84 lines
2.2 KiB
C
84 lines
2.2 KiB
C
/* $OpenBSD: arc4.c,v 1.3 2007/09/11 12:07:05 djm Exp $ */
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/*
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* Copyright (c) 2003 Markus Friedl <markus@openbsd.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <sys/types.h>
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#include <crypto/arc4.h>
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#define RC4SWAP(x,y) \
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do { \
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u_int8_t t = ctx->state[x]; \
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ctx->state[x] = ctx->state[y]; \
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ctx->state[y] = t; \
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} while(0)
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void
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rc4_keysetup(struct rc4_ctx *ctx, u_char *key, u_int32_t klen)
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{
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u_int8_t x, y;
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u_int32_t i;
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x = y = 0;
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for (i = 0; i < RC4STATE; i++)
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ctx->state[i] = i;
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for (i = 0; i < RC4STATE; i++) {
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y = (key[x] + ctx->state[i] + y) & (RC4STATE - 1);
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RC4SWAP(i, y);
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x = (x + 1) % klen;
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}
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ctx->x = ctx->y = 0;
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}
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void
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rc4_crypt(struct rc4_ctx *ctx, u_char *src, u_char *dst,
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u_int32_t len)
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{
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u_int32_t i;
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for (i = 0; i < len; i++) {
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ctx->x = (ctx->x + 1) & (RC4STATE - 1);
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ctx->y = (ctx->state[ctx->x] + ctx->y) & (RC4STATE - 1);
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RC4SWAP(ctx->x, ctx->y);
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dst[i] = src[i] ^ ctx->state[
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(ctx->state[ctx->x] + ctx->state[ctx->y]) & (RC4STATE - 1)];
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}
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}
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void
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rc4_getbytes(struct rc4_ctx *ctx, u_char *dst, u_int32_t len)
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{
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u_int32_t i;
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for (i = 0; i < len; i++) {
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ctx->x = (ctx->x + 1) & (RC4STATE - 1);
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ctx->y = (ctx->state[ctx->x] + ctx->y) & (RC4STATE - 1);
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RC4SWAP(ctx->x, ctx->y);
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dst[i] = ctx->state[
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(ctx->state[ctx->x] + ctx->state[ctx->y]) & (RC4STATE - 1)];
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}
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}
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void
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rc4_skip(struct rc4_ctx *ctx, u_int32_t len)
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{
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for (; len > 0; len--) {
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ctx->x = (ctx->x + 1) & (RC4STATE - 1);
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ctx->y = (ctx->state[ctx->x] + ctx->y) & (RC4STATE - 1);
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RC4SWAP(ctx->x, ctx->y);
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}
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}
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