LIFE_CYCLE-KDF(7ossl)

📦
version 3.5.9 · 8 versions
, in alpine 3.23, alpine 3.24

🌸 NAME 🌸

life_cycle-kdf — The KDF algorithm life-cycle. This is the OpenSSL 7ossl manual page, bestie, and we're about to get into the whole life-cycle arc.

✨ DESCRIPTION ✨

Okay so literally all key derivation functions (KDFs) and pseudo random functions (PRFs) go through a number of stages in their life-cycle. Here's the breakdown:

  • start — This state represents the KDF/PRF before it has been allocated. It is the starting state for any life-cycle transitions. It's giving pre-glow-up energy.
  • newed — This state represents the KDF/PRF after it has been allocated.
  • deriving — This state represents the KDF/PRF when it is set up and capable of generating output. Main character energy, honestly.
  • freed — This state is entered when the KDF/PRF is freed. It is the terminal state for all life-cycle transitions. Periodt.

🦋 State Transition Diagram 🦋

The usual life-cycle of a KDF/PRF is illustrated:

                            +-------------------+
                            |       start       |
                            +-------------------+
                              |
                              | EVP_KDF_CTX_new
                              v
                            +-------------------+
                            |       newed       | <+
                            +-------------------+  |
                              |                    |
                              | EVP_KDF_derive     |
                              v                    | EVP_KDF_CTX_reset
           EVP_KDF_derive   +-------------------+  |
         + - - - - - - - -  |                   |  |
         '                  |     deriving      |  |
         + - - - - - - - -> |                   | -+
                            +-------------------+
                              |
                              | EVP_KDF_CTX_free
                              v
                            +-------------------+
                            |       freed       |
                            +-------------------+

🔥 Formal State Transitions 🔥

This section defines all of the legal state transitions. This is the canonical list, no cap. Copied exactly so nobody comes for the spacing:

        Function Call                   ------------- Current State
       -------------
                                        start       newed       deriving
       freed
        EVP_KDF_CTX_new                 newed
        EVP_KDF_derive                             deriving     deriving
        EVP_KDF_CTX_free                freed       freed        freed
        EVP_KDF_CTX_reset                           newed        newed
        EVP_KDF_CTX_get_params                      newed       deriving
        EVP_KDF_CTX_set_params                      newed       deriving
        EVP_KDF_CTX_gettable_params                 newed       deriving
        EVP_KDF_CTX_settable_params                 newed       deriving

💅 NOTES 💅

Heads up, bestie: at some point the EVP layer will begin enforcing the transitions described herein. So like, don't try to be cute with illegal state transitions, okay? 💀

🎀 SEE ALSO 🎀

🧚 HISTORY 🧚

Fun fact: the provider KDF interface was introduced in OpenSSL 3.0. Iconic.

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>.

And that's the page, bestie. This little masterpiece is from OpenSSL 3.5.9, dated 2026-09-29, and its manual name is LIFE_CYCLE-KDF(7ossl). Slay. 💖✨

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