I'm trying to setup my RPi Zero W as a Terrarium Controller and I want to be able to create an Android app to control the settings and and such over Bluetooth. I've found tons of tutorials on setting up the RPi as a Bluetooth server, but none of them quite fit what I'm trying to do and I'm not sure how to adapt them to work as intended. I do want it to be secure, by either a single-paired device or requiring a code input or something to that nature. What would be the simplest solution to this? Thanks for your time.
Simplest way to do this would be setting up a Bluetooth socket server in Python, adding a simple communication over it - then adding some security algorithm, such as basic password check or even data (or text, if you wish to make it command-oriented) encryption of traffic - Python is simple and quick way to perform these tasks with little to no difficulty. Note that Python is language that only server has to work with - Android app does not need it to connect and communicate.