crypto/rc4/rc4_enc.c

   1 /* crypto/rc4/rc4_enc.c */
   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 <openssl/rc4.h>
  60 #include "rc4_locl.h"
  61
  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 RC4(RC4_KEY *key, size_t len, const unsigned char *indata,
  72          unsigned char *outdata)
  73 {
  74     register RC4_INT *d;
  75     register RC4_INT x, y, tx, ty;
  76     size_t i;
  77
  78     x = key->x;
  79     y = key->y;
  80     d = key->data;
  81
  82 #if defined(RC4_CHUNK) && !defined(PEDANTIC)
  83         /*-
  84          * The original reason for implementing this(*) was the fact that
  85          * pre-21164a Alpha CPUs don't have byte load/store instructions
  86          * and e.g. a byte store has to be done with 64-bit load, shift,
  87          * and, or and finally 64-bit store. Peaking data and operating
  88          * at natural word size made it possible to reduce amount of
  89          * instructions as well as to perform early read-ahead without
  90          * suffering from RAW (read-after-write) hazard. This resulted
  91          * in ~40%(**) performance improvement on 21064 box with gcc.
  92          * But it's not only Alpha users who win here:-) Thanks to the
  93          * early-n-wide read-ahead this implementation also exhibits
  94          * >40% speed-up on SPARC and 20-30% on 64-bit MIPS (depending
  95          * on sizeof(RC4_INT)).
  96          *
  97          * (*)  "this" means code which recognizes the case when input
  98          *      and output pointers appear to be aligned at natural CPU
  99          *      word boundary
 100          * (**) i.e. according to 'apps/openssl speed rc4' benchmark,
 101          *      crypto/rc4/rc4speed.c exhibits almost 70% speed-up...
 102          *
 103          * Cavets.
 104          *
 105          * - RC4_CHUNK="unsigned long long" should be a #1 choice for
 106          *   UltraSPARC. Unfortunately gcc generates very slow code
 107          *   (2.5-3 times slower than one generated by Sun's WorkShop
 108          *   C) and therefore gcc (at least 2.95 and earlier) should
 109          *   always be told that RC4_CHUNK="unsigned long".
 110          *
 111          *                                      <appro@fy.chalmers.se>
 112          */
 113
 114 # define RC4_STEP       ( \
 115                         x=(x+1) &0xff,  \
 116                         tx=d[x],        \
 117                         y=(tx+y)&0xff,  \
 118                         ty=d[y],        \
 119                         d[y]=tx,        \
 120                         d[x]=ty,        \
 121                         (RC4_CHUNK)d[(tx+ty)&0xff]\
 122                         )
 123
 124     if ((((size_t)indata & (sizeof(RC4_CHUNK) - 1)) |
 125          ((size_t)outdata & (sizeof(RC4_CHUNK) - 1))) == 0) {
 126         RC4_CHUNK ichunk, otp;
 127         const union {
 128             long one;
 129             char little;
 130         } is_endian = {
 131             1
 132         };
 133
 134                 /*-
 135                  * I reckon we can afford to implement both endian
 136                  * cases and to decide which way to take at run-time
 137                  * because the machine code appears to be very compact
 138                  * and redundant 1-2KB is perfectly tolerable (i.e.
 139                  * in case the compiler fails to eliminate it:-). By
 140                  * suggestion from Terrel Larson <terr@terralogic.net>
 141                  * who also stands for the is_endian union:-)
 142                  *
 143                  * Special notes.
