From 32e1b104f8fbc0f80bf2b6a93492aa01fa323e35 Mon Sep 17 00:00:00 2001
From: Gustav Simonsson <gustav.simonsson@gmail.com>
Date: Mon, 1 Jun 2015 20:27:20 +0200
Subject: Add EC signature validations before call to libsecp256k1

---
 crypto/crypto.go | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

(limited to 'crypto/crypto.go')

diff --git a/crypto/crypto.go b/crypto/crypto.go
index 4bbd62f7f..d5291fe1d 100644
--- a/crypto/crypto.go
+++ b/crypto/crypto.go
@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
+	"math/big"
 	"os"
 
 	"encoding/hex"
@@ -151,6 +152,19 @@ func GenerateKey() (*ecdsa.PrivateKey, error) {
 	return ecdsa.GenerateKey(S256(), rand.Reader)
 }
 
+func ValidateSignatureValues(v byte, r, s *big.Int) bool {
+	secp256k1n := common.String2Big("0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141")
+	vint := uint32(v)
+	if r.Cmp(common.Big0) == 0 || s.Cmp(common.Big0) == 0 {
+		return false
+	}
+	if r.Cmp(secp256k1n) < 0 && s.Cmp(secp256k1n) < 0 && (vint == 27 || vint == 28) {
+		return true
+	} else {
+		return false
+	}
+}
+
 func SigToPub(hash, sig []byte) (*ecdsa.PublicKey, error) {
 	s, err := Ecrecover(hash, sig)
 	if err != nil {
-- 
cgit