You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
304 lines
6.4 KiB
304 lines
6.4 KiB
/* OPENBSD ORIGINAL: lib/libc/crypto/arc4random.c */
|
|
|
|
/* $OpenBSD: arc4random.c,v 1.25 2013/10/01 18:34:57 markus Exp $ */
|
|
|
|
/*
|
|
* Copyright (c) 1996, David Mazieres <dm@uun.org>
|
|
* Copyright (c) 2008, Damien Miller <djm@openbsd.org>
|
|
* Copyright (c) 2013, Markus Friedl <markus@openbsd.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.
|
|
*/
|
|
|
|
/*
|
|
* ChaCha based random number generator for OpenBSD.
|
|
*/
|
|
|
|
#include <stdlib.h>
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
#include <fcntl.h>
|
|
#include <sys/types.h>
|
|
#include <err.h>
|
|
|
|
#ifndef HAVE_ARC4RANDOM
|
|
|
|
#define KEYSTREAM_ONLY
|
|
#include "chacha_private.h"
|
|
|
|
#ifdef __GNUC__
|
|
#define inline __inline
|
|
#else /* !__GNUC__ */
|
|
#define inline
|
|
#endif /* !__GNUC__ */
|
|
|
|
#ifndef MAX
|
|
# define MAX(a,b) (((a)>(b))?(a):(b))
|
|
# define MIN(a,b) (((a)<(b))?(a):(b))
|
|
#endif
|
|
|
|
/* Not multithreaded */
|
|
#define _ARC4_LOCK()
|
|
#define _ARC4_UNLOCK()
|
|
|
|
#define RANDOMDEV "/dev/urandom"
|
|
|
|
#define KEYSZ 32
|
|
#define IVSZ 8
|
|
#define BLOCKSZ 64
|
|
#define RSBUFSZ (16*BLOCKSZ)
|
|
static int rs_initialized;
|
|
static pid_t rs_stir_pid;
|
|
static chacha_ctx rs; /* chacha context for random keystream */
|
|
static u_char rs_buf[RSBUFSZ]; /* keystream blocks */
|
|
static size_t rs_have; /* valid bytes at end of rs_buf */
|
|
static size_t rs_count; /* bytes till reseed */
|
|
|
|
static inline void _rs_rekey(u_char *dat, size_t datlen);
|
|
|
|
static inline void
|
|
_rs_init(u_char *buf, size_t n)
|
|
{
|
|
if (n < KEYSZ + IVSZ)
|
|
return;
|
|
chacha_keysetup(&rs, buf, KEYSZ * 8, 0);
|
|
chacha_ivsetup(&rs, buf + KEYSZ);
|
|
}
|
|
|
|
static void
|
|
_rs_stir(void)
|
|
{
|
|
u_char rnd[KEYSZ + IVSZ];
|
|
int fd, bytes;
|
|
|
|
if((fd = open(RANDOMDEV, O_RDONLY | O_NOFOLLOW)) == -1)
|
|
errx(1, "Couldn't obtain random bytes");
|
|
|
|
bytes = read(fd, rnd, sizeof(rnd));
|
|
|
|
close(fd);
|
|
|
|
if(bytes != sizeof(rnd))
|
|
errx(1, "Couldn't obtain random bytes");
|
|
|
|
if (!rs_initialized) {
|
|
rs_initialized = 1;
|
|
_rs_init(rnd, sizeof(rnd));
|
|
} else
|
|
_rs_rekey(rnd, sizeof(rnd));
|
|
explicit_bzero(rnd, sizeof(rnd));
|
|
|
|
/* invalidate rs_buf */
|
|
rs_have = 0;
|
|
memset(rs_buf, 0, RSBUFSZ);
|
|
|
|
rs_count = 1600000;
|
|
}
|
|
|
|
static inline void
|
|
_rs_stir_if_needed(size_t len)
|
|
{
|
|
pid_t pid = getpid();
|
|
|
|
if (rs_count <= len || !rs_initialized || rs_stir_pid != pid) {
|
|
rs_stir_pid = pid;
|
|
_rs_stir();
|
|
} else
|
|
rs_count -= len;
|
|
}
|
|
|
|
static inline void
|
|
_rs_rekey(u_char *dat, size_t datlen)
|
|
{
|
|
#ifndef KEYSTREAM_ONLY
|
|
memset(rs_buf, 0,RSBUFSZ);
|
|
#endif
|
|
/* fill rs_buf with the keystream */
|
|
chacha_encrypt_bytes(&rs, rs_buf, rs_buf, RSBUFSZ);
