life_cycle-rand7ssl
The rand algorithm life-cycle
Overview
All random number generator (RANDs) go through a number of stages in their life-cycle:
- start
-
This state represents the RAND before it has been allocated. It is the starting state for any life-cycle transitions.
- newed
-
This state represents the RAND after it has been allocated but unable to generate any output.
- instantiated
-
This state represents the RAND when it is set up and capable of generating output.
- uninstantiated
-
This state represents the RAND when it has been shutdown and it is no longer capable of generating output.
- freed
-
This state is entered when the RAND is freed. It is the terminal state for all life-cycle transitions.
State Transition Diagram
The usual life-cycle of a RAND is illustrated:
+-------------------------+
| start |
+-------------------------+
|
| EVP_RAND_CTX_new
v
+-------------------------+
| newed |
+-------------------------+
|
| EVP_RAND_instantiate
v
EVP_RAND_generate +-------------------------+
+-------------------- | |
| | instantiated |
+-------------------> | | <+
+-------------------------+ '
| '
| EVP_RAND_uninstantiate ' EVP_RAND_instantiate
v '
+-------------------------+ '
| uninstantiated | -+
+-------------------------+
|
| EVP_RAND_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 instantiated uninstantiated freed
EVP_RAND_CTX_new newed
EVP_RAND_instantiate instantiated
EVP_RAND_generate instantiated
EVP_RAND_uninstantiate uninstantiated
EVP_RAND_CTX_free freed freed freed freed
EVP_RAND_CTX_get_params newed instantiated uninstantiated freed
EVP_RAND_CTX_set_params newed instantiated uninstantiated freed
EVP_RAND_CTX_gettable_params newed instantiated uninstantiated freed
EVP_RAND_CTX_settable_params newed instantiated uninstantiated freed
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.