APPLAUS: A privacy-preserving location proof updating system for location-based services

Today's location-sensitive service relies on user's mobile device to determine its location and send the location to the application. This approach allows the user to cheat by having his device transmit a fake location, which might enable the user to access a restricted resource erroneously or provide bogus alibis. To address this issue, we propose A Privacy-Preserving LocAtion proof Updating System (APPLAUS) in which co-located Bluetooth enabled mobile devices mutually generate location proofs, and update to a location proof server. Periodically changed pseudonyms are used by the mobile devices to protect source location privacy from each other, and from the untrusted location proof server. We also develop user-centric location privacy model in which individual users evaluate their location privacy levels in real-time and decide whether and when to accept a location proof exchange request based on their location privacy levels. APPLAUS can be implemented with the existing network infrastructure and the current mobile devices, and can be easily deployed in Bluetooth enabled mobile devices with little computation or power cost. Extensive experimental results show that our scheme, besides providing location proofs effectively, can significantly preserve the source location privacy.