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Commit	Line	Data
	1
	2	/*
	3	* rc4.c
	4	*
	5	* Copyright (c) 1996-2000 Whistle Communications, Inc.
	6	* All rights reserved.
	7	*
	8	* Subject to the following obligations and disclaimer of warranty, use and
	9	* redistribution of this software, in source or object code forms, with or
	10	* without modifications are expressly permitted by Whistle Communications;
	11	* provided, however, that:
	12	* 1. Any and all reproductions of the source or object code must include the
	13	* copyright notice above and the following disclaimer of warranties; and
	14	* 2. No rights are granted, in any manner or form, to use Whistle
	15	* Communications, Inc. trademarks, including the mark "WHISTLE
	16	* COMMUNICATIONS" on advertising, endorsements, or otherwise except as
	17	* such appears in the above copyright notice or in the software.
	18	*
	19	* THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
	20	* TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
	21	* REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
	22	* INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
	23	* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
	24	* WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
	25	* REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
	26	* SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
	27	* IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
	28	* RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
	29	* WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
	30	* PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
	31	* SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
	32	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	33	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	34	* THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
	35	* OF SUCH DAMAGE.
	36	*
	37	* $FreeBSD: src/sys/crypto/rc4/rc4.c,v 1.2.2.1 2000/04/18 04:48:31 archie Exp $
	38	*/
	39
	40	#include <sys/types.h>
	41	#include <crypto/rc4/rc4.h>
	42
	43	static __inline void
	44	swap_bytes(u_char a, u_char b)
	45	{
	46	u_char temp;
	47
	48	temp = *a;
	49	a = b;
	50	*b = temp;
	51	}
	52
	53	/*
	54	* Initialize an RC4 state buffer using the supplied key,
	55	* which can have arbitrary length.
	56	*/
	57	void
	58	rc4_init(struct rc4_state const state, const u_char key, int keylen)
	59	{
	60	u_char j;
	61	int i;
	62
	63	/* Initialize state with identity permutation */
	64	for (i = 0; i < 256; i++)
	65	state->perm[i] = (u_char)i;
	66	state->index1 = 0;
	67	state->index2 = 0;
	68
	69	/* Randomize the permutation using key data */
	70	for (j = i = 0; i < 256; i++) {
	71	j += state->perm[i] + key[i % keylen];
	72	swap_bytes(&state->perm[i], &state->perm[j]);
	73	}
	74	}
	75
	76	/*
	77	* Encrypt some data using the supplied RC4 state buffer.
	78	* The input and output buffers may be the same buffer.
	79	* Since RC4 is a stream cypher, this function is used
	80	* for both encryption and decryption.
	81	*/
	82	void
	83	rc4_crypt(struct rc4_state *const state,
	84	const u_char inbuf, u_char outbuf, int buflen)
	85	{
	86	int i;
	87	u_char j;
	88
	89	for (i = 0; i < buflen; i++) {
	90
	91	/* Update modification indicies */
	92	state->index1++;
	93	state->index2 += state->perm[state->index1];
	94
	95	/* Modify permutation */
	96	swap_bytes(&state->perm[state->index1],
	97	&state->perm[state->index2]);
	98
	99	/* Encrypt/decrypt next byte */
	100	j = state->perm[state->index1] + state->perm[state->index2];
	101	outbuf[i] = inbuf[i] ^ state->perm[j];
	102	}
	103	}
	104