/* crypto/rc4/rc4_enc.c */

/* Copyright (C) 1995-1998 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 <openssl/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

 */

EXPORT_C void RC4(RC4_KEY *key, unsigned long len, const 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; 

#if defined(RC4_CHUNK)

	/*

	 * The original reason for implementing this(*) was the fact that

	 * pre-21164a Alpha CPUs don't have byte load/store instructions

	 * and e.g. a byte store has to be done with 64-bit load, shift,

	 * and, or and finally 64-bit store. Peaking data and operating

	 * at natural word size made it possible to reduce amount of

	 * instructions as well as to perform early read-ahead without

	 * suffering from RAW (read-after-write) hazard. This resulted

	 * in ~40%(**) performance improvement on 21064 box with gcc.

	 * But it's not only Alpha users who win here:-) Thanks to the

	 * early-n-wide read-ahead this implementation also exhibits

	 * >40% speed-up on SPARC and 20-30% on 64-bit MIPS (depending

	 * on sizeof(RC4_INT)).

	 *

	 * (*)	"this" means code which recognizes the case when input

	 *	and output pointers appear to be aligned at natural CPU

	 *	word boundary

	 * (**)	i.e. according to 'apps/openssl speed rc4' benchmark,

	 *	crypto/rc4/rc4speed.c exhibits almost 70% speed-up...

	 *

	 * Cavets.

	 *

	 * - RC4_CHUNK="unsigned long long" should be a #1 choice for

	 *   UltraSPARC. Unfortunately gcc generates very slow code

	 *   (2.5-3 times slower than one generated by Sun's WorkShop

	 *   C) and therefore gcc (at least 2.95 and earlier) should

	 *   always be told that RC4_CHUNK="unsigned long".

	 *

	 *					<appro@fy.chalmers.se>

	 */

# define RC4_STEP	( \

			x=(x+1) &0xff,	\

			tx=d[x],	\

			y=(tx+y)&0xff,	\

			ty=d[y],	\

			d[y]=tx,	\

			d[x]=ty,	\

			(RC4_CHUNK)d[(tx+ty)&0xff]\

			)

	if ( ( ((unsigned long)indata  & (sizeof(RC4_CHUNK)-1)) | 

	       ((unsigned long)outdata & (sizeof(RC4_CHUNK)-1)) ) == 0 )

		{

		RC4_CHUNK ichunk,otp;

		const union { long one; char little; } is_endian = {1};

		/*

		 * I reckon we can afford to implement both endian

		 * cases and to decide which way to take at run-time

		 * because the machine code appears to be very compact

		 * and redundant 1-2KB is perfectly tolerable (i.e.

		 * in case the compiler fails to eliminate it:-). By

		 * suggestion from Terrel Larson <terr@terralogic.net>

		 * who also stands for the is_endian union:-)

		 *

		 * Special notes.

		 *

		 * - is_endian is declared automatic as doing otherwise

		 *   (declaring static) prevents gcc from eliminating

		 *   the redundant code;

		 * - compilers (those I've tried) don't seem to have

		 *   problems eliminating either the operators guarded

		 *   by "if (sizeof(RC4_CHUNK)==8)" or the condition

		 *   expressions themselves so I've got 'em to replace

		 *   corresponding #ifdefs from the previous version;

		 * - I chose to let the redundant switch cases when

		 *   sizeof(RC4_CHUNK)!=8 be (were also #ifdefed

		 *   before);

		 * - in case you wonder "&(sizeof(RC4_CHUNK)*8-1)" in

		 *   [LB]ESHFT guards against "shift is out of range"

		 *   warnings when sizeof(RC4_CHUNK)!=8 

		 *

		 *			<appro@fy.chalmers.se>

		 */

		if (!is_endian.little)

			{	/* BIG-ENDIAN CASE */

# define BESHFT(c)	(((sizeof(RC4_CHUNK)-(c)-1)*8)&(sizeof(RC4_CHUNK)*8-1))

			for (;len&~(sizeof(RC4_CHUNK)-1);len-=sizeof(RC4_CHUNK))

