From 0f147750aedc0c07eec22e7d8c82d3c045fc6a3b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bogdan-=C8=98tefan=20Neac=C8=99u?= <bogdan@nymtech.net>
Date: Mon, 12 Sep 2022 12:54:33 +0300
Subject: [PATCH] Add sign function

---
 common/ledger/src/error.rs          |  6 ++++
 common/ledger/src/lib.rs            | 48 ++++++++++++++++++++++++++++-
 common/ledger/src/sign_secp265k1.rs | 25 +++++++++++++++
 3 files changed, 78 insertions(+), 1 deletion(-)
 create mode 100644 common/ledger/src/sign_secp265k1.rs

diff --git a/common/ledger/src/error.rs b/common/ledger/src/error.rs
index d871c729bd..fc4a0a1b49 100644
--- a/common/ledger/src/error.rs
+++ b/common/ledger/src/error.rs
@@ -28,4 +28,10 @@ pub enum LedgerError {
 
     #[error("Bip32 - {0}")]
     Bip32(#[from] bip32::Error),
+
+    #[error("Signature error - {0}")]
+    Signature(#[from] k256::ecdsa::Error),
+
+    #[error("No message found for signing transaction")]
+    NoMessageFound,
 }
diff --git a/common/ledger/src/lib.rs b/common/ledger/src/lib.rs
index d3119b6d86..ab745e7609 100644
--- a/common/ledger/src/lib.rs
+++ b/common/ledger/src/lib.rs
@@ -4,10 +4,13 @@
 pub mod addr_secp265k1;
 pub mod error;
 pub(crate) mod helpers;
+mod sign_secp265k1;
 pub mod version;
 
 use crate::addr_secp265k1::AddrSecp265k1Response;
+use crate::error::LedgerError;
 use crate::helpers::path_bytes;
+use crate::sign_secp265k1::SignSecp265k1Response;
 use crate::version::VersionResponse;
 use bip32::DerivationPath;
 use error::Result;
@@ -17,9 +20,14 @@ use ledger_transport_hid::TransportNativeHID;
 
 const CLA: u8 = 0x55;
 const INS_GET_VERSION: u8 = 0x00;
-const _INS_SIGN_SECP256K1: u8 = 0x02;
+const INS_SIGN_SECP256K1: u8 = 0x02;
 const INS_GET_ADDR_SECP256K1: u8 = 0x04;
 
+const PAYLOAD_TYPE_INIT: u8 = 0x00;
+const PAYLOAD_TYPE_ADD: u8 = 0x01;
+const PAYLOAD_TYPE_LAST: u8 = 0x02;
+const CHUNK_SIZE: usize = 250;
+
 /// Manage hardware Ledger device with Cosmos specific operations, as described in the
 /// specification: https://github.com/cosmos/ledger-cosmos/blob/main/docs/APDUSPEC.md
 pub struct CosmosLedger {
@@ -81,4 +89,42 @@ impl CosmosLedger {
         let response = self.transport.exchange(&command)?;
         AddrSecp265k1Response::try_from(response)
     }
+
+    pub fn sign_secp265k1(
+        &self,
+        path: DerivationPath,
+        message: String,
+    ) -> Result<SignSecp265k1Response> {
+        let serialized_path: Vec<u8> = path_bytes(path)?.into_iter().flatten().collect();
+        let mut chunks = vec![serialized_path];
+        if message.is_empty() {
+            return Err(LedgerError::NoMessageFound);
+        }
+        for chunk in message.into_bytes().chunks(CHUNK_SIZE) {
+            chunks.push(chunk.to_vec());
+        }
+        let length = chunks.len();
+        for (idx, chunk) in chunks.into_iter().enumerate() {
+            let payload_desc = if idx == 0 {
+                PAYLOAD_TYPE_INIT
+            } else if idx + 1 == length {
+                PAYLOAD_TYPE_LAST
+            } else {
+                PAYLOAD_TYPE_ADD
+            };
+            let command = APDUCommand {
+                cla: CLA,
+                ins: INS_SIGN_SECP256K1,
+                p1: payload_desc,
+                p2: 0,
+                data: chunk,
+            };
+            let sign_response = self.transport.exchange(&command)?;
+            if payload_desc == PAYLOAD_TYPE_LAST {
+                return SignSecp265k1Response::try_from(sign_response);
+            }
+        }
+        // It should never reach this, as the message is not empty
+        Err(LedgerError::NoMessageFound)
+    }
 }
diff --git a/common/ledger/src/sign_secp265k1.rs b/common/ledger/src/sign_secp265k1.rs
new file mode 100644
index 0000000000..25596d6492
--- /dev/null
+++ b/common/ledger/src/sign_secp265k1.rs
@@ -0,0 +1,25 @@
+// Copyright 2022 - Nym Technologies SA <contact@nymtech.net>
+// SPDX-License-Identifier: Apache-2.0
+
+use crate::error::LedgerError;
+use crate::helpers::answer_bytes;
+use k256::ecdsa::Signature;
+use ledger_transport::APDUAnswer;
+
+/// Version and status data of the device.
+pub struct SignSecp265k1Response {
+    /// DER encoded signature data
+    pub signature: Signature,
+}
+
+impl TryFrom<APDUAnswer<Vec<u8>>> for SignSecp265k1Response {
+    type Error = LedgerError;
+
+    fn try_from(answer: APDUAnswer<Vec<u8>>) -> Result<Self, Self::Error> {
+        let bytes = answer_bytes(&answer)?;
+
+        Ok(SignSecp265k1Response {
+            signature: Signature::from_der(bytes)?,
+        })
+    }
+}