/// <summary>
/// 根据私钥创建公钥
/// </summary>
/// <param name="privateKey"></param>
/// <returns></returns>
unsafe public static PublicKey CreatePublicKey(ReadOnlySpan <byte> privateKey)
{
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 retPoint = ModP.MulG(k);
Clear(&k);
return(new PublicKey(ModP.ToU256(retPoint.X), ModP.ToU256(retPoint.Y)));
}
/// <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)));
}