private void SendNegotiateFrame()
{
ClientNegotiateFrame frame = new ClientNegotiateFrame();
frame.MinVersion = MIN_VERSION;
frame.MaxVersion = MAX_VERSION;
frame.Nonce = ServerNonce;
frame.IsMutual = MutualAuthenticationRequired;
frame.Difficulty = ChallengeDifficulty;
SendFrame(frame);
}
private void HandleNegotiateFrame(ClientNegotiateFrame frame)
{
if (frame.MinVersion > MAX_VERSION || frame.MaxVersion < MIN_VERSION)
{
OnExceptionThrown(new InvalidDataException("Invalid protocol version."));
return;
}
if (frame.Difficulty > MAX_DIFFICULTY)
{
OnExceptionThrown(new InvalidDataException("Challenge difficulty is too high."));
return;
}
if (frame.IsMutual && LocalTag == null)
{
OnExceptionThrown(new InvalidOperationException("Server requires mutual authentication."));
return;
}
HashPuzzle puzzle = new HashPuzzle(HashAlgorithmName.SHA256, frame.Difficulty, frame.Nonce);
bool success = puzzle.FindSolution();
if (success)
{
Version = Math.Min(frame.MaxVersion, MAX_VERSION);
ServerNonce = frame.Nonce;
ClientNonce = CreateNonce(NONCE_LENGTH);
BufferFrame(new ClientExchangeFrame(), FrameState.ClientExchange);
}
else
{
BufferFrame(new ClientNegotiateFrame(), FrameState.ClientNegotiate);
}
SendExchangeFrame(success, puzzle.Solution);
}