RAND_set_rand_method(3)

NAME
RAND_set_rand_method, RAND_get_rand_method, RAND_SSLeay - select RAND method

SYNOPSIS

 #include <openssl/rand.h>
 void RAND_set_rand_method(RAND_METHOD *meth);
 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. Initially, the default is to use the OpenSSL internal implementation. RAND_SSLeay() returns a pointer to that method.

RAND_set_rand_method() sets the RAND method to meth. RAND_get_rand_method() returns a pointer to the current method.

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.

SEE ALSO
rand(3)

HISTORY
RAND_set_rand_method(), RAND_get_rand_method() and RAND_SSLeay() are available in all versions of OpenSSL.