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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: }