[OpenTRV-dev] Proposed mechanism to keep main V0P2BASELIB and OTAESGCM lib separate

[Damon Hart-Davis]

Hi,

I have been deciding how best to get at the encryption needed for secure frame support in OTRadioLink/BASELIB without making the OTAESGCM and OTRadioLink libraries interdependent.

In particular I want to keep OTAESGCM as lightweight as possible and in no way dependent on our V0p2 hardware support for example.

I also don’t want to force occasional developers against V0P2 code to load up lots of code and libs that they may not even need (eg OTAESGCM) in some kind of DLL hell equivalent.

I propose to require pointers to enc/dec routines with the right signature to be made available at run-time to the OTRadioLink frame RX/TX support routines, which means that only the top level code that needs the secure frame functionality need link in the OTAESGCM lib, and other apps get no dependency.  (Note, I’m relying on C++ type safety on signatures here ideally, to completely minimise mutual dependencies, though there’s still the issue of retained/opaque state to deal with, etc, etc.)

It also means that different enc/auth mechanisms can be selected at run-time or compile-time.

Any comments?

Rgds

Damon