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/***************************************************************************
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* Copyright (C) 2005-2006 by Tarek Saidi *
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* tarek.saidi@arcor.de *
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; version 2 of the License. *
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* *
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* This program is distributed in the hope that it will be useful, *
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* but WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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* GNU General Public License for more details. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program; if not, write to the *
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* Free Software Foundation, Inc., *
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* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
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***************************************************************************/
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#include <QByteArray>
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#include "arcfour.h"
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static inline void swap_byte(unsigned char *a, unsigned char *b)
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{
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unsigned char swapByte;
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swapByte = *a;
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*a = *b;
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*b = swapByte;
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}
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void CArcFour::setKey(byte* key_data_ptr, int key_data_len){
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RawKey=QByteArray((const char*)key_data_ptr,key_data_len);
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}
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void CArcFour::prepareKey(){
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unsigned char index1;
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unsigned char index2;
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unsigned char* state;
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short counter;
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state = &key.state[0];
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for(counter = 0; counter < 256; counter++)
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state[counter] = counter;
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key.x = 0;
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key.y = 0;
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index1 = 0;
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index2 = 0;
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for(counter = 0; counter < 256; counter++)
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{
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index2 = (RawKey.at(index1) + state[counter] + index2) % 256;
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swap_byte(&state[counter], &state[index2]);
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index1 = (index1 + 1) % RawKey.size();
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}
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}
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void CArcFour::encrypt(const byte* src, byte* dst,int length){
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prepareKey();
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unsigned char x;
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unsigned char y;
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unsigned char* state;
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unsigned char xorIndex;
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short counter;
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x = key.x;
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y = key.y;
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state = &key.state[0];
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for(counter = 0; counter < length; counter ++)
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{
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x = (x + 1) % 256;
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y = (state[x] + y) % 256;
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swap_byte(&state[x], &state[y]);
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xorIndex = (state[x] + state[y]) % 256;
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dst[counter]=src[counter]^state[xorIndex];
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}
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key.x = x;
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key.y = y;
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}
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