private void StartNegotiation(bool bOutgoing)
{
if (!bOutgoing)
{
negotiatingState_ = NegotiatingStateEnum.ONS_BASIC_CLIENTA_RANDOMPART;
streamCryptState_ = StreamCryptStateEnum.ECS_NEGOTIATING;
receiveBytesWanted_ = 4;
}
else if (streamCryptState_ == StreamCryptStateEnum.ECS_PENDING)
{
SafeMemFile fileRequest = MpdObjectManager.CreateSafeMemFile(29);
byte bySemiRandomNotProtocolMarker = GetSemiRandomNotProtocolMarker();
fileRequest.WriteUInt8(bySemiRandomNotProtocolMarker);
fileRequest.WriteUInt32(randomKeyPart_);
fileRequest.WriteUInt32(MuleConstants.MAGICVALUE_SYNC);
byte bySupportedEncryptionMethod = Convert.ToByte(EncryptionMethodsEnum.ENM_OBFUSCATION); // we do not support any further encryption in this version
fileRequest.WriteUInt8(bySupportedEncryptionMethod);
fileRequest.WriteUInt8(bySupportedEncryptionMethod); // so we also prefer this one
byte byPadding = Convert.ToByte(MpdUtilities.GetRandomUInt8() %
(MuleApplication.Instance.Preference.CryptTCPPaddingLength + 1));
fileRequest.WriteUInt8(byPadding);
for (int i = 0; i < byPadding; i++)
{
fileRequest.WriteUInt8(MpdUtilities.GetRandomUInt8());
}
negotiatingState_ = NegotiatingStateEnum.ONS_BASIC_CLIENTB_MAGICVALUE;
streamCryptState_ = StreamCryptStateEnum.ECS_NEGOTIATING;
receiveBytesWanted_ = 4;
SendNegotiatingData(fileRequest.Buffer, (uint)fileRequest.Length, 5);
}
else if (streamCryptState_ == StreamCryptStateEnum.ECS_PENDING_SERVER)
{
SafeMemFile fileRequest = MpdObjectManager.CreateSafeMemFile(113);
byte bySemiRandomNotProtocolMarker = GetSemiRandomNotProtocolMarker();
fileRequest.WriteUInt8(bySemiRandomNotProtocolMarker);
cryptDHA_.genRandomBits((int)MuleConstants.DHAGREEMENT_A_BITS, new Random()); // our random a
BigInteger cryptDHPrime =
new BigInteger(dh768_p_, (int)MuleConstants.PRIMESIZE_BYTES); // our fixed prime
// calculate g^a % p
BigInteger cryptDHGexpAmodP =
new BigInteger(2).modPow(cryptDHA_, cryptDHPrime);
// put the result into a buffer
byte[] aBuffer = new byte[MuleConstants.PRIMESIZE_BYTES];
Array.Copy(cryptDHGexpAmodP.getBytes(), aBuffer, MuleConstants.PRIMESIZE_BYTES);
fileRequest.Write(aBuffer);
byte byPadding = (byte)(MpdUtilities.GetRandomUInt8() % 16); // add random padding
fileRequest.WriteUInt8(byPadding);
for (int i = 0; i < byPadding; i++)
{
fileRequest.WriteUInt8(MpdUtilities.GetRandomUInt8());
}
negotiatingState_ = NegotiatingStateEnum.ONS_BASIC_SERVER_DHANSWER;
streamCryptState_ = StreamCryptStateEnum.ECS_NEGOTIATING;
receiveBytesWanted_ = 96;
SendNegotiatingData(fileRequest.Buffer, (uint)fileRequest.Length, (uint)fileRequest.Length);
}
else
{
Debug.Assert(false);
streamCryptState_ = StreamCryptStateEnum.ECS_NONE;
return;
}
}
private int Negotiate(byte[] pBuffer, int offset, int nLen)
{
int nRead = 0;
Debug.Assert(receiveBytesWanted_ > 0);
try
{
while (negotiatingState_ != NegotiatingStateEnum.ONS_COMPLETE && receiveBytesWanted_ > 0)
{
if (receiveBytesWanted_ > 512)
{
Debug.Assert(false);
return(0);
}
if (fiReceiveBuffer_ == null)
{
byte[] pReceiveBuffer = new byte[512]; // use a fixed size buffer
fiReceiveBuffer_ = MpdObjectManager.CreateSafeMemFile(pReceiveBuffer);
}
int nToRead = Math.Min(Convert.ToInt32(nLen) - nRead, Convert.ToInt32(receiveBytesWanted_));
fiReceiveBuffer_.Write(pBuffer, nRead, nToRead);
