Android Things BLE peripheral encrypted write and read permissions

Question

There isn't much documentation in regards to setting up a pin with a Bluetooth Low Energy peripheral device. In my Gatt service I have set the BluetoothGattCharacteristic.PERMISSION_WRITE_ENCRYPTED_MITM and receive a GATT_INSUFFICIENT_PERMISSION message in my log upon attempting to write to the Bluetooth Write Characteristic I have set up. I was wondering what the process is for enabling encryption for the peripheral.

Thanks

Answer 1

Bluetooth LE requires to devices to be bonded (paired) before they can successfully encrypt transmissions used to read/write a given characteristic. Android does not handle this process for you, so you will need to initiate pairing between the two devices before any GATT transactions are attempted.

With the current Android Things previews, development of the Settings app (which generally handles much of the device pairing process) is heavily in flux. As such, traditional workflows for pairing a device are likely not to work at the moment until these changes are complete.

You could try initiating a pairing request from your Android Things device via createBond(), listening to the ACTION_PAIRING_REQUEST broadcast, and applying the necessary PIN code with setPin(). Some combination of those may work for you in the short term until a more official solution is available.