Dummy Based Privacy Preservation in Continuous Querying Road Network Services

Dummies are useful for improving success rate because they can be always available, however, using dummies have two main challenges. The first is how to generate a dummy that is indistinguishable from a real user especially on road networks which have varied movement trends. Secondly, dummies can be used to launch attacks on the location based server by malicious clients which affects the business of the service providers. In this paper, we propose a novel client orientated privacy preserving scheme for continuously querying road network service that is also capable of protecting location based servers from attacks. We employed an offline trajectory clustering algorithm that clustered users' trajectory and used the derived parameters to generate a cost effective reusable realistic dummies on road network. To overcome malicious clients using dummies to launch attacks on location based servers, we developed a privacy preserving verification protocol capable of checking the activities of all clients in privacy preserving manner to curb such attacks. We tested the efficiency of our algorithm with some defined evaluation metrics, and it provided an effective privacy protection, satisfied clients at all times within an excellent processing time at a reasonable dummy processing cost when continuously querying road network services.