Merge pull request #6 from Kirillvs/bip146-using-lower-s

BIP-146 using lower S at start

.gitignore

@@ -1,2 +1,4 @@
 
 dist/
+.idea
+.tmp

ecc/sign.go

@@ -86,6 +86,10 @@ func SingDer(message []byte, privateKey []byte, entryPointes []byte) []byte {
  edr := new(big.Int).Add(e, dr)
  s = new(big.Int).Mod(new(big.Int).Mul(kinv, edr), n)
 
+ if s.Cmp(new(big.Int).Div(n, big.NewInt(2))) > 0 {
+ s = new(big.Int).Sub(n, s)
+ }
+
  if s.Cmp(big.NewInt(0)) != 0 {
  break
  }
@@ -118,21 +122,10 @@ func SingInput(privateKey []byte, message []byte, sigHash int) string {
  R := signature[4 : 4+lengthR]
  lengthS := int(signature[5+lengthR])
  S := signature[5+lengthR+1:]
- sAsBigint := formating.BytesToInt(S)
-
- var newS []byte
 
- if lengthS == 33 {
- newSAsBigint := new(big.Int).Sub(P256k1().Params().N, sAsBigint)
- newS = encodeBigInt(newSAsBigint)
- lengthS -= 1
- lengthTotal -= 1
- } else {
- newS = S
- }
  newSignature := append([]byte{derPrefix, byte(lengthTotal), byte(derTypeInt), byte(lengthR)}, R...)
  newSignature = append(newSignature, byte(derTypeInt), byte(lengthS))
- newSignature = append(newSignature, newS...)
+ newSignature = append(newSignature, S...)
  newSignature = append(newSignature, byte(sigHash))
  return formating.BytesToHex(newSignature)
 }