Result ChangeCipherSpecAndFinished()
{
if (State == TLSSessionState.Client_Finished)
{
var clienthello_clientfinish = GetHandshakeMessages();
var finishedVerify = _params.Cipher.GetVerifyData("server finished", clienthello_clientfinish);
var finishedMessage = new byte[] { 0x14, 0x00, 0x00, 0x0C }.Concat(finishedVerify).ToArray();
var macSeed = Utils.GetMacSeed(_sendSeqNum, (byte)RecordType.Handshake, finishedMessage);
var myMac = _params.Cipher.ServerMessageAuthCode(macSeed);
var finished = new List <byte>();
finished.AddRange(finishedMessage);
finished.AddRange(myMac);
var serverIv = Utils.Random(16);
var encryptedFinished = _params.Cipher.BulkEncrypt(finished.ToArray(), serverIv);
var serverFinishFragment = new Handshakes.EncryptedFragment(serverIv.Concat(encryptedFinished).ToArray());
var changeCipherRecord = new Records.ChangeCipherSpec();
var serverFinishRecord = new Records.Handshake(new[] { serverFinishFragment });
_sendSeqNum++;
State = TLSSessionState.Server_Finished;
return(new PacketResult(new Records.TLSRecord[] { changeCipherRecord, serverFinishRecord }));
}
else
{
return(Result.FatalAlert(AlertDescription.unexpected_message, $"State [{State}] check failed on ChangeCipherSpecAndFinished"));
}
}
Result Fragment_EncryptedHandshake(Handshakes.EncryptedFragment frag)
{
if (State == TLSSessionState.Client_ChangeCipherSpec)
{
var encrypt = frag.EncryptedData;
var decryptedBytes = _params.Cipher.BulkDecrypt(encrypt, frag.IV);
// 14 00 00 0C
// 12-bytes-verify-data
// 32-bytes-mac
// 15-bytes-padding
// 0x0F(padding-length)
if (decryptedBytes[0] == 0x14 && Utils.ToUInt24(decryptedBytes, 1) == 12)
{
var fragWithoutMac = new Handshakes.Fragment(decryptedBytes.Take(4 + _params.Cipher.VerifyDataLength).ToArray());
AppendHandshakeMessages(fragWithoutMac);
var fragWithMac = new Handshakes.Fragment(decryptedBytes);
return(Fragment_Handshake(fragWithMac));
}
else
{
return(Result.FatalAlert(AlertDescription.decrypt_error, $"invalid Client_EncryptedHandshake message"));
}
}
else
{
return(Result.FatalAlert(AlertDescription.unexpected_message, $"State [{State}] check failed on Client_EncryptedHandshake message"));
}
}