NAME

life_cycle-cipher - The cipher algorithm life-cycle

DESCRIPTION

All symmetric ciphers (CIPHERs) go through a number of stages in their life-cycle:

start

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

newed

This state represents the CIPHER after it has been allocated.

initialised

These states represent the CIPHER when it is set up and capable of processing input. There are three possible initialised states:

initialised using EVP_CipherInit
initialised for decryption using EVP_DecryptInit
initialised for encryption using EVP_EncryptInit
updated

These states represent the CIPHER when it is set up and capable of processing additional input or generating output. The three possible states directly correspond to those for initialised above. The three different streams should not be mixed.

finaled

This state represents the CIPHER when it has generated output.

freed

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

State Transition Diagram

The usual life-cycle of a CIPHER is illustrated:

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 initialised
decryption		 updated
decryption		 initialised
encryption		 updated
encryption		 freed
EVP_CIPHER_CTX_new newed
EVP_CipherInit initialised initialised initialised initialised initialised initialised initialised initialised
EVP_DecryptInit initialised
decryption		 initialised
decryption		 initialised
decryption		 initialised
decryption		 initialised
decryption		 initialised
decryption		 initialised
decryption		 initialised
decryption
EVP_EncryptInit initialised
encryption		 initialised
encryption		 initialised
encryption		 initialised
encryption		 initialised
encryption		 initialised
encryption		 initialised
encryption		 initialised
encryption
EVP_CipherUpdate updated updated
EVP_DecryptUpdate updated
decryption		 updated
decryption
EVP_EncryptUpdate updated
encryption		 updated
encryption
EVP_CipherFinal finaled
EVP_DecryptFinal finaled
decryption
EVP_EncryptFinal finaled
decryption
EVP_CIPHER_CTX_free freed freed freed freed freed freed freed freed freed
EVP_CIPHER_CTX_reset newed newed newed newed newed newed newed
EVP_CIPHER_CTX_get_params newed initialised updated initialised
decryption		 updated
decryption		 initialised
encryption		 updated
encryption
EVP_CIPHER_CTX_set_params newed initialised updated initialised
decryption		 updated
decryption		 initialised
encryption		 updated
encryption
EVP_CIPHER_CTX_gettable_params newed initialised updated initialised
decryption		 updated
decryption		 initialised
encryption		 updated
encryption
EVP_CIPHER_CTX_settable_params newed initialised updated initialised
decryption		 updated
decryption		 initialised
encryption		 updated
encryption

NOTES

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

SEE ALSO

provider-cipher(7), EVP_EncryptInit(3)

COPYRIGHT

Copyright 2021 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.