crypto/heimdal-0.6.3/lib/des/rc4_skey.c

   1 /* crypto/rc4/rc4_skey.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 "des_locl.h"
  60 #include "rc4.h"
  61
  62 RCSID("$Id: rc4_skey.c,v 1.2 1999/10/21 12:58:52 joda Exp $");
  63
  64 /* RC4 as implemented from a posting from
  65  * Newsgroups: sci.crypt
  66  * From: sterndark@netcom.com (David Sterndark)
  67  * Subject: RC4 Algorithm revealed.
  68  * Message-ID: <sternCvKL4B.Hyy@netcom.com>
  69  * Date: Wed, 14 Sep 1994 06:35:31 GMT
  70  */
  71
  72 void RC4_set_key(RC4_KEY *key, int len, register unsigned char *data)
  73         {
  74         register RC4_INT tmp;
  75         register int id1,id2;
  76         register RC4_INT *d;
  77         unsigned int i;
  78
  79         d= &(key->data[0]);
  80         for (i=0; i<256; i++)
  81                 d[i]=i;
  82         key->x = 0;
  83         key->y = 0;
  84         id1=id2=0;
  85
  86 #define SK_LOOP(n) { \
  87                 tmp=d[(n)]; \
  88                 id2 = (data[id1] + tmp + id2) & 0xff; \
  89                 if (++id1 == len) id1=0; \
  90                 d[(n)]=d[id2]; \
  91                 d[id2]=tmp; }
  92
  93         for (i=0; i < 256; i+=4)
  94                 {
  95                 SK_LOOP(i+0);
  96                 SK_LOOP(i+1);
  97                 SK_LOOP(i+2);
  98                 SK_LOOP(i+3);
  99                 }
 100         }
 101