public static bool verify(string message, Signature signature, PublicKey publicKey)
{
string hashMessage = sha256(message);
BigInteger numberMessage = Utils.BinaryAscii.numberFromHex(hashMessage);
CurveFp curve = publicKey.curve;
BigInteger sigR = signature.r;
BigInteger sigS = signature.s;
BigInteger inv = EcdsaMath.inv(sigS, curve.N);
Point u1 = EcdsaMath.multiply(
curve.G,
Utils.Integer.modulo((numberMessage * inv), curve.N),
curve.N,
curve.A,
curve.P
);
Point u2 = EcdsaMath.multiply(
publicKey.point,
Utils.Integer.modulo((sigR * inv), curve.N),
curve.N,
curve.A,
curve.P
);
Point add = EcdsaMath.add(
u1,
u2,
curve.A,
curve.P
);
return(sigR == add.x);
}
public static Signature sign(string message, PrivateKey privateKey)
{
string hashMessage = sha256(message);
BigInteger numberMessage = Utils.BinaryAscii.numberFromHex(hashMessage);
CurveFp curve = privateKey.curve;
BigInteger randNum = Utils.Integer.randomBetween(BigInteger.One, curve.N - 1);
Point randSignPoint = EcdsaMath.multiply(curve.G, randNum, curve.N, curve.A, curve.P);
BigInteger r = Utils.Integer.modulo(randSignPoint.x, curve.N);
BigInteger s = Utils.Integer.modulo((numberMessage + r * privateKey.secret) * (EcdsaMath.inv(randNum, curve.N)), curve.N);
return(new Signature(r, s));
}