KeyExchangeECCurve25519
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Agreement;
using Org.BouncyCastle.Crypto.Generators;
using Org.BouncyCastle.Crypto.Parameters;
using Renci.SshNet.Abstractions;
using Renci.SshNet.Common;
using Renci.SshNet.Messages.Transport;
namespace Renci.SshNet.Security
{
internal class KeyExchangeECCurve25519 : KeyExchangeEC
{
protected sealed class BouncyCastleImpl : Impl
{
private X25519Agreement _keyAgreement;
public override byte[] GenerateClientPublicKey()
{
X25519KeyPairGenerator val = new X25519KeyPairGenerator();
val.Init(new X25519KeyGenerationParameters(CryptoAbstraction.SecureRandom));
AsymmetricCipherKeyPair val2 = val.GenerateKeyPair();
_keyAgreement = new X25519Agreement();
_keyAgreement.Init(val2.get_Private());
return val2.get_Public().GetEncoded();
}
public override byte[] CalculateAgreement(byte[] serverPublicKey)
{
X25519PublicKeyParameters val = new X25519PublicKeyParameters(serverPublicKey);
byte[] array = new byte[_keyAgreement.get_AgreementSize()];
_keyAgreement.CalculateAgreement(val, array, 0);
return array;
}
}
protected BouncyCastleImpl _impl;
public override string Name => "curve25519-sha256";
protected override int HashSize => 256;
public override void Start(Session session, KeyExchangeInitMessage message, bool sendClientInitMessage)
{
base.Start(session, message, sendClientInitMessage);
_impl = new BouncyCastleImpl();
StartImpl();
}
protected virtual void StartImpl()
{
base.Session.RegisterMessage("SSH_MSG_KEX_ECDH_REPLY");
base.Session.KeyExchangeEcdhReplyMessageReceived += Session_KeyExchangeEcdhReplyMessageReceived;
_clientExchangeValue = _impl.GenerateClientPublicKey();
SendMessage(new KeyExchangeEcdhInitMessage(_clientExchangeValue));
}
public override void Finish()
{
base.Finish();
FinishImpl();
}
protected virtual void FinishImpl()
{
base.Session.KeyExchangeEcdhReplyMessageReceived -= Session_KeyExchangeEcdhReplyMessageReceived;
}
protected override byte[] Hash(byte[] hashData)
{
return CryptoAbstraction.HashSHA256(hashData);
}
private void Session_KeyExchangeEcdhReplyMessageReceived(object sender, MessageEventArgs<KeyExchangeEcdhReplyMessage> e)
{
KeyExchangeEcdhReplyMessage message = e.Message;
base.Session.UnRegisterMessage("SSH_MSG_KEX_ECDH_REPLY");
HandleServerEcdhReply(message.KS, message.QS, message.Signature);
Finish();
}
private void HandleServerEcdhReply(byte[] hostKey, byte[] serverExchangeValue, byte[] signature)
{
_serverExchangeValue = serverExchangeValue;
_hostKey = hostKey;
_signature = signature;
byte[] data = _impl.CalculateAgreement(serverExchangeValue);
base.SharedKey = Extensions.ToByteArray(data.ToBigInteger2(), false, true);
}
protected override void Dispose(bool disposing)
{
base.Dispose(disposing);
if (disposing)
_impl?.Dispose();
}
}
}