From beac44bcef9f4b0a2546399a35e113b1f3b1a5dd Mon Sep 17 00:00:00 2001
From: Ilya Koltsov <koltsov.iv@gmail.com>
Date: Wed, 18 Oct 2023 20:01:53 +0100
Subject: [PATCH] fix to much old sign format

---
 types/keypair/secp256k1/private_key.go |  3 ++-
 types/keypair/secp256k1/public_key.go  | 24 ++++++++++++++++++++----
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/types/keypair/secp256k1/private_key.go b/types/keypair/secp256k1/private_key.go
index b5970ee..55d671e 100644
--- a/types/keypair/secp256k1/private_key.go
+++ b/types/keypair/secp256k1/private_key.go
@@ -19,7 +19,8 @@ func (v PrivateKey) PublicKeyBytes() []byte {
 
 func (v PrivateKey) Sign(mes []byte) ([]byte, error) {
 	hash := sha256.Sum256(mes)
-	return ecdsa.Sign(v.key, hash[:]).Serialize(), nil
+	// Return the signature as a concatenation of the R and S values in big-endian to match the old signature format.
+	return ecdsa.SignCompact(v.key, hash[:], false)[1:], nil
 }
 
 func NewPrivateKeyFromPemFile(path string) (PrivateKey, error) {
diff --git a/types/keypair/secp256k1/public_key.go b/types/keypair/secp256k1/public_key.go
index 3a06aa3..123e451 100644
--- a/types/keypair/secp256k1/public_key.go
+++ b/types/keypair/secp256k1/public_key.go
@@ -22,10 +22,26 @@ func (v PublicKey) Bytes() []byte {
 // VerifySignature verifies a signature of the form R || S.
 // It rejects signatures which are not in lower-S form.
 func (v PublicKey) VerifySignature(msg []byte, sigStr []byte) bool {
-	signature, err := ecdsa.ParseDERSignature(sigStr)
-	if err != nil {
-		log.Println(err)
-		return false
+	var signature *ecdsa.Signature
+	var err error
+	// if old signature len = 64, parse it as raw signature
+	if len(sigStr) == 64 {
+		// Split the signature bytes into r and s values and parse them into ModNScalar
+		var r, s secp256k1.ModNScalar
+		var bytesR [32]byte
+		var bytesS [32]byte
+		copy(bytesR[:], sigStr[:32])
+		copy(bytesS[:], sigStr[32:])
+		r.SetBytes(&bytesR)
+		s.SetBytes(&bytesS)
+
+		signature = ecdsa.NewSignature(&r, &s)
+	} else {
+		signature, err = ecdsa.ParseDERSignature(sigStr)
+		if err != nil {
+			log.Println(err)
+			return false
+		}
 	}
 	hash := sha256.Sum256(msg)
 	return signature.Verify(hash[:], v.key)