1RAND_DRBG_RESEED(3) OpenSSL RAND_DRBG_RESEED(3)
2
6 RAND_DRBG_reseed, RAND_DRBG_set_reseed_interval,
7 RAND_DRBG_set_reseed_time_interval, RAND_DRBG_set_reseed_defaults -
8 reseed a RAND_DRBG instance
9
11 #include <openssl/rand_drbg.h>
12 int RAND_DRBG_reseed(RAND_DRBG *drbg,
14 const unsigned char *adin, size_t adinlen,
15 int prediction_resistance);
16 int RAND_DRBG_set_reseed_interval(RAND_DRBG *drbg,
18 unsigned int interval);
19 int RAND_DRBG_set_reseed_time_interval(RAND_DRBG *drbg,
21 time_t interval);
22 int RAND_DRBG_set_reseed_defaults(
24 unsigned int master_reseed_interval,
25 unsigned int slave_reseed_interval,
26 time_t master_reseed_time_interval,
27 time_t slave_reseed_time_interval
28 );
29
31 RAND_DRBG_reseed() reseeds the given drbg, obtaining entropy input from
32 its entropy source and mixing in the specified additional data provided
33 in the buffer adin of length adinlen. The additional data can be
34 omitted by setting adin to NULL and adinlen to 0. An immediate
35 reseeding from a live entropy source can be requested by setting the
36 prediction_resistance flag to 1. This feature is not implemented yet,
37 so reseeding with prediction resistance requested will always fail.
38 RAND_DRBG_set_reseed_interval() sets the reseed interval of the drbg,
40 which is the maximum allowed number of generate requests between
41 consecutive reseedings. If interval > 0, then the drbg will reseed
42 automatically whenever the number of generate requests since its last
43 seeding exceeds the given reseed interval. If interval == 0, then this
44 feature is disabled.
45 RAND_DRBG_set_reseed_time_interval() sets the reseed time interval of
47 the drbg, which is the maximum allowed number of seconds between
48 consecutive reseedings. If interval > 0, then the drbg will reseed
49 automatically whenever the elapsed time since its last reseeding
50 exceeds the given reseed time interval. If interval == 0, then this
51 feature is disabled.
52 RAND_DRBG_set_reseed_defaults() sets the default values for the reseed
54 interval (master_reseed_interval and slave_reseed_interval) and the
55 reseed time interval (master_reseed_time_interval and
56 slave_reseed_tme_interval) of DRBG instances. The default values are
57 set independently for master DRBG instances (which don't have a parent)
58 and slave DRBG instances (which are chained to a parent DRBG).
59
61 RAND_DRBG_reseed(), RAND_DRBG_set_reseed_interval(), and
62 RAND_DRBG_set_reseed_time_interval(), return 1 on success, 0 on
63 failure.
64
66 The default OpenSSL random generator is already set up for automatic
67 reseeding, so in general it is not necessary to reseed it explicitly,
68 or to modify its reseeding thresholds.
69 Normally, the entropy input for seeding a DRBG is either obtained from
71 a trusted os entropy source or from a parent DRBG instance, which was
72 seeded (directly or indirectly) from a trusted os entropy source. In
73 exceptional cases it is possible to replace the reseeding mechanism
74 entirely by providing application defined callbacks using
75 RAND_DRBG_set_callbacks().
76 The reseeding default values are applied only during creation of a DRBG
78 instance. To ensure that they are applied to the global and thread-
79 local DRBG instances (<master>, resp. <public> and <private>), it is
80 necessary to call RAND_DRBG_set_reseed_defaults() before creating any
81 thread and before calling any
82 cryptographic routines that obtain random data directly or indirectly.
83
85 RAND_DRBG_generate(3), RAND_DRBG_bytes(3), RAND_DRBG_set_callbacks(3).
86 RAND_DRBG(7)
87
89 The RAND_DRBG functions were added in OpenSSL 1.1.1.
90
92 Copyright 2017-2019 The OpenSSL Project Authors. All Rights Reserved.
93 Licensed under the OpenSSL license (the "License"). You may not use
95 this file except in compliance with the License. You can obtain a copy
96 in the file LICENSE in the source distribution or at
97 <https://www.openssl.org/source/license.html>.
981.1.1q 2023-07-20 RAND_DRBG_RESEED(3)