89 lines
3 KiB
Text
89 lines
3 KiB
Text
|
=pod
|
||
|
|
|
||
|
|
=head1 NAME
|
||
|
|
|
||
|
|
RAND_DRBG_generate,
|
||
|
|
RAND_DRBG_bytes
|
||
|
|
- generate random bytes using the given drbg instance
|
||
|
|
|
||
|
|
=head1 SYNOPSIS
|
||
|
|
|
||
|
|
#include <openssl/rand_drbg.h>
|
||
|
|
|
||
|
|
int RAND_DRBG_generate(RAND_DRBG *drbg,
|
||
|
|
unsigned char *out, size_t outlen,
|
||
|
|
int prediction_resistance,
|
||
|
|
const unsigned char *adin, size_t adinlen);
|
||
|
|
|
||
|
|
int RAND_DRBG_bytes(RAND_DRBG *drbg,
|
||
|
|
unsigned char *out, size_t outlen);
|
||
|
|
|
||
|
|
|
||
|
|
=head1 DESCRIPTION
|
||
|
|
|
||
|
|
RAND_DRBG_generate() generates B<outlen> random bytes using the given
|
||
|
|
DRBG instance B<drbg> and stores them in the buffer at B<out>.
|
||
|
|
|
||
|
|
Before generating the output, the DRBG instance checks whether the maximum
|
||
|
|
number of generate requests (I<reseed interval>) or the maximum timespan
|
||
|
|
(I<reseed time interval>) since its last seeding have been reached.
|
||
|
|
If this is the case, the DRBG reseeds automatically.
|
||
|
|
Additionally, an immediate reseeding can be requested by setting the
|
||
|
|
B<prediction_resistance> flag to 1. See NOTES section for more details.
|
||
|
|
|
||
|
|
The caller can optionally provide additional data to be used for reseeding
|
||
|
|
by passing a pointer B<adin> to a buffer of length B<adinlen>.
|
||
|
|
This additional data is mixed into the internal state of the random
|
||
|
|
generator but does not contribute to the entropy count.
|
||
|
|
The additional data can be omitted by setting B<adin> to NULL and
|
||
|
|
B<adinlen> to 0;
|
||
|
|
|
||
|
|
RAND_DRBG_bytes() generates B<outlen> random bytes using the given
|
||
|
|
DRBG instance B<drbg> and stores them in the buffer at B<out>.
|
||
|
|
This function is a wrapper around the RAND_DRBG_generate() call,
|
||
|
|
which collects some additional data from low entropy sources
|
||
|
|
(e.g., a high resolution timer) and calls
|
||
|
|
RAND_DRBG_generate(drbg, out, outlen, 0, adin, adinlen).
|
||
|
|
|
||
|
|
|
||
|
|
=head1 RETURN VALUES
|
||
|
|
|
||
|
|
RAND_DRBG_generate() and RAND_DRBG_bytes() return 1 on success,
|
||
|
|
and 0 on failure.
|
||
|
|
|
||
|
|
=head1 NOTES
|
||
|
|
|
||
|
|
The I<reseed interval> and I<reseed time interval> of the B<drbg> are set to
|
||
|
|
reasonable default values, which in general do not have to be adjusted.
|
||
|
|
If necessary, they can be changed using L<RAND_DRBG_set_reseed_interval(3)>
|
||
|
|
and L<RAND_DRBG_set_reseed_time_interval(3)>, respectively.
|
||
|
|
|
||
|
|
A request for prediction resistance can only be satisfied by pulling fresh
|
||
|
|
entropy from one of the approved entropy sources listed in section 5.5.2 of
|
||
|
|
[NIST SP 800-90C].
|
||
|
|
Since the default DRBG implementation does not have access to such an approved
|
||
|
|
entropy source, a request for prediction resistance will always fail.
|
||
|
|
In other words, prediction resistance is currently not supported yet by the DRBG.
|
||
|
|
|
||
|
|
=head1 HISTORY
|
||
|
|
|
||
|
|
The RAND_DRBG functions were added in OpenSSL 1.1.1.
|
||
|
|
|
||
|
|
=head1 SEE ALSO
|
||
|
|
|
||
|
|
L<RAND_bytes(3)>,
|
||
|
|
L<RAND_DRBG_set_reseed_interval(3)>,
|
||
|
|
L<RAND_DRBG_set_reseed_time_interval(3)>,
|
||
|
|
L<RAND_DRBG(7)>
|
||
|
|
|
||
|
|
=head1 COPYRIGHT
|
||
|
|
|
||
|
|
Copyright 2017-2018 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
|