Updated: 2021/Apr/14


RAND_set_rand_method(3)             OpenSSL            RAND_set_rand_method(3)



NAME
       RAND_set_rand_method, RAND_get_rand_method, RAND_OpenSSL - select RAND
       method

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
        #include <openssl/rand.h>

        RAND_METHOD *RAND_OpenSSL(void);

        int RAND_set_rand_method(const RAND_METHOD *meth);

        const RAND_METHOD *RAND_get_rand_method(void);

DESCRIPTION
       A RAND_METHOD specifies the functions that OpenSSL uses for random
       number generation.

       RAND_OpenSSL() returns the default RAND_METHOD implementation by
       OpenSSL.  This implementation ensures that the PRNG state is unique for
       each thread.

       If an ENGINE is loaded that provides the RAND API, however, it will be
       used instead of the method returned by RAND_OpenSSL().

       RAND_set_rand_method() makes meth the method for PRNG use.  If an
       ENGINE was providing the method, it will be released first.

       RAND_get_rand_method() returns a pointer to the current RAND_METHOD.

THE RAND_METHOD STRUCTURE
        typedef struct rand_meth_st {
            int (*seed)(const void *buf, int num);
            int (*bytes)(unsigned char *buf, int num);
            void (*cleanup)(void);
            int (*add)(const void *buf, int num, double entropy);
            int (*pseudorand)(unsigned char *buf, int num);
            int (*status)(void);
        } RAND_METHOD;

       The fields point to functions that are used by, in order, RAND_seed(),
       RAND_bytes(), internal RAND cleanup, RAND_add(), RAND_pseudo_rand() and
       RAND_status().  Each pointer may be NULL if the function is not
       implemented.

RETURN VALUES
       RAND_set_rand_method() returns 1 on success and 0 on failure.
       RAND_get_rand_method() and RAND_OpenSSL() return pointers to the
       respective methods.

SEE ALSO
       RAND_bytes(3), ENGINE_by_id(3), RAND(7)

COPYRIGHT
       Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (the "License").  You may not use
       this file except in compliance with the License.  You can obtain a copy
       in the file LICENSE in the source distribution or at
       <https://www.openssl.org/source/license.html>.



1.1.1i                            2020-04-24           RAND_set_rand_method(3)