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Use BCL MLKem #1659

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1 change: 1 addition & 0 deletions Directory.Packages.props
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
<PackageVersion Include="Meziantou.Analyzer" Version="2.0.201" />

<!-- Should stay on LTS .NET releases. -->
<PackageVersion Include="Microsoft.Bcl.Cryptography" Version="10.0.0-preview.5.25277.114" />
<PackageVersion Include="Microsoft.Extensions.Logging.Abstractions" Version="8.0.3" />
<PackageVersion Include="Microsoft.Extensions.Logging.Console" Version="9.0.5" />
<PackageVersion Include="MSTest" Version="3.9.1" />
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5 changes: 3 additions & 2 deletions src/Renci.SshNet/Renci.SshNet.csproj
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Expand Up @@ -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>
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61 changes: 46 additions & 15 deletions src/Renci.SshNet/Security/KeyExchangeMLKem768X25519Sha256.cs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
using System.Globalization;
using System.Linq;
using System;
using System.Globalization;
using System.Security.Cryptography;

using Org.BouncyCastle.Crypto.Agreement;
using Org.BouncyCastle.Crypto.Generators;
Expand All @@ -12,8 +13,11 @@

namespace Renci.SshNet.Security
{
#pragma warning disable SYSLIB5006 // Type is for evaluation purposes only and is subject to change or removal in future updates. Suppress this diagnostic to proceed.
internal sealed class KeyExchangeMLKem768X25519Sha256 : KeyExchangeEC
{
private readonly MLKemAlgorithm _mlkem768 = MLKemAlgorithm.MLKem768;
private MLKem _mlkem;
private MLKemDecapsulator _mlkemDecapsulator;
private X25519Agreement _x25519Agreement;

Expand Down Expand Up @@ -45,12 +49,22 @@ public override void Start(Session session, KeyExchangeInitMessage message, bool

Session.KeyExchangeHybridReplyMessageReceived += Session_KeyExchangeHybridReplyMessageReceived;

var mlkem768KeyPairGenerator = new MLKemKeyPairGenerator();
mlkem768KeyPairGenerator.Init(new MLKemKeyGenerationParameters(CryptoAbstraction.SecureRandom, MLKemParameters.ml_kem_768));
var mlkem768KeyPair = mlkem768KeyPairGenerator.GenerateKeyPair();
if (MLKem.IsSupported)
{
_mlkem = MLKem.GenerateKey(_mlkem768);
_clientExchangeValue = _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);
_clientExchangeValue = ((MLKemPublicKeyParameters)mlkem768KeyPair.Public).GetEncoded();
}

var x25519KeyPairGenerator = new X25519KeyPairGenerator();
x25519KeyPairGenerator.Init(new X25519KeyGenerationParameters(CryptoAbstraction.SecureRandom));
Expand All @@ -59,10 +73,9 @@ public override void Start(Session session, KeyExchangeInitMessage message, bool
_x25519Agreement = new X25519Agreement();
_x25519Agreement.Init(x25519KeyPair.Private);

var mlkem768PublicKey = ((MLKemPublicKeyParameters)mlkem768KeyPair.Public).GetEncoded();
var x25519PublicKey = ((X25519PublicKeyParameters)x25519KeyPair.Public).GetEncoded();
Array.Resize(ref _clientExchangeValue, _mlkem768.EncapsulationKeySizeInBytes + X25519PublicKeyParameters.KeySize);

_clientExchangeValue = mlkem768PublicKey.Concat(x25519PublicKey);
((X25519PublicKeyParameters)x25519KeyPair.Public).Encode(_clientExchangeValue, _mlkem768.EncapsulationKeySizeInBytes);

SendMessage(new KeyExchangeHybridInitMessage(_clientExchangeValue));
}
Expand Down Expand Up @@ -114,21 +127,39 @@ private void HandleServerHybridReply(byte[] hostKey, byte[] serverExchangeValue,
_hostKey = hostKey;
_signature = signature;

if (serverExchangeValue.Length != _mlkemDecapsulator.EncapsulationLength + _x25519Agreement.AgreementSize)
if (serverExchangeValue.Length != _mlkem768.CiphertextSizeInBytes + _x25519Agreement.AgreementSize)
{
throw new SshConnectionException(
string.Format(CultureInfo.CurrentCulture, "Bad S_Reply length: {0}.", serverExchangeValue.Length),
DisconnectReason.KeyExchangeFailed);
}

var secret = new byte[_mlkemDecapsulator.SecretLength + _x25519Agreement.AgreementSize];
var secret = new byte[_mlkem768.SharedSecretSizeInBytes + _x25519Agreement.AgreementSize];

_mlkemDecapsulator.Decapsulate(serverExchangeValue, 0, _mlkemDecapsulator.EncapsulationLength, secret, 0, _mlkemDecapsulator.SecretLength);
if (MLKem.IsSupported)
{
_mlkem.Decapsulate(serverExchangeValue.AsSpan(0, _mlkem768.CiphertextSizeInBytes), secret.AsSpan(0, _mlkem768.SharedSecretSizeInBytes));
}
else
{
_mlkemDecapsulator.Decapsulate(serverExchangeValue, 0, _mlkemDecapsulator.EncapsulationLength, secret, 0, _mlkemDecapsulator.SecretLength);
}

var x25519PublicKey = new X25519PublicKeyParameters(serverExchangeValue, _mlkemDecapsulator.EncapsulationLength);
_x25519Agreement.CalculateAgreement(x25519PublicKey, secret, _mlkemDecapsulator.SecretLength);
var x25519PublicKey = new X25519PublicKeyParameters(serverExchangeValue, _mlkem768.CiphertextSizeInBytes);
_x25519Agreement.CalculateAgreement(x25519PublicKey, secret, _mlkem768.SharedSecretSizeInBytes);

SharedKey = CryptoAbstraction.HashSHA256(secret);
}

protected override void Dispose(bool disposing)
{
if (disposing)
{
_mlkem?.Dispose();
}

base.Dispose(disposing);
}
}
#pragma warning restore SYSLIB5006 // Type is for evaluation purposes only and is subject to change or removal in future updates. Suppress this diagnostic to proceed.
}