crypto/rc4/rc4_skey.c

   1 /*
   2  * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <openssl/rc4.h>
  11 #include "rc4_local.h"
  12 #include <openssl/opensslv.h>
  13
  14 const char *RC4_options(void)
  15 {
  16     if (sizeof(RC4_INT) == 1)
  17         return "rc4(char)";
  18     else
  19         return "rc4(int)";
  20 }
  21
  22 /*-
  23  * RC4 as implemented from a posting from
  24  * Newsgroups: sci.crypt
  25  * Subject: RC4 Algorithm revealed.
  26  * Message-ID: <sternCvKL4B.Hyy@netcom.com>
  27  * Date: Wed, 14 Sep 1994 06:35:31 GMT
  28  */
  29
  30 void RC4_set_key(RC4_KEY *key, int len, const unsigned char *data)
  31 {
  32     register RC4_INT tmp;
  33     register int id1, id2;
  34     register RC4_INT *d;
  35     unsigned int i;
  36
  37     d = &(key->data[0]);
  38     key->x = 0;
  39     key->y = 0;
  40     id1 = id2 = 0;
  41
  42 #define SK_LOOP(d,n) { \
  43                 tmp=d[(n)]; \
  44                 id2 = (data[id1] + tmp + id2) & 0xff; \
  45                 if (++id1 == len) id1=0; \
  46                 d[(n)]=d[id2]; \
  47                 d[id2]=tmp; }
  48
  49     for (i = 0; i < 256; i++)
  50         d[i] = i;
  51     for (i = 0; i < 256; i += 4) {
  52         SK_LOOP(d, i + 0);
  53         SK_LOOP(d, i + 1);
  54         SK_LOOP(d, i + 2);
  55         SK_LOOP(d, i + 3);
  56     }
  57 }