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.IX Title "LIFE_CYCLE-RAND 7SSL"
.TH LIFE_CYCLE-RAND 7SSL 2026-08-18 3.0.13 OpenSSL
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.SH NAME
life_cycle\-rand \- The RAND algorithm life\-cycle
.SH DESCRIPTION
.IX Header "DESCRIPTION"
All random number generator (RANDs)
go through a number of stages in their life-cycle:
.IP start 4
.IX Item "start"
This state represents the RAND before it has been allocated.  It is the
starting state for any life-cycle transitions.
.IP newed 4
.IX Item "newed"
This state represents the RAND after it has been allocated but unable to
generate any output.
.IP instantiated 4
.IX Item "instantiated"
This state represents the RAND when it is set up and capable of generating
output.
.IP uninstantiated 4
.IX Item "uninstantiated"
This state represents the RAND when it has been shutdown and it is no longer
capable of generating output.
.IP freed 4
.IX Item "freed"
This state is entered when the RAND is freed.  It is the terminal state
for all life-cycle transitions.
.SS "State Transition Diagram"
.IX Subsection "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          |
                        +-------------------------+
.SS "Formal State Transitions"
.IX Subsection "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
.SH NOTES
.IX Header "NOTES"
At some point the EVP layer will begin enforcing the transitions described
herein.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBprovider\-rand\fR\|(7), \fBEVP_RAND\fR\|(3).
.SH HISTORY
.IX Header "HISTORY"
The provider RAND interface was introduced in OpenSSL 3.0.
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright 2021 The OpenSSL Project Authors. All Rights Reserved.
.PP
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>.
