A user-centric location privacy-preserving method with differential perturbation for location-based services

A user-centric location privacy-preserving method with differential perturbations (Ulp2mDP) is proposed to solve the problem that the location obfuscation technique using cloaking region requires a trusted third part (TTP) and cannot sufficiently prevent inference attacks based on background information, and hence is easy to leak location privacy. The method can enhance the user's location privacy without requiring a TTP. The Ulp2mDP uses a modified Hilbert curve to project each 2-D geographical location of user into a 1-D space, and then randomly generates a reasonable perturbed location by combining the k anonymity with differential privacy technique. The perturbed value is then submitted as the user's real location to the service provider. In order to address the resource limitation of mobile devices, a quad-tree based scheme is used to transform and to store the user's context information as bit stream, which are highly efficient with respect to time and space complexities, hence to achieves high precision of retrieval. Security analysis shows that the Ulp2mDP can effectively protect user's location privacy. Experimental evaluation and a comparison with the approach using standard Hilbert curve show that the average retrieval accuracy of the Ulp2mDP increases by 15.4%. It is concluded that the Ulp2mDP provides a tradeoff between privacy preserving and service accuracy, and has a certain theoretical and practical significance for the design of privacy-preserving systems.