| RAND_set_rand_method(3ssl) - phpMan
RAND_set_rand_method(3SSL) OpenSSL RAND_set_rand_method(3SSL)
NAME
RAND_set_rand_method, RAND_get_rand_method, RAND_SSLeay - select RAND method
SYNOPSIS
#include <openssl/rand.h>
void RAND_set_rand_method(const RAND_METHOD *meth);
const RAND_METHOD *RAND_get_rand_method(void);
RAND_METHOD *RAND_SSLeay(void);
DESCRIPTION
A RAND_METHOD specifies the functions that OpenSSL uses for random number generation. By
modifying the method, alternative implementations such as hardware RNGs may be used.
IMPORTANT: See the NOTES section for important information about how these RAND API
functions are affected by the use of ENGINE API calls.
Initially, the default RAND_METHOD is the OpenSSL internal implementation, as returned by
RAND_SSLeay().
RAND_set_default_method() makes meth the method for PRNG use. NB: This is true only whilst
no ENGINE has been set as a default for RAND, so this function is no longer recommended.
RAND_get_default_method() returns a pointer to the current RAND_METHOD. However, the
meaningfulness of this result is dependent on whether the ENGINE API is being used, so
this function is no longer recommended.
THE RAND_METHOD STRUCTURE
typedef struct rand_meth_st
{
void (*seed)(const void *buf, int num);
int (*bytes)(unsigned char *buf, int num);
void (*cleanup)(void);
void (*add)(const void *buf, int num, int entropy);
int (*pseudorand)(unsigned char *buf, int num);
int (*status)(void);
} RAND_METHOD;
The components point to the implementation of RAND_seed(), RAND_bytes(), RAND_cleanup(),
RAND_add(), RAND_pseudo_rand() and RAND_status(). Each component may be NULL if the
function is not implemented.
RETURN VALUES
RAND_set_rand_method() returns no value. RAND_get_rand_method() and RAND_SSLeay() return
pointers to the respective methods.
NOTES
As of version 0.9.7, RAND_METHOD implementations are grouped together with other
algorithmic APIs (eg. RSA_METHOD, EVP_CIPHER, etc) in ENGINE modules. If a default ENGINE
is specified for RAND functionality using an ENGINE API function, that will override any
RAND defaults set using the RAND API (ie. RAND_set_rand_method()). For this reason, the
ENGINE API is the recommended way to control default implementations for use in RAND and
other cryptographic algorithms.
SEE ALSO
rand(3), engine(3)
HISTORY
RAND_set_rand_method(), RAND_get_rand_method() and RAND_SSLeay() are available in all
versions of OpenSSL.
In the engine version of version 0.9.6, RAND_set_rand_method() was altered to take an
ENGINE pointer as its argument. As of version 0.9.7, that has been reverted as the ENGINE
API transparently overrides RAND defaults if used, otherwise RAND API functions work as
before. RAND_set_rand_engine() was also introduced in version 0.9.7.
1.0.1t 2016-05-03 RAND_set_rand_method(3SSL)
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