mirror of
git://anongit.mindrot.org/openssh.git
synced 2024-11-28 07:14:31 +08:00
151 lines
3.5 KiB
C
151 lines
3.5 KiB
C
/*
|
|
* 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 <sys/types.h>
|
|
|
|
#include <string.h>
|
|
#include <stdlib.h>
|
|
#include <stdarg.h>
|
|
|
|
#include "log.h"
|
|
|
|
#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 */
|
|
|
|
#ifndef HAVE_ARC4RANDOM_BUF
|
|
void
|
|
arc4random_buf(void *_buf, size_t n)
|
|
{
|
|
size_t i;
|
|
u_int32_t r = 0;
|
|
char *buf = (char *)_buf;
|
|
|
|
for (i = 0; i < n; i++) {
|
|
if (i % 4 == 0)
|
|
r = arc4random();
|
|
buf[i] = r & 0xff;
|
|
r >>= 8;
|
|
}
|
|
i = r = 0;
|
|
}
|
|
#endif /* !HAVE_ARC4RANDOM_BUF */
|
|
|
|
#ifndef HAVE_ARC4RANDOM_UNIFORM
|
|
/*
|
|
* Calculate a uniformly distributed random number less than upper_bound
|
|
* avoiding "modulo bias".
|
|
*
|
|
* Uniformity is achieved by generating new random numbers until the one
|
|
* returned is outside the range [0, 2**32 % upper_bound). This
|
|
* guarantees the selected random number will be inside
|
|
* [2**32 % upper_bound, 2**32) which maps back to [0, upper_bound)
|
|
* after reduction modulo upper_bound.
|
|
*/
|
|
u_int32_t
|
|
arc4random_uniform(u_int32_t upper_bound)
|
|
{
|
|
u_int32_t r, min;
|
|
|
|
if (upper_bound < 2)
|
|
return 0;
|
|
|
|
#if (ULONG_MAX > 0xffffffffUL)
|
|
min = 0x100000000UL % upper_bound;
|
|
#else
|
|
/* Calculate (2**32 % upper_bound) avoiding 64-bit math */
|
|
if (upper_bound > 0x80000000)
|
|
min = 1 + ~upper_bound; /* 2**32 - upper_bound */
|
|
else {
|
|
/* (2**32 - (x * 2)) % x == 2**32 % x when x <= 2**31 */
|
|
min = ((0xffffffff - (upper_bound * 2)) + 1) % upper_bound;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* This could theoretically loop forever but each retry has
|
|
* p > 0.5 (worst case, usually far better) of selecting a
|
|
* number inside the range we need, so it should rarely need
|
|
* to re-roll.
|
|
*/
|
|
for (;;) {
|
|
r = arc4random();
|
|
if (r >= min)
|
|
break;
|
|
}
|
|
|
|
return r % upper_bound;
|
|
}
|
|
#endif /* !HAVE_ARC4RANDOM_UNIFORM */
|