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Title "RAND_GET0_PRIMARY 3"
RAND_GET0_PRIMARY 3 "2023-05-30" "3.0.9" "OpenSSL"
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"NAME"
RAND_get0_primary, RAND_get0_public, RAND_get0_private \- get access to the global EVP_RAND_CTX instances
"SYNOPSIS"
Header "SYNOPSIS" .Vb 1 #include <openssl/rand.h> \& EVP_RAND_CTX *RAND_get0_primary(OSSL_LIB_CTX *ctx); EVP_RAND_CTX *RAND_get0_public(OSSL_LIB_CTX *ctx); EVP_RAND_CTX *RAND_get0_private(OSSL_LIB_CTX *ctx); .Ve
"DESCRIPTION"
Header "DESCRIPTION" The default \s-1RAND API\s0 implementation (RAND_OpenSSL()) utilizes three shared \s-1DRBG\s0 instances which are accessed via the \s-1RAND API:\s0

The public and private \s-1DRBG\s0 are thread-local instances, which are used by RAND_bytes() and RAND_priv_bytes(), respectively. The primary \s-1DRBG\s0 is a global instance, which is not intended to be used directly, but is used internally to reseed the other two instances.

These functions here provide access to the shared \s-1DRBG\s0 instances.

"RETURN VALUES"
Header "RETURN VALUES" \fBRAND_get0_primary() returns a pointer to the primary \s-1DRBG\s0 instance for the given \s-1OSSL_LIB_CTX\s0 ctx.

\fBRAND_get0_public() returns a pointer to the public \s-1DRBG\s0 instance for the given \s-1OSSL_LIB_CTX\s0 ctx.

\fBRAND_get0_private() returns a pointer to the private \s-1DRBG\s0 instance for the given \s-1OSSL_LIB_CTX\s0 ctx.

In all the above cases the ctx parameter can be \s-1NULL\s0 in which case the default \s-1OSSL_LIB_CTX\s0 is used.

"NOTES"
Header "NOTES" It is not thread-safe to access the primary \s-1DRBG\s0 instance. The public and private \s-1DRBG\s0 instance can be accessed safely, because they are thread-local. Note however, that changes to these two instances apply only to the current thread.

For that reason it is recommended not to change the settings of these three instances directly. Instead, an application should change the default settings for new \s-1DRBG\s0 instances at initialization time, before creating additional threads.

During initialization, it is possible to change the reseed interval and reseed time interval. It is also possible to exchange the reseeding callbacks entirely.

To set the type of \s-1DRBG\s0 that will be instantiated, use the \fBRAND_set_DRBG_type\|(3) call before accessing the random number generation infrastructure.

"SEE ALSO"
Header "SEE ALSO" \s-1EVP_RAND\s0\|(3), \fBRAND_set_DRBG_type\|(3)
"HISTORY"
Header "HISTORY" These functions were added in OpenSSL 3.0.
"COPYRIGHT"
Header "COPYRIGHT" Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.