LIFE_CYCLE-PKEY(7)

LIFE_CYCLE-PKEY(7) | OpenSSL | 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>.

2026-06-09 | 3.5.7