public ECPoint CreatePoint(string hex)
{
if (hex == "00")
{
return(null);
}
if (hex.StartsWith("02"))
{
var x = BigIntegerExt.ParseHexUnsigned(hex.Substring(2));
return(CreatePoint(x, false));
}
else if (hex.StartsWith("03"))
{
var x = BigIntegerExt.ParseHexUnsigned(hex.Substring(2));
return(CreatePoint(x, true));
}
else if (hex.StartsWith("04"))
{
var keySize = (int)KeySize8 * 2;
var x = BigIntegerExt.ParseHexUnsigned(hex.Substring(2, keySize));
var y = BigIntegerExt.ParseHexUnsigned(hex.Substring(keySize + 2));
return(CreatePoint(x, y));
}
throw new System.FormatException();
}
public static ECPrivateKey Create(ECCurve curve)
{
var priv = BigIntegerExt.ModRandom(curve.Order);
//todo: check not zero
return(new ECPrivateKey(priv, curve));
}
public bool VerifySignature(BigInteger hash, ECSignature signature)
{
hash = Curve.TruncateHash(hash);
var w = signature.S.ModInverse(Curve.Order);
var u1 = (hash * w) % Curve.Order;
var u2 = (signature.R * w) % Curve.Order;
var p = Curve.G * u1 + Point * u2;
return(BigIntegerExt.ModEqual(signature.R, p.X, Curve.Order));
}
public bool Has(ECPoint p)
{
if (p == ECPoint.Infinity)
{
return(true);
}
var left = p.Y * p.Y;
var right = p.X * p.X * p.X + A * p.X + B;
return(BigIntegerExt.ModEqual(left, right, Modulus));
}
public ECSignature Sign(BigInteger message)
{
message = Curve.TruncateHash(message);
ECSignature signature = null;
do
{
var random = BigIntegerExt.ModRandom(Curve.Order);
signature = SignTruncated(message, random);
} while (signature == null);
return(signature);
}
private ECSignature SignTruncated(BigInteger message, BigInteger random)
{
var p = Curve.G * random;
var r = p.X % Curve.Order;
if (r == 0)
{
return(null);
}
var s = ((message + r * D) * BigIntegerExt.ModInverse(random, Curve.Order)) % Curve.Order;
if (s == 0)
{
return(null);
}
return(new ECSignature(r, s, Curve));
}
public ECPrivateKey CreatePrivateKey(byte[] data)
{
return(new ECPrivateKey(BigIntegerExt.FromBigEndianBytes(data), this));
}
public BigInteger TruncateHash(byte[] hash)
{
return(TruncateHash(hash, BigIntegerExt.FromBigEndianBytes(hash)));
}
public bool VerifySignature(byte[] hash, ECSignature signature)
{
return(VerifySignature(BigIntegerExt.FromBigEndianBytes(hash), signature));
}
public static ECPrivateKey ParseHex(string hex, ECCurve curve)
{
return(new ECPrivateKey(BigIntegerExt.ParseHexUnsigned(hex), curve));
}
public ECSignature Sign(byte[] hash, BigInteger random)
{
var num = BigIntegerExt.FromBigEndianBytes(hash);
return(Sign(num, random));
}
