KeyExchangeMLKem768X25519Sha256
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Agreement;
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 : KeyExchangeEC
{
private MLKemDecapsulator _mlkemDecapsulator;
private X25519Agreement _x25519Agreement;
public override string Name => "mlkem768x25519-sha256";
protected override int HashSize => 256;
public override void Start(Session session, KeyExchangeInitMessage message, bool sendClientInitMessage)
{
base.Start(session, message, sendClientInitMessage);
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);
X25519KeyPairGenerator x25519KeyPairGenerator = new X25519KeyPairGenerator();
x25519KeyPairGenerator.Init(new X25519KeyGenerationParameters(CryptoAbstraction.SecureRandom));
AsymmetricCipherKeyPair asymmetricCipherKeyPair2 = x25519KeyPairGenerator.GenerateKeyPair();
_x25519Agreement = new X25519Agreement();
_x25519Agreement.Init(asymmetricCipherKeyPair2.Private);
byte[] encoded = ((MLKemPublicKeyParameters)asymmetricCipherKeyPair.Public).GetEncoded();
byte[] encoded2 = ((X25519PublicKeyParameters)asymmetricCipherKeyPair2.Public).GetEncoded();
_clientExchangeValue = encoded.Concat(encoded2);
SendMessage(new KeyExchangeHybridInitMessage(_clientExchangeValue));
}
public override void Finish()
{
base.Finish();
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 + _x25519Agreement.AgreementSize)
throw new SshConnectionException(string.Format(CultureInfo.CurrentCulture, "Bad S_Reply length: {0}.", serverExchangeValue.Length), DisconnectReason.KeyExchangeFailed);
byte[] array = new byte[_mlkemDecapsulator.SecretLength + _x25519Agreement.AgreementSize];
_mlkemDecapsulator.Decapsulate(serverExchangeValue, 0, _mlkemDecapsulator.EncapsulationLength, array, 0, _mlkemDecapsulator.SecretLength);
X25519PublicKeyParameters publicKey = new X25519PublicKeyParameters(serverExchangeValue, _mlkemDecapsulator.EncapsulationLength);
_x25519Agreement.CalculateAgreement(publicKey, array, _mlkemDecapsulator.SecretLength);
base.SharedKey = CryptoAbstraction.HashSHA256(array);
}
}
}