예제 #1
0
int CEncryptedDatagramSocket::EncryptSendServer(uchar** ppbyBuf, int nBufLen, uint32 dwBaseKey) const{
	ASSERT( thePrefs.IsServerCryptLayerUDPEnabled() );
	ASSERT( dwBaseKey != 0 );
	
	uint8 byPadLen = 0;			// padding disabled for UDP currently
	uint32 nCryptedLen = nBufLen + byPadLen + CRYPT_HEADER_WITHOUTPADDING;
	uchar* pachCryptedBuffer = new uchar[nCryptedLen];
	
	uint16 nRandomKeyPart = (uint16)cryptRandomGen.GenerateWord32(0x0000, 0xFFFF);

	uchar achKeyData[7];
	memcpy(achKeyData, &dwBaseKey, 4);
	achKeyData[4] = MAGICVALUE_UDP_CLIENTSERVER;
	memcpy(achKeyData + 5, &nRandomKeyPart, 2);
	MD5Sum md5(achKeyData, sizeof(achKeyData));
	RC4_Key_Struct keySendKey;
	RC4CreateKey(md5.GetRawHash(), 16, &keySendKey, true);

	// create the semi random byte encryption header
	uint8 bySemiRandomNotProtocolMarker = 0;
	int i;
	for (i = 0; i < 128; i++){
		bySemiRandomNotProtocolMarker = cryptRandomGen.GenerateByte();
		if (bySemiRandomNotProtocolMarker != OP_EDONKEYPROT) // not allowed values
			break;
	}
	if (i >= 128){
		// either we have _real_ bad luck or the randomgenerator is a bit messed up
		ASSERT( false );
		bySemiRandomNotProtocolMarker = 0x01;
	}

	uint32 dwMagicValue = MAGICVALUE_UDP_SYNC_SERVER;
	pachCryptedBuffer[0] = bySemiRandomNotProtocolMarker;
	memcpy(pachCryptedBuffer + 1, &nRandomKeyPart, 2);
	RC4Crypt((uchar*)&dwMagicValue, pachCryptedBuffer + 3, 4, &keySendKey);
	RC4Crypt((uchar*)&byPadLen, pachCryptedBuffer + 7, 1, &keySendKey);

	for (int j = 0; j < byPadLen; j++){
		uint8 byRand = (uint8)rand();	// they actually dont really need to be random, but it doesn't hurts either
		RC4Crypt((uchar*)&byRand, pachCryptedBuffer + CRYPT_HEADER_WITHOUTPADDING + j, 1, &keySendKey);
	}
	RC4Crypt(*ppbyBuf, pachCryptedBuffer + CRYPT_HEADER_WITHOUTPADDING + byPadLen, nBufLen, &keySendKey);
	delete[] *ppbyBuf;
	*ppbyBuf = pachCryptedBuffer;

	//Xman
	// Maella -Accurate measure of bandwidth: eDonkey data + control, network adapter-
	/*
	theStats.AddUpDataOverheadCrypt(nCryptedLen - nBufLen);
	*/
	theApp.pBandWidthControl->AddeMuleOutObfuscationUDP(nCryptedLen - nBufLen);
	//Xman end
	return nCryptedLen;
}
uint8_t CEncryptedStreamSocket::GetSemiRandomNotProtocolMarker() const{
	uint8_t bySemiRandomNotProtocolMarker = 0;
	int i;
	for (i = 0; i < 128; i++){
		bySemiRandomNotProtocolMarker = cryptRandomGen.GenerateByte();
		bool bOk = false;
		switch (bySemiRandomNotProtocolMarker){ // not allowed values
				case OP_EDONKEYPROT:
				case OP_PACKEDPROT:
				case OP_EMULEPROT:
					break;
				default:
					bOk = true;
		}
		if (bOk)
			break;
	}
	if (i >= 128){
		// either we have _real_ bad luck or the randomgenerator is a bit messed up
		ASSERT( false );
		bySemiRandomNotProtocolMarker = 0x01;
	}
	return bySemiRandomNotProtocolMarker;
}
예제 #3
0
// Encrypt packet. Key used:
// pachClientHashOrKadID != NULL									-> pachClientHashOrKadID
// pachClientHashOrKadID == NULL && bKad && nReceiverVerifyKey != 0 -> nReceiverVerifyKey
// else																-> ASSERT
int CEncryptedDatagramSocket::EncryptSendClient(uchar** ppbyBuf, int nBufLen, const uchar* pachClientHashOrKadID, bool bKad, uint32 nReceiverVerifyKey, uint32 nSenderVerifyKey) const{
	ASSERT( theApp.GetPublicIP() != 0 || bKad );
	ASSERT( thePrefs.IsClientCryptLayerSupported() );
	ASSERT( pachClientHashOrKadID != NULL || nReceiverVerifyKey != 0 );
	ASSERT( (nReceiverVerifyKey == 0 && nSenderVerifyKey == 0) || bKad );

