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/*
* Copyright (c) 2007 Rozhuk Ivan <rozhuk.im@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
#if !defined(AFX_RC4__H__INCLUDED_)
#define AFX_RC4__H__INCLUDED_
#pragma once
__inline void RC4(LPBYTE lpBuff,size_t dwBuffSize,LPBYTE lpKey,size_t dwKeySize)
{// RC4
// www.codeproject.com/cpp/crypt_routine.asp%3Fdf%3D100%26forumid%3D4418%26exp%3D0%26select%3D251879+RC4+c%2B%2B+source+DWORD&hl=ru&gl=ru&ct=clnk&cd=2
// http://www.thecodeproject.com/cpp/crypt_routine.asp
// http://forum.ixbt.com/topic.cgi?id=40:3020
//we will consider size of sbox 256 bytes
//(extra byte are only to prevent any mishep just in case)
BYTE temp;
BYTE Sbox[260]={0},Sbox2[260]={0};
size_t i,j,t,x;
i=j=t=x=0;
temp=0;
//initialize sbox i
for(i=0;i<256;i++) Sbox[i]=(BYTE)i;
j=0;
//whether user has sent any inpur lpKey
//initialize the sbox2 with user lpKey
for(i=0;i<256;i++)
{
if (j==dwKeySize) j=0;
Sbox2[i]=lpKey[j++];
}
j=0; //Initialize j
//scramble sbox1 with sbox2
for(i=0;i<256;i++)
{
j=(j+(unsigned long)Sbox[i]+(unsigned long)Sbox2[i]) % 256U;
temp=Sbox[i];
Sbox[i]=Sbox[j];
Sbox[j]=temp;
}
i=j=0;
for(x=0;x<dwBuffSize;x++)
{
//increment i
i=(i+1U)%256U;
//increment j
j=(j+(unsigned long)Sbox[i])%256U;
//Scramble SBox #1 further so encryption routine will
//will repeat itself at great interval
temp=Sbox[i];
Sbox[i]=Sbox[j];
Sbox[j]=temp;
//Get ready to create pseudo random byte for encryption lpKey
t=((unsigned long)Sbox[i]+(unsigned long)Sbox[j])%256U;
//get the random byte
//xor with the data and done
lpBuff[x]=(lpBuff[x]^Sbox[t]);
}
}
#endif // !defined(AFX_RC4__H__INCLUDED_)
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