Annotation of sys/crypto/arc4.c, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: arc4.c,v 1.2 2007/07/24 19:35:20 damien Exp $ */
2: /*
3: * Copyright (c) 2003 Markus Friedl <markus@openbsd.org>
4: *
5: * Permission to use, copy, modify, and distribute this software for any
6: * purpose with or without fee is hereby granted, provided that the above
7: * copyright notice and this permission notice appear in all copies.
8: *
9: * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10: * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11: * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12: * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13: * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14: * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15: * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16: */
17:
18: #include <sys/types.h>
19:
20: #include <crypto/arc4.h>
21:
22: #define RC4SWAP(x,y) \
23: do { \
24: u_int8_t t = ctx->state[x]; \
25: ctx->state[x] = ctx->state[y]; \
26: ctx->state[y] = t; \
27: } while(0)
28:
29: void
30: rc4_keysetup(struct rc4_ctx *ctx, u_char *key, u_int32_t klen)
31: {
32: u_int8_t x, y;
33: u_int32_t i;
34:
35: x = y = 0;
36: for (i = 0; i < RC4STATE; i++)
37: ctx->state[i] = i;
38: for (i = 0; i < RC4STATE; i++) {
39: y = (key[x] + ctx->state[i] + y) % RC4STATE;
40: RC4SWAP(i, y);
41: x = (x + 1) % klen;
42: }
43: ctx->x = ctx->y = 0;
44: }
45:
46: void
47: rc4_crypt(struct rc4_ctx *ctx, u_char *src, u_char *dst,
48: u_int32_t len)
49: {
50: u_int32_t i;
51:
52: for (i = 0; i < len; i++) {
53: ctx->x = (ctx->x + 1) % RC4STATE;
54: ctx->y = (ctx->state[ctx->x] + ctx->y) % RC4STATE;
55: RC4SWAP(ctx->x, ctx->y);
56: dst[i] = src[i] ^ ctx->state[
57: (ctx->state[ctx->x] + ctx->state[ctx->y]) % RC4STATE];
58: }
59: }
60:
61: void
62: rc4_skip(struct rc4_ctx *ctx, u_int32_t len)
63: {
64: for (; len > 0; len--) {
65: ctx->x = (ctx->x + 1) % RC4STATE;
66: ctx->y = (ctx->state[ctx->x] + ctx->y) % RC4STATE;
67: RC4SWAP(ctx->x, ctx->y);
68: }
69: }
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