LPPS: Location Privacy Protection for Smartphones

Location-based service (LBS) is useful for many applications. However, LBS has raised serious concerns about users' location privacy. Utilizing the computation and storage capacity of smart phones, we propose a novel system architecture, called Location Privacy Protection for Smartphone (LPPS), to provide a privacy-preserving top-k query. LPPS does not rely on a trust third party (TTP), nor does it requires LBS servers to change their business model. The main idea of LPPS is to rank the Points of Interests (POIs) on the client side of the application using a small amount of metadata and then to make a request to the LBS server for real-time and detailed information about the POIs. Based on LPPS, we propose a novel metric called location indistinguishability to evaluate the privacy level of users in the proposed scheme. Then, we propose two dummy-POI selection algorithms to generate a superset of the actual top-k POIs when the query cannot meet the privacy requirement. Our experimental results demonstrate the validity and practicality of the proposed schemes.