117 lines
4.1 KiB
Plaintext
117 lines
4.1 KiB
Plaintext
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=pod
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=head1 NAME
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RAND_DRBG_reseed,
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RAND_DRBG_set_reseed_interval,
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RAND_DRBG_set_reseed_time_interval,
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RAND_DRBG_set_reseed_defaults
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- reseed a RAND_DRBG instance
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=head1 SYNOPSIS
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#include <openssl/rand_drbg.h>
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int RAND_DRBG_reseed(RAND_DRBG *drbg,
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const unsigned char *adin, size_t adinlen,
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int prediction_resistance);
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int RAND_DRBG_set_reseed_interval(RAND_DRBG *drbg,
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unsigned int interval);
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int RAND_DRBG_set_reseed_time_interval(RAND_DRBG *drbg,
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time_t interval);
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int RAND_DRBG_set_reseed_defaults(
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unsigned int master_reseed_interval,
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unsigned int slave_reseed_interval,
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time_t master_reseed_time_interval,
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time_t slave_reseed_time_interval
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);
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=head1 DESCRIPTION
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RAND_DRBG_reseed()
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reseeds the given B<drbg>, obtaining entropy input from its entropy source
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and mixing in the specified additional data provided in the buffer B<adin>
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of length B<adinlen>.
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The additional data can be omitted by setting B<adin> to NULL and B<adinlen>
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to 0.
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An immediate reseeding from a live entropy source can be requested by setting
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the B<prediction_resistance> flag to 1.
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This feature is not implemented yet, so reseeding with prediction resistance
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requested will always fail.
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RAND_DRBG_set_reseed_interval()
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sets the reseed interval of the B<drbg>, which is the maximum allowed number
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of generate requests between consecutive reseedings.
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If B<interval> > 0, then the B<drbg> will reseed automatically whenever the
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number of generate requests since its last seeding exceeds the given reseed
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interval.
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If B<interval> == 0, then this feature is disabled.
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RAND_DRBG_set_reseed_time_interval()
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sets the reseed time interval of the B<drbg>, which is the maximum allowed
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number of seconds between consecutive reseedings.
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If B<interval> > 0, then the B<drbg> will reseed automatically whenever the
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elapsed time since its last reseeding exceeds the given reseed time interval.
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If B<interval> == 0, then this feature is disabled.
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RAND_DRBG_set_reseed_defaults() sets the default values for the reseed interval
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(B<master_reseed_interval> and B<slave_reseed_interval>)
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and the reseed time interval
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(B<master_reseed_time_interval> and B<slave_reseed_tme_interval>)
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of DRBG instances.
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The default values are set independently for master DRBG instances (which don't
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have a parent) and slave DRBG instances (which are chained to a parent DRBG).
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=head1 RETURN VALUES
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RAND_DRBG_reseed(),
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RAND_DRBG_set_reseed_interval(), and
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RAND_DRBG_set_reseed_time_interval(),
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return 1 on success, 0 on failure.
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=head1 NOTES
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The default OpenSSL random generator is already set up for automatic reseeding,
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so in general it is not necessary to reseed it explicitly, or to modify
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its reseeding thresholds.
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Normally, the entropy input for seeding a DRBG is either obtained from a
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trusted os entropy source or from a parent DRBG instance, which was seeded
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(directly or indirectly) from a trusted os entropy source.
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In exceptional cases it is possible to replace the reseeding mechanism entirely
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by providing application defined callbacks using RAND_DRBG_set_callbacks().
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The reseeding default values are applied only during creation of a DRBG instance.
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To ensure that they are applied to the global and thread-local DRBG instances
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(<master>, resp. <public> and <private>), it is necessary to call
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RAND_DRBG_set_reseed_defaults() before creating any thread and before calling any
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cryptographic routines that obtain random data directly or indirectly.
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=head1 SEE ALSO
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L<RAND_DRBG_generate(3)>,
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L<RAND_DRBG_bytes(3)>,
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L<RAND_DRBG_set_callbacks(3)>.
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L<RAND_DRBG(7)>
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=head1 HISTORY
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The RAND_DRBG functions were added in OpenSSL 1.1.1.
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=head1 COPYRIGHT
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Copyright 2017-2019 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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