/* crypto/rc4/rc4_enc.org */
/* Copyright (C) 1995-1997 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
* 
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to.  The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code.  The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
* 
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
* 
* 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 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.
* 3. All advertising materials mentioning features or use of this software
*    must display the following acknowledgement:
*    "This product includes cryptographic software written by
*     Eric Young (eay@cryptsoft.com)"
*    The word 'cryptographic' can be left out if the rouines from the library
*    being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from 
*    the apps directory (application code) you must include an acknowledgement:
*    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
* 
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``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 AUTHOR 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.
* 
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed.  i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.]
*/

#include "stdafx.h"
#include "rc4.h"
#include "rc4_locl.h"

/* RC4 as implemented from a posting from
* Newsgroups: sci.crypt
* From: sterndark@netcom.com (David Sterndark)
* Subject: RC4 Algorithm revealed.
* Message-ID: <sternCvKL4B.Hyy@netcom.com>
* Date: Wed, 14 Sep 1994 06:35:31 GMT
*/

void RC4(RC4_KEY *key, unsigned long len, unsigned char *indata, unsigned char *outdata)
{
	register RC4_INT *d;
	register RC4_INT x,y,tx,ty;
	int i;

	x=key->x;     
	y=key->y;     
	d=key->data; 

#define LOOP(in,out) \
	x=((x+1)&0xff); \
	tx=d[x]; \
	y=(tx+y)&0xff; \
	d[x]=ty=d[y]; \
	d[y]=tx; \
	(out) = d[(tx+ty)&0xff]^ (in);

#ifndef RC4_INDEX
#define RC4_LOOP(a,b,i)	LOOP(*((a)++),*((b)++))
#else
#define RC4_LOOP(a,b,i)	LOOP(a[i],b[i])
#endif

	i= -(int)len;
	i=(int)(len>>3L);
	if (i)
	{
		for (;;)
		{
			RC4_LOOP(indata,outdata,0);
			RC4_LOOP(indata,outdata,1);
			RC4_LOOP(indata,outdata,2);
			RC4_LOOP(indata,outdata,3);
			RC4_LOOP(indata,outdata,4);
			RC4_LOOP(indata,outdata,5);
			RC4_LOOP(indata,outdata,6);
			RC4_LOOP(indata,outdata,7);
#ifdef RC4_INDEX
			indata+=8;
			outdata+=8;
#endif
			if (--i == 0) break;
		}
	}
	i=(int)len&0x07;
	if (i)
	{
		for (;;)
		{
			RC4_LOOP(indata,outdata,0); if (--i == 0) break;
			RC4_LOOP(indata,outdata,1); if (--i == 0) break;
			RC4_LOOP(indata,outdata,2); if (--i == 0) break;
			RC4_LOOP(indata,outdata,3); if (--i == 0) break;
			RC4_LOOP(indata,outdata,4); if (--i == 0) break;
			RC4_LOOP(indata,outdata,5); if (--i == 0) break;
			RC4_LOOP(indata,outdata,6); if (--i == 0) break;
		}
	}               
	key->x=x;     
	key->y=y;
}