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=pod
=head1 NAME
RAND_set_rand_method, RAND_get_rand_method, RAND_OpenSSL - select RAND method
=head1 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);
=head1 DESCRIPTION
A B<RAND_METHOD> specifies the functions that OpenSSL uses for random number
generation.
RAND_OpenSSL() returns the default B<RAND_METHOD> implementation by OpenSSL.
This implementation ensures that the PRNG state is unique for each thread.
If an B<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 B<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 B<RAND_METHOD>.
=head1 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.
=head1 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.
=head1 SEE ALSO
L<RAND_bytes(3)>,
L<ENGINE_by_id(3)>,
L<RAND(7)>
=head1 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
L<https://www.openssl.org/source/license.html>.
=cut
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