hcs_random.h File Reference

Provides secure random state for use in functions which require random values. More...

#include <gmp.h>

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Data Structures
struct	hcs_random
	Random state used by a number of cryptographic functions. More...

Macros
#define	HCS_RAND_SEED_BITS   256
	If this define is set, then a static seed of 0 will always be used in any hcs_random functions. More...

Functions
hcs_random *	hcs_init_random (void)
	Initialise an hcs_random and return a pointer to the newly created structure. More...
int	hcs_reseed_random (hcs_random *hr)
	Reseed the given hcs_random. More...
void	hcs_free_random (hcs_random *hr)
	Frees a hcs_random and all associated memory. More...

Detailed Description

Provides secure random state for use in functions which require random values.

This is a wrapper around gmp_randstate_t, and utilizes them internally as a PRNG. Currently, it uses gmp_randinit_default for choice of PRNG.

Seed is gathered from the operating systems provided entropy. For example, /dev/urandom is used under Linux. This may be slightly altered, but for now it satisfies the required randomness.

Macro Definition Documentation

#define HCS_RAND_SEED_BITS   256

If this define is set, then a static seed of 0 will always be used in any hcs_random functions.

ONLY use this for testing. The number of bits of seed which is gathered from our entropy source.

Function Documentation

hcs_random* hcs_init_random

(

void

)

Initialise an hcs_random and return a pointer to the newly created structure.

Returns

A pointer to an hcs_random type on success, NULL on allocation failure

int hcs_reseed_random

(

hcs_random *

hr

)

Reseed the given hcs_random.

If we fail to gather sufficient entropy, we return with an error.

Todo:

Potentially expand error codes so we can explain exactly what went wrong to the caller. For now though, it is better than aborting.

Parameters

hr	A pointer to an initialised hcs_random

Returns

non-zero on successful reseed, zero on failure

void hcs_free_random

(

hcs_random *

hr

)

Frees a hcs_random and all associated memory.

Parameters

hr	A pointer to an initliased hcs_random