2 = manager.get_state_machine_id(sm_2).unwrap();
-        let retrieved3 = manager.get_state_machine_id(sm_3).unwrap();
+            let retrieved1 = manager.get_state_machine_id(sm_1).unwrap();
+            let retrieved2 = manager.get_state_machine_id(sm_2).unwrap();
+            let retrieved3 = manager.get_state_machine_id(sm_3).unwrap();
 
-        assert_eq!(retrieved1, sm_1);
-        assert_eq!(retrieved2, sm_2);
-        assert_eq!(retrieved3, sm_3);
+            assert_eq!(retrieved1, sm_1);
+            assert_eq!(retrieved2, sm_2);
+            assert_eq!(retrieved3, sm_3);
+        }
     }
 
     #[test]
@@ -206,7 +206,7 @@ mod tests {
 
         let sesion = mock_session_for_test();
 
-        let sm = manager.create_session_state_machine(sesion);
+        let sm = manager.create_session_state_machine(sesion).unwrap();
         assert_eq!(manager.session_count(), 1);
 
         let retrieved = manager.get_state_machine_id(sm);