Example with encrypted payloads

[Scottapotamas]

Should demonstrate how encrypted data can be managed.

This can be done at the payload level, leaving the header information intact for the length, along with the CRC and framing functionality. Plaintext ack/response bits in the header are probably fine as part of the demonstration.

Need to do:

• [ ] Find suitable encryption library
• [ ] Example embedded program
• [ ] Example UI implementation for tests/validation
• [ ] How to do first key exchange, rotations, etc