diff options
Diffstat (limited to 'sys/libkern/arc4random.c')
| -rw-r--r-- | sys/libkern/arc4random.c | 24 |
1 files changed, 9 insertions, 15 deletions
diff --git a/sys/libkern/arc4random.c b/sys/libkern/arc4random.c index 62ace2c..9de5a84 100644 --- a/sys/libkern/arc4random.c +++ b/sys/libkern/arc4random.c @@ -22,7 +22,7 @@ __FBSDID("$FreeBSD$"); #define ARC4_RESEED_BYTES 65536 #define ARC4_RESEED_SECONDS 300 -#define ARC4_KEYBYTES (256 / 8) +#define ARC4_KEYBYTES 256 int arc4rand_iniseed_state = ARC4_ENTR_NONE; @@ -48,39 +48,33 @@ arc4_swap(u_int8_t *a, u_int8_t *b) * Stir our S-box. */ static void -arc4_randomstir (void) +arc4_randomstir(void) { - u_int8_t key[256]; - int r, n; + u_int8_t key[ARC4_KEYBYTES]; + int n; struct timeval tv_now; /* - * XXX read_random() returns unsafe numbers if the entropy - * device is not loaded -- MarkM. + * XXX: FIX!! This isn't brilliant. Need more confidence. + * This returns zero entropy before random(4) is seeded. */ - r = read_random(key, ARC4_KEYBYTES); + (void)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.) + * + * http://dl.acm.org/citation.cfm?id=646557.694759 */ for (n = 0; n < 256*4; n++) arc4_randbyte(); |
