life_cycle-kdf7ssl
The kdf algorithm life-cycle
Overview
All key derivation functions (KDFs) and pseudo random functions (PRFs) go through a number of stages in their life-cycle:
- start
-
This state represents the KDF/PRF before it has been allocated. It is the starting state for any life-cycle transitions.
- 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.
- freed
-
This state is entered when the KDF/PRF is freed. It is the terminal state for all life-cycle transitions.
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.
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
At some point the EVP layer will begin enforcing the transitions described herein.
Releases
3 releases since Debian 12 (Bookworm); the text changed 2 times.