life_cycle-mac - The MAC algorithm life-cycle
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.
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 |
 +-------------------+
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
At some point the EVP layer will begin enforcing the transitions described
  herein.
provider-mac(7), EVP_MAC(3).
The provider MAC interface was introduced in OpenSSL 3.0.
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