lib/libcrypto/rc4/rc4_enc.c

   1 /* $OpenBSD: rc4_enc.c,v 1.16 2017/08/13 17:46:24 bcook Exp $ */
   2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   3  * All rights reserved.
   4  *
   5  * This package is an SSL implementation written
   6  * by Eric Young (eay@cryptsoft.com).
   7  * The implementation was written so as to conform with Netscapes SSL.
   8  *
   9  * This library is free for commercial and non-commercial use as long as
  10  * the following conditions are aheared to.  The following conditions
  11  * apply to all code found in this distribution, be it the RC4, RSA,
  12  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  13  * included with this distribution is covered by the same copyright terms
  14  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  15  *
  16  * Copyright remains Eric Young's, and as such any Copyright notices in
  17  * the code are not to be removed.
  18  * If this package is used in a product, Eric Young should be given attribution
  19  * as the author of the parts of the library used.
  20  * This can be in the form of a textual message at program startup or
  21  * in documentation (online or textual) provided with the package.
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  * 3. All advertising materials mentioning features or use of this software
  32  *    must display the following acknowledgement:
  33  *    "This product includes cryptographic software written by
  34  *     Eric Young (eay@cryptsoft.com)"
  35  *    The word 'cryptographic' can be left out if the rouines from the library
  36  *    being used are not cryptographic related :-).
  37  * 4. If you include any Windows specific code (or a derivative thereof) from
  38  *    the apps directory (application code) you must include an acknowledgement:
  39  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51  * SUCH DAMAGE.
  52  *
  53  * The licence and distribution terms for any publically available version or
  54  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  55  * copied and put under another distribution licence
  56  * [including the GNU Public Licence.]
  57  */
  58
  59 #include <machine/endian.h>
  60 #include <openssl/rc4.h>
  61 #include "rc4_locl.h"
  62
  63 /* RC4 as implemented from a posting from
  64  * Newsgroups: sci.crypt
  65  * From: sterndark@netcom.com (David Sterndark)
  66  * Subject: RC4 Algorithm revealed.
  67  * Message-ID: <sternCvKL4B.Hyy@netcom.com>
  68  * Date: Wed, 14 Sep 1994 06:35:31 GMT
  69  */
  70
  71 void
  72 RC4(RC4_KEY *key, size_t len, const unsigned char *indata,
  73     unsigned char *outdata)
  74 {
  75         RC4_INT *d;
  76         RC4_INT x, y,tx, ty;
  77         size_t i;
  78
  79         x = key->x;
  80         y = key->y;
  81         d = key->data;
  82
  83 #if defined(RC4_CHUNK)
  84         /*
  85          * The original reason for implementing this(*) was the fact that
  86          * pre-21164a Alpha CPUs don't have byte load/store instructions
  87          * and e.g. a byte store has to be done with 64-bit load, shift,
  88          * and, or and finally 64-bit store. Peaking data and operating
  89          * at natural word size made it possible to reduce amount of
  90          * instructions as well as to perform early read-ahead without
  91          * suffering from RAW (read-after-write) hazard. This resulted
  92          * in ~40%(**) performance improvement on 21064 box with gcc.
  93          * But it's not only Alpha users who win here:-) Thanks to the
  94          * early-n-wide read-ahead this implementation also exhibits
  95          * >40% speed-up on SPARC and 20-30% on 64-bit MIPS (depending
  96          * on sizeof(RC4_INT)).
  97          *
  98          * (*)  "this" means code which recognizes the case when input
  99          *      and output pointers appear to be aligned at natural CPU
 100          *      word boundary
 101          * (**) i.e. according to 'apps/openssl speed rc4' benchmark,
 102          *      crypto/rc4/rc4speed.c exhibits almost 70% speed-up...
 103          *
 104          * Caveats.
 105          *
 106          * - RC4_CHUNK="unsigned long long" should be a #1 choice for
 107          *   UltraSPARC. Unfortunately gcc generates very slow code
 108          *   (2.5-3 times slower than one generated by Sun's WorkShop
 109          *   C) and therefore gcc (at least 2.95 and earlier) should
 110          *   always be told that RC4_CHUNK="unsigned long".
 111          *
 112          *                                      <appro@fy.chalmers.se>
 113          */
 114
 115 # define RC4_STEP       ( \
 116                         x=(x+1) &0xff,  \
 117                         tx=d[x],        \
 118                         y=(tx+y)&0xff,  \
 119                         ty=d[y],        \
 120                         d[y]=tx,        \
 121                         d[x]=ty,        \
 122                         (RC4_CHUNK)d[(tx+ty)&0xff]\
 123                         )
 124
 125         if ((((size_t)indata & (sizeof(RC4_CHUNK) - 1)) |
 126             ((size_t)outdata & (sizeof(RC4_CHUNK) - 1))) == 0 ) {
 127                 RC4_CHUNK ichunk, otp;
 128
 129                 /*
 130                  * I reckon we can afford to implement both endian
 131                  * cases and to decide which way to take at run-time
 132                  * because the machine code appears to be very compact
 133                  * and redundant 1-2KB is perfectly tolerable (i.e.
 134                  * in case the compiler fails to eliminate it:-). By
 135                  * suggestion from Terrel Larson <terr@terralogic.net>.
 136                  *
 137                  * Special notes.
