life_cycle-mac - The MAC algorithm life-cycle

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3.5.0                                              2025-06-04                               LIFE_CYCLE-MAC(7SSL)

       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.

   StateTransitionDiagram
       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       |
                        +-------------------+

   FormalStateTransitions
       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

       The provider MAC interface was introduced in OpenSSL 3.0.

       life_cycle-mac - The MAC algorithm life-cycle

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

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