	uint8 byPadLen = 0;			// padding disabled for UDP currently
	const uint32 nCryptHeaderLen = byPadLen + CRYPT_HEADER_WITHOUTPADDING + (bKad ? 8 : 0);
	
	uint32 nCryptedLen = nBufLen + nCryptHeaderLen;
	uchar* pachCryptedBuffer = new uchar[nCryptedLen];
	bool bKadRecKeyUsed = false;
	
	uint16 nRandomKeyPart = (uint16)cryptRandomGen.GenerateWord32(0x0000, 0xFFFF);
	MD5Sum md5;
	if (bKad){
		if ((pachClientHashOrKadID == NULL || isnulmd4(pachClientHashOrKadID)) && nReceiverVerifyKey != 0) {
			bKadRecKeyUsed = true;
			uchar achKeyData[6];
			PokeUInt32(achKeyData, nReceiverVerifyKey);
			PokeUInt16(achKeyData+4, nRandomKeyPart);
			md5.Calculate(achKeyData, sizeof(achKeyData));
			//DEBUG_ONLY( DebugLog(_T("Creating obfuscated Kad packet encrypted by ReceiverKey (%u)"), nReceiverVerifyKey) );  
		}
		else if (pachClientHashOrKadID != NULL && !isnulmd4(pachClientHashOrKadID)) {
			uchar achKeyData[18];
			md4cpy(achKeyData, pachClientHashOrKadID);
			PokeUInt16(achKeyData+16, nRandomKeyPart);
			md5.Calculate(achKeyData, sizeof(achKeyData));
			//DEBUG_ONLY( DebugLog(_T("Creating obfuscated Kad packet encrypted by Hash/NodeID %s"), md4str(pachClientHashOrKadID)) );  
		}
		else {
			ASSERT( false );
			delete[] pachCryptedBuffer;
			return nBufLen;
		}
	}
	else{
		uchar achKeyData[23];
		md4cpy(achKeyData, pachClientHashOrKadID);
		uint32 dwIP = theApp.GetPublicIP();
		memcpy(achKeyData+16, &dwIP, 4);
		memcpy(achKeyData+21, &nRandomKeyPart, 2);
		achKeyData[20] = MAGICVALUE_UDP;
		md5.Calculate(achKeyData, sizeof(achKeyData));
	}
	RC4_Key_Struct keySendKey;
	RC4CreateKey(md5.GetRawHash(), 16, &keySendKey, true);

	// create the semi random byte encryption header
	uint8 bySemiRandomNotProtocolMarker = 0;
	int i;
	for (i = 0; i < 128; i++){
		bySemiRandomNotProtocolMarker = cryptRandomGen.GenerateByte();
		bySemiRandomNotProtocolMarker = bKad ? (bySemiRandomNotProtocolMarker & 0xFE) : (bySemiRandomNotProtocolMarker | 0x01); // set the ed2k/kad marker bit
		if (bKad)
			bySemiRandomNotProtocolMarker = bKadRecKeyUsed ? ((bySemiRandomNotProtocolMarker & 0xFE) | 0x02) : (bySemiRandomNotProtocolMarker & 0xFC); // set the ed2k/kad and nodeid/reckey markerbit
		else
			bySemiRandomNotProtocolMarker = (bySemiRandomNotProtocolMarker | 0x01); // set the ed2k/kad marker bit
		
