XKRC4.cpp

/*
**********************************
**********************************
**      BROUGHT TO YOU BY:		**
**********************************
**********************************
**								**
**		  [TEAM ASSEMBLY]		**
**								**
**		www.team-assembly.com	**
**								**
******************************************************************************************************
* This 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., 675 Mass Ave, Cambridge, MA 02139, USA.
******************************************************************************************************

********************************************************************************************************
**	     XKRC4.CPP - General RC4 Encryption Class' Implementation
********************************************************************************************************
**
**	This is the Class Contains basic RC4 encryption functionality...
**
********************************************************************************************************


********************************************************************************************************
**	CREDITS:
********************************************************************************************************
**	SPEEDBUMP:
**	---------
**		My utmost greatfullness and admiration goes towards SpeedBump for all his hard work..
**		I used most of his code and converted to C++ objects etc..
**
**	XBOX-LINUX TEAM:
**	---------------
**		Wow, you guys are awsome !!  I bow down to your greatness !!  
**		REFERENCE URL:  http://xbox-linux.sourceforge.net
**
********************************************************************************************************

UPDATE LOG:
--------------------------------------------------------------------------------------------------------
Date: 02/18/2003
By: UNDEAD [team-assembly]
Reason: Prepared 0.2 for Public Release
--------------------------------------------------------------------------------------------------------
Date: 01/06/2003
By: UNDEAD [team-assembly]
Reason: Prepared for Public Release
--------------------------------------------------------------------------------------------------------

*/
#include "XKRC4.h"

XKRC4::XKRC4(void)
{
}

XKRC4::~XKRC4(void)
{
}

void XKRC4::InitRC4Key(UCHAR* pRC4KeyData, int KeyLen, RC4KEY *pRC4Key)
{
	UCHAR index1;
	UCHAR index2;
	UCHAR* state;
	short counter;

	state = &pRC4Key->state[0];

	for(counter = 0; counter < 256; counter++)
		state[counter] = (UCHAR)counter;

	pRC4Key->x = 0;
	pRC4Key->y = 0;
	index1 = 0;
	index2 = 0;

	for(counter = 0; counter < 256; counter++)
	{
		index2 = (pRC4KeyData[index1] + state[counter] + index2) % 256;
		swap_byte(&state[counter], &state[index2]);
		index1 = (index1 + 1) % KeyLen;
	}
}

void XKRC4::RC4EnDecrypt(UCHAR* pData, int DataLen, RC4KEY *pRC4key)
{
	unsigned char x;
	unsigned char y;
	unsigned char* state;
	unsigned char xorIndex;
	long counter;

	x = pRC4key->x;
	y = pRC4key->y;
	state = &pRC4key->state[0];

	for(counter = 0; counter < DataLen; counter ++)
	{
		x = (x + 1) % 256;
		y = (state[x] + y) % 256;
		swap_byte(&state[x], &state[y]);
		xorIndex = (state[x] + state[y]) % 256;
		pData[counter] ^= state[xorIndex];
	}

	pRC4key->x = x;
	pRC4key->y = y;
}

void XKRC4::swap_byte(unsigned char *a, unsigned char *b)
{
	unsigned char swapByte;
	swapByte = *a;
	*a = *b;
	*b = swapByte;
}