public string SignData(byte[] data)
{
byte[] hash;
using (SHA256 sha = SHA256.Create())
{
hash = sha.ComputeHash(data, 0, data.Length);
}
Signature signature = SignHash(hash);
byte[] checksum;
string prefix;
data = signature.GetBytes();
switch (KeyType)
{
case KeyTypes.K1:
checksum = RIPEMD160.ComputeHash(data.Concat(K1Salt)).TakePart(0, 4);
prefix = Signature.K1Prefix;
break;
case KeyTypes.R1:
checksum = RIPEMD160.ComputeHash(data.Concat(R1Salt)).TakePart(0, 4);
prefix = Signature.R1Prefix;
break;
default: throw new InvalidKeyException(Resources.WrongKeyType);
}
string result = prefix + data.Concat(checksum).ToBase58();
return(result);
}
public static byte[] ComputeK1Checksum(byte[] buffer, int offset, int length)
{
byte[] hash = RIPEMD160.ComputeHash(buffer, offset, length);
byte[] result = new byte[ChecksumLength];
Array.Copy(hash, 0, result, 0, ChecksumLength);
return(result);
}
public static byte[] ComputeR1Checksum(byte[] buffer, int offset, int length)
{
byte[] buf = new byte[length + R1Salt.Length];
Array.Copy(buffer, offset, buf, 0, length);
Array.Copy(R1Salt, 0, buf, buf.Length - R1Salt.Length, R1Salt.Length);
byte[] hash = RIPEMD160.ComputeHash(buf);
byte[] result = new byte[ChecksumLength];
Array.Copy(hash, result, ChecksumLength);
return(result);
}
public bool VerifySignature(byte[] data, string signature)
{
if (!signature.StartsWith(Signature.K1Prefix) && !signature.StartsWith(Signature.R1Prefix))
{
return(false);
}
byte[] buf = Base58.Decode(signature.Substring(Signature.PrefixLength));
if (buf.Length != Signature.Length + ChecksumLength)
{
return(false);
}
byte[] signatureBuf = new byte[buf.Length - ChecksumLength];
Array.Copy(buf, 0, signatureBuf, 0, Signature.Length);
byte[] checksum;
if (signature.StartsWith(Signature.R1Prefix))
{
checksum = RIPEMD160.ComputeHash(signatureBuf.Concat(R1Salt)).TakePart(0, 4);
}
else
{
checksum = RIPEMD160.ComputeHash(signatureBuf.Concat(K1Salt)).TakePart(0, 4);
}
if (!CheckChecksum(buf, checksum))
{
return(false);
}
byte[] hash;
using (SHA256 sha = SHA256.Create())
{
hash = sha.ComputeHash(data, 0, data.Length);
}
byte recoveryId = (byte)(signatureBuf[0] - 31);
BigInteger r = signatureBuf.ToInt256(1);
BigInteger s = signatureBuf.ToInt256(33);
var q = RecoverPublicKey(hash, r, s, recoveryId, Curve);
if (q.X.Value != Q.X.Value && q.Y.Value != Q.Y.Value)
{
return(false);
}
if (r.Sign < 1 || s.Sign < 1 || r.CompareTo(Curve.N) >= 0 || s.CompareTo(Curve.N) >= 0)
{
return(false);
}
BigInteger e = hash.ToInt256();
BigInteger c = s.ModInverse(Curve.N);
BigInteger u1 = (e * c).Mod(Curve.N);
BigInteger u2 = (r * c).Mod(Curve.N);
Point R = Curve.G.MultiplyTwo(u1, q, u2);
BigInteger v = R.X.Value.Mod(Curve.N);
return(v.Equals(r));
}