		bool bOk = false;
		switch (bySemiRandomNotProtocolMarker){ // not allowed values
			case OP_EMULEPROT:
			case OP_KADEMLIAPACKEDPROT:
			case OP_KADEMLIAHEADER:
			case OP_UDPRESERVEDPROT1:
			case OP_UDPRESERVEDPROT2:
			case OP_PACKEDPROT:
				break;
			default:
				bOk = true;
		}
		if (bOk)
			break;
	}
	if (i >= 128){
		// either we have _really_ bad luck or the randomgenerator is a bit messed up
		ASSERT( false );
		bySemiRandomNotProtocolMarker = 0x01;
	}

	uint32 dwMagicValue = MAGICVALUE_UDP_SYNC_CLIENT;
	pachCryptedBuffer[0] = bySemiRandomNotProtocolMarker;
	memcpy(pachCryptedBuffer + 1, &nRandomKeyPart, 2);
	RC4Crypt((uchar*)&dwMagicValue, pachCryptedBuffer + 3, 4, &keySendKey);
	RC4Crypt((uchar*)&byPadLen, pachCryptedBuffer + 7, 1, &keySendKey);

	for (int j = 0; j < byPadLen; j++){
		uint8 byRand = (uint8)rand();	// they actually dont really need to be random, but it doesn't hurts either
		RC4Crypt((uchar*)&byRand, pachCryptedBuffer + CRYPT_HEADER_WITHOUTPADDING + j, 1, &keySendKey);
	}

	if (bKad){
		RC4Crypt((uchar*)&nReceiverVerifyKey, pachCryptedBuffer + CRYPT_HEADER_WITHOUTPADDING + byPadLen, 4, &keySendKey);
		RC4Crypt((uchar*)&nSenderVerifyKey, pachCryptedBuffer + CRYPT_HEADER_WITHOUTPADDING + byPadLen + 4, 4, &keySendKey);
	}

	RC4Crypt(*ppbyBuf, pachCryptedBuffer + nCryptHeaderLen, nBufLen, &keySendKey);
	delete[] *ppbyBuf;
	*ppbyBuf = pachCryptedBuffer;

	//Xman
	// Maella -Accurate measure of bandwidth: eDonkey data + control, network adapter-
	/*
	theStats.AddUpDataOverheadCrypt(nCryptedLen - nBufLen);
	*/
	theApp.pBandWidthControl->AddeMuleOutObfuscationUDP(nCryptedLen - nBufLen);
	//Xman end

	return nCryptedLen;
}
예제 #4
0
int CEncryptedDatagramSocket::EncryptSendClient(uchar** ppbyBuf, int nBufLen, const uchar* pachClientHashOrKadID, bool bKad, uint16 nReceiverVerifyKey, uint16 nSenderVerifyKey) const{
	ASSERT( theApp.GetPublicIP() != 0 || bKad );
	ASSERT( thePrefs.IsClientCryptLayerSupported() );

	uint8 byPadLen = 0;			// padding disabled for UDP currently
	const uint32 nCryptHeaderLen = byPadLen + CRYPT_HEADER_WITHOUTPADDING + (bKad ? 4 : 0);
	uint32 nCryptedLen = nBufLen + nCryptHeaderLen;
	uchar* pachCryptedBuffer = new uchar[nCryptedLen];
	
	uint16 nRandomKeyPart = (uint16)cryptRandomGen.GenerateWord32(0x0000, 0xFFFF);
	MD5Sum md5;
	if (bKad){
		uchar achKeyData[18];
		md4cpy(achKeyData, pachClientHashOrKadID);
		memcpy(achKeyData+16, &nRandomKeyPart, 2);
		md5.Calculate(achKeyData, sizeof(achKeyData));
	}
	else{
		uchar achKeyData[23];
		md4cpy(achKeyData, pachClientHashOrKadID);
		uint32 dwIP = theApp.GetPublicIP();
		memcpy(achKeyData+16, &dwIP, 4);
		memcpy(achKeyData+21, &nRandomKeyPart, 2);
		achKeyData[20] = MAGICVALUE_UDP;
		md5.Calculate(achKeyData, sizeof(achKeyData));
	}
	RC4_Key_Struct keySendKey;
	RC4CreateKey(md5.GetRawHash(), 16, &keySendKey, true);

