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LIFE_CYCLE-RAND(7)                  OpenSSL                 LIFE_CYCLE-RAND(7)



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>.



3.0.12                            2023-05-07                LIFE_CYCLE-RAND(7)