life_cycle-mac.7ossl - Man Page

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.

Referenced By

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

2022-09-01 3.0.5 OpenSSL