Shortest Path Computation with No Information Leakage

Shortest path computation is one of the most common queries in location-based services (LBSs). Although particularly useful, such queries raise serious privacy concerns. Exposing to a (potentially untrusted) LBS the client's position and her destination may reveal personal information, such as social habits, health condition, shopping preferences, lifestyle choices, etc. The only existing method for privacy-preserving shortest path computation follows the obfuscation paradigm; it prevents the LBS from inferring the source and destination of the query with a probability higher than a threshold. This implies, however, that the LBS still deduces some information (albeit not exact) about the client's location and her destination. In this paper we aim at strong privacy, where the adversary learns nothing about the shortest path query. We achieve this via established private information retrieval techniques, which we treat as black-box building blocks. Experiments on real, large-scale road networks assess the practicality of our schemes.Comment: VLDB201

VSPN: VANET-based Secure and Privacy-preserving Navigation

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Effective mix-zone anonymization techniques for mobile travelers

Mix-zones are recognized as an alternative and complementary approach to spatial cloaking based location privacy protection. Unlike spatial cloaking techniques that perturb the location resolution through location k-anonymization, mix-zones break the continuity of location exposure by ensuring that users' movements cannot be traced while they are inside a mix-zone. In this paper we provide an overview of some known attacks that make mix-zones on road networks vulnerable and discuss a set of counter measures to make road network mix-zones attack-resilient. Concretely, we categorize the vulnerabilities of road network mix-zones into two classes: one due to the road network characteristics and user mobility, and the other due to the temporal, spatial and semantic correlations of location queries. We propose efficient road network mix-zone construction techniques that are resilient to attacks based on road network characteristics. Furthermore, we enhance the road network mix-zone framework with the concept of delay-tolerant mix-zones that introduce a combination of spatial and temporal shifts in the location exposure of the users to achieve higher anonymity. We study the factors that impact on the effectiveness of each of these attacks and evaluate the efficiency of the counter measures through extensive experiments on traces produced by GTMobiSim at different scales of geographic maps. © 2013 Springer Science+Business Media New York