/***************************************************************************
 *   Copyright (C) 2005 by Joris Guisson                                   *
 *   joris.guisson@gmail.com                                               *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program 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, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.             *
 ***************************************************************************/
#ifndef MSERC4ENCRYPTOR_H
#define MSERC4ENCRYPTOR_H

#include <gcrypt.h>
#include <util/sha1hash.h>
#include <util/constants.h>
#include <ktorrent_export.h>

using bt::Uint8;
using bt::Uint32;

namespace mse
{

/**
 * @author Joris Guisson <joris.guisson@gmail.com>
 *
 * RC4 encryptor. Uses the RC4 algorithm to encrypt and decrypt data.
 * This class has a static encryption buffer, which makes it not thread safe
 * because the buffer is not protected by mutexes.
*/
class KTORRENT_EXPORT RC4Encryptor
{
public:
    RC4Encryptor(const bt::SHA1Hash & dkey, const bt::SHA1Hash & ekey);
    virtual ~RC4Encryptor();

    /**
     * Decrypt some data, decryption happens in place (original data gets overwritten)
     * @param data The data
     * @param len Size of the data
     */
    void decrypt(Uint8* data, Uint32 len);

    /**
     * Encrypt the data. Encryption happens into the static buffer.
     * So that the data passed to this function is never overwritten.
     * If we send pieces we point directly to the mmap region of data,
     * this cannot be overwritten, hence the static buffer.
     * @param data The data
     * @param len The length of the data
     * @return Pointer to the static buffer
     */
    const Uint8* encrypt(const Uint8* data, Uint32 len);

    /**
     * Encrypt data, encryption will happen in the same buffer. So data will
     * be changed replaced by it's encrypted version.
     * @param data The data to encrypt
     * @param len The length of the data
     */
    void encryptReplace(Uint8* data, Uint32 len);

private:
    gcry_cipher_hd_t enc;
    gcry_cipher_hd_t dec;
};

}

#endif
