LIFE_CYCLE-PKEY(7)

NAME
life_cycle-pkey - The PKEY algorithm life-cycle

DESCRIPTION
All public keys (PKEYs) go through a number of stages in their life-cycle:

start
    This state represents the PKEY before it has been allocated. It is the starting state for any life-cycle transitions.

newed
    This state represents the PKEY after it has been allocated.

decapsulate
    This state represents the PKEY when it is ready to perform a private key decapsulation operation.

decrypt
    This state represents the PKEY when it is ready to decrypt some ciphertext.

derive
    This state represents the PKEY when it is ready to derive a shared secret.

digest sign
    This state represents the PKEY when it is ready to perform a private key signature operation.

encapsulate
    This state represents the PKEY when it is ready to perform a public key encapsulation operation.

encrypt
    This state represents the PKEY when it is ready to encrypt some plaintext.

key generation
    This state represents the PKEY when it is ready to generate a new public/private key.

parameter generation
    This state represents the PKEY when it is ready to generate key parameters.

verify
    This state represents the PKEY when it is ready to verify a public key signature.

verify recover
    This state represents the PKEY when it is ready to recover a public key signature data.

freed
    This state is entered when the PKEY is freed. It is the terminal state for all life-cycle transitions.

  State Transition Diagram
The usual life-cycle of a PKEY object is illustrated:
                        +-------------+
                        | |
                        | start |
                        | |
                   EVP_PKEY_derive +-------------+
 +-------------+ EVP_PKEY_derive_set_peer | +-------------+
 | |----------------------------+ | +----------------------------| |
 | derive | | | | EVP_PKEY_verify | verify |
 | |<---------------------------+ | +--------------------------->| |
 +-------------+ | +-------------+
             ^ | ^
             | EVP_PKEY_derive_init | EVP_PKEY_verify_init |
             +---------------------------------------+ | +---------------------------------------+
                        | | |
 +-------------+ | | | +-------------+
 | |----------------------------+ | | | +----------------------------| |
 | digest sign | EVP_PKEY_sign | | | | | EVP_PKEY_verify_recover | verify |
 | |<---------------------------+ | | | +--------------------------->| recover |
 +-------------+ | | | +-------------+
             ^ | | | ^
             | EVP_PKEY_sign_init | | | EVP_PKEY_verify_recover_init |
             +---------------------------------+ | | | +---------------------------------+
                        | | | | |
 +-------------+ | | | | | +-------------+
 | |----------------------------+ | | | | | +----------------------------| |
 | decapsulate | EVP_PKEY_decapsulate | | | | | | | EVP_PKEY_decrypt | decrypt |
 | |<---------------------------+ | | v | | +--------------------------->| |
 +-------------+ | +-------------+ | +-------------+
             ^ +---| |---+ ^
             | EVP_PKEY_decapsulate_init | | EVP_PKEY_decrypt_init |
             +-------------------------------------| newed |-------------------------------------+
                        | |
                        +---| |---+
 +-------------+ | +-------------+ | +-------------+
 | |----------------------------+ | | | | +----------------------------| |
 | encapsulate | EVP_PKEY_encapsulate | | | | | | EVP_PKEY_encrypt | encrypt |
 | |<---------------------------+ | | | | +--------------------------->| |
 +-------------+ | | | | +-------------+
             ^ | | | | ^
             | EVP_PKEY_encapsulate_init | | | | EVP_PKEY_encrypt_init |
             +---------------------------------+ | | +---------------------------------+
                        | |
             +---------------------------------------+ +---------------------------------------+
             | EVP_PKEY_paramgen_init EVP_PKEY_keygen_init |
             v v
 +-------------+ +-------------+
 | |----------------------------+ +----------------------------| |
 | parameter | | | | key |
 | generation |<---------------------------+ +--------------------------->| generation |
 +-------------+ EVP_PKEY_paramgen EVP_PKEY_keygen +-------------+
                   EVP_PKEY_gen EVP_PKEY_gen
                        + - - - - - + +-----------+
                        ' ' EVP_PKEY_CTX_free | |
                        ' any state '------------------->| freed |
                        ' ' | |
                        + - - - - - + +-----------+