				{

				ichunk  = *(RC4_CHUNK *)indata;

				otp  = RC4_STEP<<BESHFT(0);

				otp |= RC4_STEP<<BESHFT(1);

				otp |= RC4_STEP<<BESHFT(2);

				otp |= RC4_STEP<<BESHFT(3);

				if (sizeof(RC4_CHUNK)==8)

					{

					otp |= RC4_STEP<<BESHFT(4);

					otp |= RC4_STEP<<BESHFT(5);

					otp |= RC4_STEP<<BESHFT(6);

					otp |= RC4_STEP<<BESHFT(7);

					}

				*(RC4_CHUNK *)outdata = otp^ichunk;

				indata  += sizeof(RC4_CHUNK);

				outdata += sizeof(RC4_CHUNK);

				}

			if (len)

				{

				RC4_CHUNK mask=(RC4_CHUNK)-1, ochunk;

				ichunk = *(RC4_CHUNK *)indata;

				ochunk = *(RC4_CHUNK *)outdata;

				otp = 0;

				i = BESHFT(0);

				mask <<= (sizeof(RC4_CHUNK)-len)<<3;

				switch (len&(sizeof(RC4_CHUNK)-1))

					{

					case 7:	otp  = RC4_STEP<<i, i-=8;

					case 6:	otp |= RC4_STEP<<i, i-=8;

					case 5:	otp |= RC4_STEP<<i, i-=8;

					case 4:	otp |= RC4_STEP<<i, i-=8;

					case 3:	otp |= RC4_STEP<<i, i-=8;

					case 2:	otp |= RC4_STEP<<i, i-=8;

					case 1:	otp |= RC4_STEP<<i, i-=8;

					case 0: ; /*

						   * it's never the case,

						   * but it has to be here

						   * for ultrix?

						   */

					}

				ochunk &= ~mask;

				ochunk |= (otp^ichunk) & mask;

				*(RC4_CHUNK *)outdata = ochunk;

				}

			key->x=x;     

			key->y=y;

			return;

			}

		else

			{	/* LITTLE-ENDIAN CASE */

# define LESHFT(c)	(((c)*8)&(sizeof(RC4_CHUNK)*8-1))

			for (;len&~(sizeof(RC4_CHUNK)-1);len-=sizeof(RC4_CHUNK))

				{

				ichunk  = *(RC4_CHUNK *)indata;

				otp  = RC4_STEP;

				otp |= RC4_STEP<<8;

				otp |= RC4_STEP<<16;

				otp |= RC4_STEP<<24;

				if (sizeof(RC4_CHUNK)==8)

					{

					otp |= RC4_STEP<<LESHFT(4);

					otp |= RC4_STEP<<LESHFT(5);

					otp |= RC4_STEP<<LESHFT(6);

					otp |= RC4_STEP<<LESHFT(7);

					}

				*(RC4_CHUNK *)outdata = otp^ichunk;

				indata  += sizeof(RC4_CHUNK);

				outdata += sizeof(RC4_CHUNK);

				}

			if (len)

				{

				RC4_CHUNK mask=(RC4_CHUNK)-1, ochunk;

				ichunk = *(RC4_CHUNK *)indata;

				ochunk = *(RC4_CHUNK *)outdata;

				otp = 0;

				i   = 0;

				mask >>= (sizeof(RC4_CHUNK)-len)<<3;

				switch (len&(sizeof(RC4_CHUNK)-1))

					{

					case 7:	otp  = RC4_STEP,    i+=8;

					case 6:	otp |= RC4_STEP<<i, i+=8;

					case 5:	otp |= RC4_STEP<<i, i+=8;

					case 4:	otp |= RC4_STEP<<i, i+=8;

					case 3:	otp |= RC4_STEP<<i, i+=8;

					case 2:	otp |= RC4_STEP<<i, i+=8;

					case 1:	otp |= RC4_STEP<<i, i+=8;

					case 0: ; /*

						   * it's never the case,

						   * but it has to be here

						   * for ultrix?

						   */

					}

				ochunk &= ~mask;

				ochunk |= (otp^ichunk) & mask;

				*(RC4_CHUNK *)outdata = ochunk;

				}

			key->x=x;     

			key->y=y;

			return;

			}

		}

#endif

#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>>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;

	}