Feature/spend coconut (#1261)

* Add coconut verifier structure for coconut protocol in gateway

* Add endpoint for validator-api cred verification

* Remove unused signature field

* Register new endpoint

* Improve validator-api config handling

* Aggregate verif result from all apis

* Simplify aggregate functions

* Verify cred on apis correctly

* Introduced coconut bandwidth contract to validator client

* Fix rebase double import

* Fix clippy on non-coconut

* Add multisig contract address to validator client

* Refactor Credential struct

* Do bincode magic in the coconut interface

* Implement serialization for credential and remove bindcode

* Fix clippy and don't remove dkg

* Client release funds proposal

* Add wrapper for blinded serial number

Also compare theta with a blinded serial number (in base 58 form)
for future double spend protection.

* Only post blinded serial number to blockchain

* Validator api propose credential spending

* Fix wallet

* Gateway calls proposal creation

* Query for proposal in verify coconut

* Remove db from git

* Verify against proposal description

* Validator apis vote based on verification of cred

* Fix wallet fmt

* Execute the release of funds

* Fix translation between token and bytes

* Update CHANGELOG

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

@@ -3,7 +3,11 @@
 
 use crate::validator_api::error::ValidatorAPIError;
 use crate::validator_api::routes::{CORE_STATUS_COUNT, SINCE_ARG};
-use coconut_interface::{BlindSignRequestBody, BlindedSignatureResponse, VerificationKeyResponse};
+use coconut_interface::{
+    BlindSignRequestBody, BlindedSignatureResponse, ExecuteReleaseFundsRequestBody,
+    ProposeReleaseFundsRequestBody, ProposeReleaseFundsResponse, VerificationKeyResponse,
+    VerifyCredentialBody, VerifyCredentialResponse,
+};
 use mixnet_contract_common::{GatewayBond, IdentityKeyRef, MixNodeBond};
 use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
@@ -371,6 +375,57 @@ impl Client {
         )
         .await
     }
+
+    pub async fn verify_bandwidth_credential(
+        &self,
+        request_body: &VerifyCredentialBody,
+    ) -> Result<VerifyCredentialResponse, ValidatorAPIError> {
+        self.post_validator_api(
+            &[
+                routes::API_VERSION,
+                routes::COCONUT_ROUTES,
+                routes::BANDWIDTH,
+                routes::COCONUT_VERIFY_BANDWIDTH_CREDENTIAL,
+            ],
+            NO_PARAMS,
+            request_body,
+        )
+        .await
+    }
+
+    pub async fn propose_release_funds(
+        &self,
+        request_body: &ProposeReleaseFundsRequestBody,
+    ) -> Result<ProposeReleaseFundsResponse, ValidatorAPIError> {
+        self.post_validator_api(
+            &[
+                routes::API_VERSION,
+                routes::COCONUT_ROUTES,
+                routes::BANDWIDTH,
+                routes::COCONUT_PROPOSE_RELEASE_FUNDS,
+            ],
+            NO_PARAMS,
+            request_body,
+        )
+        .await
+    }
+
+    pub async fn execute_release_funds(
+        &self,
+        request_body: &ExecuteReleaseFundsRequestBody,
+    ) -> Result<(), ValidatorAPIError> {
+        self.post_validator_api(
+            &[
+                routes::API_VERSION,
+                routes::COCONUT_ROUTES,
+                routes::BANDWIDTH,
+                routes::COCONUT_EXECUTE_RELEASE_FUNDS,
+            ],
+            NO_PARAMS,
+            request_body,
+        )
+        .await
+    }
 }
 
 // utility function that should solve the double slash problem in validator API forever.

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

@@ -17,6 +17,9 @@ pub const BANDWIDTH: &str = "bandwidth";
 pub const COCONUT_BLIND_SIGN: &str = "blind-sign";
 pub const COCONUT_PARTIAL_BANDWIDTH_CREDENTIAL: &str = "partial-bandwidth-credential";
 pub const COCONUT_VERIFICATION_KEY: &str = "verification-key";
+pub const COCONUT_VERIFY_BANDWIDTH_CREDENTIAL: &str = "verify-bandwidth-credential";
+pub const COCONUT_PROPOSE_RELEASE_FUNDS: &str = "propose-release-funds";
+pub const COCONUT_EXECUTE_RELEASE_FUNDS: &str = "execute-release-funds";
 
 pub const STATUS_ROUTES: &str = "status";
 pub const MIXNODE: &str = "mixnode";