使用以下方法派生共享密钥：
- C#
ECDiffieHellmanCng.DeriveKeyMaterial(ECDiffieHellmanPublicKey otherPartyPublicKey) - Kotlin
KeyAgreement.generateSecret()接着KeyAgreement.doPhase(key: Key!, lastPhase: Boolean)
在曲线“secp384r1”下会产生不同的结果。
Kotlin 相关链接指向 Kotlin for Android 文档以提高可读性。
简化的驱动程序代码，用于演示问题，假设 C# .NET 7.0.1 控制台应用程序是“服务器”，而 Kotlin OpenJDK 19.0.1 应用程���是“客户端”：
C#:
using System.Net;
using System.Net.Sockets;
using System.Security.Cryptography;
var listener = new TcpListener(IPAddress.Any, 13000);
listener.Start();
using var client = await listener.AcceptTcpClientAsync();
var sharedKey = await GetSharedKey(client, CancellationToken.None);
async Task<byte[]> GetSharedKey(TcpClient client, CancellationToken token)
{
//Generate ECDH key pair using secp384r1 curve
var ecdh = new ECDiffieHellmanCng(ECCurve.CreateFromFriendlyName("secp384r1"));
var publicKeyBytes = ecdh.ExportSubjectPublicKeyInfo();
Console.WriteLine($"Server Public Key: {Convert.ToBase64String(publicKeyBytes)}, " +
$"Length: {publicKeyBytes.Length}");
//Send the generated public key encoded in X.509 to client.
var stream = client.GetStream();
await stream.WriteAsync(publicKeyBytes, token);
//Receive client's public key bytes (X.509 encoding).
var otherPublicKeyBytes = new byte[publicKeyBytes.Length];
await stream.ReadExactlyAsync(otherPublicKeyBytes, 0, otherPublicKeyBytes.Length, token);
//Decode client's public key bytes.
var otherEcdh = new ECDiffieHellmanCng(ECCurve.CreateFromFriendlyName("secp384r1"));
otherEcdh.ImportSubjectPublicKeyInfo(otherPublicKeyBytes, out _);
Console.WriteLine($"Client Public Key: {Convert.ToBase64String(otherEcdh.ExportSubjectPublicKeyInfo())}, " +
$"Length: {otherEcdh.ExportSubjectPublicKeyInfo().Length}");
//Derive shared key.
var sharedKey = ecdh.DeriveKeyMaterial(otherEcdh.PublicKey);
Console.WriteLine($"Shared key: {Convert.ToBase64String(sharedKey)}, " +
$"Length: {sharedKey.Length}");
return sharedKey;
}
Kotlin：
import java.net.Socket
import java.security.KeyFactory
import java.security.KeyPairGenerator
import java.security.spec.ECGenParameterSpec
import java.security.spec.X509EncodedKeySpec
import java.util.*
import javax.crypto.KeyAgreement
fun main(args: Array<String>) {
val socket = Socket("127.0.0.1", 13000)
val sharedKey = getSharedKey(socket)
}
private fun getSharedKey(socket: Socket): ByteArray {
//Generate ECDH key pair using secp384r1 curve
val keyGen = KeyPairGenerator.getInstance("EC")
keyGen.initialize(ECGenParameterSpec("secp384r1"))
val keyPair = keyGen.generateKeyPair()
println("Client Public Key: ${Base64.getEncoder().encodeToString(keyPair.public.encoded)}, Length: ${keyPair.public.encoded.size}")
//Receive server's public key bytes (encoded in X.509)
val input = socket.getInputStream()
val publicKeyBytes = input.readNBytes(keyPair.public.encoded.size)
