life_cycle-rand

- NAME
- DESCRIPTION

- State Transition Diagram
- Formal State Transitions

- NOTES
- SEE ALSO
- HISTORY
- COPYRIGHT

# 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:

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

# 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.