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/*
* rc4.c
*
* Copyright (c) 1996-2000 Whistle Communications, Inc.
* All rights reserved.
*
* Subject to the following obligations and disclaimer of warranty, use and
* redistribution of this software, in source or object code forms, with or
* without modifications are expressly permitted by Whistle Communications;
* provided, however, that:
* 1. Any and all reproductions of the source or object code must include the
* copyright notice above and the following disclaimer of warranties; and
* 2. No rights are granted, in any manner or form, to use Whistle
* Communications, Inc. trademarks, including the mark "WHISTLE
* COMMUNICATIONS" on advertising, endorsements, or otherwise except as
* such appears in the above copyright notice or in the software.
*
* THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
* TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
* REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
* INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
* WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
* REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
* SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
* IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
* RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
* WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
* PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
* OF SUCH DAMAGE.
*
* $FreeBSD: src/sys/crypto/rc4/rc4.c,v 1.2.2.1 2000/04/18 04:48:31 archie Exp $
*/
#include <stdint.h>
#include "rc4.h"
static inline void
swap_bytes(u_char *a, u_char *b)
{
u_char temp;
temp = *a;
*a = *b;
*b = temp;
}
/*
* Initialize an RC4 state buffer using the supplied key,
* which can have arbitrary length.
*/
void
rc4_init(struct rc4_state *const state, const u_char *key, int keylen)
{
u_char j;
int i;
/* Initialize state with identity permutation */
for (i = 0; i < 256; i++)
state->perm[i] = (u_char)i;
state->index1 = 0;
state->index2 = 0;
/* Randomize the permutation using key data */
for (j = i = 0; i < 256; i++) {
j += state->perm[i] + key[i % keylen];
swap_bytes(&state->perm[i], &state->perm[j]);
}
}
/*
* Encrypt some data using the supplied RC4 state buffer.
* The input and output buffers may be the same buffer.
* Since RC4 is a stream cypher, this function is used
* for both encryption and decryption.
*/
void
rc4_crypt(struct rc4_state *const state,
const u_char *inbuf, u_char *outbuf, int buflen)
{
int i;
u_char j;
for (i = 0; i < buflen; i++) {
/* Update modification indicies */
state->index1++;
state->index2 += state->perm[state->index1];
/* Modify permutation */
swap_bytes(&state->perm[state->index1],
&state->perm[state->index2]);
/* Encrypt/decrypt next byte */
j = state->perm[state->index1] + state->perm[state->index2];
outbuf[i] = inbuf[i] ^ state->perm[j];
}
}