Updated: 2022/Sep/29

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LIFE_CYCLE-MAC(7)                   OpenSSL                  LIFE_CYCLE-MAC(7)



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:
                        +-------------------+
                        |       start       |
                        +-------------------+
                          |
                          | EVP_MAC_CTX_new
                          v
                        +-------------------+
                        |       newed       |
                        +-------------------+
                          |
                          | EVP_MAC_init
                          v
                        +-------------------+
                     +> |    initialised    | <+
                     |  +-------------------+  |
                     |    |                    |
                     |    | EVP_MAC_update     | EVP_MAC_init
                     |    v                    |
        EVP_MAC_init |  +-------------------+  |
                     |  |      updated      | -+
                     |  +-------------------+
                     |    |               |
                     |    | EVP_MAC_final | EVP_MAC_finalXOF
                     |    v               v
                     |  +-------------------+
                     +- |      finaled      |
                        +-------------------+
                          |
                          | EVP_MAC_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    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>.



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