public static bool Verify(byte[] data, byte[] sigBytes, BigInteger pub)
{
EcdsaSignature signature = EcdsaSignature.DecodeFromDer(sigBytes);
var signer = new ECDsaSigner();
ECPoint pubPoint = Secp256K1.Curve().DecodePoint(pub.ToByteArray());
var parameters = new ECPublicKeyParameters(pubPoint, Secp256K1.Params());
signer.Init(false, parameters);
try
{
return(signer.VerifySignature(data, signature.R, signature.S));
}
catch (Exception)
{
return(false);
}
}
private static EcdsaSignature CreateEcdsaSignature(byte[] bytes, BigInteger secret)
{
var signer = new ECDsaSigner();
var privKey = new ECPrivateKeyParameters(secret, Secp256K1.Params());
signer.Init(true, privKey);
BigInteger[] sigs = signer.GenerateSignature(bytes);
BigInteger r = sigs[0], s = sigs[1];
BigInteger otherS = Secp256K1.Order().Subtract(s);
if (s.CompareTo(otherS) == 1)
{
s = otherS;
}
return(new EcdsaSignature(r, s));
}
public static IKeyPair CreateKeyPair(byte[] seedBytes)
{
BigInteger secret, pub, privateGen, order = Secp256K1.Order();
byte[] privateGetBytes;
byte[] publicGetBytes;
int i = 0, seq = 0;
while (true)
{
privateGetBytes = HashedIncrement(seedBytes, i++);
privateGen = Utils.Utils.UBigInt(privateGetBytes);
if (privateGen.CompareTo(order) == -1)
{
break;
}
}
publicGetBytes = Secp256K1.BasePointMultipliedBy(privateGen);
i = 0;
while (true)
{
byte[] secretBytes = HashedIncrement(AppendIntBytes(publicGetBytes, seq), i++);
secret = Utils.Utils.UBigInt(secretBytes);
if (secret.CompareTo(order) == -1)
{
break;
}
}
secret = secret.Add(privateGen).Mod(order);
pub = Utils.Utils.UBigInt(Secp256K1.BasePointMultipliedBy(secret));
return(new KeyPair(secret, pub));
}
public static bool CheckIsCanonical(byte[] sig, bool strict)
{
// Make sure signature is canonical
// To protect against signature morphing attacks
// Signature should be:
// <30> <len> [ <02> <lenR> <R> ] [ <02> <lenS> <S> ]
// where
// 6 <= len <= 70
// 1 <= lenR <= 33
// 1 <= lenS <= 33
int sigLen = sig.Length;
if ((sigLen < 8) || (sigLen > 72))
{
return(false);
}
if ((sig[0] != 0x30) || (sig[1] != (sigLen - 2)))
{
return(false);
}
// Find R and check its length
const int rPos = 4;
int rLen = sig[rPos - 1];
if ((rLen < 1) || (rLen > 33) || ((rLen + 7) > sigLen))
{
return(false);
}
// Find S and check its length
int sPos = rLen + 6, sLen = sig[sPos - 1];
if ((sLen < 1) || (sLen > 33) || ((rLen + sLen + 6) != sigLen))
{
return(false);
}
if ((sig[rPos - 2] != 0x02) || (sig[sPos - 2] != 0x02))
{
return(false); // R or S have wrong type
}
if ((sig[rPos] & 0x80) != 0)
{
return(false); // R is negative
}
if ((sig[rPos] == 0) && rLen == 1)
{
return(false); // R is zero
}
if ((sig[rPos] == 0) && ((sig[rPos + 1] & 0x80) == 0))
{
return(false); // R is padded
}
if ((sig[sPos] & 0x80) != 0)
{
return(false); // S is negative
}
if ((sig[sPos] == 0) && sLen == 1)
{
return(false); // S is zero
}
if ((sig[sPos] == 0) && ((sig[sPos + 1] & 0x80) == 0))
{
return(false); // S is padded
}
var rBytes = new byte[rLen];
var sBytes = new byte[sLen];
Array.Copy(sig, rPos, rBytes, 0, rLen);
Array.Copy(sig, sPos, sBytes, 0, sLen);
BigInteger r = new BigInteger(1, rBytes), s = new BigInteger(1, sBytes);
BigInteger order = Secp256K1.Order();
if (r.CompareTo(order) != -1 || s.CompareTo(order) != -1)
{
return(false); // R or S greater than modulus
}
if (strict)
{
return(order.Subtract(s).CompareTo(s) != -1);
}
return(true);
}
