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Annotation of sys/crypto/arc4.c, Revision 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: }