- NAME
- SYNOPSIS
- DESCRIPTION
- RETURN VALUES
- NOTES
- EXAMPLES
- SEE ALSO
- HISTORY
- COPYRIGHT

# NAME

RAND_set_DRBG_type, RAND_set_seed_source_type - specify the global random number generator types

# 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);

# DESCRIPTION

`RAND_set_DRBG_type()` specifies the random bit generator that will be used within the library context ctx. A generator of name drbg with properties propq will be fetched. It will be instantiated with either cipher or 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 ctx. The seed source of name seed with properties propq will be fetched and used to seed the primary random bit generator.

# RETURN VALUES

These function return 1 on success and 0 on failure.

# 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 -DOPENSSL_DEFAULT_SEED_SRC=SEED-SRC. If not set then "SEED-SRC" is used.

# EXAMPLES

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

# SEE ALSO

EVP_RAND(3), RAND_get0_primary(3)

# HISTORY

These functions were added in OpenSSL 3.0.

# 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 https://www.openssl.org/source/license.html.