nRead += nToRead;
receiveBytesWanted_ -= Convert.ToUInt32(nToRead);
if (receiveBytesWanted_ > 0)
{
return(nRead);
}
uint nCurrentBytesLen = (uint)fiReceiveBuffer_.Position;
if (negotiatingState_ != NegotiatingStateEnum.ONS_BASIC_CLIENTA_RANDOMPART &&
negotiatingState_ != NegotiatingStateEnum.ONS_BASIC_SERVER_DHANSWER)
{ // don't have the keys yet
byte[] pCryptBuffer = fiReceiveBuffer_.Buffer;
MuleUtilities.RC4Crypt(pCryptBuffer, pCryptBuffer, nCurrentBytesLen, rc4ReceiveKey_);
}
fiReceiveBuffer_.SeekToBegin();
switch (negotiatingState_)
{
case NegotiatingStateEnum.ONS_NONE: // would be a bug
Debug.Assert(false);
return(0);
case NegotiatingStateEnum.ONS_BASIC_CLIENTA_RANDOMPART:
{
Debug.Assert(rc4ReceiveKey_ == null);
byte[] achKeyData = new byte[21];
MpdUtilities.Md4Cpy(achKeyData, MuleApplication.Instance.Preference.UserHash);
achKeyData[16] = Convert.ToByte(MuleConstants.MAGICVALUE_REQUESTER);
fiReceiveBuffer_.Read(achKeyData, 17, 4); // random key part sent from remote client
MD5 md5 = MD5.Create();
rc4ReceiveKey_ =
MuleUtilities.RC4CreateKey(md5.ComputeHash(achKeyData), 16);
achKeyData[16] = Convert.ToByte(MuleConstants.MAGICVALUE_SERVER);
rc4SendKey_ =
MuleUtilities.RC4CreateKey(md5.ComputeHash(achKeyData), 16);
negotiatingState_ = NegotiatingStateEnum.ONS_BASIC_CLIENTA_MAGICVALUE;
receiveBytesWanted_ = 4;
break;
}
case NegotiatingStateEnum.ONS_BASIC_CLIENTA_MAGICVALUE:
{
uint dwValue = fiReceiveBuffer_.ReadUInt32();
if (dwValue == MuleConstants.MAGICVALUE_SYNC)
{
// yup, the one or the other way it worked, this is an encrypted stream
//DEBUG_ONLY( MpdUtilities.DebugLog(("Received proper magic value, clientIP: %s"), DbgGetIPString()) );
// set the receiver key
negotiatingState_ = NegotiatingStateEnum.ONS_BASIC_CLIENTA_METHODTAGSPADLEN;
receiveBytesWanted_ = 3;
}
else
{
MpdUtilities.DebugLogError(("CEncryptedStreamSocket: Received wrong magic value from clientIP %s on a supposly encrytped stream / Wrong Header"), DbgGetIPString());
OnError(Convert.ToInt32(EMSocketErrorCodeEnum.ERR_ENCRYPTION));
return(-1);
}
break;
}
case NegotiatingStateEnum.ONS_BASIC_CLIENTA_METHODTAGSPADLEN:
DbgByEncryptionSupported = fiReceiveBuffer_.ReadUInt8();
DbgByEncryptionRequested = fiReceiveBuffer_.ReadUInt8();
if (DbgByEncryptionRequested != Convert.ToByte(EncryptionMethodsEnum.ENM_OBFUSCATION))
{
MpdUtilities.AddDebugLogLine(EDebugLogPriority.DLP_LOW, false, ("CEncryptedStreamSocket: Client %s preffered unsupported encryption method (%i)"), DbgGetIPString(), DbgByEncryptionRequested);
}
receiveBytesWanted_ = fiReceiveBuffer_.ReadUInt8();
negotiatingState_ = NegotiatingStateEnum.ONS_BASIC_CLIENTA_PADDING;
if (receiveBytesWanted_ > 0)
{
break;
}
else
{
goto case NegotiatingStateEnum.ONS_BASIC_CLIENTA_PADDING;
}
case NegotiatingStateEnum.ONS_BASIC_CLIENTA_PADDING:
{
// ignore the random bytes, send the response, set status complete
SafeMemFile fileResponse = MpdObjectManager.CreateSafeMemFile(26);
fileResponse.WriteUInt32(MuleConstants.MAGICVALUE_SYNC);
byte bySelectedEncryptionMethod = Convert.ToByte(EncryptionMethodsEnum.ENM_OBFUSCATION); // we do not support any further encryption in this version, so no need to look which the other client preferred
fileResponse.WriteUInt8(bySelectedEncryptionMethod);
