/* 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;

 	}