|
|
/* mix in optional user provided data */
|
|
if (dat) {
|
|
size_t i, m;
|
|
|
|
m = MIN(datlen, KEYSZ + IVSZ);
|
|
for (i = 0; i < m; i++)
|
|
rs_buf[i] ^= dat[i];
|
|
}
|
|
/* immediately reinit for backtracking resistance */
|
|
_rs_init(rs_buf, KEYSZ + IVSZ);
|
|
memset(rs_buf, 0, KEYSZ + IVSZ);
|
|
rs_have = RSBUFSZ - KEYSZ - IVSZ;
|
|
}
|
|
|
|
static inline void
|
|
_rs_random_buf(void *_buf, size_t n)
|
|
{
|
|
u_char *buf = (u_char *)_buf;
|
|
size_t m;
|
|
|
|
_rs_stir_if_needed(n);
|
|
while (n > 0) {
|
|
if (rs_have > 0) {
|
|
m = MIN(n, rs_have);
|
|
memcpy(buf, rs_buf + RSBUFSZ - rs_have, m);
|
|
memset(rs_buf + RSBUFSZ - rs_have, 0, m);
|
|
buf += m;
|
|
n -= m;
|
|
rs_have -= m;
|
|
}
|
|
if (rs_have == 0)
|
|
_rs_rekey(NULL, 0);
|
|
}
|
|
}
|
|
|
|
static inline void
|
|
_rs_random_u32(u_int32_t *val)
|
|
{
|
|
_rs_stir_if_needed(sizeof(*val));
|
|
if (rs_have < sizeof(*val))
|
|
_rs_rekey(NULL, 0);
|
|
memcpy(val, rs_buf + RSBUFSZ - rs_have, sizeof(*val));
|
|
memset(rs_buf + RSBUFSZ - rs_have, 0, sizeof(*val));
|
|
rs_have -= sizeof(*val);
|
|
return;
|
|
}
|
|
|
|
void
|
|
arc4random_stir(void)
|
|
{
|
|
_ARC4_LOCK();
|
|
_rs_stir();
|
|
_ARC4_UNLOCK();
|
|
}
|
|
|
|
void
|
|
arc4random_addrandom(u_char *dat, int datlen)
|
|
{
|
|
int m;
|
|
|
|
_ARC4_LOCK();
|
|
if (!rs_initialized)
|
|
_rs_stir();
|
|
while (datlen > 0) {
|
|
m = MIN(datlen, KEYSZ + IVSZ);
|
|
_rs_rekey(dat, m);
|
|
dat += m;
|
|
datlen -= m;
|
|
}
|
|
_ARC4_UNLOCK();
|
|
}
|
|
|
|
u_int32_t
|
|
arc4random(void)
|
|
{
|
|
u_int32_t val;
|
|
|
|
_ARC4_LOCK();
|
|
_rs_random_u32(&val);
|
|
_ARC4_UNLOCK();
|
|
return val;
|
|
}
|
|
|
|
/*
|
|
* If we are providing arc4random, then we can provide a more efficient
|
|
* arc4random_buf().
|
|
*/
|
|
# ifndef HAVE_ARC4RANDOM_BUF
|
|
void
|
|
arc4random_buf(void *buf, size_t n)
|
|
{
|
|
_ARC4_LOCK();
|
|
_rs_random_buf(buf, n);
|
|
_ARC4_UNLOCK();
|
|
}
|
|
# endif /* !HAVE_ARC4RANDOM_BUF */
|
|
#endif /* !HAVE_ARC4RANDOM */
|
|
|
|
/* arc4random_buf() that uses platform arc4random() */
|
|
#if !defined(HAVE_ARC4RANDOM_BUF) && defined(HAVE_ARC4RANDOM)
|
|
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;
|
|
}
|
|
explicit_bzero(&r, sizeof(r));
|
|
}
|
|
#endif /* !defined(HAVE_ARC4RANDOM_BUF) && defined(HAVE_ARC4RANDOM) */
|
|
|
|
#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;
|
|
|
|
/* 2**32 % x == (2**32 - x) % x */
|
|
min = -upper_bound % upper_bound;
|
|
|
|
/*
|
|
* 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 */
|
|
|
|
#if 0
|
|
/*-------- Test code for i386 --------*/
|
|
#include <stdio.h>
|
|
#include <machine/pctr.h>
|
|
int
|
|
main(int argc, char **argv)
|
|
{
|
|
const int iter = 1000000;
|
|
int i;
|
|
pctrval v;
|
|
|
|
v = rdtsc();
|
|
for (i = 0; i < iter; i++)
|
|
arc4random();
|
|
v = rdtsc() - v;
|
|
v /= iter;
|
|
|
|
printf("%qd cycles\n", v);
|
|
exit(0);
|
|
}
|
|
#endif
|
|
|