  Formal State Transitions
This section defines all of the legal state transitions. This is the canonical list.
 Function Call ---------------------------------------------------------------------- Current State ----------------------------------------------------------------------
                        start newed digest verify verify encrypt decrypt derive encapsulate decapsulate parameter key freed
                        sign recover generation generation
 EVP_PKEY_CTX_new newed
 EVP_PKEY_CTX_new_id newed
 EVP_PKEY_CTX_new_from_name newed
 EVP_PKEY_CTX_new_from_pkey newed
 EVP_PKEY_sign_init digest digest digest digest digest digest digest digest digest digest digest
                        sign sign sign sign sign sign sign sign sign sign sign
 EVP_PKEY_sign digest
                        sign
 EVP_PKEY_verify_init verify verify verify verify verify verify verify verify verify verify verify
 EVP_PKEY_verify verify
 EVP_PKEY_verify_recover_init verify verify verify verify verify verify verify verify verify verify verify
                        recover recover recover recover recover recover recover recover recover recover recover
 EVP_PKEY_verify_recover verify
                        recover
 EVP_PKEY_encrypt_init encrypt encrypt encrypt encrypt encrypt encrypt encrypt encrypt encrypt encrypt encrypt
 EVP_PKEY_encrypt encrypt
 EVP_PKEY_decrypt_init decrypt decrypt decrypt decrypt decrypt decrypt decrypt decrypt decrypt decrypt decrypt
 EVP_PKEY_decrypt decrypt
 EVP_PKEY_derive_init derive derive derive derive derive derive derive derive derive derive derive
 EVP_PKEY_derive_set_peer derive
 EVP_PKEY_derive derive
 EVP_PKEY_encapsulate_init encapsulate encapsulate encapsulate encapsulate encapsulate encapsulate encapsulate encapsulate encapsulate encapsulate encapsulate
 EVP_PKEY_encapsulate encapsulate
 EVP_PKEY_decapsulate_init decapsulate decapsulate decapsulate decapsulate decapsulate decapsulate decapsulate decapsulate decapsulate decapsulate decapsulate
 EVP_PKEY_decapsulate decapsulate
 EVP_PKEY_paramgen_init parameter parameter parameter parameter parameter parameter parameter parameter parameter parameter parameter
                        generation generation generation generation generation generation generation generation generation generation generation
 EVP_PKEY_paramgen parameter
                        generation
 EVP_PKEY_keygen_init key key key key key key key key key key key
                        generation generation generation generation generation generation generation generation generation generation generation
 EVP_PKEY_keygen key
                        generation
 EVP_PKEY_gen parameter key
                        generation generation
 EVP_PKEY_CTX_get_params newed digest verify verify encrypt decrypt derive encapsulate decapsulate parameter key
                        sign recover generation generation
 EVP_PKEY_CTX_set_params newed digest verify verify encrypt decrypt derive encapsulate decapsulate parameter key
                        sign recover generation generation
 EVP_PKEY_CTX_gettable_params newed digest verify verify encrypt decrypt derive encapsulate decapsulate parameter key
                        sign recover generation generation
 EVP_PKEY_CTX_settable_params newed digest verify verify encrypt decrypt derive encapsulate decapsulate parameter key
                        sign recover generation generation
 EVP_PKEY_CTX_free freed freed freed freed freed freed freed freed freed freed freed freed

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

SEE ALSO
EVP_PKEY_new(3), EVP_PKEY_decapsulate(3), EVP_PKEY_decrypt(3), EVP_PKEY_encapsulate(3), EVP_PKEY_encrypt(3), EVP_PKEY_derive(3), EVP_PKEY_keygen(3), EVP_PKEY_sign(3), EVP_PKEY_verify(3), EVP_PKEY_verify_recover(3)

HISTORY
The provider PKEY interface was introduced in OpenSSL 3.0.

COPYRIGHT
Copyright 2021-2022 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>.