hardened_malloc/random.h

#ifndef RANDOM_H
#define RANDOM_H

#include "chacha.h"
#include "util.h"

#define RANDOM_CACHE_SIZE 256U
#define RANDOM_RESEED_SIZE (256U * 1024)

struct random_state {
    unsigned index;
    unsigned reseed;
    chacha_ctx ctx;
    u8 cache[RANDOM_CACHE_SIZE];
};

void random_state_init(struct random_state *state);
void random_state_init_from_random_state(struct random_state *state, struct random_state *source);
void get_random_bytes(struct random_state *state, void *buf, size_t size);
u16 get_random_u16(struct random_state *state);
u16 get_random_u16_uniform(struct random_state *state, u16 bound);
u64 get_random_u64(struct random_state *state);
u64 get_random_u64_uniform(struct random_state *state, u64 bound);

#endif
initial commit 2018-08-21 15:23:22 -04:00			`#ifndef RANDOM_H`
			`#define RANDOM_H`

use ChaCha8-based CSPRNG 2018-08-25 23:00:00 -04:00			`#include "chacha.h"`
use a consistent style for fixed-size int types The stdint.h types don't cover 128-bit integers and the underscore makes them ill suited to usage in function suffixes. Instead, use the common naming style in the Linux kernel and elsewhere including the ChaCha8 implementation included here. 2018-10-04 14:25:16 -04:00			`#include "util.h"`
use ChaCha8-based CSPRNG 2018-08-25 23:00:00 -04:00
use smaller integers for random cache state 2018-11-04 14:23:12 -05:00			`#define RANDOM_CACHE_SIZE 256U`
			`#define RANDOM_RESEED_SIZE (256U * 1024)`
implement a cache for the CSPRNG 2018-08-23 16:30:44 -04:00
initial commit 2018-08-21 15:23:22 -04:00			`struct random_state {`
use smaller integers for random cache state 2018-11-04 14:23:12 -05:00			`unsigned index;`
			`unsigned reseed;`
use ChaCha8-based CSPRNG 2018-08-25 23:00:00 -04:00			`chacha_ctx ctx;`
use a consistent style for fixed-size int types The stdint.h types don't cover 128-bit integers and the underscore makes them ill suited to usage in function suffixes. Instead, use the common naming style in the Linux kernel and elsewhere including the ChaCha8 implementation included here. 2018-10-04 14:25:16 -04:00			`u8 cache[RANDOM_CACHE_SIZE];`
initial commit 2018-08-21 15:23:22 -04:00			`};`

			`void random_state_init(struct random_state *state);`
initialize size class CSPRNGs from init CSPRNG This avoids making a huge number of getrandom system calls during initialization. The init CSPRNG is unmapped before initialization finishes and these are still reseeded from the OS. The purpose of the independent CSPRNGs is simply to avoid the massive performance hit of synchronization and there's no harm in doing it this way. Keeping around the init CSPRNG and reseeding from it would defeat the purpose of reseeding, and it isn't a measurable performance issue since it can just be tuned to reseed less often. 2019-04-15 06:29:57 -04:00			`void random_state_init_from_random_state(struct random_state state, struct random_state source);`
add generic get_random_bytes function 2019-04-15 04:52:18 -04:00			`void get_random_bytes(struct random_state state, void buf, size_t size);`
use a consistent style for fixed-size int types The stdint.h types don't cover 128-bit integers and the underscore makes them ill suited to usage in function suffixes. Instead, use the common naming style in the Linux kernel and elsewhere including the ChaCha8 implementation included here. 2018-10-04 14:25:16 -04:00			`u16 get_random_u16(struct random_state *state);`
			`u16 get_random_u16_uniform(struct random_state *state, u16 bound);`
			`u64 get_random_u64(struct random_state *state);`
			`u64 get_random_u64_uniform(struct random_state *state, u64 bound);`
initial commit 2018-08-21 15:23:22 -04:00
			`#endif`