Git-Mirrors/hardened_malloc
1
0
Fork 0
mirror of https://github.com/GrapheneOS/hardened_malloc.git synced 2025-05-24 17:01:21 -04:00
Code Issues Projects Releases Packages Wiki Activity

use ChaCha8-based CSPRNG

Browse source
This commit is contained in:
Daniel Micay 2018-08-25 23:00:00 -04:00
parent 2b7c9362bb
commit c41e659383
5 changed files with 235 additions and 7 deletions
Download patch file Download diff file Expand all files Collapse all files

24
random.c
View file

@ -16,6 +16,8 @@ static ssize_t getrandom(void *buf, size_t buflen, unsigned int flags) {
}
#endif
#include "chacha.h"
static void get_random_seed(void *buf, size_t size) {
while (size > 0) {
ssize_t r;
@ -33,20 +35,34 @@ static void get_random_seed(void *buf, size_t size) {
}
}
#define KEY_SIZE 32
#define IV_SIZE 8
void random_state_init(struct random_state *state) {
state->index = RANDOM_CACHE_SIZE;
uint8_t rnd[KEY_SIZE + IV_SIZE];
get_random_seed(rnd, sizeof(rnd));
chacha_keysetup(&state->ctx, rnd, KEY_SIZE * 8);
chacha_ivsetup(&state->ctx, rnd + KEY_SIZE);
chacha_keystream_bytes(&state->ctx, state->cache, RANDOM_CACHE_SIZE);
state->index = 0;
state->reseed = 0;
}
void get_random_bytes(struct random_state *state, void *buf, size_t size) {
if (size > RANDOM_CACHE_SIZE / 2) {
get_random_seed(buf, size);
chacha_keystream_bytes(&state->ctx, state->cache, RANDOM_CACHE_SIZE);
return;
}
while (size) {
if (state->index == RANDOM_CACHE_SIZE) {
state->index = 0;
get_random_seed(state->cache, RANDOM_CACHE_SIZE);
if (state->reseed >= RANDOM_RESEED_SIZE) {
random_state_init(state);
} else {
chacha_keystream_bytes(&state->ctx, state->cache, RANDOM_CACHE_SIZE);
state->index = 0;
state->reseed += RANDOM_CACHE_SIZE;
}
}
size_t remaining = RANDOM_CACHE_SIZE - state->index;
size_t copy_size = size < remaining ? size : remaining;