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 /* RC4 as implemented from a posting from
  63  * Newsgroups: sci.crypt
  64  * From: sterndark@netcom.com (David Sterndark)
  65  * Subject: RC4 Algorithm revealed.
  66  * Message-ID: <sternCvKL4B.Hyy@netcom.com>
  67  * Date: Wed, 14 Sep 1994 06:35:31 GMT
  68  */
  69
  70 void RC4(RC4_KEY *key, unsigned long len, const unsigned char *indata,
  71              unsigned char *outdata)
  72         {
  73         register RC4_INT *d;
  74         register RC4_INT x,y,tx,ty;
  75         int i;
  76
  77         x=key->x;
  78         y=key->y;
  79         d=key->data;
  80
  81 #if defined(RC4_CHUNK)
  82         /*
  83          * The original reason for implementing this(*) was the fact that
  84          * pre-21164a Alpha CPUs don't have byte load/store instructions
  85          * and e.g. a byte store has to be done with 64-bit load, shift,
  86          * and, or and finally 64-bit store. Peaking data and operating
  87          * at natural word size made it possible to reduce amount of
  88          * instructions as well as to perform early read-ahead without
  89          * suffering from RAW (read-after-write) hazard. This resulted
  90          * in ~40%(**) performance improvement on 21064 box with gcc.
  91          * But it's not only Alpha users who win here:-) Thanks to the
  92          * early-n-wide read-ahead this implementation also exhibits
  93          * >40% speed-up on SPARC and 20-30% on 64-bit MIPS (depending
  94          * on sizeof(RC4_INT)).
  95          *
  96          * (*)  "this" means code which recognizes the case when input
  97          *      and output pointers appear to be aligned at natural CPU
  98          *      word boundary
  99          * (**) i.e. according to 'apps/openssl speed rc4' benchmark,
 100          *      crypto/rc4/rc4speed.c exhibits almost 70% speed-up...
 101          *
 102          * Cavets.
 103          *
 104          * - RC4_CHUNK="unsigned long long" should be a #1 choice for
 105          *   UltraSPARC. Unfortunately gcc generates very slow code
 106          *   (2.5-3 times slower than one generated by Sun's WorkShop
 107          *   C) and therefore gcc (at least 2.95 and earlier) should
 108          *   always be told that RC4_CHUNK="unsigned long".
 109          *
 110          *                                      <appro@fy.chalmers.se>
 111          */
 112
 113 # define RC4_STEP       ( \
 114                         x=(x+1) &0xff,  \
 115                         tx=d[x],        \
 116                         y=(tx+y)&0xff,  \
 117                         ty=d[y],        \
 118                         d[y]=tx,        \
 119                         d[x]=ty,        \
 120                         (RC4_CHUNK)d[(tx+ty)&0xff]\
 121                         )
 122
 123         if ( ( ((unsigned long)indata  & (sizeof(RC4_CHUNK)-1)) |
 124                ((unsigned long)outdata & (sizeof(RC4_CHUNK)-1)) ) == 0 )
 125                 {
 126                 RC4_CHUNK ichunk,otp;
 127                 const union { long one; char little; } is_endian = {1};
 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                  * who also stands for the is_endian union:-)
 137                  *
 138                  * Special notes.
