LIFE_CYCLE-RAND(7SSL) OpenSSL LIFE_CYCLE-RAND(7SSL)
NAME
life_cycle-rand - The RAND algorithm life-cycle
DESCRIPTION
All random number generator (RANDs) go through a number of stages in
their life-cycle:
start
This state represents the RAND before it has been allocated. It is
the starting state for any life-cycle transitions.
newed
This state represents the RAND after it has been allocated but
unable to generate any output.
instantiated
This state represents the RAND when it is set up and capable of
generating output.
uninstantiated
This state represents the RAND when it has been shutdown and it is
no longer capable of generating output.
freed
This state is entered when the RAND is freed. It is the terminal
state for all life-cycle transitions.
State Transition Diagram
The usual life-cycle of a RAND is illustrated:
+-------------------------+
| start |
+-------------------------+
|
| EVP_RAND_CTX_new
v
+-------------------------+
| newed |
+-------------------------+
|
| EVP_RAND_instantiate
v
EVP_RAND_generate +-------------------------+
+-------------------- | |
| | instantiated |
+-------------------> | | <+
+-------------------------+ '
| '
| EVP_RAND_uninstantiate '
EVP_RAND_instantiate
v '
+-------------------------+ '
| uninstantiated | -+
+-------------------------+
|
| EVP_RAND_CTX_free
v
+-------------------------+
| freed |
+-------------------------+
Formal State Transitions
This section defines all of the legal state transitions. This is the
canonical list.
Function Call ------------------ Current State
------------------
start newed instantiated uninstantiated
freed
EVP_RAND_CTX_new newed
EVP_RAND_instantiate instantiated
EVP_RAND_generate instantiated
EVP_RAND_uninstantiate uninstantiated
EVP_RAND_CTX_free freed freed freed freed
EVP_RAND_CTX_get_params newed instantiated uninstantiated
freed
EVP_RAND_CTX_set_params newed instantiated uninstantiated
freed
EVP_RAND_CTX_gettable_params newed instantiated uninstantiated
freed
EVP_RAND_CTX_settable_params newed instantiated uninstantiated
freed
NOTES
At some point the EVP layer will begin enforcing the transitions
described herein.
SEE ALSO
provider-rand(7), EVP_RAND(3).
HISTORY
The provider RAND interface was introduced in OpenSSL 3.0.
COPYRIGHT
Copyright 2021 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>.
3.5.4 2025-09-30 LIFE_CYCLE-RAND(7SSL)
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