	// create the semi random byte encryption header
	uint8 bySemiRandomNotProtocolMarker = 0;
	int i;
	for (i = 0; i < 128; i++){
		bySemiRandomNotProtocolMarker = cryptRandomGen.GenerateByte();
		bySemiRandomNotProtocolMarker = bKad ? (bySemiRandomNotProtocolMarker & 0xFE) : (bySemiRandomNotProtocolMarker | 0x01); // set the ed2k/kad marker bit

		bool bOk = false;
		switch (bySemiRandomNotProtocolMarker){ // not allowed values
			case OP_EMULEPROT:
			case OP_KADEMLIAPACKEDPROT:
			case OP_KADEMLIAHEADER:
			case OP_UDPRESERVEDPROT1:
			case OP_UDPRESERVEDPROT2:
			case OP_PACKEDPROT:
				break;
			default:
				bOk = true;
		}
		if (bOk)
			break;
	}
	if (i >= 128){
		// either we have _real_ bad luck or the randomgenerator is a bit messed up
		ASSERT( false );
		bySemiRandomNotProtocolMarker = 0x01;
	}

	uint32 dwMagicValue = MAGICVALUE_UDP_SYNC_CLIENT;
	pachCryptedBuffer[0] = bySemiRandomNotProtocolMarker;
	memcpy(pachCryptedBuffer + 1, &nRandomKeyPart, 2);
	RC4Crypt((uchar*)&dwMagicValue, pachCryptedBuffer + 3, 4, &keySendKey);
	RC4Crypt((uchar*)&byPadLen, pachCryptedBuffer + 7, 1, &keySendKey);

	for (int j = 0; j < byPadLen; j++){
		uint8 byRand = (uint8)rand();	// they actually dont really need to be random, but it doesn't hurts either
		RC4Crypt((uchar*)&byRand, pachCryptedBuffer + CRYPT_HEADER_WITHOUTPADDING + j, 1, &keySendKey);
	}

	if (bKad){
		RC4Crypt((uchar*)&nReceiverVerifyKey, pachCryptedBuffer + CRYPT_HEADER_WITHOUTPADDING + byPadLen, 2, &keySendKey);
		RC4Crypt((uchar*)&nSenderVerifyKey, pachCryptedBuffer + CRYPT_HEADER_WITHOUTPADDING + byPadLen + 2, 2, &keySendKey);
	}

	RC4Crypt(*ppbyBuf, pachCryptedBuffer + nCryptHeaderLen, nBufLen, &keySendKey);
	delete[] *ppbyBuf;
	*ppbyBuf = pachCryptedBuffer;

	theStats.AddUpDataOverheadCrypt(nCryptedLen - nBufLen);
	return nCryptedLen;
}
int CEncryptedStreamSocket::Negotiate(const uchar* pBuffer, uint32_t nLen){
	uint32_t nRead = 0;
	ASSERT( m_nReceiveBytesWanted > 0 );
	try{
		while (m_NegotiatingState != ONS_COMPLETE && m_nReceiveBytesWanted > 0){		
			if (m_nReceiveBytesWanted > 512){
				ASSERT( false );
				return 0;
			}
			
			if (m_pfiReceiveBuffer == NULL){
				BYTE* pReceiveBuffer = (BYTE*)malloc(512); // use a fixed size buffer
				if (pReceiveBuffer == NULL)
					AfxThrowMemoryException();
				m_pfiReceiveBuffer = new CSafeMemFile(pReceiveBuffer, 512);
			}
			const uint32_t nToRead =  min(nLen - nRead, m_nReceiveBytesWanted);
			m_pfiReceiveBuffer->Write(pBuffer + nRead, nToRead);
			nRead += nToRead;
			m_nReceiveBytesWanted -= nToRead;
			if (m_nReceiveBytesWanted > 0)
				return nRead;
			const uint32_t nCurrentBytesLen = (uint32_t)m_pfiReceiveBuffer->GetPosition();