 139                  *
 140                  * - is_endian is declared automatic as doing otherwise
 141                  *   (declaring static) prevents gcc from eliminating
 142                  *   the redundant code;
 143                  * - compilers (those I've tried) don't seem to have
 144                  *   problems eliminating either the operators guarded
 145                  *   by "if (sizeof(RC4_CHUNK)==8)" or the condition
 146                  *   expressions themselves so I've got 'em to replace
 147                  *   corresponding #ifdefs from the previous version;
 148                  * - I chose to let the redundant switch cases when
 149                  *   sizeof(RC4_CHUNK)!=8 be (were also #ifdefed
 150                  *   before);
 151                  * - in case you wonder "&(sizeof(RC4_CHUNK)*8-1)" in
 152                  *   [LB]ESHFT guards against "shift is out of range"
 153                  *   warnings when sizeof(RC4_CHUNK)!=8
 154                  *
 155                  *                      <appro@fy.chalmers.se>
 156                  */
 157                 if (!is_endian.little)
 158                         {       /* BIG-ENDIAN CASE */
 159 # define BESHFT(c)      (((sizeof(RC4_CHUNK)-(c)-1)*8)&(sizeof(RC4_CHUNK)*8-1))
 160                         for (;len&-sizeof(RC4_CHUNK);len-=sizeof(RC4_CHUNK))
 161                                 {
 162                                 ichunk  = *(RC4_CHUNK *)indata;
 163                                 otp  = RC4_STEP<<BESHFT(0);
 164                                 otp |= RC4_STEP<<BESHFT(1);
 165                                 otp |= RC4_STEP<<BESHFT(2);
 166                                 otp |= RC4_STEP<<BESHFT(3);
 167                                 if (sizeof(RC4_CHUNK)==8)
 168                                         {
 169                                         otp |= RC4_STEP<<BESHFT(4);
 170                                         otp |= RC4_STEP<<BESHFT(5);
 171                                         otp |= RC4_STEP<<BESHFT(6);
 172                                         otp |= RC4_STEP<<BESHFT(7);
 173                                         }
 174                                 *(RC4_CHUNK *)outdata = otp^ichunk;
 175                                 indata  += sizeof(RC4_CHUNK);
 176                                 outdata += sizeof(RC4_CHUNK);
 177                                 }
 178                         if (len)
 179                                 {
 180                                 RC4_CHUNK mask=(RC4_CHUNK)-1, ochunk;
 181
 182                                 ichunk = *(RC4_CHUNK *)indata;
 183                                 ochunk = *(RC4_CHUNK *)outdata;
 184                                 otp = 0;
 185                                 i = BESHFT(0);
 186                                 mask <<= (sizeof(RC4_CHUNK)-len)<<3;
 187                                 switch (len&(sizeof(RC4_CHUNK)-1))
 188                                         {
 189                                         case 7: otp  = RC4_STEP<<i, i-=8;
 190                                         case 6: otp |= RC4_STEP<<i, i-=8;
 191                                         case 5: otp |= RC4_STEP<<i, i-=8;
 192                                         case 4: otp |= RC4_STEP<<i, i-=8;
 193                                         case 3: otp |= RC4_STEP<<i, i-=8;
 194                                         case 2: otp |= RC4_STEP<<i, i-=8;
 195                                         case 1: otp |= RC4_STEP<<i, i-=8;
 196                                         case 0: ; /*
 197                                                    * it's never the case,
 198                                                    * but it has to be here
 199                                                    * for ultrix?
 200                                                    */
 201                                         }
 202                                 ochunk &= ~mask;
 203                                 ochunk |= (otp^ichunk) & mask;
 204                                 *(RC4_CHUNK *)outdata = ochunk;
 205                                 }
 206                         key->x=x;
 207                         key->y=y;
 208                         return;
 209                         }
 210                 else
 211                         {       /* LITTLE-ENDIAN CASE */
 212 # define LESHFT(c)      (((c)*8)&(sizeof(RC4_CHUNK)*8-1))
 213                         for (;len&-sizeof(RC4_CHUNK);len-=sizeof(RC4_CHUNK))
 214                                 {
 215                                 ichunk  = *(RC4_CHUNK *)indata;
 216                                 otp  = RC4_STEP;
 217                                 otp |= RC4_STEP<<8;
