[openssh.git] / bsd-arc4random.c

/*
 * Copyright (c) 1999-2000 Damien Miller.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON 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 ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "includes.h"

#ifndef HAVE_ARC4RANDOM

#include <openssl/rand.h>
#include <openssl/rc4.h>

/* Size of key to use */
#define SEED_SIZE 20

/* Number of bytes to reseed after */
#define REKEY_BYTES	(1 << 18)

static int rc4_ready = 0;
static RC4_KEY rc4;

unsigned int arc4random(void)
{
	unsigned int r = 0;

	if (rc4_ready <= 0)
		arc4random_stir();
	
	RC4(&rc4, sizeof(r), (unsigned char *)&r, (unsigned char *)&r);

	rc4_ready -= sizeof(r);
	
	return(r);
}

void arc4random_stir(void)
{
	unsigned char rand_buf[SEED_SIZE];
	
	memset(&rc4, 0, sizeof(rc4));

	seed_rng();

	RAND_bytes(rand_buf, sizeof(rand_buf));
	
	RC4_set_key(&rc4, sizeof(rand_buf), rand_buf);

	memset(rand_buf, 0, sizeof(rand_buf));
	
	rc4_ready = REKEY_BYTES;
}
#endif /* !HAVE_ARC4RANDOM */
Commit	Line	Data
416ed5a7	1	/*
	2	* Copyright (c) 1999-2000 Damien Miller. All rights reserved.
	3	*
	4	* Redistribution and use in source and binary forms, with or without
	5	* modification, are permitted provided that the following conditions
	6	* are met:
	7	* 1. Redistributions of source code must retain the above copyright
	8	* notice, this list of conditions and the following disclaimer.
	9	* 2. Redistributions in binary form must reproduce the above copyright
	10	* notice, this list of conditions and the following disclaimer in the
	11	* documentation and/or other materials provided with the distribution.
416ed5a7	12	*
	13	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	14	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	15	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	16	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	17	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	18	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	19	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	20	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	21	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	22	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	23	*/
	24
	25	#include "includes.h"
416ed5a7	26
	27	#ifndef HAVE_ARC4RANDOM
	28
2f125ca1	29	#include <openssl/rand.h>
	30	#include <openssl/rc4.h>
	31
10fa00c8	32	/* Size of key to use */
	33	#define SEED_SIZE 20
	34
	35	/* Number of bytes to reseed after */
7efa2776	36	#define REKEY_BYTES (1 << 18)
10fa00c8	37
416ed5a7	38	static int rc4_ready = 0;
	39	static RC4_KEY rc4;
	40
	41	unsigned int arc4random(void)
	42	{
	43	unsigned int r = 0;
	44
10fa00c8	45	if (rc4_ready <= 0)
416ed5a7	46	arc4random_stir();
	47
	48	RC4(&rc4, sizeof(r), (unsigned char )&r, (unsigned char )&r);
10fa00c8	49
10fa00c8	50	rc4_ready -= sizeof(r);
416ed5a7	51
	52	return(r);
	53	}
	54
	55	void arc4random_stir(void)
	56	{
10fa00c8	57	unsigned char rand_buf[SEED_SIZE];
416ed5a7	58
	59	memset(&rc4, 0, sizeof(rc4));
	60
	61	seed_rng();
10fa00c8	62
416ed5a7	63	RAND_bytes(rand_buf, sizeof(rand_buf));
	64
	65	RC4_set_key(&rc4, sizeof(rand_buf), rand_buf);
	66
	67	memset(rand_buf, 0, sizeof(rand_buf));
ea788c22	68
10fa00c8	69	rc4_ready = REKEY_BYTES;
416ed5a7	70	}
416ed5a7	71	#endif /* !HAVE_ARC4RANDOM */