crypto_rand.c File Reference

Functions for initialising and seeding (pseudo-)random number generators, and working with randomness. More...

#include "crypto_rand.h"
#include "container.h"
#include "compat.h"
#include "compat_openssl.h"
#include "crypto_util.h"
#include "sandbox.h"
#include "testsupport.h"
#include "torlog.h"
#include "util.h"
#include "util_format.h"
#include <openssl/rand.h>

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Macros
#define	CRYPTO_RAND_PRIVATE
#define	ADD_ENTROPY   32
#define	MAX_DNS_LABEL_SIZE   63
#define	MAX_STRONGEST_RAND_SIZE   256
#define	DLEN   SHA512_DIGEST_LENGTH

Functions
void	crypto_seed_weak_rng (tor_weak_rng_t *rng)
STATIC int	crypto_strongest_rand_raw (uint8_t *out, size_t out_len)
void	crypto_strongest_rand (uint8_t *out, size_t out_len)
int	crypto_seed_rng (void)
	MOCK_IMPL (void, crypto_rand,(char *to, size_t n))
void	crypto_rand_unmocked (char *to, size_t n)
int	crypto_rand_int (unsigned int max)
int	crypto_rand_int_range (unsigned int min, unsigned int max)
uint64_t	crypto_rand_uint64_range (uint64_t min, uint64_t max)
time_t	crypto_rand_time_range (time_t min, time_t max)
uint64_t	crypto_rand_uint64 (uint64_t max)
double	crypto_rand_double (void)
char *	crypto_random_hostname (int min_rand_len, int max_rand_len, const char *prefix, const char *suffix)
void *	smartlist_choose (const smartlist_t *sl)
void	smartlist_shuffle (smartlist_t *sl)
int	crypto_force_rand_ssleay (void)

Detailed Description

Functions for initialising and seeding (pseudo-)random number generators, and working with randomness.

Macro Definition Documentation

ADD_ENTROPY

#define ADD_ENTROPY   32

How many bytes of entropy we add at once.

This is how much entropy OpenSSL likes to add right now, so maybe it will work for us too.

MAX_DNS_LABEL_SIZE

#define MAX_DNS_LABEL_SIZE   63

Longest recognized DNS query.

MAX_STRONGEST_RAND_SIZE

#define MAX_STRONGEST_RAND_SIZE   256

Largest strong entropy request permitted.

Function Documentation

crypto_force_rand_ssleay()

int crypto_force_rand_ssleay

(

void

)

Make sure that openssl is using its default PRNG. Return 1 if we had to adjust it; 0 otherwise.

crypto_rand_double()

double crypto_rand_double

(

void

)

Return a pseudorandom double d, chosen uniformly from the range 0.0 <= d < 1.0.

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crypto_rand_int()

int crypto_rand_int

(

unsigned int

max

)

Return a pseudorandom integer, chosen uniformly from the values between 0 and max-1 inclusive. max must be between 1 and INT_MAX+1, inclusive.

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crypto_rand_int_range()

int crypto_rand_int_range	(	unsigned int	min,
		unsigned int	max
	)

Return a pseudorandom integer, chosen uniformly from the values i such that min <= i < max.

min MUST be in range [0, max). max MUST be in range (min, INT_MAX].

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crypto_rand_time_range()

time_t crypto_rand_time_range	(	time_t	min,
		time_t	max
	)

As crypto_rand_int_range, but supports time_t.

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crypto_rand_uint64()

uint64_t crypto_rand_uint64

(

uint64_t

max

)

Return a pseudorandom 64-bit integer, chosen uniformly from the values between 0 and max-1 inclusive.

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crypto_rand_uint64_range()

uint64_t crypto_rand_uint64_range	(	uint64_t	min,
		uint64_t	max
	)

As crypto_rand_int_range, but supports uint64_t.

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crypto_rand_unmocked()

void crypto_rand_unmocked	(	char *	to,
		size_t	n
	)

Write n bytes of strong random data to to. Most callers will want crypto_rand instead.

This function is not allowed to fail; if it would fail to generate strong entropy, it must terminate the process instead.

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crypto_random_hostname()

char* crypto_random_hostname	(	int	min_rand_len,
		int	max_rand_len,
		const char *	prefix,
		const char *	suffix
	)

Generate and return a new random hostname starting with prefix, ending with suffix, and containing no fewer than min_rand_len and no more than max_rand_len random base32 characters. Does not check for failure.

Clip max_rand_len to MAX_DNS_LABEL_SIZE.

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crypto_seed_rng()

int crypto_seed_rng

(

void

)

Seed OpenSSL's random number generator with bytes from the operating system. Return 0 on success, -1 on failure.

crypto_seed_weak_rng()

void crypto_seed_weak_rng

(

tor_weak_rng_t *

rng

)

Set the seed of the weak RNG to a random value.

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crypto_strongest_rand()

void crypto_strongest_rand	(	uint8_t *	out,
		size_t	out_len
	)

Try to get out_len bytes of the strongest entropy we can generate, storing it into out.

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crypto_strongest_rand_raw()

STATIC int crypto_strongest_rand_raw	(	uint8_t *	out,
		size_t	out_len
	)

Try to get out_len bytes of the strongest entropy we can generate, storing it into out. Return 0 on success, -1 on failure. A maximum request size of 256 bytes is imposed.

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MOCK_IMPL()

MOCK_IMPL	(	void	,
		crypto_rand	,
		(char *to, size_t n)
	)

Write n bytes of strong random data to to. Supports mocking for unit tests.

This function is not allowed to fail; if it would fail to generate strong entropy, it must terminate the process instead.

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smartlist_choose()

void* smartlist_choose

(

const smartlist_t *

sl

)

Return a randomly chosen element of sl; or NULL if sl is empty.

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smartlist_shuffle()

void smartlist_shuffle

(

smartlist_t *

sl

)

Scramble the elements of sl into a random order.

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