Line data    Source code

       1             : /*
       2             :  * Copyright (c) 2004 Kungliga Tekniska Högskolan
       3             :  * (Royal Institute of Technology, Stockholm, Sweden).
       4             :  * All rights reserved.
       5             :  *
       6             :  * Redistribution and use in source and binary forms, with or without
       7             :  * modification, are permitted provided that the following conditions
       8             :  * are met:
       9             :  *
      10             :  * 1. Redistributions of source code must retain the above copyright
      11             :  *    notice, this list of conditions and the following disclaimer.
      12             :  *
      13             :  * 2. Redistributions in binary form must reproduce the above copyright
      14             :  *    notice, this list of conditions and the following disclaimer in the
      15             :  *    documentation and/or other materials provided with the distribution.
      16             :  *
      17             :  * 3. Neither the name of the Institute nor the names of its contributors
      18             :  *    may be used to endorse or promote products derived from this software
      19             :  *    without specific prior written permission.
      20             :  *
      21             :  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
      22             :  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
      23             :  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
      24             :  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
      25             :  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
      26             :  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
      27             :  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
      28             :  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
      29             :  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
      30             :  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
      31             :  * SUCH DAMAGE.
      32             :  */
      33             : 
      34             : /* implemented from description in draft-kaukonen-cipher-arcfour-03.txt */
      35             : 
      36             : #include <config.h>
      37             : #include <roken.h>
      38             : 
      39             : #include <rc4.h>
      40             : 
      41             : #define SWAP(k,x,y)                             \
      42             : { unsigned int _t;                              \
      43             :   _t = k->state[x];                          \
      44             :   k->state[x] = k->state[y];                      \
      45             :   k->state[y] = _t;                          \
      46             : }
      47             : 
      48             : void
      49      753890 : RC4_set_key(RC4_KEY *key, const int len, const unsigned char *data)
      50             : {
      51        4648 :     int i, j;
      52             : 
      53   193749730 :     for (i = 0; i < 256; i++)
      54   192995840 :         key->state[i] = i;
      55   193749730 :     for (i = 0, j = 0; i < 256; i++) {
      56   192995840 :         j = (j + key->state[i] + data[i % len]) % 256;
      57   192995840 :         SWAP(key, i, j);
      58             :     }
      59      753890 :     key->x = key->y = 0;
      60      753890 : }
      61             : 
      62             : void
      63      502511 : RC4(RC4_KEY *key, const int len, const unsigned char *in, unsigned char *out)
      64             : {
      65        4560 :     int i, t;
      66        4560 :     unsigned x, y;
      67             : 
      68      502511 :     x = key->x;
      69      502511 :     y = key->y;
      70   144858465 :     for (i = 0; i < len; i++) {
      71   144355954 :         x = (x + 1) % 256;
      72   144355954 :         y = (y + key->state[x]) % 256;
      73   144355954 :         SWAP(key, x, y);
      74   144355954 :         t = (key->state[x] + key->state[y]) % 256;
      75   144355954 :         *out++ = key->state[t] ^ *in++;
      76             :     }
      77      502511 :     key->x = x;
      78      502511 :     key->y = y;
      79      502511 : }