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 | |
43 | static __inline void |
44 | swap_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 | */ |
57 | void |
58 | rc4_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 | */ |
82 | void |
83 | rc4_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 | |