=pod
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=head1 NAME
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RAND_set_rand_method, RAND_get_rand_method, RAND_OpenSSL - select RAND method
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=head1 SYNOPSIS
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#include <openssl/rand.h>
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RAND_METHOD *RAND_OpenSSL(void);
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int RAND_set_rand_method(const RAND_METHOD *meth);
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const RAND_METHOD *RAND_get_rand_method(void);
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=head1 DESCRIPTION
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A B<RAND_METHOD> specifies the functions that OpenSSL uses for random number
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generation.
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RAND_OpenSSL() returns the default B<RAND_METHOD> implementation by OpenSSL.
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This implementation ensures that the PRNG state is unique for each thread.
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If an B<ENGINE> is loaded that provides the RAND API, however, it will
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be used instead of the method returned by RAND_OpenSSL().
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RAND_set_rand_method() makes B<meth> the method for PRNG use. If an
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ENGINE was providing the method, it will be released first.
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RAND_get_rand_method() returns a pointer to the current B<RAND_METHOD>.
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=head1 THE RAND_METHOD STRUCTURE
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typedef struct rand_meth_st {
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int (*seed)(const void *buf, int num);
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int (*bytes)(unsigned char *buf, int num);
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void (*cleanup)(void);
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int (*add)(const void *buf, int num, double entropy);
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int (*pseudorand)(unsigned char *buf, int num);
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int (*status)(void);
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} RAND_METHOD;
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The fields point to functions that are used by, in order,
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RAND_seed(), RAND_bytes(), internal RAND cleanup, RAND_add(), RAND_pseudo_rand()
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and RAND_status().
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Each pointer may be NULL if the function is not implemented.
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=head1 RETURN VALUES
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RAND_set_rand_method() returns 1 on success and 0 on failure.
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RAND_get_rand_method() and RAND_OpenSSL() return pointers to the respective
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methods.
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=head1 SEE ALSO
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L<RAND_bytes(3)>,
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L<ENGINE_by_id(3)>,
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L<RAND(7)>
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=head1 COPYRIGHT
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Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the OpenSSL license (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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