Using dynamic pseudo-IDs to protect privacy in location-based services

Location-based services (LBSs) are attracting more and more attentions with the increasing popularity of mobile devices and online social networking. In LBSs, users can conveniently obtain their interested information by sending queries to the LBS server. However, users´ queries include their identities, locations, interests, etc, which may result in the leakage of users´ trajectory and other sensitive information. Although the existing obfuscation and location anonymization techniques along with a long-term pseudonym can protect users´ location privacy to some extent, users´ real identities and moving trajectories can still be deduced through long-term observation and side information aided inference attacks. To address these problems, we propose a dynamic pseudo-ID system, where unlinkable pseudo-IDs are used by users to completely hide their identities in the queries, in order to break the link between users´ identities and their locations. Moreover, we employ certificates to ensure the verifiability and traceability of the dynamic pseudo-IDs. Security analysis and evaluation results show that the proposed scheme can enhance user´ privacy and is feasible to implement into mobile devices.