# life_cycle-mac

- NAME
- DESCRIPTION
  - State Transition Diagram
  - Formal State Transitions
- NOTES
- SEE ALSO
- HISTORY
- COPYRIGHT

# NAME

life_cycle-mac - The MAC algorithm life-cycle

# DESCRIPTION

All message authentication codes (MACs) go through a number of stages in their life-cycle:

start

  This state represents the MAC before it has been allocated. It is the starting state for any life-cycle transitions.

newed

  This state represents the MAC after it has been allocated.

initialised

  This state represents the MAC when it is set up and capable of processing input.

updated

  This state represents the MAC when it is set up and capable of processing additional input or generating output.

finaled

  This state represents the MAC when it has generated output.

freed

  This state is entered when the MAC is freed. It is the terminal state for all life-cycle transitions.

## State Transition Diagram

The usual life-cycle of a MAC 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 | initialised | updated | finaled | freed
EVP_MAC_CTX_new | newed |  |  |  |  |
EVP_MAC_init |  | initialised | initialised | initialised | initialised |
EVP_MAC_update |  |  | updated | updated |  |
EVP_MAC_final |  |  |  | finaled |  |
EVP_MAC_finalXOF |  |  |  | finaled |  |
EVP_MAC_CTX_free | freed | freed | freed | freed | freed |
EVP_MAC_CTX_get_params |  | newed | initialised | updated |  |
EVP_MAC_CTX_set_params |  | newed | initialised | updated |  |
EVP_MAC_CTX_gettable_params |  | newed | initialised | updated |  |
EVP_MAC_CTX_settable_params |  | newed | initialised | updated |  |

# NOTES

At some point the EVP layer will begin enforcing the transitions described herein.

# SEE ALSO

provider-mac(7), EVP_MAC(3).

# HISTORY

The provider MAC 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.