KeyExchangeMLKem768X25519Sha256
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Generators;
using Org.BouncyCastle.Crypto.Kems;
using Org.BouncyCastle.Crypto.Parameters;
using Renci.SshNet.Abstractions;
using Renci.SshNet.Common;
using Renci.SshNet.Messages.Transport;
using System.Globalization;
namespace Renci.SshNet.Security
{
internal sealed class KeyExchangeMLKem768X25519Sha256 : KeyExchangeECCurve25519
{
private MLKemDecapsulator _mlkemDecapsulator;
public override string Name => "mlkem768x25519-sha256";
protected override int HashSize => 256;
protected override void StartImpl()
{
base.Session.RegisterMessage("SSH_MSG_KEX_HYBRID_REPLY");
base.Session.KeyExchangeHybridReplyMessageReceived += Session_KeyExchangeHybridReplyMessageReceived;
MLKemKeyPairGenerator mLKemKeyPairGenerator = new MLKemKeyPairGenerator();
mLKemKeyPairGenerator.Init(new MLKemKeyGenerationParameters(CryptoAbstraction.SecureRandom, MLKemParameters.ml_kem_768));
AsymmetricCipherKeyPair asymmetricCipherKeyPair = mLKemKeyPairGenerator.GenerateKeyPair();
_mlkemDecapsulator = new MLKemDecapsulator(MLKemParameters.ml_kem_768);
_mlkemDecapsulator.Init(asymmetricCipherKeyPair.Private);
byte[] encoded = ((MLKemPublicKeyParameters)asymmetricCipherKeyPair.Public).GetEncoded();
byte[] second = _impl.GenerateClientPublicKey();
_clientExchangeValue = encoded.Concat(second);
SendMessage(new KeyExchangeHybridInitMessage(_clientExchangeValue));
}
protected override void FinishImpl()
{
base.Session.KeyExchangeHybridReplyMessageReceived -= Session_KeyExchangeHybridReplyMessageReceived;
}
protected override byte[] Hash(byte[] hashData)
{
return CryptoAbstraction.HashSHA256(hashData);
}
private void Session_KeyExchangeHybridReplyMessageReceived(object sender, MessageEventArgs<KeyExchangeHybridReplyMessage> e)
{
KeyExchangeHybridReplyMessage message = e.Message;
base.Session.UnRegisterMessage("SSH_MSG_KEX_HYBRID_REPLY");
HandleServerHybridReply(message.KS, message.SReply, message.Signature);
Finish();
}
private void HandleServerHybridReply(byte[] hostKey, byte[] serverExchangeValue, byte[] signature)
{
_serverExchangeValue = serverExchangeValue;
_hostKey = hostKey;
_signature = signature;
if (serverExchangeValue.Length != _mlkemDecapsulator.EncapsulationLength + X25519PublicKeyParameters.KeySize)
throw new SshConnectionException(string.Format(CultureInfo.CurrentCulture, "Bad S_Reply length: {0}.", serverExchangeValue.Length), DisconnectReason.KeyExchangeFailed);
byte[] array = new byte[_mlkemDecapsulator.SecretLength];
_mlkemDecapsulator.Decapsulate(serverExchangeValue, 0, _mlkemDecapsulator.EncapsulationLength, array, 0, _mlkemDecapsulator.SecretLength);
byte[] second = _impl.CalculateAgreement(serverExchangeValue.Take(_mlkemDecapsulator.EncapsulationLength, X25519PublicKeyParameters.KeySize));
base.SharedKey = CryptoAbstraction.HashSHA256(array.Concat(second));
}
}
}