Use BCL MLKem

Author: scott-xu

Directory.Packages.props

@@ -11,6 +11,7 @@
     <PackageVersion Include="GitHubActionsTestLogger" Version="2.4.1" />
     <PackageVersion Include="Meziantou.Analyzer" Version="2.0.220" />
     <!-- Should stay on LTS .NET releases. -->
+    <PackageVersion Include="Microsoft.Bcl.Cryptography" Version="10.0.0-rc.1.25451.107" />
     <PackageVersion Include="Microsoft.Extensions.Logging.Abstractions" Version="8.0.3" />
     <PackageVersion Include="Microsoft.Extensions.Logging.Console" Version="9.0.9" />
     <PackageVersion Include="MSTest" Version="3.9.3" />

src/Renci.SshNet/Renci.SshNet.csproj

@@ -49,10 +49,11 @@
     </PackageReference>
   </ItemGroup>
 
-  <ItemGroup Condition=" !$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net8.0')) ">
-    <PackageReference Include="System.Formats.Asn1" />
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Bcl.Cryptography" />
   </ItemGroup>
 
+
   <ItemGroup>
     <None Include="..\..\images\logo\png\SS-NET-icon-h500.png">
       <Pack>True</Pack>

src/Renci.SshNet/Security/KeyExchangeMLKem768X25519Sha256.cs

@@ -1,5 +1,6 @@
-using System.Globalization;
-using System.Linq;
+using System;
+using System.Globalization;
+using System.Security.Cryptography;
 
 using Org.BouncyCastle.Crypto.Generators;
 using Org.BouncyCastle.Crypto.Kems;
@@ -13,6 +14,8 @@ namespace Renci.SshNet.Security
 {
     internal sealed class KeyExchangeMLKem768X25519Sha256 : KeyExchangeECCurve25519
     {
+        private readonly MLKemAlgorithm _mlkem768 = MLKemAlgorithm.MLKem768;
+        private MLKem _mlkem;
         private MLKemDecapsulator _mlkemDecapsulator;
 
         /// <summary>
@@ -41,14 +44,23 @@ protected override void StartImpl()
 
             Session.KeyExchangeHybridReplyMessageReceived += Session_KeyExchangeHybridReplyMessageReceived;
 
-            var mlkem768KeyPairGenerator = new MLKemKeyPairGenerator();
-            mlkem768KeyPairGenerator.Init(new MLKemKeyGenerationParameters(CryptoAbstraction.SecureRandom, MLKemParameters.ml_kem_768));
-            var mlkem768KeyPair = mlkem768KeyPairGenerator.GenerateKeyPair();
+            byte[] mlkem768PublicKey;
+            if (MLKem.IsSupported)
+            {
+                _mlkem = MLKem.GenerateKey(_mlkem768);
+                mlkem768PublicKey = _mlkem.ExportEncapsulationKey();
+            }
+            else
+            {
+                var mlkem768KeyPairGenerator = new MLKemKeyPairGenerator();
+                mlkem768KeyPairGenerator.Init(new MLKemKeyGenerationParameters(CryptoAbstraction.SecureRandom, MLKemParameters.ml_kem_768));
+                var mlkem768KeyPair = mlkem768KeyPairGenerator.GenerateKeyPair();
 
-            _mlkemDecapsulator = new MLKemDecapsulator(MLKemParameters.ml_kem_768);
-            _mlkemDecapsulator.Init(mlkem768KeyPair.Private);
+                _mlkemDecapsulator = new MLKemDecapsulator(MLKemParameters.ml_kem_768);
+                _mlkemDecapsulator.Init(mlkem768KeyPair.Private);
 
-            var mlkem768PublicKey = ((MLKemPublicKeyParameters)mlkem768KeyPair.Public).GetEncoded();
+                mlkem768PublicKey = ((MLKemPublicKeyParameters)mlkem768KeyPair.Public).GetEncoded();
+            }
 
             var x25519PublicKey = _impl.GenerateClientPublicKey();
 
@@ -109,11 +121,28 @@ private void HandleServerHybridReply(byte[] hostKey, byte[] serverExchangeValue,
 
             var mlkemSecret = new byte[_mlkemDecapsulator.SecretLength];
 
-            _mlkemDecapsulator.Decapsulate(serverExchangeValue, 0, _mlkemDecapsulator.EncapsulationLength, mlkemSecret, 0, _mlkemDecapsulator.SecretLength);
+            if (MLKem.IsSupported)
+            {
+                _mlkem.Decapsulate(serverExchangeValue.AsSpan(0, _mlkem768.CiphertextSizeInBytes), mlkemSecret);
+            }
+            else
+            {
+                _mlkemDecapsulator.Decapsulate(serverExchangeValue, 0, _mlkemDecapsulator.EncapsulationLength, mlkemSecret, 0, _mlkemDecapsulator.SecretLength);
+            }
 
             var x25519Agreement = _impl.CalculateAgreement(serverExchangeValue.Take(_mlkemDecapsulator.EncapsulationLength, X25519PublicKeyParameters.KeySize));
 
             SharedKey = CryptoAbstraction.HashSHA256(mlkemSecret.Concat(x25519Agreement));
         }
+
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                _mlkem?.Dispose();
+            }
+
+            base.Dispose(disposing);
+        }
     }
 }