text: /* 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
   */
  
  void RC4(RC4_KEY *key, size_t len, const unsigned char *indata,
           unsigned char *outdata)
  {
      register RC4_INT *d;
      register RC4_INT x, y, tx, ty;
      size_t i;
  
      x = key->x;
      y = key->y;
      d = key->data;
  
  #if defined(RC4_CHUNK) && !defined(PEDANTIC)
      /*-
       * 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 ((((size_t)indata & (sizeof(RC4_CHUNK) - 1)) |
           ((size_t)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 & (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);
              }
              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 & (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);
              }
              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 = 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;
  }
  