1=pod 2 3=head1 NAME 4 5RAND_get0_primary, 6RAND_get0_public, 7RAND_get0_private, 8RAND_set0_public, 9RAND_set0_private 10- get access to the global EVP_RAND_CTX instances 11 12=head1 SYNOPSIS 13 14 #include <openssl/rand.h> 15 16 EVP_RAND_CTX *RAND_get0_primary(OSSL_LIB_CTX *ctx); 17 EVP_RAND_CTX *RAND_get0_public(OSSL_LIB_CTX *ctx); 18 EVP_RAND_CTX *RAND_get0_private(OSSL_LIB_CTX *ctx); 19 int RAND_set0_public(OSSL_LIB_CTX *ctx, EVP_RAND_CTX *rand); 20 int RAND_set0_private(OSSL_LIB_CTX *ctx, EVP_RAND_CTX *rand); 21 22=head1 DESCRIPTION 23 24The default RAND API implementation (RAND_OpenSSL()) utilizes three 25shared DRBG instances which are accessed via the RAND API: 26 27The I<public> and I<private> DRBG are thread-local instances, which are used 28by RAND_bytes() and RAND_priv_bytes(), respectively. 29The I<primary> DRBG is a global instance, which is not intended to be used 30directly, but is used internally to reseed the other two instances. 31 32The three get functions provide access to the shared DRBG instances. 33 34The two set functions allow the public and private DRBG instances to be 35replaced by another random number generator. 36 37=head1 RETURN VALUES 38 39RAND_get0_primary() returns a pointer to the I<primary> DRBG instance 40for the given OSSL_LIB_CTX B<ctx>. 41 42RAND_get0_public() returns a pointer to the I<public> DRBG instance 43for the given OSSL_LIB_CTX B<ctx>. 44 45RAND_get0_private() returns a pointer to the I<private> DRBG instance 46for the given OSSL_LIB_CTX B<ctx>. 47 48RAND_set0_public() and RAND_set0_private() return 1 on success and 0 49on error. 50 51=head1 NOTES 52 53It is not thread-safe to access the I<primary> DRBG instance. 54The I<public> and I<private> DRBG instance can be accessed safely, because 55they are thread-local. Note however, that changes to these two instances 56apply only to the current thread. 57 58For that reason it is recommended not to change the settings of these 59three instances directly. 60Instead, an application should change the default settings for new DRBG instances 61at initialization time, before creating additional threads. 62 63During initialization, it is possible to change the reseed interval 64and reseed time interval. 65It is also possible to exchange the reseeding callbacks entirely. 66 67To set the type of DRBG that will be instantiated, use the 68L<RAND_set_DRBG_type(3)> call before accessing the random number generation 69infrastructure. 70 71The two set functions, operate on the current thread. If you want to 72use the same random number generator across all threads, each thread 73must individually call the set functions. 74 75=head1 SEE ALSO 76 77L<EVP_RAND(3)>, 78L<RAND_set_DRBG_type(3)> 79 80=head1 HISTORY 81 82RAND_set0_public() and RAND_set0_private() were added in OpenSSL 3.1. 83 84The remaining functions were added in OpenSSL 3.0. 85 86=head1 COPYRIGHT 87 88Copyright 2020-2024 The OpenSSL Project Authors. All Rights Reserved. 89 90Licensed under the Apache License 2.0 (the "License"). You may not use 91this file except in compliance with the License. You can obtain a copy 92in the file LICENSE in the source distribution or at 93L<https://www.openssl.org/source/license.html>. 94 95=cut 96