 144                  *
 145                  * - is_endian is declared automatic as doing otherwise
 146                  *   (declaring static) prevents gcc from eliminating
 147                  *   the redundant code;
 148                  * - compilers (those I've tried) don't seem to have
 149                  *   problems eliminating either the operators guarded
 150                  *   by "if (sizeof(RC4_CHUNK)==8)" or the condition
 151                  *   expressions themselves so I've got 'em to replace
 152                  *   corresponding #ifdefs from the previous version;
 153                  * - I chose to let the redundant switch cases when
 154                  *   sizeof(RC4_CHUNK)!=8 be (were also #ifdefed
 155                  *   before);
 156                  * - in case you wonder "&(sizeof(RC4_CHUNK)*8-1)" in
 157                  *   [LB]ESHFT guards against "shift is out of range"
 158                  *   warnings when sizeof(RC4_CHUNK)!=8
 159                  *
 160                  *                      <appro@fy.chalmers.se>
 161                  */
 162         if (!is_endian.little) { /* BIG-ENDIAN CASE */
 163 # define BESHFT(c)      (((sizeof(RC4_CHUNK)-(c)-1)*8)&(sizeof(RC4_CHUNK)*8-1))
 164             for (; len & (0 - sizeof(RC4_CHUNK)); len -= sizeof(RC4_CHUNK)) {
 165                 ichunk = *(RC4_CHUNK *) indata;
 166                 otp = RC4_STEP << BESHFT(0);
 167                 otp |= RC4_STEP << BESHFT(1);
 168                 otp |= RC4_STEP << BESHFT(2);
 169                 otp |= RC4_STEP << BESHFT(3);
 170                 if (sizeof(RC4_CHUNK) == 8) {
 171                     otp |= RC4_STEP << BESHFT(4);
 172                     otp |= RC4_STEP << BESHFT(5);
 173                     otp |= RC4_STEP << BESHFT(6);
 174                     otp |= RC4_STEP << BESHFT(7);
 175                 }
 176                 *(RC4_CHUNK *) outdata = otp ^ ichunk;
 177                 indata += sizeof(RC4_CHUNK);
 178                 outdata += sizeof(RC4_CHUNK);
 179             }
 180             if (len) {
 181                 RC4_CHUNK mask = (RC4_CHUNK) - 1, ochunk;
 182
 183                 ichunk = *(RC4_CHUNK *) indata;
 184                 ochunk = *(RC4_CHUNK *) outdata;
 185                 otp = 0;
 186                 i = BESHFT(0);
 187                 mask <<= (sizeof(RC4_CHUNK) - len) << 3;
 188                 switch (len & (sizeof(RC4_CHUNK) - 1)) {
 189                 case 7:
 190                     otp = RC4_STEP << i, i -= 8;
 191                 case 6:
 192                     otp |= RC4_STEP << i, i -= 8;
 193                 case 5:
 194                     otp |= RC4_STEP << i, i -= 8;
 195                 case 4:
 196                     otp |= RC4_STEP << i, i -= 8;
 197                 case 3:
 198                     otp |= RC4_STEP << i, i -= 8;
 199                 case 2:
 200                     otp |= RC4_STEP << i, i -= 8;
 201                 case 1:
 202                     otp |= RC4_STEP << i, i -= 8;
 203                 case 0:;       /*
 204                                  * it's never the case,
 205                                  * but it has to be here
 206                                  * for ultrix?
