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/*
* Copyright (c) 1999,2000,2004 Damien Miller <djm@mindrot.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 "includes.h"
#include "log.h"
RCSID("$Id: bsd-arc4random.c,v 1.10 2005/02/16 02:01:28 djm Exp $");
#ifndef HAVE_ARC4RANDOM
#include <openssl/rand.h>
#include <openssl/rc4.h>
#include <openssl/err.h>
/* Size of key to use */
#define SEED_SIZE 20
/* Number of bytes to reseed after */
#define REKEY_BYTES (1 << 24)
static int rc4_ready = 0;
static RC4_KEY rc4;
unsigned int
arc4random(void)
{
unsigned int r = 0;
static int first_time = 1;
if (rc4_ready <= 0) {
if (first_time)
seed_rng();
first_time = 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];
int i;
memset(&rc4, 0, sizeof(rc4));
if (RAND_bytes(rand_buf, sizeof(rand_buf)) <= 0)
fatal("Couldn't obtain random bytes (error %ld)",
ERR_get_error());
RC4_set_key(&rc4, sizeof(rand_buf), rand_buf);
/*
* Discard early keystream, as per recommendations in:
* http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/Rc4_ksa.ps
*/
for(i = 0; i <= 256; i += sizeof(rand_buf))
RC4(&rc4, sizeof(rand_buf), rand_buf, rand_buf);
memset(rand_buf, 0, sizeof(rand_buf));
rc4_ready = REKEY_BYTES;
}
#endif /* !HAVE_ARC4RANDOM */
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