private void HandleExchangeFrame(ClientExchangeFrame frame)
{
if (frame.Tag.Length > MAX_TAG_LENGTH)
{
OnExceptionThrown(new InvalidDataException("Invalid tag length."));
return;
}
if (MutualAuthenticationRequired && !frame.IsMutual)
{
OnExceptionThrown(new InvalidDataException("Server authentication failed."));
return;
}
Tag remoteTag = Tag.Deserialize(frame.Tag);
if (!remoteTag.Verify(TrustedIssuers))
{
OnExceptionThrown(new InvalidDataException("Invalid tag."));
return;
}
IsMutuallyAuthenticated = frame.IsMutual;
List <byte[]> signatureParts = new List <byte[]>();
signatureParts.Add(frame.PublicKey);
signatureParts.Add(ClientNonce);
signatureParts.Add(new byte[] { frame.IsMutual ? (byte)1 : (byte)0 });
if (IsMutuallyAuthenticated)
{
signatureParts.Add(LocalTag.RawData);
}
if (!VerifyData(remoteTag.Holder.Key, frame.Signature, signatureParts.ToArray()))
{
OnExceptionThrown(new InvalidDataException("Invalid signature."));
return;
}
SendValidateFrame(GetPublicKey(), remoteTag);
InitializeCrypto(frame.PublicKey, false);
ClientNonce = CreateNonce(NONCE_LENGTH);
BufferFrame(new ClientEchoFrame(), FrameState.ClientEcho);
SendEchoFrame(ClientNonce);
}
private void SendExchangeFrame(byte[] publicKey, bool isMutual)
{
List <byte[]> signatureParts = new List <byte[]>();
signatureParts.Add(publicKey);
signatureParts.Add(ClientNonce);
signatureParts.Add(new byte[] { isMutual ? (byte)1 : (byte)0 });
if (IsMutuallyAuthenticated)
{
signatureParts.Add(_remoteTag.RawData);
}
ClientExchangeFrame frame = new ClientExchangeFrame();
frame.IsMutual = isMutual;
frame.PublicKey = publicKey;
frame.Signature = SignData(LocalTag.Holder.Key, signatureParts.ToArray());
frame.Tag = LocalTag.RawData;
SendFrame(frame);
}