 207                                  */
 208                 }
 209                 ochunk &= ~mask;
 210                 ochunk |= (otp ^ ichunk) & mask;
 211                 *(RC4_CHUNK *) outdata = ochunk;
 212             }
 213             key->x = x;
 214             key->y = y;
 215             return;
 216         } else {                /* LITTLE-ENDIAN CASE */
 217 # define LESHFT(c)      (((c)*8)&(sizeof(RC4_CHUNK)*8-1))
 218             for (; len & (0 - sizeof(RC4_CHUNK)); len -= sizeof(RC4_CHUNK)) {
 219                 ichunk = *(RC4_CHUNK *) indata;
 220                 otp = RC4_STEP;
 221                 otp |= RC4_STEP << 8;
 222                 otp |= RC4_STEP << 16;
 223                 otp |= RC4_STEP << 24;
 224                 if (sizeof(RC4_CHUNK) == 8) {
 225                     otp |= RC4_STEP << LESHFT(4);
 226                     otp |= RC4_STEP << LESHFT(5);
 227                     otp |= RC4_STEP << LESHFT(6);
 228                     otp |= RC4_STEP << LESHFT(7);
 229                 }
 230                 *(RC4_CHUNK *) outdata = otp ^ ichunk;
 231                 indata += sizeof(RC4_CHUNK);
 232                 outdata += sizeof(RC4_CHUNK);
 233             }
 234             if (len) {
 235                 RC4_CHUNK mask = (RC4_CHUNK) - 1, ochunk;
 236
 237                 ichunk = *(RC4_CHUNK *) indata;
 238                 ochunk = *(RC4_CHUNK *) outdata;
 239                 otp = 0;
 240                 i = 0;
 241                 mask >>= (sizeof(RC4_CHUNK) - len) << 3;
 242                 switch (len & (sizeof(RC4_CHUNK) - 1)) {
 243                 case 7:
 244                     otp = RC4_STEP, i += 8;
 245                 case 6:
 246                     otp |= RC4_STEP << i, i += 8;
 247                 case 5:
 248                     otp |= RC4_STEP << i, i += 8;
 249                 case 4:
 250                     otp |= RC4_STEP << i, i += 8;
 251                 case 3:
 252                     otp |= RC4_STEP << i, i += 8;
 253                 case 2:
 254                     otp |= RC4_STEP << i, i += 8;
 255                 case 1:
 256                     otp |= RC4_STEP << i, i += 8;
 257                 case 0:;       /*
 258                                  * it's never the case,
 259                                  * but it has to be here
 260                                  * for ultrix?
 261                                  */
 262                 }
 263                 ochunk &= ~mask;
 264                 ochunk |= (otp ^ ichunk) & mask;
 265                 *(RC4_CHUNK *) outdata = ochunk;
 266             }
 267             key->x = x;
 268             key->y = y;
 269             return;
 270         }
 271     }
 272 #endif
 273 #define LOOP(in,out) \
 274                 x=((x+1)&0xff); \
 275                 tx=d[x]; \
 276                 y=(tx+y)&0xff; \
 277                 d[x]=ty=d[y]; \
 278                 d[y]=tx; \
 279                 (out) = d[(tx+ty)&0xff]^ (in);
 280
 281 #ifndef RC4_INDEX
 282 # define RC4_LOOP(a,b,i) LOOP(*((a)++),*((b)++))
 283 #else
 284 # define RC4_LOOP(a,b,i) LOOP(a[i],b[i])
 285 #endif
 286
 287     i = len >> 3;
 288     if (i) {
 289         for (;;) {
 290             RC4_LOOP(indata, outdata, 0);
 291             RC4_LOOP(indata, outdata, 1);
 292             RC4_LOOP(indata, outdata, 2);
 293             RC4_LOOP(indata, outdata, 3);
 294             RC4_LOOP(indata, outdata, 4);
 295             RC4_LOOP(indata, outdata, 5);
 296             RC4_LOOP(indata, outdata, 6);
 297             RC4_LOOP(indata, outdata, 7);
 298 #ifdef RC4_INDEX
 299             indata += 8;
 300             outdata += 8;
 301 #endif
 302             if (--i == 0)
 303                 break;
 304         }
 305     }
 306     i = len & 0x07;
 307     if (i) {
 308         for (;;) {
 309             RC4_LOOP(indata, outdata, 0);
 310             if (--i == 0)
 311                 break;
 312             RC4_LOOP(indata, outdata, 1);
 313             if (--i == 0)
 314                 break;
 315             RC4_LOOP(indata, outdata, 2);
 316             if (--i == 0)
 317                 break;
 318             RC4_LOOP(indata, outdata, 3);
 319             if (--i == 0)
 320                 break;
 321             RC4_LOOP(indata, outdata, 4);
 322             if (--i == 0)
 323                 break;
 324             RC4_LOOP(indata, outdata, 5);
 325             if (--i == 0)
 326                 break;
 327             RC4_LOOP(indata, outdata, 6);
 328             if (--i == 0)
 329                 break;
 330         }
 331     }
 332     key->x = x;
 333     key->y = y;
 334 }