Ephemeral Identifiers: Mitigating Tracking & Spoofing Threats to BLE Beacons

Bluetooth Low Energy (BLE) beacons broadcast their presence in order to enable proximity-based applications by observer devices. This results in a privacy and security exposure: broadcast devices are typically susceptible to tracking and spoofing based on the IDs used by the beacons. We introduce a scheme consisting of cloud-based Ephemeral Identifiers (EID) which allows only authorized parties to properly identify the beacons broadcast; it mitigates the basic tracking and security threats while keeping high utility. We outline a formal model of privacy which is obtained with our scheme, present its implementation within the Eddystone BLE format, and discuss possible extensions.