openssl/doc/man3/RAND_DRBG_new.pod
Joshua Lock 18bad53564 Update various man pages to place HISTORY section after SEE ALSO
SEE ALSO before HISTORY is the more common pattern in OpenSSL manual
pages and seems to be the prevalent order based on sampling my system
manual pages.

Fixes #8631

Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
Reviewed-by: Richard Levitte <levitte@openssl.org>

(cherry picked from commit b5c4bbbe54)

 Conflicts:
	doc/man3/RAND_DRBG_generate.pod
	doc/man3/RAND_DRBG_reseed.pod

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8736)
2019-04-15 12:26:49 +02:00

127 lines
3.9 KiB
Text

=pod
=head1 NAME
RAND_DRBG_new,
RAND_DRBG_secure_new,
RAND_DRBG_set,
RAND_DRBG_set_defaults,
RAND_DRBG_instantiate,
RAND_DRBG_uninstantiate,
RAND_DRBG_free
- initialize and cleanup a RAND_DRBG instance
=head1 SYNOPSIS
#include <openssl/rand_drbg.h>
RAND_DRBG *RAND_DRBG_new(int type,
unsigned int flags,
RAND_DRBG *parent);
RAND_DRBG *RAND_DRBG_secure_new(int type,
unsigned int flags,
RAND_DRBG *parent);
int RAND_DRBG_set(RAND_DRBG *drbg,
int type, unsigned int flags);
int RAND_DRBG_set_defaults(int type, unsigned int flags);
int RAND_DRBG_instantiate(RAND_DRBG *drbg,
const unsigned char *pers, size_t perslen);
int RAND_DRBG_uninstantiate(RAND_DRBG *drbg);
void RAND_DRBG_free(RAND_DRBG *drbg);
=head1 DESCRIPTION
RAND_DRBG_new() and RAND_DRBG_secure_new()
create a new DRBG instance of the given B<type>, allocated from the heap resp.
the secure heap
(using OPENSSL_zalloc() resp. OPENSSL_secure_zalloc()).
RAND_DRBG_set() initializes the B<drbg> with the given B<type> and B<flags>.
RAND_DRBG_set_defaults() sets the default B<type> and B<flags> for new DRBG
instances.
Currently, all DRBG types are based on AES-CTR, so B<type> can be one of the
following values: NID_aes_128_ctr, NID_aes_192_ctr, NID_aes_256_ctr.
Before the DRBG can be used to generate random bits, it is necessary to set
its type and to instantiate it.
The optional B<flags> argument specifies a set of bit flags which can be
joined using the | operator. Currently, the only flag is
RAND_DRBG_FLAG_CTR_NO_DF, which disables the use of a the derivation function
ctr_df. For an explanation, see [NIST SP 800-90A Rev. 1].
If a B<parent> instance is specified then this will be used instead of
the default entropy source for reseeding the B<drbg>. It is said that the
B<drbg> is I<chained> to its B<parent>.
For more information, see the NOTES section.
RAND_DRBG_instantiate()
seeds the B<drbg> instance using random input from trusted entropy sources.
Optionally, a personalization string B<pers> of length B<perslen> can be
specified.
To omit the personalization string, set B<pers>=NULL and B<perslen>=0;
RAND_DRBG_uninstantiate()
clears the internal state of the B<drbg> and puts it back in the
uninstantiated state.
=head1 RETURN VALUES
RAND_DRBG_new() and RAND_DRBG_secure_new() return a pointer to a DRBG
instance allocated on the heap, resp. secure heap.
RAND_DRBG_set(),
RAND_DRBG_instantiate(), and
RAND_DRBG_uninstantiate()
return 1 on success, and 0 on failure.
RAND_DRBG_free() does not return a value.
=head1 NOTES
The DRBG design supports I<chaining>, which means that a DRBG instance can
use another B<parent> DRBG instance instead of the default entropy source
to obtain fresh random input for reseeding, provided that B<parent> DRBG
instance was properly instantiated, either from a trusted entropy source,
or from yet another parent DRBG instance.
For a detailed description of the reseeding process, see L<RAND_DRBG(7)>.
The default DRBG type and flags are applied only during creation of a DRBG
instance.
To ensure that they are applied to the global and thread-local DRBG instances
(<master>, resp. <public> and <private>), it is necessary to call
RAND_DRBG_set_defaults() before creating any thread and before calling any
cryptographic routines that obtain random data directly or indirectly.
=head1 SEE ALSO
L<OPENSSL_zalloc(3)>,
L<OPENSSL_secure_zalloc(3)>,
L<RAND_DRBG_generate(3)>,
L<RAND_DRBG(7)>
=head1 HISTORY
The RAND_DRBG functions were added in OpenSSL 1.1.1.
=head1 COPYRIGHT
Copyright 2017-2019 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