			if (m_NegotiatingState != ONS_BASIC_CLIENTA_RANDOMPART && m_NegotiatingState != ONS_BASIC_SERVER_DHANSWER){ // don't have the keys yet
				BYTE* pCryptBuffer = m_pfiReceiveBuffer->Detach();
				RC4Crypt(pCryptBuffer, pCryptBuffer, nCurrentBytesLen, m_pRC4ReceiveKey);
				m_pfiReceiveBuffer->Attach(pCryptBuffer, 512);
			}
			m_pfiReceiveBuffer->SeekToBegin();

			switch (m_NegotiatingState){
				case ONS_NONE: // would be a bug
					ASSERT( false ); 
					return 0;
				case ONS_BASIC_CLIENTA_RANDOMPART:{
					ASSERT( m_pRC4ReceiveKey == NULL );

					uchar achKeyData[21];
					md4cpy(achKeyData, thePrefs.GetUserHash());
					achKeyData[16] = MAGICVALUE_REQUESTER;
					m_pfiReceiveBuffer->Read(achKeyData + 17, 4); // random key part sent from remote client

					MD5Sum md5(achKeyData, sizeof(achKeyData));
					m_pRC4ReceiveKey = RC4CreateKey(md5.GetRawHash(), 16, NULL);
					achKeyData[16] = MAGICVALUE_SERVER;
					md5.Calculate(achKeyData, sizeof(achKeyData));
					m_pRC4SendKey = RC4CreateKey(md5.GetRawHash(), 16, NULL);
						
					m_NegotiatingState = ONS_BASIC_CLIENTA_MAGICVALUE;
					m_nReceiveBytesWanted = 4;
					break;
				}
				case ONS_BASIC_CLIENTA_MAGICVALUE:{
					uint32_t dwValue = m_pfiReceiveBuffer->ReadUInt32();
					if (dwValue == MAGICVALUE_SYNC){
						// yup, the one or the other way it worked, this is an encrypted stream
						//DEBUG_ONLY( DebugLog(_T("Received proper magic value, clientIP: %s"), DbgGetIPString()) );
						// set the receiver key
						m_NegotiatingState = ONS_BASIC_CLIENTA_METHODTAGSPADLEN;
						m_nReceiveBytesWanted = 3;	
					}
					else{
						DebugLogError(_T("CEncryptedStreamSocket: Received wrong magic value from clientIP %s on a supposly encrytped stream / Wrong Header"), DbgGetIPString());
						OnError(ERR_ENCRYPTION);
						return (-1);
					}
					break;
			    }
				case ONS_BASIC_CLIENTA_METHODTAGSPADLEN:
					m_dbgbyEncryptionSupported = m_pfiReceiveBuffer->ReadUInt8();
					m_dbgbyEncryptionRequested = m_pfiReceiveBuffer->ReadUInt8();
					if (m_dbgbyEncryptionRequested != ENM_OBFUSCATION)
						AddDebugLogLine(DLP_LOW, false, _T("CEncryptedStreamSocket: Client %s preffered unsupported encryption method (%i)"), DbgGetIPString(), m_dbgbyEncryptionRequested);
					m_nReceiveBytesWanted = m_pfiReceiveBuffer->ReadUInt8();
					m_NegotiatingState = ONS_BASIC_CLIENTA_PADDING;
					//if (m_nReceiveBytesWanted > 16)
					//	AddDebugLogLine(DLP_LOW, false, _T("CEncryptedStreamSocket: Client %s sent more than 16 (%i) padding bytes"), DbgGetIPString(), m_nReceiveBytesWanted);
					if (m_nReceiveBytesWanted > 0)
						break;
				case ONS_BASIC_CLIENTA_PADDING:{
					// ignore the random bytes, send the response, set status complete
					CSafeMemFile fileResponse(26);
					fileResponse.WriteUInt32(MAGICVALUE_SYNC);
					const uint8_t bySelectedEncryptionMethod = 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);
					
