/*
* Stir our S-box.
*/
static void
arc4_randomstir(void)
{
u_int8_t key[ARC4_KEYBYTES];
int n;
struct timeval tv_now;
/*
* XXX: FIX!! This isn't brilliant. Need more confidence.
* This returns zero entropy before random(4) is seeded.
*/
(void)read_random(key, ARC4_KEYBYTES);
getmicrouptime(&tv_now);
mtx_lock(&arc4_mtx);
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.)
*
* http://dl.acm.org/citation.cfm?id=646557.694759
*/
for (n = 0; n < 256*4; n++)
arc4_randbyte();
mtx_unlock(&arc4_mtx);
}
u_int32_t
arc4random(void)
{
u_int32_t ret;
struct timeval tv_now;
/* Initialize array if needed. */
if (!arc4_initialized)
arc4_init();
microtime(&tv_now);
if ((++arc4_numruns > ARC4_MAXRUNS) ||
(tv_now.tv_sec > arc4_tv_nextreseed.tv_sec))
{
arc4_randomstir();
}
ret = arc4_randbyte();
ret |= arc4_randbyte() << 8;
ret |= arc4_randbyte() << 16;
ret |= arc4_randbyte() << 24;
return ret;
}
/*
* MPSAFE
*/
void
arc4rand(void *ptr, u_int len, int reseed)
{
u_char *p;
struct timeval tv;
getmicrotime(&tv);
if (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);
}
/*
* MPSAFE
*/
void
arc4rand(void *ptr, u_int len, int reseed)
{
u_int8_t *p;
struct timeval tv;
GETKTIME(&tv);
if (reseed ||
(arc4_numruns > ARC4_RESEED_BYTES) ||
(tv.tv_sec > arc4_t_reseed))
arc4_randomstir();
MUTEX_ENTER(&arc4_mtx);
arc4_numruns += len;
p = ptr;
while (len--)
*p++ = arc4_randbyte();
MUTEX_EXIT(&arc4_mtx);
}
/*
* 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);
}
/*
* Initialize our S-box to its beginning defaults.
*/
static void
arc4_init(void)
{
int n;
arc4_i = arc4_j = 0;
for (n = 0; n < 256; n++)
arc4_sbox[n] = (u_int8_t) n;
arc4_randomstir();
arc4_initialized = 1;
/*
* 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();
}
/*
* 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]);
}
/* 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);
}
