- add a security level for writing the cccd (reading is always allowed)

[stemschmidt]

This might be related to #10:

It would be good to set the security level for writing a cccd.

Example:
You have a service for bi-directional communication. The service has a notification characteristic for receiving data and a write-no-response (for maximum throughput) for sending data. The communication should be encrypted.

Currently there is no trigger to enforce encryption even if both characteristics have a security level > SecurityLevel.OPEN

Being able to assign e.g. SecurityLevel.JUST_WORKS for writing to the cccd of the notification would trigger a "Insufficient Authentication" response which then results in a pairing/bonding

[stemschmidt]

This is the part of the specification which I think is relevant: Chapter 3.3.3.3 Client Characteristic Configuration, BLUETOOTH CORE SPECIFICATION Version 5.2 | Vol 3, Part G

The table on page 1556 has this information in the Attribute Permission column:
Readable with no authentication or authorization.
Writable with authentication and authorization defined by a higher layer specification or is
implementation specific

So readable should always be allowed, writeable is implementation specific (mmmmh) or defined by a higher layer, which could be the definition of services and characteristics...

[ThomasGerstenberg]

Thanks for the contribution! Just one small change to request

[stemschmidt]

Sorry, that was nonsense... I remember I had the parameter somewhere else and faces some issues... I will update it...

[stemschmidt]

Thank you!