Q:

Is it possible to regenerate the link key of a Bluetooth connection?

I have a Bluetooth device, which pairs with an Android smartphone. This creates a link key that I want to change later on. Does the Bluetooth protocol support a method of regenerating it?

A:

Link Key gets regenerated,if you delete and pair again. Bluetooth Specification does describe APIs to change link keys in Host Controller Interface Layer. But, it is up to the operating system/ third party stack to expose it, because of security issues.
Some Bluetooth stack, may provide an option to regenerate link keys[automatically] after every bluetooth session. 

