Add support for sntrup761x25519Sha512 key exchange method (sshnet#1562)

Author: scott-xu

src/Renci.SshNet/ConnectionInfo.cs

@@ -349,6 +349,7 @@ public ConnectionInfo(string host, int port, string username, ProxyTypes proxyTy
 
             KeyExchangeAlgorithms = new Dictionary<string, Func<IKeyExchange>>
                 {
+                    { "mlkem768x25519-sha256", () => new KeyExchangeMLKem768X25519Sha256() },
                     { "sntrup761x25519-sha512", () => new KeyExchangeSNtruP761X25519Sha512() },
                     { "[email protected]", () => new KeyExchangeSNtruP761X25519Sha512() },
                     { "curve25519-sha256", () => new KeyExchangeECCurve25519() },

src/Renci.SshNet/Security/KeyExchangeSNtruP761X25519Sha512.cs

@@ -114,7 +114,11 @@ private void HandleServerEcdhReply(byte[] hostKey, byte[] serverExchangeValue, b
             _hostKey = hostKey;
             _signature = signature;
 
+<<<<<<<< HEAD:src/Renci.SshNet/Security/KeyExchangeSNtruP761X25519Sha512.cs
             if (serverExchangeValue.Length != _sntrup761Extractor.EncapsulationLength + X25519PublicKeyParameters.KeySize)
+========
+            if (serverExchangeValue.Length != _mlkemDecapsulator.EncapsulationLength + X25519PublicKeyParameters.KeySize)
+>>>>>>>> 9f21a396 (Add support for sntrup761x25519Sha512 key exchange method (#1562)):src/Renci.SshNet/Security/KeyExchangeMLKem768X25519Sha256.cs
             {
                 throw new SshConnectionException(
                     string.Format(CultureInfo.CurrentCulture, "Bad Q_S length: {0}.", serverExchangeValue.Length),

test/Renci.SshNet.IntegrationTests/KeyExchangeAlgorithmTests.cs

@@ -53,6 +53,37 @@ public void SNtruP761X25519Sha512OpenSsh()
             }
         }
 
+        [TestMethod]
+        [Ignore]
+        public void SNtruP761X25519Sha512()
+        {
+            _remoteSshdConfig.ClearKeyExchangeAlgorithms()
+                             .AddKeyExchangeAlgorithm(KeyExchangeAlgorithm.SNtruP761X25519Sha512)
+                             .Update()
+                             .Restart();
+
+            using (var client = new SshClient(_connectionInfoFactory.Create()))
+            {
+                client.Connect();
+                client.Disconnect();
+            }
+        }
+
+        [TestMethod]
+        public void SNtruP761X25519Sha512OpenSsh()
+        {
+            _remoteSshdConfig.ClearKeyExchangeAlgorithms()
+                             .AddKeyExchangeAlgorithm(KeyExchangeAlgorithm.SNtruP761X25519Sha512OpenSsh)
+                             .Update()
+                             .Restart();
+
+            using (var client = new SshClient(_connectionInfoFactory.Create()))
+            {
+                client.Connect();
+                client.Disconnect();
+            }
+        }
+
         [TestMethod]
         public void Curve25519Sha256()
         {

test/Renci.SshNet.TestTools.OpenSSH/KeyExchangeAlgorithm.cs

@@ -16,6 +16,7 @@ public sealed class KeyExchangeAlgorithm
         public static readonly KeyExchangeAlgorithm Curve25519Sha256Libssh = new KeyExchangeAlgorithm("[email protected]");
         public static readonly KeyExchangeAlgorithm SNtruP761X25519Sha512 = new KeyExchangeAlgorithm("sntrup761x25519-sha512");
         public static readonly KeyExchangeAlgorithm SNtruP761X25519Sha512OpenSsh = new KeyExchangeAlgorithm("[email protected]");
+        public static readonly KeyExchangeAlgorithm MLKem768X25519Sha256 = new KeyExchangeAlgorithm("mlkem768x25519-sha256");
 
         public KeyExchangeAlgorithm(string name)
         {