 218                                 otp |= RC4_STEP<<16;
 219                                 otp |= RC4_STEP<<24;
 220                                 if (sizeof(RC4_CHUNK)==8)
 221                                         {
 222                                         otp |= RC4_STEP<<LESHFT(4);
 223                                         otp |= RC4_STEP<<LESHFT(5);
 224                                         otp |= RC4_STEP<<LESHFT(6);
 225                                         otp |= RC4_STEP<<LESHFT(7);
 226                                         }
 227                                 *(RC4_CHUNK *)outdata = otp^ichunk;
 228                                 indata  += sizeof(RC4_CHUNK);
 229                                 outdata += sizeof(RC4_CHUNK);
 230                                 }
 231                         if (len)
 232                                 {
 233                                 RC4_CHUNK mask=(RC4_CHUNK)-1, ochunk;
 234
 235                                 ichunk = *(RC4_CHUNK *)indata;
 236                                 ochunk = *(RC4_CHUNK *)outdata;
 237                                 otp = 0;
 238                                 i   = 0;
 239                                 mask >>= (sizeof(RC4_CHUNK)-len)<<3;
 240                                 switch (len&(sizeof(RC4_CHUNK)-1))
 241                                         {
 242                                         case 7: otp  = RC4_STEP,    i+=8;
 243                                         case 6: otp |= RC4_STEP<<i, i+=8;
 244                                         case 5: otp |= RC4_STEP<<i, i+=8;
 245                                         case 4: otp |= RC4_STEP<<i, i+=8;
 246                                         case 3: otp |= RC4_STEP<<i, i+=8;
 247                                         case 2: otp |= RC4_STEP<<i, i+=8;
 248                                         case 1: otp |= RC4_STEP<<i, i+=8;
 249                                         case 0: ; /*
 250                                                    * it's never the case,
 251                                                    * but it has to be here
 252                                                    * for ultrix?
 253                                                    */
 254                                         }
 255                                 ochunk &= ~mask;
 256                                 ochunk |= (otp^ichunk) & mask;
 257                                 *(RC4_CHUNK *)outdata = ochunk;
 258                                 }
 259                         key->x=x;
 260                         key->y=y;
 261                         return;
 262                         }
 263                 }
 264 #endif
 265 #define LOOP(in,out) \
 266                 x=((x+1)&0xff); \
 267                 tx=d[x]; \
 268                 y=(tx+y)&0xff; \
 269                 d[x]=ty=d[y]; \
 270                 d[y]=tx; \
 271                 (out) = d[(tx+ty)&0xff]^ (in);
 272
 273 #ifndef RC4_INDEX
 274 #define RC4_LOOP(a,b,i) LOOP(*((a)++),*((b)++))
 275 #else
 276 #define RC4_LOOP(a,b,i) LOOP(a[i],b[i])
 277 #endif
 278
 279         i=(int)(len>>3L);
 280         if (i)
 281                 {
 282                 for (;;)
 283                         {
 284                         RC4_LOOP(indata,outdata,0);
 285                         RC4_LOOP(indata,outdata,1);
 286                         RC4_LOOP(indata,outdata,2);
 287                         RC4_LOOP(indata,outdata,3);
 288                         RC4_LOOP(indata,outdata,4);
 289                         RC4_LOOP(indata,outdata,5);
 290                         RC4_LOOP(indata,outdata,6);
 291                         RC4_LOOP(indata,outdata,7);
 292 #ifdef RC4_INDEX
 293                         indata+=8;
 294                         outdata+=8;
 295 #endif
 296                         if (--i == 0) break;
 297                         }
 298                 }
 299         i=(int)len&0x07;
 300         if (i)
 301                 {
 302                 for (;;)
 303                         {
 304                         RC4_LOOP(indata,outdata,0); if (--i == 0) break;
 305                         RC4_LOOP(indata,outdata,1); if (--i == 0) break;
 306                         RC4_LOOP(indata,outdata,2); if (--i == 0) break;
 307                         RC4_LOOP(indata,outdata,3); if (--i == 0) break;
 308                         RC4_LOOP(indata,outdata,4); if (--i == 0) break;
 309                         RC4_LOOP(indata,outdata,5); if (--i == 0) break;
 310                         RC4_LOOP(indata,outdata,6); if (--i == 0) break;
 311                         }
 312                 }
 313         key->x=x;
 314         key->y=y;
 315         }