PRIVE: Anonymous Location-Based Queries in Distributed Mobile Systems
Gabriel Ghinita (National University of Singapore)
Panos Kalnis (National University of Singapore)
Spiros Skiadopoulos (University of Peloponnese)
Nowadays, mobile users with positioning devices can access Location Based Services (LBS) and query about points of interest in their proximity. For such applications to succeed, privacy and confidentiality are essential. Encryption alone is not adequate; although it safeguards the system against eavesdroppers, the queries themselves may disclose the location and identity of the user. Recently, there have been proposed centralized architectures based on k-Anonymity, which utilize an intermediate anonymizer between the mobile users and the LBS. However, the anonymizer must be updated continuously with the current locations of all users. Moreover, the complete knowledge of the entire system poses a security threat, if the anonymizer is compromised.
In this paper we address two issues: (i) We show that existing approaches may fail to provide spatial anonymity for some distributions of user locations and describe a novel technique which solves this problem. (ii) We propose PRIVE, a decentralized architecture for preserving the anonymity of users issuing spatial queries to LBSs. Mobile users self-organize into an overlay network with good fault tolerance and load balancing properties. PRIVE avoids the bottleneck caused by centralized techniques both in terms of anonymization and location updates. Moreover, the status is distributed in numerous users, rendering the system resilient to attacks. Extensive experimental studies suggest that PRIVE is applicable to real-life scenarios with large populations of mobile users.
Beatty, Thursday, May 10, 2007, 10:30am to 12 noon.