Bluetooth LE notify security

[stefanomerotta]

I'm trying to secure a notify characteristic but I didn't find any setting.

I've just tested it on current latest version (1.8.1.166) and there is an option for "read" and "write" actions, but not for "notify".
I checked also into nf-interpreter native code and I find only flags for "read" and "write" actions.
On project "mynewt-nimble" there is already an old open issue related to this missing feature that seems related to this use case.

apache/mynewt-nimble#1360

By using an "overall" flag for all actions and supported security we need to enlarge it due to missing free bitflags for "notify" options.
As now, a client could not read without pairing/bonding but can subscribe for notifications, that could be an inconsistent or unwanted behavior.
I didn't find any other way to set the security descriptor from managed code.

Am I missing something that could be used in order to achieve this scenario?