GSP
Quick Navigator

Search Site

Unix VPS
A - Starter
B - Basic
C - Preferred
D - Commercial
MPS - Dedicated
Previous VPSs
* Sign Up! *

Support
Contact Us
Online Help
Handbooks
Domain Status
Man Pages

FAQ
Virtual Servers
Pricing
Billing
Technical

Network
Facilities
Connectivity
Topology Map

Miscellaneous
Server Agreement
Year 2038
Credits
 

USA Flag

 

 

Man Pages
LIFE_CYCLE-DIGEST(7ossl) OpenSSL LIFE_CYCLE-DIGEST(7ossl)

life_cycle-digest - The digest algorithm life-cycle

All message digests (MDs) go through a number of stages in their life-cycle:

This state represents the MD before it has been allocated. It is the starting state for any life-cycle transitions.
This state represents the MD after it has been allocated.
This state represents the MD when it is set up and capable of processing input.
This state represents the MD when it is set up and capable of processing additional input or generating output.
This state represents the MD when it has generated output. For an XOF digest, this state represents the MD when it has generated a single-shot output.
For an XOF digest, this state represents the MD when it has generated output. It can be called multiple times to generate more output. The output length is variable for each call.
This state is entered when the MD is freed. It is the terminal state for all life-cycle transitions.

The usual life-cycle of a MD is illustrated:
+--------------------+
| start |
+--------------------+
| EVP_MD_CTX_reset
| EVP_MD_CTX_new +-------------------------------------------------+
v v |
EVP_MD_CTX_reset + - - - - - - - - - - - - - - - - - - - - - - + EVP_MD_CTX_reset |
+-------------------> ' newed ' <--------------------+ |
| + - - - - - - - - - - - - - - - - - - - - - - + | |
| | | |
| | EVP_DigestInit | |
| v | |
| EVP_DigestInit + - - - - - - - - - - - - - - - - - - - - - - + | |
+----+-------------------> ' initialised ' <+ EVP_DigestInit | |
| | + - - - - - - - - - - - - - - - - - - - - - - + | | |
| | | ^ | | |
| | | EVP_DigestUpdate | EVP_DigestInit | | |
| | v | | | |
| | +---------------------------------------------+ | | |
| +-------------------- | | | | |
| | | | | |
| EVP_DigestUpdate | | | | |
| +-------------------- | | | | |
| | | updated | | | |
| +-------------------> | | | | |
| | | | | |
| | | | | |
+----+------------------------- | | -+-------------------+----+ |
| | +---------------------------------------------+ | | | |
| | | | | | |
| | | EVP_DigestSqueeze +-------------------+ | | |
| | v | | | |
| | EVP_DigestSqueeze +---------------------------------------------+ | | |
| | +-------------------- | | | | |
| | | | squeezed | | | |
| | +-------------------> | | ---------------------+ | |
| | +---------------------------------------------+ | |
| | | | |
| | +---------------------------------------+ | |
| | | | |
| | +---------------------------------------------+ EVP_DigestFinalXOF | | |
| +------------------------- | finaled | <--------------------+----+ |
| +---------------------------------------------+ | |
| EVP_DigestFinal ^ | | | |
+---------------------------------+ | | EVP_MD_CTX_free | |
| v | |
| +------------------+ EVP_MD_CTX_free | |
| | freed | <--------------------+ |
| +------------------+ |
| |
+------------------------------------------------------+

This section defines all of the legal state transitions. This is the canonical list.
Function Call --------------------- Current State -----------------------------------
start newed initialised updated finaled squeezed freed
EVP_MD_CTX_new newed
EVP_DigestInit initialised initialised initialised initialised initialised
EVP_DigestUpdate updated updated
EVP_DigestFinal finaled
EVP_DigestFinalXOF finaled
EVP_DigestSqueeze squeezed squeezed
EVP_MD_CTX_free freed freed freed freed freed
EVP_MD_CTX_reset newed newed newed newed
EVP_MD_CTX_get_params newed initialised updated
EVP_MD_CTX_set_params newed initialised updated
EVP_MD_CTX_gettable_params newed initialised updated
EVP_MD_CTX_settable_params newed initialised updated
EVP_MD_CTX_copy_ex newed initialised updated squeezed

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

provider-digest(7), EVP_DigestInit(3)

Copyright 2021-2023 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>.

2025-04-08 3.5.0

Search for    or go to Top of page |  Section 7 |  Main Index

Powered by GSP Visit the GSP FreeBSD Man Page Interface.
Output converted with ManDoc.