在.net framework 4.7中实现ECDiffieHellmancing时有关保密协议的问题？

我有以下代码：

        var curve = ECCurve.NamedCurves.nistP256;
        var ecdhSender = ECDiffieHellman.Create(curve);
        var ecdhReceiver = ECDiffieHellman.Create(curve);

我的理解是，我应该能够使用ecdhSender对象和ecdhReceiver.PublicKey计算秘密协议，或者使用ecdhReceiver对象和ecdhSender.PublicKey计算秘密协议，并且两个秘密协议值应该相同。如果这是一个错误的假设，请让我知道

由于ECDiffieHellman.Create返回ECDiffieHellman类型，因此我编写了以下代码以获得秘密协议：

        string receiverHexString = null;
        using (SafeNCryptSecretHandle secretAgreement = (ecdhReceiver as ECDiffieHellmanCng).DeriveSecretAgreementHandle(ecdhSender.PublicKey))
        {
            byte[] secretAgreementBytes = new byte[32];
            IntPtr pointer = secretAgreement.DangerousGetHandle();
            Marshal.Copy(pointer, secretAgreementBytes, 0, secretAgreementBytes.Length);
            receiverHexString = BitConverter.ToString(secretAgreementBytes).Replace("-", string.Empty).ToLower();
            Console.WriteLine($"receiver secretAgreement: 0x{receiverHexString}");
        }

        string senderHexString = null;
        using (SafeNCryptSecretHandle secretAgreement = (ecdhSender as ECDiffieHellmanCng).DeriveSecretAgreementHandle(ecdhReceiver.PublicKey))
        {
            byte[] secretAgreementBytes = new byte[32];
            IntPtr pointer = secretAgreement.DangerousGetHandle();
            Marshal.Copy(pointer, secretAgreementBytes, 0, secretAgreementBytes.Length);
            senderHexString = BitConverter.ToString(secretAgreementBytes).Replace("-", string.Empty).ToLower();
            Console.WriteLine($"sender secretAgreement: 0x{senderHexString}");
        }

        Assert.AreEqual(receiverHexString, senderHexString);

我的主张失败了。显然我做错了什么（如果秘密协议应该是一样的）

这就是我将字节从句柄中提取出来的方式吗？还是别的什么？

到目前为止，还并没有从CNG获取原始秘密协议值的书面方法，这就是.NET不公开它的原因

NET中ECDH的预期用途是

ECCurve curve = ECCurve.NamedCurves.nistP256;

// Usually you'll only have one private key (yours), so this isn't representative of
// real code.  An `ECDiffieHellman` object doesn't necessarily have a private key,
// but an `ECDiffieHellmanPublicKey` object definitely doesn't.
using (ECDiffieHellman bobPrivate = ECDiffieHellman.Create(curve))
using (ECDiffieHellman alicePrivate = ECDiffieHellman.Create(curve))
using (ECDiffieHellmanPublicKey bobPublic = bobPrivate.PublicKey)
using (ECDiffieHellmanPublicKey alicePublic = alicePrivate.PublicKey)
{
    byte[] ba = bobPrivate.DeriveKeyFromHash(alicePublic, HashAlgorithmName.SHA256);
    byte[] ab = alicePrivate.DeriveKeyFromHash(bobPublic, HashAlgorithmName.SHA256);

    // ba and ab have the same contents.
}

还有

• DeriveKeyFromHash（ECDiffieHellmanPublicKey otherPartyPublicKey，HashAlgorithmName hashAlgorithm，byte[]secretPrepend，byte[]secretAppend）

• DeriveKeyFromHmac（ECDiffieHellmanPublicKey otherPartyPublicKey，HashAlgorithmName hashAlgorithm，byte[]hmacKey）

• DeriveKeyFromHmac（ECDiffieHellmanPublicKey otherPartyPublicKey，HashAlgorithmName hashAlgorithm，byte[]hmacKey，byte[]secretPrepend，byte[]secretAppend）

• DeriveKeyTls（ECDiffieHellmanPublicKey其他部分publickey，byte[]prfLabel，byte[]prfSeed）

如果bobPrivate和alicePublic（或者相反，alicePrivate和bobPublic）保持不变，则提供相同的输入将产生相同的输出

---

注意：如果可以的话，你应该避免特别谈论

ecdiffiehellmancing

。当ECDH最终成为.NET标准时，ECDHCng类就不会了。从.NET 4.6.2开始，所有操作都可以在基类上完成（除了打开持久化键）；NET内核倾向于不从其

Create（）

工厂方法返回公共类型。

您想实现什么？NCRYPT_SECRET_句柄结构不透明，您不应该读取它的内存。请尝试使用详细步骤验证合作伙伴的结果。在问题的第一部分，你能评论一下我的假设是正确的还是错误的吗？