					SOCKADDR_IN sockAddr = {0};
					int nSockAddrLen = sizeof(sockAddr);
					GetPeerName((SOCKADDR*)&sockAddr, &nSockAddrLen);	
					const uint8_t byPaddingLen = theApp.serverconnect->AwaitingTestFromIP(sockAddr.sin_addr.S_un.S_addr) ? 16 : (thePrefs.GetCryptTCPPaddingLength() + 1);
					uint8_t byPadding = (uint8_t)(cryptRandomGen.GenerateByte() % byPaddingLen);
					
					fileResponse.WriteUInt8(byPadding);
					for (int i = 0; i < byPadding; i++)
						fileResponse.WriteUInt8(static_cast<uint8_t>(rand() & 0xFF));
					SendNegotiatingData(fileResponse.GetBuffer(), (uint32_t)fileResponse.GetLength());
					m_NegotiatingState = ONS_COMPLETE;
					m_StreamCryptState = ECS_ENCRYPTING;
					//DEBUG_ONLY( DebugLog(_T("CEncryptedStreamSocket: Finished Obufscation handshake with client %s (incoming)"), DbgGetIPString()) );
					break;
				}
				case ONS_BASIC_CLIENTB_MAGICVALUE:{
					if (m_pfiReceiveBuffer->ReadUInt32() != MAGICVALUE_SYNC){
						DebugLogError(_T("CEncryptedStreamSocket: EncryptedstreamSyncError: Client sent wrong Magic Value as answer, cannot complete handshake (%s)"), DbgGetIPString());
						OnError(ERR_ENCRYPTION);
						return (-1);
					}
					m_NegotiatingState = ONS_BASIC_CLIENTB_METHODTAGSPADLEN;
					m_nReceiveBytesWanted = 2;
					break;
				}
				case ONS_BASIC_CLIENTB_METHODTAGSPADLEN:{
					m_dbgbyEncryptionMethodSet = m_pfiReceiveBuffer->ReadUInt8();
					if (m_dbgbyEncryptionMethodSet != ENM_OBFUSCATION){
						DebugLogError( _T("CEncryptedStreamSocket: Client %s set unsupported encryption method (%i), handshake failed"), DbgGetIPString(), m_dbgbyEncryptionMethodSet);
						OnError(ERR_ENCRYPTION);
						return (-1);						
					}
					m_nReceiveBytesWanted = m_pfiReceiveBuffer->ReadUInt8();
					m_NegotiatingState = ONS_BASIC_CLIENTB_PADDING;
					if (m_nReceiveBytesWanted > 0)
						break;
				}
				case ONS_BASIC_CLIENTB_PADDING:
					// ignore the random bytes, the handshake is complete
					m_NegotiatingState = ONS_COMPLETE;
					m_StreamCryptState = ECS_ENCRYPTING;
					//DEBUG_ONLY( DebugLog(_T("CEncryptedStreamSocket: Finished Obufscation handshake with client %s (outgoing)"), DbgGetIPString()) );
					break;
				case ONS_BASIC_SERVER_DHANSWER:{
					ASSERT( !m_cryptDHA.IsZero() );
					uchar aBuffer[PRIMESIZE_BYTES + 1];
					m_pfiReceiveBuffer->Read(aBuffer, PRIMESIZE_BYTES);
					CryptoPP::Integer cryptDHAnswer((byte*)aBuffer, PRIMESIZE_BYTES);
					CryptoPP::Integer cryptDHPrime((byte*)dh768_p, PRIMESIZE_BYTES);  // our fixed prime
					CryptoPP::Integer cryptResult = CryptoPP::a_exp_b_mod_c(cryptDHAnswer, m_cryptDHA, cryptDHPrime);
					
					m_cryptDHA = 0;
					DEBUG_ONLY( ZeroMemory(aBuffer, sizeof(aBuffer)) );
					ASSERT( cryptResult.MinEncodedSize() <= PRIMESIZE_BYTES );
					
