BFT-457: Add 27 to V

node/libs/crypto/src/secp256k1/mod.rs

@@ -84,7 +84,10 @@ impl Hash for PublicKey {
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct Signature {
     sig: k256::ecdsa::Signature,
-    // TODO: Look up where we need to shift the recovery ID for Solidity
+    /// Standard Recover ID.
+    ///
+    /// To verify signatures with Solidity, for example with the [OpenZeppelin](https://docs.openzeppelin.com/contracts/2.x/api/cryptography#ECDSA-recover-bytes32-bytes-)
+    /// library, we need to shift this by 27 when it's serailized to bytes. See [ECDSA.sol](https://github.com/OpenZeppelin/openzeppelin-contracts/blob/de4154710bcc7c6ca5417097f34ce14e9205c3ac/contracts/utils/cryptography/ECDSA.sol#L128-L136).
     recid: k256::ecdsa::RecoveryId,
 }
 
@@ -149,7 +152,7 @@ impl ByteFmt for Signature {
         let (r, s) = self.sig.split_bytes();
         bz[..32].copy_from_slice(&r);
         bz[32..64].copy_from_slice(&s);
-        bz[64] = self.recid.to_byte();
+        bz[64] = self.recid.to_byte() + 27;
         bz
     }
 }

node/libs/crypto/src/secp256k1/tests.rs

@@ -188,4 +188,7 @@ fn test_ethereum_example() {
     assert_eq!(hex::encode(sig.sig.r().to_bytes()), r, "r matches");
     assert_eq!(hex::encode(sig.sig.s().to_bytes()), s, "s matches");
     assert_eq!(sig.recid.to_byte(), 0x0, "v is not shifted");
+
+    let bz = sig.encode();
+    assert!(bz[64] == 27 || bz[64] == 28, "v is shifted when encoded");
 }