mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-27 11:55:06 +00:00
2b50ce65be
reinitialization from yarrow right after good entropy is harvested. Approved by: secteam (delphij) MFC after: 1 week
157 lines
3.0 KiB
C
157 lines
3.0 KiB
C
/*-
|
|
* THE BEER-WARE LICENSE
|
|
*
|
|
* <dan@FreeBSD.ORG> wrote this file. As long as you retain this notice you
|
|
* can do whatever you want with this stuff. If we meet some day, and you
|
|
* think this stuff is worth it, you can buy me a beer in return.
|
|
*
|
|
* Dan Moschuk
|
|
*/
|
|
|
|
#include <sys/cdefs.h>
|
|
__FBSDID("$FreeBSD$");
|
|
|
|
#include <sys/types.h>
|
|
#include <sys/param.h>
|
|
#include <sys/kernel.h>
|
|
#include <sys/random.h>
|
|
#include <sys/libkern.h>
|
|
#include <sys/lock.h>
|
|
#include <sys/mutex.h>
|
|
#include <sys/time.h>
|
|
|
|
#define ARC4_RESEED_BYTES 65536
|
|
#define ARC4_RESEED_SECONDS 300
|
|
#define ARC4_KEYBYTES (256 / 8)
|
|
|
|
int arc4rand_iniseed_state = ARC4_ENTR_NONE;
|
|
|
|
static u_int8_t arc4_i, arc4_j;
|
|
static int arc4_numruns = 0;
|
|
static u_int8_t arc4_sbox[256];
|
|
static time_t arc4_t_reseed;
|
|
static struct mtx arc4_mtx;
|
|
|
|
static u_int8_t arc4_randbyte(void);
|
|
|
|
static __inline void
|
|
arc4_swap(u_int8_t *a, u_int8_t *b)
|
|
{
|
|
u_int8_t c;
|
|
|
|
c = *a;
|
|
*a = *b;
|
|
*b = c;
|
|
}
|
|
|
|
/*
|
|
* Stir our S-box.
|
|
*/
|
|
static void
|
|
arc4_randomstir (void)
|
|
{
|
|
u_int8_t key[256];
|
|
int r, n;
|
|
struct timeval tv_now;
|
|
|
|
/*
|
|
* XXX read_random() returns unsafe numbers if the entropy
|
|
* device is not loaded -- MarkM.
|
|
*/
|
|
r = read_random(key, ARC4_KEYBYTES);
|
|
getmicrouptime(&tv_now);
|
|
mtx_lock(&arc4_mtx);
|
|
/* If r == 0 || -1, just use what was on the stack. */
|
|
if (r > 0) {
|
|
for (n = r; n < sizeof(key); n++)
|
|
key[n] = key[n % r];
|
|
}
|
|
|
|
for (n = 0; n < 256; n++) {
|
|
arc4_j = (arc4_j + arc4_sbox[n] + key[n]) % 256;
|
|
arc4_swap(&arc4_sbox[n], &arc4_sbox[arc4_j]);
|
|
}
|
|
arc4_i = arc4_j = 0;
|
|
|
|
/* Reset for next reseed cycle. */
|
|
arc4_t_reseed = tv_now.tv_sec + ARC4_RESEED_SECONDS;
|
|
arc4_numruns = 0;
|
|
|
|
/*
|
|
* Throw away the first N words of output, as suggested in the
|
|
* paper "Weaknesses in the Key Scheduling Algorithm of RC4"
|
|
* by Fluher, Mantin, and Shamir. (N = 256 in our case.)
|
|
*/
|
|
for (n = 0; n < 256*4; n++)
|
|
arc4_randbyte();
|
|
mtx_unlock(&arc4_mtx);
|
|
}
|
|
|
|
/*
|
|
* Initialize our S-box to its beginning defaults.
|
|
*/
|
|
static void
|
|
arc4_init(void)
|
|
{
|
|
int n;
|
|
|
|
mtx_init(&arc4_mtx, "arc4_mtx", NULL, MTX_DEF);
|
|
arc4_i = arc4_j = 0;
|
|
for (n = 0; n < 256; n++)
|
|
arc4_sbox[n] = (u_int8_t) n;
|
|
|
|
arc4_t_reseed = 0;
|
|
}
|
|
|
|
SYSINIT(arc4_init, SI_SUB_LOCK, SI_ORDER_ANY, arc4_init, NULL);
|
|
|
|
/*
|
|
* Generate a random byte.
|
|
*/
|
|
static u_int8_t
|
|
arc4_randbyte(void)
|
|
{
|
|
u_int8_t arc4_t;
|
|
|
|
arc4_i = (arc4_i + 1) % 256;
|
|
arc4_j = (arc4_j + arc4_sbox[arc4_i]) % 256;
|
|
|
|
arc4_swap(&arc4_sbox[arc4_i], &arc4_sbox[arc4_j]);
|
|
|
|
arc4_t = (arc4_sbox[arc4_i] + arc4_sbox[arc4_j]) % 256;
|
|
return arc4_sbox[arc4_t];
|
|
}
|
|
|
|
/*
|
|
* MPSAFE
|
|
*/
|
|
void
|
|
arc4rand(void *ptr, u_int len, int reseed)
|
|
{
|
|
u_char *p;
|
|
struct timeval tv;
|
|
|
|
getmicrouptime(&tv);
|
|
if (atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_HAVE,
|
|
ARC4_ENTR_SEED) || reseed ||
|
|
(arc4_numruns > ARC4_RESEED_BYTES) ||
|
|
(tv.tv_sec > arc4_t_reseed))
|
|
arc4_randomstir();
|
|
|
|
mtx_lock(&arc4_mtx);
|
|
arc4_numruns += len;
|
|
p = ptr;
|
|
while (len--)
|
|
*p++ = arc4_randbyte();
|
|
mtx_unlock(&arc4_mtx);
|
|
}
|
|
|
|
uint32_t
|
|
arc4random(void)
|
|
{
|
|
uint32_t ret;
|
|
|
|
arc4rand(&ret, sizeof ret, 0);
|
|
return ret;
|
|
}
|