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