barrier/src/lib/synergy/CCryptoStream.h

/*
 * synergy -- mouse and keyboard sharing utility
 * Copyright (C) 2013 Bolton Software Ltd.
 * 
 * This package is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * found in the file COPYING that should have accompanied this file.
 * 
 * This package is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#pragma once

#include "BasicTypes.h"
#include "CStreamFilter.h"
#include <cryptopp562/gcm.h>
#include <cryptopp562/modes.h>
#include <cryptopp562/aes.h>
#include <cryptopp562/osrng.h>

#define CRYPTO_IV_SIZE CryptoPP::AES::BLOCKSIZE

//! Bidirectional encrypted stream
/*!
Encrypts (on write) and decrypts (on read) to and from an underlying stream.
*/
class CCryptoStream : public CStreamFilter {
public:
	CCryptoStream(IEventQueue& eventQueue, synergy::IStream* stream, bool adoptStream = true);
	virtual ~CCryptoStream();

	//! @name manipulators
	//@{

	//! Read from stream
	/*!
	Read up to \p n bytes into \p buffer to the stream using encryption.
	Returns the number of bytes read by the underlying stream.
	*/
	virtual UInt32		read(void* out, UInt32 n);

	//! Write to stream
	/*!
	Write \c n bytes from \c buffer to the stream using encryption.
	*/
	virtual void		write(const void* in, UInt32 n);

    //! Set the key and IV
    void                setKeyWithIv(const byte* key, size_t length, const byte* iv);

    //! Set the IV
    void                setIv(const byte* iv);

	//! Get a new IV
	/*!
	Writes a new IV to the \c out buffer, and also uses the IV for further
	crypto.
	*/
	void				newIv(byte* out);

private:
	// TODO: allow user to change the block cypher mode.
	/*
	For CBC and CFB, reusing an IV leaks some information about the first block of plaintext,
	and about any common prefix shared by the two messages. For OFB and CTR, reusing an IV
	completely destroys security. http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation
	*/
	CryptoPP::OFB_Mode<CryptoPP::AES>::Encryption		m_encryption;
	CryptoPP::OFB_Mode<CryptoPP::AES>::Decryption		m_decryption;
	//CryptoPP::CFB_Mode<CryptoPP::AES>::Encryption		m_encryption;
	//CryptoPP::CFB_Mode<CryptoPP::AES>::Decryption		m_decryption;
	//CryptoPP::GCM<CryptoPP::AES>::Encryption			m_encryption;
	//CryptoPP::GCM<CryptoPP::AES>::Decryption			m_decryption;
	//CryptoPP::CTR_Mode<CryptoPP::AES>::Encryption		m_encryption;
	//CryptoPP::CTR_Mode<CryptoPP::AES>::Decryption		m_decryption;

	void				logBuffer(const char* name, const byte* buf, int length);

    const byte*			m_key;
    size_t				m_keyLength;
	CryptoPP::AutoSeededRandomPool m_autoSeedRandomPool;
};