IPEndPoint remoteEp = RemoteEndPoint as IPEndPoint;
byte byPaddingLen =
MuleApplication.Instance.ServerConnect.AwaitingTestFromIP(BitConverter.ToUInt32(remoteEp.Address.GetAddressBytes(), 0))
? Convert.ToByte(16) :
Convert.ToByte(MuleApplication.Instance.Preference.CryptTCPPaddingLength + 1);
byte byPadding = Convert.ToByte(MpdUtilities.GetRandomUInt8() % byPaddingLen);
fileResponse.WriteUInt8(byPadding);
for (int i = 0; i < byPadding; i++)
{
fileResponse.WriteUInt8(MpdUtilities.GetRandomUInt8());
}
SendNegotiatingData(fileResponse.Buffer, (uint)fileResponse.Length);
negotiatingState_ = NegotiatingStateEnum.ONS_COMPLETE;
streamCryptState_ = StreamCryptStateEnum.ECS_ENCRYPTING;
//DEBUG_ONLY( MpdUtilities.DebugLog(("CEncryptedStreamSocket: Finished Obufscation handshake with client %s (incoming)"), DbgGetIPString()) );
break;
}
case NegotiatingStateEnum.ONS_BASIC_CLIENTB_MAGICVALUE:
{
if (fiReceiveBuffer_.ReadUInt32() != MuleConstants.MAGICVALUE_SYNC)
{
MpdUtilities.DebugLogError(("CEncryptedStreamSocket: EncryptedstreamSyncError: Client sent wrong Magic Value as answer, cannot complete handshake (%s)"), DbgGetIPString());
OnError(Convert.ToInt32(EMSocketErrorCodeEnum.ERR_ENCRYPTION));
return(-1);
}
negotiatingState_ = NegotiatingStateEnum.ONS_BASIC_CLIENTB_METHODTAGSPADLEN;
receiveBytesWanted_ = 2;
break;
}
case NegotiatingStateEnum.ONS_BASIC_CLIENTB_METHODTAGSPADLEN:
{
DbgByEncryptionMethodSet = fiReceiveBuffer_.ReadUInt8();
if (DbgByEncryptionMethodSet != Convert.ToByte(EncryptionMethodsEnum.ENM_OBFUSCATION))
{
MpdUtilities.DebugLogError(("CEncryptedStreamSocket: Client %s set unsupported encryption method (%i), handshake failed"),
DbgGetIPString(), DbgByEncryptionMethodSet);
OnError(Convert.ToInt32(EMSocketErrorCodeEnum.ERR_ENCRYPTION));
return(-1);
}
receiveBytesWanted_ = fiReceiveBuffer_.ReadUInt8();
negotiatingState_ = NegotiatingStateEnum.ONS_BASIC_CLIENTB_PADDING;
if (receiveBytesWanted_ > 0)
{
break;
}
else
{
goto case NegotiatingStateEnum.ONS_BASIC_CLIENTB_PADDING;
}
}
case NegotiatingStateEnum.ONS_BASIC_CLIENTB_PADDING:
// ignore the random bytes, the handshake is complete
negotiatingState_ = NegotiatingStateEnum.ONS_COMPLETE;
streamCryptState_ = StreamCryptStateEnum.ECS_ENCRYPTING;
//DEBUG_ONLY( MpdUtilities.DebugLog(("CEncryptedStreamSocket: Finished Obufscation handshake with client %s (outgoing)"), DbgGetIPString()) );
break;
case NegotiatingStateEnum.ONS_BASIC_SERVER_DHANSWER:
{
Debug.Assert(cryptDHA_ != new BigInteger(0));
byte[] aBuffer = new byte[MuleConstants.PRIMESIZE_BYTES + 1];
fiReceiveBuffer_.Read(aBuffer, 0, Convert.ToInt32(MuleConstants.PRIMESIZE_BYTES));
BigInteger cryptDHAnswer =
new BigInteger(aBuffer, (int)MuleConstants.PRIMESIZE_BYTES);
BigInteger cryptDHPrime =
new BigInteger(dh768_p_, (int)MuleConstants.PRIMESIZE_BYTES); // our fixed prime
BigInteger cryptResult =
cryptDHAnswer.modPow(cryptDHA_, cryptDHPrime);
cryptDHA_ = 0;
Array.Clear(aBuffer, 0, aBuffer.Length);
// create the keys
Array.Copy(cryptResult.getBytes(), aBuffer, MuleConstants.PRIMESIZE_BYTES);
aBuffer[MuleConstants.PRIMESIZE_BYTES] = Convert.ToByte(MuleConstants.MAGICVALUE_REQUESTER);
MD5 md5 = MD5.Create();
rc4SendKey_ =
MuleUtilities.RC4CreateKey(md5.ComputeHash(aBuffer), 16);
