1 /* SPDX-License-Identifier: LGPL-2.1+ */
8 typedef enum RandomFlags
{
9 RANDOM_EXTEND_WITH_PSEUDO
= 1 << 0, /* If we can't get enough genuine randomness, but some, fill up the rest with pseudo-randomness */
10 RANDOM_BLOCK
= 1 << 1, /* Rather block than return crap randomness (only if the kernel supports that) */
11 RANDOM_MAY_FAIL
= 1 << 2, /* If we can't get any randomness at all, return early with -ENODATA */
12 RANDOM_ALLOW_RDRAND
= 1 << 3, /* Allow usage of the CPU RNG */
13 RANDOM_ALLOW_INSECURE
= 1 << 4, /* Allow usage of GRND_INSECURE flag to kernel's getrandom() API */
16 int genuine_random_bytes(void *p
, size_t n
, RandomFlags flags
); /* returns "genuine" randomness, optionally filled up with pseudo random, if not enough is available */
17 void pseudo_random_bytes(void *p
, size_t n
); /* returns only pseudo-randommess (but possibly seeded from something better) */
18 void random_bytes(void *p
, size_t n
); /* returns genuine randomness if cheaply available, and pseudo randomness if not. */
20 void initialize_srand(void);
22 static inline uint64_t random_u64(void) {
24 random_bytes(&u
, sizeof(u
));
28 static inline uint32_t random_u32(void) {
30 random_bytes(&u
, sizeof(u
));
34 int rdrand(unsigned long *ret
);
36 /* Some limits on the pool sizes when we deal with the kernel random pool */
37 #define RANDOM_POOL_SIZE_MIN 512U
38 #define RANDOM_POOL_SIZE_MAX (10U*1024U*1024U)
40 size_t random_pool_size(void);