=pod

=head1 NAME

RAND_set_DRBG_type,
RAND_set_seed_source_type
- specify the global random number generator types

=head1 SYNOPSIS

 #include <openssl/rand.h>

 int RAND_set_DRBG_type(OSSL_LIB_CTX *ctx, const char *drbg, const char *propq,
                        const char *cipher, const char *digest);
 int RAND_set_seed_source_type(OSSL_LIB_CTX *ctx, const char *seed,
                               const char *propq);

=head1 DESCRIPTION

RAND_set_DRBG_type() specifies the random bit generator that will be
used within the library context I<ctx>.  A generator of name I<drbg>
with properties I<propq> will be fetched.  It will be instantiated with
either I<cipher> or I<digest> as its underlying cryptographic algorithm.
This specifies the type that will be used for the primary, public and
private random instances.

RAND_set_seed_source_type() specifies the seed source that will be used
within the library context I<ctx>.  The seed source of name I<seed>
with properties I<propq> will be fetched and used to seed the primary
random bit generator.

=head1 RETURN VALUES

These function return 1 on success and 0 on failure.

=head1 NOTES

These functions must be called before the random bit generators are first
created in the library context.  They will return an error if the call
is made too late.

The default DRBG is "CTR-DRBG" using the "AES-256-CTR" cipher.

The default seed source can be configured when OpenSSL is compiled by
setting B<-DOPENSSL_DEFAULT_SEED_SRC=SEED-SRC>. If not set then
"SEED-SRC" is used.

=head1 EXAMPLES

 unsigned char bytes[100];
 RAND_set_seed_source_type(NULL, "JITTER", NULL);
 RAND_bytes(bytes, 100);

=head1 SEE ALSO

L<EVP_RAND(3)>,
L<RAND_get0_primary(3)>

=head1 HISTORY

These functions were added in OpenSSL 3.0.

=head1 COPYRIGHT

Copyright 2021-2024 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (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
