diff --git a/docs/proposed/psa-driver-interface.md b/docs/proposed/psa-driver-interface.md index 3b46084aeb..9b98406a4b 100644 --- a/docs/proposed/psa-driver-interface.md +++ b/docs/proposed/psa-driver-interface.md @@ -915,6 +915,16 @@ An example use case for updating the persistent state at arbitrary times is to r `psa_crypto_driver_get_persistent_state` does not identify the calling driver, so the driver needs to remember which driver it's calling. This may require a thread-local variable in a multithreaded core. Is this ok? +### Randomness + +#### Input to `"add_entropy"` + +Should the input to the [`"add_entropy"` entry point](#entropy-injection) be a full-entropy buffer (with data from all entropy sources already mixed), raw entropy direct from the entropy sources, or give the core a choice? + +* Raw data: drivers must implement entropy mixing. `"add_entropy"` needs an extra parameter to indicate the amount of entropy in the data. The core must not do any conditioning. +* Choice: drivers must implement entropy mixing. `"add_entropy"` needs an extra parameter to indicate the amount of entropy in the data. The core may do conditioning if it wants, but doesn't have to. +* Full entropy: drivers don't need to do entropy mixing. +