dad64c978f
arc4random.c - CVS rev. 1.22 Change arc4random_uniform() to calculate ``2**32 % upper_bound'' as ``-upper_bound % upper_bound''. Simplifies the code and makes it the same on both ILP32 and LP64 architectures, and also slightly faster on LP64 architectures by using a 32-bit remainder instead of a 64-bit remainder. - CVS rev. 1.23 Spacing readpassphrase.c -CVS rev. v 1.24 most obvious unsigned char casts for ctype Obtained from: OpenBSD MFC after: 5 days
315 lines
6.3 KiB
C
315 lines
6.3 KiB
C
/* $OpenBSD: arc4random.c,v 1.24 2013/06/11 16:59:50 deraadt Exp $ */
|
|
|
|
/*
|
|
* Copyright (c) 1996, David Mazieres <dm@uun.org>
|
|
* Copyright (c) 2008, Damien Miller <djm@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.
|
|
*/
|
|
|
|
/*
|
|
* Arc4 random number generator for OpenBSD.
|
|
*
|
|
* This code is derived from section 17.1 of Applied Cryptography,
|
|
* second edition, which describes a stream cipher allegedly
|
|
* compatible with RSA Labs "RC4" cipher (the actual description of
|
|
* which is a trade secret). The same algorithm is used as a stream
|
|
* cipher called "arcfour" in Tatu Ylonen's ssh package.
|
|
*
|
|
* RC4 is a registered trademark of RSA Laboratories.
|
|
*/
|
|
|
|
#include <sys/cdefs.h>
|
|
__FBSDID("$FreeBSD$");
|
|
|
|
#include "namespace.h"
|
|
#include <fcntl.h>
|
|
#include <limits.h>
|
|
#include <stdlib.h>
|
|
#include <unistd.h>
|
|
#include <sys/types.h>
|
|
#include <sys/param.h>
|
|
#include <sys/sysctl.h>
|
|
#include <sys/time.h>
|
|
#include <pthread.h>
|
|
|
|
#include "libc_private.h"
|
|
#include "un-namespace.h"
|
|
|
|
#ifdef __GNUC__
|
|
#define inline __inline
|
|
#else /* !__GNUC__ */
|
|
#define inline
|
|
#endif /* !__GNUC__ */
|
|
|
|
struct arc4_stream {
|
|
u_int8_t i;
|
|
u_int8_t j;
|
|
u_int8_t s[256];
|
|
};
|
|
|
|
static pthread_mutex_t arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;
|
|
|
|
#define RANDOMDEV "/dev/random"
|
|
#define KEYSIZE 128
|
|
#define _ARC4_LOCK() \
|
|
do { \
|
|
if (__isthreaded) \
|
|
_pthread_mutex_lock(&arc4random_mtx); \
|
|
} while (0)
|
|
|
|
#define _ARC4_UNLOCK() \
|
|
do { \
|
|
if (__isthreaded) \
|
|
_pthread_mutex_unlock(&arc4random_mtx); \
|
|
} while (0)
|
|
|
|
static int rs_initialized;
|
|
static struct arc4_stream rs;
|
|
static pid_t arc4_stir_pid;
|
|
static int arc4_count;
|
|
|
|
extern int __sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp,
|
|
void *newp, size_t newlen);
|
|
|
|
static inline u_int8_t arc4_getbyte(void);
|
|
static void arc4_stir(void);
|
|
|
|
static inline void
|
|
arc4_init(void)
|
|
{
|
|
int n;
|
|
|
|
for (n = 0; n < 256; n++)
|
|
rs.s[n] = n;
|
|
rs.i = 0;
|
|
rs.j = 0;
|
|
}
|
|
|
|
static inline void
|
|
arc4_addrandom(u_char *dat, int datlen)
|
|
{
|
|
int n;
|
|
u_int8_t si;
|
|
|
|
rs.i--;
|
|
for (n = 0; n < 256; n++) {
|
|
rs.i = (rs.i + 1);
|
|
si = rs.s[rs.i];
|
|
rs.j = (rs.j + si + dat[n % datlen]);
|
|