					// create the keys
					cryptResult.Encode(aBuffer, PRIMESIZE_BYTES);					
					aBuffer[PRIMESIZE_BYTES] = MAGICVALUE_REQUESTER;
					MD5Sum md5(aBuffer, sizeof(aBuffer));
					m_pRC4SendKey = RC4CreateKey(md5.GetRawHash(), 16, NULL);
					aBuffer[PRIMESIZE_BYTES] = MAGICVALUE_SERVER;
					md5.Calculate(aBuffer, sizeof(aBuffer));
					m_pRC4ReceiveKey = RC4CreateKey(md5.GetRawHash(), 16, NULL);

					m_NegotiatingState = ONS_BASIC_SERVER_MAGICVALUE;
					m_nReceiveBytesWanted = 4;
					break;
				}
				case ONS_BASIC_SERVER_MAGICVALUE:{
					uint32_t dwValue = m_pfiReceiveBuffer->ReadUInt32();
					if (dwValue == MAGICVALUE_SYNC){
						// yup, the one or the other way it worked, this is an encrypted stream
						DebugLog(_T("Received proper magic value after DH-Agreement from Serverconnection IP: %s"), DbgGetIPString());
						// set the receiver key
						m_NegotiatingState = ONS_BASIC_SERVER_METHODTAGSPADLEN;
						m_nReceiveBytesWanted = 3;	
					}
					else{
						DebugLogError(_T("CEncryptedStreamSocket: Received wrong magic value after DH-Agreement from Serverconnection"), DbgGetIPString());
						OnError(ERR_ENCRYPTION);
						return (-1);
					}
					break;
			    }
				case ONS_BASIC_SERVER_METHODTAGSPADLEN:
					m_dbgbyEncryptionSupported = m_pfiReceiveBuffer->ReadUInt8();
					m_dbgbyEncryptionRequested = m_pfiReceiveBuffer->ReadUInt8();
					if (m_dbgbyEncryptionRequested != ENM_OBFUSCATION)
						AddDebugLogLine(DLP_LOW, false, _T("CEncryptedStreamSocket: Server %s preffered unsupported encryption method (%i)"), DbgGetIPString(), m_dbgbyEncryptionRequested);
					m_nReceiveBytesWanted = m_pfiReceiveBuffer->ReadUInt8();
					m_NegotiatingState = ONS_BASIC_SERVER_PADDING;
					if (m_nReceiveBytesWanted > 16)
						AddDebugLogLine(DLP_LOW, false, _T("CEncryptedStreamSocket: Server %s sent more than 16 (%i) padding bytes"), DbgGetIPString(), m_nReceiveBytesWanted);
					if (m_nReceiveBytesWanted > 0)
						break;
				case ONS_BASIC_SERVER_PADDING:{
					// ignore the random bytes (they are decrypted already), send the response, set status complete
					CSafeMemFile fileResponse(26);
					fileResponse.WriteUInt32(MAGICVALUE_SYNC);
					const uint8_t bySelectedEncryptionMethod = 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);
					uint8_t byPadding = (uint8_t)(cryptRandomGen.GenerateByte() % 16);
					fileResponse.WriteUInt8(byPadding);
					for (int i = 0; i < byPadding; i++)
						fileResponse.WriteUInt8(static_cast<uint8_t>(rand() & 0xFF));
					
					m_NegotiatingState = ONS_BASIC_SERVER_DELAYEDSENDING;
					SendNegotiatingData(fileResponse.GetBuffer(), (uint32_t)fileResponse.GetLength(), 0, true); // don't actually send it right now, store it in our sendbuffer
					m_StreamCryptState = ECS_ENCRYPTING;
					DEBUG_ONLY( DebugLog(_T("CEncryptedStreamSocket: Finished DH Obufscation handshake with Server %s"), DbgGetIPString()) );
					break;
				}
				default:
					ASSERT( false );
			}
			m_pfiReceiveBuffer->SeekToBegin();
		}
		if (m_pfiReceiveBuffer != NULL)
			free(m_pfiReceiveBuffer->Detach());
		delete m_pfiReceiveBuffer;
		m_pfiReceiveBuffer = NULL;
		return nRead;
	}
	catch(CFileException* error){
		// can only be caused by a bug in negationhandling, not by the datastream
		error->Delete();
		ASSERT( false );
		OnError(ERR_ENCRYPTION);
		if (m_pfiReceiveBuffer != NULL)
			free(m_pfiReceiveBuffer->Detach());
		delete m_pfiReceiveBuffer;
		m_pfiReceiveBuffer = NULL;
		return (-1);
	}

