1/*
2 * rc4.c
3 *
4 * Copyright (c) 1996-2000 Whistle Communications, Inc.
5 * All rights reserved.
6 *
7 * Subject to the following obligations and disclaimer of warranty, use and
8 * redistribution of this software, in source or object code forms, with or
9 * without modifications are expressly permitted by Whistle Communications;
10 * provided, however, that:
11 * 1. Any and all reproductions of the source or object code must include the
12 *    copyright notice above and the following disclaimer of warranties; and
13 * 2. No rights are granted, in any manner or form, to use Whistle
14 *    Communications, Inc. trademarks, including the mark "WHISTLE
15 *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
16 *    such appears in the above copyright notice or in the software.
17 *
18 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
19 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
20 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
21 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
22 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
23 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
24 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
25 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
26 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
27 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
28 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
29 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
30 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
33 * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
34 * OF SUCH DAMAGE.
35 */
36
37#include <sys/cdefs.h>
38__FBSDID("$FreeBSD$");
39
40#include <sys/param.h>
41#include <sys/kernel.h>
42#include <sys/module.h>
43#include <sys/types.h>
44#include <crypto/rc4/rc4.h>
45
46static __inline void
47swap_bytes(u_char *a, u_char *b)
48{
49	u_char temp;
50
51	temp = *a;
52	*a = *b;
53	*b = temp;
54}
55
56/*
57 * Initialize an RC4 state buffer using the supplied key,
58 * which can have arbitrary length.
59 */
60void
61rc4_init(struct rc4_state *const state, const u_char *key, int keylen)
62{
63	u_char j;
64	int i, k;
65
66	/* Initialize state with identity permutation */
67	for (i = 0; i < 256; i++)
68		state->perm[i] = (u_char)i;
69	state->index1 = 0;
70	state->index2 = 0;
71
72	/* Randomize the permutation using key data */
73	for (j = i = k = 0; i < 256; i++) {
74		j += state->perm[i] + key[k];
75		swap_bytes(&state->perm[i], &state->perm[j]);
76		if (++k >= keylen)
77			k = 0;
78	}
79}
80
81/*
82 * Encrypt some data using the supplied RC4 state buffer.
83 * The input and output buffers may be the same buffer.
84 * Since RC4 is a stream cypher, this function is used
85 * for both encryption and decryption.
86 */
87void
88rc4_crypt(struct rc4_state *const state,
89	const u_char *inbuf, u_char *outbuf, int buflen)
90{
91	int i;
92	u_char j;
93
94	for (i = 0; i < buflen; i++) {
95
96		/* Update modification indicies */
97		state->index1++;
98		state->index2 += state->perm[state->index1];
99
100		/* Modify permutation */
101		swap_bytes(&state->perm[state->index1],
102		    &state->perm[state->index2]);
103
104		/* Encrypt/decrypt next byte */
105		j = state->perm[state->index1] + state->perm[state->index2];
106		outbuf[i] = inbuf[i] ^ state->perm[j];
107	}
108}
109
110static int
111rc4_modevent(module_t mod, int type, void *unused)
112{
113	switch (type) {
114	case MOD_LOAD:
115		return 0;
116	case MOD_UNLOAD:
117		return 0;
118	}
119	return EINVAL;
120}
121
122static moduledata_t rc4_mod = {
123	"rc4",
124	rc4_modevent,
125	0
126};
127DECLARE_MODULE(rc4, rc4_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST);
128MODULE_VERSION(rc4, 1);
129