rs.s[rs.i] = rs.s[rs.j];
|
|
rs.s[rs.j] = si;
|
|
}
|
|
rs.j = rs.i;
|
|
}
|
|
|
|
static size_t
|
|
arc4_sysctl(u_char *buf, size_t size)
|
|
{
|
|
int mib[2];
|
|
size_t len, done;
|
|
|
|
mib[0] = CTL_KERN;
|
|
mib[1] = KERN_ARND;
|
|
done = 0;
|
|
|
|
do {
|
|
len = size;
|
|
if (__sysctl(mib, 2, buf, &len, NULL, 0) == -1)
|
|
return (done);
|
|
done += len;
|
|
buf += len;
|
|
size -= len;
|
|
} while (size > 0);
|
|
|
|
return (done);
|
|
}
|
|
|
|
static void
|
|
arc4_stir(void)
|
|
{
|
|
int done, fd, i;
|
|
struct {
|
|
struct timeval tv;
|
|
pid_t pid;
|
|
u_char rnd[KEYSIZE];
|
|
} rdat;
|
|
|
|
if (!rs_initialized) {
|
|
arc4_init();
|
|
rs_initialized = 1;
|
|
}
|
|
done = 0;
|
|
if (arc4_sysctl((u_char *)&rdat, KEYSIZE) == KEYSIZE)
|
|
done = 1;
|
|
if (!done) {
|
|
fd = _open(RANDOMDEV, O_RDONLY | O_CLOEXEC, 0);
|
|
if (fd >= 0) {
|
|
if (_read(fd, &rdat, KEYSIZE) == KEYSIZE)
|
|
done = 1;
|
|
(void)_close(fd);
|
|
}
|
|
}
|
|
if (!done) {
|
|
(void)gettimeofday(&rdat.tv, NULL);
|
|
rdat.pid = getpid();
|
|
/* We'll just take whatever was on the stack too... */
|
|
}
|
|
|
|
arc4_addrandom((u_char *)&rdat, KEYSIZE);
|
|
|
|
/*
|
|
* Discard early keystream, as per recommendations in:
|
|
* "(Not So) Random Shuffles of RC4" by Ilya Mironov.
|
|
*/
|
|
for (i = 0; i < 1024; i++)
|
|
(void)arc4_getbyte();
|
|
arc4_count = 1600000;
|
|
}
|
|
|
|
static void
|
|
arc4_stir_if_needed(void)
|
|
{
|
|
pid_t pid = getpid();
|
|
|
|
if (arc4_count <= 0 || !rs_initialized || arc4_stir_pid != pid) {
|
|
arc4_stir_pid = pid;
|
|
arc4_stir();
|
|
}
|
|
}
|
|
|
|
static inline u_int8_t
|
|
arc4_getbyte(void)
|
|
{
|
|
u_int8_t si, sj;
|
|
|
|
rs.i = (rs.i + 1);
|
|
si = rs.s[rs.i];
|
|
rs.j = (rs.j + si);
|
|
sj = rs.s[rs.j];
|
|
rs.s[rs.i] = sj;
|
|
rs.s[rs.j] = si;
|
|
return (rs.s[(si + sj) & 0xff]);
|
|
}
|
|
|
|
static inline u_int32_t
|
|
arc4_getword(void)
|
|
{
|
|
u_int32_t val;
|
|
val = arc4_getbyte() << 24;
|
|
val |= arc4_getbyte() << 16;
|
|
val |= arc4_getbyte() << 8;
|
|
val |= arc4_getbyte();
|
|
return val;
|
|
}
|
|
|
|
void
|
|
arc4random_stir(void)
|
|
{
|
|
_ARC4_LOCK();
|
|
arc4_stir();
|
|
_ARC4_UNLOCK();
|
|
}
|
|
|
|
void
|
|
arc4random_addrandom(u_char *dat, int datlen)
|
|
{
|
|
_ARC4_LOCK();
|
|
if (!rs_initialized)
|
|
arc4_stir();
|
|
arc4_addrandom(dat, datlen);
|
|
_ARC4_UNLOCK();
|
|
}
|
|
|
|
u_int32_t
|
|
arc4random(void)
|
|
{
|
|
u_int32_t val;
|
|
_ARC4_LOCK();
|
|
arc4_count -= 4;
|
|
arc4_stir_if_needed();
|
|
val = arc4_getword();
|
|
_ARC4_UNLOCK();
|
|
return val;
|
|
}
|
|
|
|
void
|
|
arc4random_buf(void *_buf, size_t n)
|
|
{
|
|
u_char *buf = (u_char *)_buf;
|
|
_ARC4_LOCK();
|
|
arc4_stir_if_needed();
|
|
while (n--) {
|
|
if (--arc4_count <= 0)
|
|
arc4_stir();
|
|
buf[n] = arc4_getbyte();
|
|
}
|
|
_ARC4_UNLOCK();
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
#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);
|
|
}
|
|
#endif
|