1
2/*
3 * rc4.c
4 *
5 * Copyright (c) 1996-2000 Whistle Communications, Inc.
6 * All rights reserved.
7 *
8 * Subject to the following obligations and disclaimer of warranty, use and
9 * redistribution of this software, in source or object code forms, with or
10 * without modifications are expressly permitted by Whistle Communications;
11 * provided, however, that:
12 * 1. Any and all reproductions of the source or object code must include the
13 * copyright notice above and the following disclaimer of warranties; and
14 * 2. No rights are granted, in any manner or form, to use Whistle
15 * Communications, Inc. trademarks, including the mark "WHISTLE
16 * COMMUNICATIONS" on advertising, endorsements, or otherwise except as
17 * such appears in the above copyright notice or in the software.
18 *
19 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
20 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
21 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
22 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
23 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
24 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
25 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
26 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
27 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
28 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
29 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
30 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
31 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
34 * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
35 * OF SUCH DAMAGE.
36 *
37 * $FreeBSD: src/sys/crypto/rc4/rc4.c,v 1.2.2.1 2000/04/18 04:48:31 archie Exp $
38 */
39
40#include <sys/types.h>
41#include <crypto/rc4/rc4.h>
42
43static __inline void
44swap_bytes(u_char *a, u_char *b)
45{
46 u_char temp;
47
48 temp = *a;
49 *a = *b;
50 *b = temp;
51}
52
53/*
54 * Initialize an RC4 state buffer using the supplied key,
55 * which can have arbitrary length.
56 */
57void
58rc4_init(struct rc4_state *const state, const u_char *key, int keylen)
59{
60 u_char j;
61 int i;
62
63 /* Initialize state with identity permutation */
64 for (i = 0; i < 256; i++)
65 state->perm[i] = (u_char)i;
66 state->index1 = 0;
67 state->index2 = 0;
68
69 /* Randomize the permutation using key data */
70 for (j = i = 0; i < 256; i++) {
71 j += state->perm[i] + key[i % keylen];
72 swap_bytes(&state->perm[i], &state->perm[j]);
73 }
74}
75
76/*
77 * Encrypt some data using the supplied RC4 state buffer.
78 * The input and output buffers may be the same buffer.
79 * Since RC4 is a stream cypher, this function is used
80 * for both encryption and decryption.
81 */
82void
83rc4_crypt(struct rc4_state *const state,
84 const u_char *inbuf, u_char *outbuf, int buflen)
85{
86 int i;
87 u_char j;
88
89 for (i = 0; i < buflen; i++) {
90
91 /* Update modification indicies */
92 state->index1++;
93 state->index2 += state->perm[state->index1];
94
95 /* Modify permutation */
96 swap_bytes(&state->perm[state->index1],
97 &state->perm[state->index2]);
98
99 /* Encrypt/decrypt next byte */
100 j = state->perm[state->index1] + state->perm[state->index2];
101 outbuf[i] = inbuf[i] ^ state->perm[j];
102 }
103}
104
105