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 "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(key, len, indata, outdata)
  71 RC4_KEY *key;
  72 unsigned long len;
  73 unsigned char *indata;
  74 unsigned char *outdata;
  75         {
  76         register RC4_INT *d;
  77         register RC4_INT x,y,tx,ty;
  78         int i;
  79
  80         x=key->x;
  81         y=key->y;
  82         d=key->data;
  83
  84 #define LOOP(in,out) \
  85                 x=((x+1)&0xff); \
  86                 tx=d[x]; \
  87                 y=(tx+y)&0xff; \
  88                 d[x]=ty=d[y]; \
  89                 d[y]=tx; \
  90                 (out) = d[(tx+ty)&0xff]^ (in);
  91
  92 #ifndef RC4_INDEX
  93 #define RC4_LOOP(a,b,i) LOOP(*((a)++),*((b)++))
  94 #else
  95 #define RC4_LOOP(a,b,i) LOOP(a[i],b[i])
  96 #endif
  97
  98         i=(int)(len>>3L);
  99         if (i)
 100                 {
 101                 for (;;)
 102                         {
 103                         RC4_LOOP(indata,outdata,0);
 104                         RC4_LOOP(indata,outdata,1);
 105                         RC4_LOOP(indata,outdata,2);
 106                         RC4_LOOP(indata,outdata,3);
 107                         RC4_LOOP(indata,outdata,4);
 108                         RC4_LOOP(indata,outdata,5);
 109                         RC4_LOOP(indata,outdata,6);
 110                         RC4_LOOP(indata,outdata,7);
 111 #ifdef RC4_INDEX
 112                         indata+=8;
 113                         outdata+=8;
 114 #endif
 115                         if (--i == 0) break;
 116                         }
 117                 }
 118         i=(int)len&0x07;
 119         if (i)
 120                 {
 121                 for (;;)
 122                         {
 123                         RC4_LOOP(indata,outdata,0); if (--i == 0) break;
 124                         RC4_LOOP(indata,outdata,1); if (--i == 0) break;
 125                         RC4_LOOP(indata,outdata,2); if (--i == 0) break;
 126                         RC4_LOOP(indata,outdata,3); if (--i == 0) break;
 127                         RC4_LOOP(indata,outdata,4); if (--i == 0) break;
 128                         RC4_LOOP(indata,outdata,5); if (--i == 0) break;
 129                         RC4_LOOP(indata,outdata,6); if (--i == 0) break;
 130                         }
 131                 }
 132         key->x=x;
 133         key->y=y;
 134         }