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/* $OpenBSD: rc4_enc.c,v 1.16 2017/08/13 17:46:24 bcook Exp $ */
/* 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 <machine/endian.h>
#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
*/
void
RC4(RC4_KEY *key, size_t len, const unsigned char *indata,
unsigned char *outdata)
{
RC4_INT *d;
RC4_INT x, y,tx, ty;
size_t 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...
*
* Caveats.
*
* - 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 ((((size_t)indata & (sizeof(RC4_CHUNK) - 1)) |
((size_t)outdata & (sizeof(RC4_CHUNK) - 1))) == 0 ) {
RC4_CHUNK ichunk, otp;
/*
* 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>.
*
* Special notes.
*
* - 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 BYTE_ORDER == BIG_ENDIAN
# define BESHFT(c) (((sizeof(RC4_CHUNK)-(c)-1)*8)&(sizeof(RC4_CHUNK)*8-1))
for (; len & (0 - sizeof(RC4_CHUNK)); 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);
}
#else
# define LESHFT(c) (((c)*8)&(sizeof(RC4_CHUNK)*8-1))
for (; len & (0 - sizeof(RC4_CHUNK)); 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);
}
#endif
}
#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 = len >> 3;
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 = 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;
}
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