Challenges in preserving location privacy in peer-to-peer environments

In location-based services (LBS), users have to continuously report their locations to the database server to entertain the service. For example, a user asking about her nearest gas station has to report her exact location to the database server. With untrustworthy servers, LBS may pose a major privacy threat on its users. In other words, the existing model of LBS trades service for user privacy. To tackle this privacy threat, several centralized privacy-preserving frameworks are proposed for LBS, in which a third trusted party is used as a middleware to blur user exact locations into spatial regions, in order to achieve k-anonymity, i.e., a user is indistinguishable among other k - 1 users. However, the centralized third trusted party could be the system bottleneck or single point of failure. The state-of-the-art peer-to-peer (P2P) communication technology adds a new dimension to the privacy-preserving techniques in LBS. The users holding P2P communication devices possess the ability to collaborate with one another to blur their exact locations into spatial regions without any help from centralized third trusted parties. In this paper, we present the challenges and research issues that emerge from deploying the P2P privacy-preserving framework in LBS.