//Send the generated public key encoded in X.509 to server
val output = socket.getOutputStream()
output.write(keyPair.public.encoded)
// Decode the server's public key
val keySpec = X509EncodedKeySpec(publicKeyBytes)
val keyFactory = KeyFactory.getInstance("EC")
val otherPublicKey = keyFactory.generatePublic(keySpec)
println("Server Public Key: ${Base64.getEncoder().encodeToString(otherPublicKey.encoded)}, Length: ${otherPublicKey.encoded.size}")
// Use KeyAgreement to generate the shared key
val keyAgreement = KeyAgreement.getInstance("ECDH")
keyAgreement.init(keyPair.private)
keyAgreement.doPhase(otherPublicKey, true)
val sharedKey = keyAgreement.generateSecret()
println("Shared key: ${Base64.getEncoder().encodeToString(sharedKey)}, Length: ${sharedKey.size}")
return sharedKey
}
C# 输出：
Server Public Key: MHYwEAYHKoZIzj0CAQYFK4EEACIDYgAEqza/eiK23hQIEW5mVdqOc0hAP3tPqittlcvPa6bGdyJK9n64sg0qYyDoPsxJ4pf7ROLz0ACrDS7n/e5Z0J1SMsWpBDViS8NRBvKwa1rQjWdFR0wzRaeVg09LIjnGs4Mj, Length: 120
Client Public Key: MHYwEAYHKoZIzj0CAQYFK4EEACIDYgAE30zvqkljT4STiE6XfLtoN147WRGA92rz9BLZfbRkOjz7uNbQ3az46DdoyQi6+eON7QVjIf2H5LKBANSk+C5zRX6u8jjrbhURDHYBKgijOddy6mOaEwiADijD/NX72O2L, Length: 120
Shared key: /u+tZYHar4MxXfrn2oqPZAqhiB2pkSTRBZ12rUxdnII=, Length: 32
Kotlin 输出：
Client Public Key: MHYwEAYHKoZIzj0CAQYFK4EEACIDYgAE30zvqkljT4STiE6XfLtoN147WRGA92rz9BLZfbRkOjz7uNbQ3az46DdoyQi6+eON7QVjIf2H5LKBANSk+C5zRX6u8jjrbhURDHYBKgijOddy6mOaEwiADijD/NX72O2L, Length: 120
Server Public Key: MHYwEAYHKoZIzj0CAQYFK4EEACIDYgAEqza/eiK23hQIEW5mVdqOc0hAP3tPqittlcvPa6bGdyJK9n64sg0qYyDoPsxJ4pf7ROLz0ACrDS7n/e5Z0J1SMsWpBDViS8NRBvKwa1rQjWdFR0wzRaeVg09LIjnGs4Mj, Length: 120
Shared key: lErK9DJAutaJ4af7EYWvtEXicAwfSuadtQhlZxug26wGkgB/ce7hF6ihLL87Sqc3, Length: 48
公钥的导入/导出似乎没有问题，但是C#端无法生成正确长度的密钥（384 / 8 = 48）。
编辑： 有人注意到，有趣的是，C#的“共享密钥”实际上是Kotlin的共享密钥的SHA256哈希值，而不是实际密钥。
我强烈怀疑这是因为默认密钥派生函数不匹配，但并不完全确定。
我想知道我做错了什么以及如何解决这个问题。
编辑＃2 - 解决方案： 正如接受的答案所建议的那样-我的怀疑并不完全错误。 ECDiffieHellmanCng.DeriveKeyMaterial多做了一些不必要的工作-即默认返回派生密钥的SHA256哈希值而不是实际密钥，并且不提供任何返回实际密钥的方法。
对于任何对获取48字节共享密钥感兴趣的人，您只能得到其SHA384（或其他哈希算法）散列值（或使用BouncyCastle）：
C＃更改：
//Generate ECDH key pair using secp384r1 curve and change default key's hashing algorithm SHA256 to SHA384
var ecdh = new ECDiffieHellmanCng(ECCurve.CreateFromFriendlyName("secp384r1"))
{
HashAlgorithm = CngAlgorithm.Sha384
};
Kotlin 变更:
val sharedKey = keyAgreement.generateSecret()
val sharedKeyHash = MessageDigest.getInstance("SHA384").digest(sharedKey)
println("Shared key SHA384 hash: ${Base64.getEncoder().encodeToString(sharedKeyHash)}, Length: ${sharedKeyHash.size}")
return sharedKeyHash
我建议将GetSharedKey方法重命名为其实际名称-GetSharedKeysSHA384Hash。
ECDiffieHellman.DeriveKeyMaterial()的默认行为在 .NET 文档中有描述，参见 Remarks，即使用 SHA256 进行哈希。这里 是一个帖子，其中包含一个代码片段，用于计算 .NET 的 原始 共享密钥（如有需要，建议使用 BC）。 - Topaco