/// <summary>
/// 使用私钥对消息进行签名
/// </summary>
/// <param name="privateKey"></param>
/// <param name="message"></param>
/// <returns></returns>
unsafe public static Signature Sign(ReadOnlySpan <byte> privateKey, ReadOnlySpan <byte> message)
{
if (privateKey.Length != 32)
{
throw new InvalidPrivateKeyException("私钥长度必须是32字节");
}
if (message.Length != 32)
{
throw new InvalidMessageException("消息长度必须是32字节");
}
var dA = new U256N(privateKey);
var msg = new U256N(message);
Span <byte> tempPrivateKey = stackalloc byte[32];
CreatePrivateKey(tempPrivateKey);
var k = new U256N(tempPrivateKey);
var p = (Point)EllipticCurve.MulG(k);
U256N R = p.X.Value;
U256N S = (msg + dA * R) / k;
if (p.Y.Value.v0 % 2 != 0)
{
S = -S;
}
return(new Signature(R, S));
}
/// <summary>
/// 使用公钥验证消息的签名是否正确
/// </summary>
/// <param name="publicKey"></param>
/// <param name="message"></param>
/// <param name="signature"></param>
/// <returns></returns>
public static bool Verify(PublicKey publicKey, ReadOnlySpan <byte> message, Signature signature)
{
if (message.Length != 32)
{
throw new InvalidMessageException("消息长度必须是32字节");
}
var msg = new U256N(message);
var S_inv = ~(U256N)signature.S;
var u1 = S_inv * msg;
var u2 = S_inv * signature.R;
var P = EllipticCurve.MulG(u1) + new JacobianPoint(publicKey.X, publicKey.Y) * u2;
return(P.X == signature.R * (P.Z ^ 2));
}
/// <summary>
/// 从(消息,签名)恢复公钥
/// </summary>
/// <param name="message"></param>
/// <param name="signature"></param>
/// <returns></returns>
unsafe public static PublicKey RecoverPublicKey(ReadOnlySpan <byte> message, Signature signature)
{
if (message.Length != 32)
{
throw new InvalidMessageException("消息长度必须是32字节");
}
U256N s = signature.S;
var m = new U256N(message);
var rY = EllipticCurve.GetY(signature.R);
if (rY.Value.v0 % 2 != 0)
{
s = -s;
}
var rP = new JacobianPoint(signature.R, rY);
var r_inv = ~new U256N(signature.R);
var u1 = EllipticCurve.MulG(-m * r_inv);
var u2 = s * r_inv;
var p = (Point)(rP * u2 + u1);
return(new PublicKey(p.X, p.Y));
}
