We've got a use case in which a BLE connection is used to do the basic configuration of an embedded device via an Android app (later also via an iPhone app). The embedded device runs Linux and thus uses BlueZ as Bluetooth stack.
Using the DBus-API of BlueZ, bonding is made possible by making the device pairable, discoverable, and activating advertising. After bonding the apps can access the GATT services and characteristics
(which require bonding to be read/written) on the embedded device.
After the setup is done the bonding of the device (running the app) that managed the setup process, is supposed to be removed. In order to do that we call RemoveDevice() of org.bluez.Adapter1.
The BlueZ documentation states the following
void RemoveDevice(object device)
This removes the remote device object at the given path. It will remove also the pairing information.
Still the app is able to access the GATT characteristics afterwards.
If bluetoothctl is used to check the list of paired devices, the list is not containing that device anymore though. Before calling RemoveDevice() the bonded device was visible there.
If bluetootd is stopped and restarted the app is no longer able to read/write the GATT characteristics, but needs to re-bonded before doing so.
I can neither find any further information in the BlueZ documentation nor can I find anything about this topic searching anywhere else.
Is this intended behavior or is this a bug? Does "remove pairing information" also mean "remove bonding information"? If this is intended behavior, how do we properly terminate bonding with a device? Should I use the BlueZ Management API instead of the BlueZ API? I'm not sure about this as multiple source state that the DBus-API is the way to go.
RemoveDevice() indeed removes the bonding information as well. So you have to disconnect first and then call RemoveDevice(). The next time you connect the bonding information will be gone.
However, note that if you only make use of encrypted characteristics, you can still connect and discover services. Only once you start reading/writing the encrypted characteristics will Bluez check if you are bonded.