=pod =head1 NAME life_cycle-rand - The RAND algorithm life-cycle =head1 DESCRIPTION All random number generator (RANDs) go through a number of stages in their life-cycle: =over 4 =item start This state represents the RAND before it has been allocated. It is the starting state for any life-cycle transitions. =item newed This state represents the RAND after it has been allocated but unable to generate any output. =item instantiated This state represents the RAND when it is set up and capable of generating output. =item uninstantiated This state represents the RAND when it has been shutdown and it is no longer capable of generating output. =item freed This state is entered when the RAND is freed. It is the terminal state for all life-cycle transitions. =back =head2 State Transition Diagram The usual life-cycle of a RAND is illustrated: =begin man +-------------------------+ | 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 | +-------------------------+ =end man =for html =head2 Formal State Transitions This section defines all of the legal state transitions. This is the canonical list. =begin man 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 =end man =begin html

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 |
EVP_RAND_CTX_set_params |  | newed | instantiated | uninstantiated |
EVP_RAND_CTX_gettable_params |  | newed | instantiated | uninstantiated |
EVP_RAND_CTX_settable_params |  | newed | instantiated | uninstantiated |

=end html =head1 NOTES At some point the EVP layer will begin enforcing the transitions described herein. =head1 SEE ALSO L, L. =head1 HISTORY The provider RAND interface was introduced in OpenSSL 3.0. =head1 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 L. =cut