1 /* $NetBSD: rc4.c,v 1.2 2017/01/28 21:31:47 christos Exp $ */
2
3 /*
4 * Copyright (c) 2004 Kungliga Tekniska Högskolan
5 * (Royal Institute of Technology, Stockholm, Sweden).
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * 3. Neither the name of the Institute nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 /* implemented from description in draft-kaukonen-cipher-arcfour-03.txt */
37
38 #include <config.h>
39 #include <krb5/roken.h>
40
41 #include <rc4.h>
42
43 #define SWAP(k,x,y) \
44 { unsigned int _t; \
45 _t = k->state[x]; \
46 k->state[x] = k->state[y]; \
47 k->state[y] = _t; \
48 }
49
50 void
RC4_set_key(RC4_KEY * key,const int len,const unsigned char * data)51 RC4_set_key(RC4_KEY *key, const int len, const unsigned char *data)
52 {
53 int i, j;
54
55 for (i = 0; i < 256; i++)
56 key->state[i] = i;
57 for (i = 0, j = 0; i < 256; i++) {
58 j = (j + key->state[i] + data[i % len]) % 256;
59 SWAP(key, i, j);
60 }
61 key->x = key->y = 0;
62 }
63
64 void
RC4(RC4_KEY * key,const int len,const unsigned char * in,unsigned char * out)65 RC4(RC4_KEY *key, const int len, const unsigned char *in, unsigned char *out)
66 {
67 int i, t;
68 unsigned x, y;
69
70 x = key->x;
71 y = key->y;
72 for (i = 0; i < len; i++) {
73 x = (x + 1) % 256;
74 y = (y + key->state[x]) % 256;
75 SWAP(key, x, y);
76 t = (key->state[x] + key->state[y]) % 256;
77 *out++ = key->state[t] ^ *in++;
78 }
79 key->x = x;
80 key->y = y;
81 }
82