}
void CEncryptedStreamSocket::StartNegotiation(bool bOutgoing){

	if (!bOutgoing){
		m_NegotiatingState = ONS_BASIC_CLIENTA_RANDOMPART;
		m_StreamCryptState = ECS_NEGOTIATING;
		m_nReceiveBytesWanted = 4;
	}
	else if (m_StreamCryptState == ECS_PENDING){
		
		CSafeMemFile fileRequest(29);
		const uint8_t bySemiRandomNotProtocolMarker = GetSemiRandomNotProtocolMarker();	
		fileRequest.WriteUInt8(bySemiRandomNotProtocolMarker);
		fileRequest.WriteUInt32(m_nRandomKeyPart);
		fileRequest.WriteUInt32(MAGICVALUE_SYNC);
		const uint8_t bySupportedEncryptionMethod = ENM_OBFUSCATION; // we do not support any further encryption in this version
		fileRequest.WriteUInt8(bySupportedEncryptionMethod);
		fileRequest.WriteUInt8(bySupportedEncryptionMethod); // so we also prefer this one
		uint8_t byPadding = (uint8_t)(cryptRandomGen.GenerateByte() % (thePrefs.GetCryptTCPPaddingLength() + 1));
		fileRequest.WriteUInt8(byPadding);
		for (int i = 0; i < byPadding; i++)
			fileRequest.WriteUInt8(cryptRandomGen.GenerateByte());
		
		m_NegotiatingState = ONS_BASIC_CLIENTB_MAGICVALUE;
		m_StreamCryptState = ECS_NEGOTIATING;
		m_nReceiveBytesWanted = 4;
		
		SendNegotiatingData(fileRequest.GetBuffer(), (uint32_t)fileRequest.GetLength(), 5);
	}
	else if (m_StreamCryptState == ECS_PENDING_SERVER){
		CSafeMemFile fileRequest(113);
		const uint8_t bySemiRandomNotProtocolMarker = GetSemiRandomNotProtocolMarker();	
		fileRequest.WriteUInt8(bySemiRandomNotProtocolMarker);
		
		m_cryptDHA.Randomize(cryptRandomGen, DHAGREEMENT_A_BITS); // our random a
		ASSERT( m_cryptDHA.MinEncodedSize() <= DHAGREEMENT_A_BITS / 8 );
		CryptoPP::Integer cryptDHPrime((byte*)dh768_p, PRIMESIZE_BYTES);  // our fixed prime
		// calculate g^a % p
		CryptoPP::Integer cryptDHGexpAmodP = CryptoPP::a_exp_b_mod_c(CryptoPP::Integer(2), m_cryptDHA, cryptDHPrime);  
		ASSERT( m_cryptDHA.MinEncodedSize() <= PRIMESIZE_BYTES );
		// put the result into a buffer
		uchar aBuffer[PRIMESIZE_BYTES];
		cryptDHGexpAmodP.Encode(aBuffer, PRIMESIZE_BYTES);

		fileRequest.Write(aBuffer, PRIMESIZE_BYTES);
		uint8_t byPadding = (uint8_t)(cryptRandomGen.GenerateByte() % 16); // add random padding
		fileRequest.WriteUInt8(byPadding);
		for (int i = 0; i < byPadding; i++)
			fileRequest.WriteUInt8(cryptRandomGen.GenerateByte());
		
		m_NegotiatingState = ONS_BASIC_SERVER_DHANSWER;
		m_StreamCryptState = ECS_NEGOTIATING;
		m_nReceiveBytesWanted = 96;
		
		SendNegotiatingData(fileRequest.GetBuffer(), (uint32_t)fileRequest.GetLength(), (uint32_t)fileRequest.GetLength());
	}
	else{
		ASSERT( false );
		m_StreamCryptState = ECS_NONE;
		return;
	}
}