aBuffer[MuleConstants.PRIMESIZE_BYTES] = Convert.ToByte(MuleConstants.MAGICVALUE_SERVER);
rc4ReceiveKey_ =
MuleUtilities.RC4CreateKey(md5.ComputeHash(aBuffer), 16);
negotiatingState_ = NegotiatingStateEnum.ONS_BASIC_SERVER_MAGICVALUE;
receiveBytesWanted_ = 4;
break;
}
case NegotiatingStateEnum.ONS_BASIC_SERVER_MAGICVALUE:
{
uint dwValue = fiReceiveBuffer_.ReadUInt32();
if (dwValue == MuleConstants.MAGICVALUE_SYNC)
{
// yup, the one or the other way it worked, this is an encrypted stream
MpdUtilities.DebugLog(("Received proper magic value after DH-Agreement from Serverconnection IP: %s"), DbgGetIPString());
// set the receiver key
negotiatingState_ = NegotiatingStateEnum.ONS_BASIC_SERVER_METHODTAGSPADLEN;
receiveBytesWanted_ = 3;
}
else
{
MpdUtilities.DebugLogError(("CEncryptedStreamSocket: Received wrong magic value after DH-Agreement from Serverconnection"), DbgGetIPString());
OnError(Convert.ToInt32(EMSocketErrorCodeEnum.ERR_ENCRYPTION));
return(-1);
}
break;
}
case NegotiatingStateEnum.ONS_BASIC_SERVER_METHODTAGSPADLEN:
DbgByEncryptionSupported = fiReceiveBuffer_.ReadUInt8();
DbgByEncryptionRequested = fiReceiveBuffer_.ReadUInt8();
if (DbgByEncryptionRequested != Convert.ToByte(EncryptionMethodsEnum.ENM_OBFUSCATION))
{
MpdUtilities.AddDebugLogLine(EDebugLogPriority.DLP_LOW, false, ("CEncryptedStreamSocket: Server %s preffered unsupported encryption method (%i)"), DbgGetIPString(), DbgByEncryptionRequested);
}
receiveBytesWanted_ = fiReceiveBuffer_.ReadUInt8();
negotiatingState_ = NegotiatingStateEnum.ONS_BASIC_SERVER_PADDING;
if (receiveBytesWanted_ > 16)
{
MpdUtilities.AddDebugLogLine(EDebugLogPriority.DLP_LOW, false, ("CEncryptedStreamSocket: Server %s sent more than 16 (%i) padding bytes"), DbgGetIPString(), receiveBytesWanted_);
}
if (receiveBytesWanted_ > 0)
{
break;
}
else
{
goto case NegotiatingStateEnum.ONS_BASIC_SERVER_PADDING;
}
case NegotiatingStateEnum.ONS_BASIC_SERVER_PADDING:
{
// ignore the random bytes (they are decrypted already), send the response, set status complete
SafeMemFile fileResponse = MpdObjectManager.CreateSafeMemFile(26);
fileResponse.WriteUInt32(MuleConstants.MAGICVALUE_SYNC);
byte bySelectedEncryptionMethod =
Convert.ToByte(EncryptionMethodsEnum.ENM_OBFUSCATION); // we do not support any further encryption in this version, so no need to look which the other client preferred
fileResponse.WriteUInt8(bySelectedEncryptionMethod);
byte byPadding = (byte)(MpdUtilities.GetRandomUInt8() % 16);
fileResponse.WriteUInt8(byPadding);
for (int i = 0; i < byPadding; i++)
{
fileResponse.WriteUInt8(MpdUtilities.GetRandomUInt8());
}
negotiatingState_ = NegotiatingStateEnum.ONS_BASIC_SERVER_DELAYEDSENDING;
SendNegotiatingData(fileResponse.Buffer, (uint)fileResponse.Length, 0, true); // don't actually send it right now, store it in our sendbuffer
streamCryptState_ = StreamCryptStateEnum.ECS_ENCRYPTING;
MpdUtilities.DebugLog(("CEncryptedStreamSocket: Finished DH Obufscation handshake with Server %s"), DbgGetIPString());
break;
}
default:
Debug.Assert(false);
break;
}
fiReceiveBuffer_.SeekToBegin();
}
fiReceiveBuffer_ = null;
return(nRead);
}
catch (Exception)
{
Debug.Assert(false);
OnError(Convert.ToInt32(EMSocketErrorCodeEnum.ERR_ENCRYPTION));
fiReceiveBuffer_ = null;
return(-1);
}
}
