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.IX Title "LIFE_CYCLE-MAC 7ossl"
.TH LIFE_CYCLE-MAC 7ossl 2026-01-27 3.5.5 OpenSSL
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.SH NAME
life_cycle\-mac \- The MAC algorithm life\-cycle
.SH DESCRIPTION
.IX Header "DESCRIPTION"
All message authentication codes (MACs)
go through a number of stages in their life\-cycle:
.IP start 4
.IX Item "start"
This state represents the MAC before it has been allocated.  It is the
starting state for any life\-cycle transitions.
.IP newed 4
.IX Item "newed"
This state represents the MAC after it has been allocated.
.IP initialised 4
.IX Item "initialised"
This state represents the MAC when it is set up and capable of processing
input.
.IP updated 4
.IX Item "updated"
This state represents the MAC when it is set up and capable of processing
additional input or generating output.
.IP finaled 4
.IX Item "finaled"
This state represents the MAC when it has generated output.
.IP freed 4
.IX Item "freed"
This state is entered when the MAC is freed.  It is the terminal state
for all life\-cycle transitions.
.SS "State Transition Diagram"
.IX Subsection "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       |
                 +-------------------+
.SS "Formal State Transitions"
.IX Subsection "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
.SH NOTES
.IX Header "NOTES"
At some point the EVP layer will begin enforcing the transitions described
herein.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBprovider\-mac\fR\|(7), \fBEVP_MAC\fR\|(3).
.SH HISTORY
.IX Header "HISTORY"
The provider MAC interface was introduced in OpenSSL 3.0.
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright 2021 The OpenSSL Project Authors. All Rights Reserved.
.PP
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>.
