private void HandleExchangeFrame(ServerExchangeFrame frame)
{
if (frame.Success)
{
if (frame.Tag.Length > MAX_TAG_LENGTH)
{
OnExceptionThrown(new InvalidDataException("Invalid tag length."));
return;
}
HashPuzzle puzzle = new HashPuzzle(HashAlgorithmName.SHA256, ChallengeDifficulty, ServerNonce);
if (!puzzle.VerifySolution(frame.Solution))
{
OnExceptionThrown(new InvalidDataException("Challenge failed."));
return;
}
if (frame.Tag.Length == 0)
{
if (MutualAuthenticationRequired)
{
OnExceptionThrown(new InvalidDataException("Tag missing."));
return;
}
}
else
{
_remoteTag = Tag.Deserialize(frame.Tag);
if (TrustedIssuers != null && _remoteTag.Verify(TrustedIssuers))
{
IsMutuallyAuthenticated = true;
}
if (MutualAuthenticationRequired)
{
OnExceptionThrown(new InvalidDataException("Invalid tag."));
return;
}
}
ClientNonce = frame.Nonce;
BufferFrame(new ServerValidateFrame(), FrameState.ServerValidate);
SendExchangeFrame(GetPublicKey(), IsMutuallyAuthenticated);
}
else
{
OnChallengeFailed();
//TODO: check if we're disposed
ServerNonce = CreateNonce(NONCE_LENGTH);
BufferFrame(new ServerExchangeFrame(), FrameState.ServerExchange);
SendNegotiateFrame();
}
}
private void SendExchangeFrame(bool success, byte[] solution)
{
ServerExchangeFrame frame = new ServerExchangeFrame();
frame.Success = success;
frame.Solution = solution;
frame.Nonce = ClientNonce;
frame.Tag = LocalTag?.RawData;
SendFrame(frame);
}