Protecting User Trajectory in Location-Based Services

Preserving user location and trajectory privacy while using location-based service (LBS) is an important issue. To address this problem, we first construct three kinds of attack models that can expose a user´s trajectory or path while the user is sending continuous queries to a LBS server. Then we propose the k-anonymity trajectory (KAT) algorithm, which is suitable for both single query and continuous queries. Different from existing works, the KAT algorithm selects k-1 dummy locations using the sliding widow based k- anonymity mechanism when the user is making single queries and selects k-1 dummy trajectories using the trajectory selection mechanism for continuous queries. We evaluate and validate the effectiveness of our proposed algorithm by conducting simulations for the single and continuous query scenarios.