openssl/doc/man3/RAND_set_rand_method.pod
Matt Caswell 3dbf824380 Clarify the deprecation warnings in the docs
There was recently an instance where a user was confused by the
deprecation warnings in the docs. They believed the warning applied to
the immediately preceding function declarations, when it fact it applied
to the following function declarations.

https://mta.openssl.org/pipermail/openssl-users/2021-December/014665.html

We clarify the wording to make it clear that the warning applies to the
following functions.

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17180)
2021-12-06 11:23:34 +00:00

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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>
The following functions have been deprecated since OpenSSL 3.0, and can be
hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
see L<openssl_user_macros(7)>:
RAND_METHOD *RAND_OpenSSL(void);
int RAND_set_rand_method(const RAND_METHOD *meth);
const RAND_METHOD *RAND_get_rand_method(void);
=head1 DESCRIPTION
All of the functions described on this page are deprecated.
Applications should instead use L<RAND_set_DRBG_type(3)>,
L<EVP_RAND(3)> and L<EVP_RAND(7)>.
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(). This is deprecated
in OpenSSL 3.0.
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<EVP_RAND(3)>,
L<RAND_set_DRBG_type(3)>,
L<RAND_bytes(3)>,
L<ENGINE_by_id(3)>,
L<EVP_RAND(7)>,
L<RAND(7)>
=head1 HISTORY
All of these functions were deprecated in OpenSSL 3.0.
=head1 COPYRIGHT
Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (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