 138                  *
 139                  * - compilers (those I've tried) don't seem to have
 140                  *   problems eliminating either the operators guarded
 141                  *   by "if (sizeof(RC4_CHUNK)==8)" or the condition
 142                  *   expressions themselves so I've got 'em to replace
 143                  *   corresponding #ifdefs from the previous version;
 144                  * - I chose to let the redundant switch cases when
 145                  *   sizeof(RC4_CHUNK)!=8 be (were also #ifdefed
 146                  *   before);
 147                  * - in case you wonder "&(sizeof(RC4_CHUNK)*8-1)" in
 148                  *   [LB]ESHFT guards against "shift is out of range"
 149                  *   warnings when sizeof(RC4_CHUNK)!=8
 150                  *
 151                  *                      <appro@fy.chalmers.se>
 152                  */
 153 #if BYTE_ORDER == BIG_ENDIAN
 154 # define BESHFT(c)      (((sizeof(RC4_CHUNK)-(c)-1)*8)&(sizeof(RC4_CHUNK)*8-1))
 155                 for (; len & (0 - sizeof(RC4_CHUNK)); len -= sizeof(RC4_CHUNK)) {
 156                         ichunk  = *(RC4_CHUNK *)indata;
 157                         otp = RC4_STEP << BESHFT(0);
 158                         otp |= RC4_STEP << BESHFT(1);
 159                         otp |= RC4_STEP << BESHFT(2);
 160                         otp |= RC4_STEP << BESHFT(3);
 161                         if (sizeof(RC4_CHUNK) == 8) {
 162                                 otp |= RC4_STEP << BESHFT(4);
 163                                 otp |= RC4_STEP << BESHFT(5);
 164                                 otp |= RC4_STEP << BESHFT(6);
 165                                 otp |= RC4_STEP << BESHFT(7);
 166                         }
 167                         *(RC4_CHUNK *)outdata = otp^ichunk;
 168                         indata += sizeof(RC4_CHUNK);
 169                         outdata += sizeof(RC4_CHUNK);
 170                 }
 171 #else
 172 # define LESHFT(c)      (((c)*8)&(sizeof(RC4_CHUNK)*8-1))
 173                 for (; len & (0 - sizeof(RC4_CHUNK)); len -= sizeof(RC4_CHUNK)) {
 174                         ichunk = *(RC4_CHUNK *)indata;
 175                         otp = RC4_STEP;
 176                         otp |= RC4_STEP << 8;
 177                         otp |= RC4_STEP << 16;
 178                         otp |= RC4_STEP << 24;
 179                         if (sizeof(RC4_CHUNK) == 8) {
 180                                 otp |= RC4_STEP << LESHFT(4);
 181                                 otp |= RC4_STEP << LESHFT(5);
 182                                 otp |= RC4_STEP << LESHFT(6);
 183                                 otp |= RC4_STEP << LESHFT(7);
 184                         }
 185                         *(RC4_CHUNK *)outdata = otp ^ ichunk;
 186                         indata += sizeof(RC4_CHUNK);
 187                         outdata += sizeof(RC4_CHUNK);
 188                 }
 189 #endif
 190         }
 191 #endif
 192 #define LOOP(in,out) \
 193                 x=((x+1)&0xff); \
 194                 tx=d[x]; \
 195                 y=(tx+y)&0xff; \
 196                 d[x]=ty=d[y]; \
 197                 d[y]=tx; \
 198                 (out) = d[(tx+ty)&0xff]^ (in);
 199
 200 #ifndef RC4_INDEX
 201 #define RC4_LOOP(a,b,i) LOOP(*((a)++),*((b)++))
 202 #else
 203 #define RC4_LOOP(a,b,i) LOOP(a[i],b[i])
 204 #endif
 205
 206         i = len >> 3;
 207         if (i) {
 208                 for (;;) {
 209                         RC4_LOOP(indata, outdata, 0);
 210                         RC4_LOOP(indata, outdata, 1);
 211                         RC4_LOOP(indata, outdata, 2);
 212                         RC4_LOOP(indata, outdata, 3);
 213                         RC4_LOOP(indata, outdata, 4);
 214                         RC4_LOOP(indata, outdata, 5);
 215                         RC4_LOOP(indata, outdata, 6);
 216                         RC4_LOOP(indata, outdata, 7);
 217 #ifdef RC4_INDEX
 218                         indata += 8;
 219                         outdata += 8;
 220 #endif
 221                         if (--i == 0)
 222                                 break;
 223                 }
 224         }
 225         i = len&0x07;
 226         if (i) {
 227                 for (;;) {
 228                         RC4_LOOP(indata, outdata, 0);
 229                         if (--i == 0)
 230                                 break;
 231                         RC4_LOOP(indata, outdata, 1);
 232                         if (--i == 0)
 233                                 break;
 234                         RC4_LOOP(indata, outdata, 2);
 235                         if (--i == 0)
 236                                 break;
 237                         RC4_LOOP(indata, outdata, 3);
 238                         if (--i == 0)
 239                                 break;
 240                         RC4_LOOP(indata, outdata, 4);
 241                         if (--i == 0)
 242                                 break;
 243                         RC4_LOOP(indata, outdata, 5);
 244                         if (--i == 0)
 245                                 break;
 246                         RC4_LOOP(indata, outdata, 6);
 247                         if (--i == 0)
 248                                 break;
 249                 }
 250         }
 251         key->x = x;
 252         key->y = y;
 253 }