LIFE_CYCLE-CIPHER
Section: OpenSSL (7SSL)
Updated: 2024-03-03
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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:
+---------------------------+
| |
| start |
| |
+---------------------------+ + - - - - - - - - - - - - - +
| ' any of the initialised '
| EVP_CIPHER_CTX_new ' updated or finaled states '
v ' '
+---------------------------+ + - - - - - - - - - - - - - +
| | |
| newed | | EVP_CIPHER_CTX_reset
| | <----+
+---------------------------+
| | |
+---------+ | +---------+
EVP_DecryptInit | | EVP_CipherInit | EVP_EncryptInit
v v v
+---------------------------+ +---------------------------+ +---------------------------+
| | | | | |
| initialised | | initialised | | initialised |
| for decryption | | | | for encryption |
+---------------------------+ +---------------------------+ +---------------------------+
| | |
| EVP_DecryptUpdate | EVP_CipherUpdate EVP_EncryptUpdate |
| v |
| +---------------------------+ |
| | |--------------------+ |
| | updated | EVP_CipherUpdate | |
| | | <------------------+ |
v +---------------------------+ v
+---------------------------+ | +---------------------------+
| |---------------------+ | | |
| updated | EVP_DecryptUpdate | | | updated |------+
| for decryption | <-------------------+ | | for encryption | |
+---------------------------+ | +---------------------------+ |
| EVP_CipherFinal | | ^ |
+-------+ | +--------+ | |
EVP_DecryptFinal | | | EVP_EncryptFinal +-------------------+
v v v EVP_EncryptUpdate
+---------------------------+
| |-----------------------------+
| finaled | |
| | <---------------------------+
+---------------------------+ EVP_CIPHER_CTX_get_params
| (AEAD encryption)
| EVP_CIPHER_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 initialised updated initialised updated freed
decryption decryption encryption encryption
EVP_CIPHER_CTX_new newed
EVP_CipherInit initialised initialised initialised initialised initialised initialised initialised initialised
EVP_DecryptInit initialised initialised initialised initialised initialised initialised initialised initialised
decryption decryption decryption decryption decryption decryption decryption decryption
EVP_EncryptInit initialised initialised initialised initialised initialised initialised initialised initialised
encryption encryption encryption encryption encryption encryption encryption encryption
EVP_CipherUpdate updated updated
EVP_DecryptUpdate updated updated
decryption decryption
EVP_EncryptUpdate updated updated
encryption encryption
EVP_CipherFinal finaled
EVP_DecryptFinal finaled
EVP_EncryptFinal finaled
EVP_CIPHER_CTX_free freed freed freed freed freed freed freed freed freed
EVP_CIPHER_CTX_reset newed newed newed newed newed newed newed newed
EVP_CIPHER_CTX_get_params newed initialised updated initialised updated initialised updated
decryption decryption encryption encryption
EVP_CIPHER_CTX_set_params newed initialised updated initialised updated initialised updated
decryption decryption encryption encryption
EVP_CIPHER_CTX_gettable_params newed initialised updated initialised updated initialised updated
decryption decryption encryption encryption
EVP_CIPHER_CTX_settable_params newed initialised updated initialised updated initialised updated
decryption decryption encryption 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>.
Index
- NAME
-
- DESCRIPTION
-
- State Transition Diagram
-
- Formal State Transitions
-
- NOTES
-
- SEE ALSO
-
- COPYRIGHT
-
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Time: 04:40:32 GMT, April 28, 2024