/// <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 = ModN.U256(message, bigEndian: true);
var S_inv = ModN.Inverse(signature.S);
var u1 = ModN.Mul(S_inv, msg);
var u2 = ModN.Mul(S_inv, signature.R);
var P = ModP.Add(ModP.MulG(u1), ModP.Mul(publicKey.ToPoint(), u2));
return(ModP.Equal(P.X, signature.R));
}
/// <summary>
/// 使用自己的私钥与对方公钥进行密钥交换（私钥A×公钥B = 私钥B×公钥A）
/// </summary>
/// <param name="privateKey"></param>
/// <param name="publicKey"></param>
/// <returns></returns>
unsafe public static EncryptionKey CreateEncryptionKey(ReadOnlySpan <byte> privateKey, PublicKey publicKey)
{
if (privateKey.Length != 32)
{
throw new InvalidPrivateKeyException("私钥长度必须是32字节");
}
var k = new U256(privateKey, bigEndian: true);
if (k.IsZero || k >= ModN.N)
{
throw new InvalidPrivateKeyException();
}
var p = ModP.Mul(publicKey.ToPoint(), k);
Clear(&k);
return(new EncryptionKey(ModP.ToU256(p.X), ModP.ToU256(p.Y)));
}