Path privacy protection in continuous location-based services over road networks

The spatial query has been one of the highly demanded services in mobile computing system recently. To protect users´ location privacy, existing architecture provides a trustworthy anonymizer to blur users´ location from the service provider. However, with mobile capability, users´ location extends from one spot to a continuous traveling route. For such continuous spatial query, it raises much more challenges for an anonymizer to protect users´ continuous privacy. This paper conducts research on ensuring users´ location privacy under the network-constrained road network environments. We first argue that the concept of continuous location privacy should be transferred to users´ path privacy, which are consecutive road segments that needs to be protected. A novel M-cut requirement is proposed to achieve the goal of user path privacy. Mobile users can customize their privacy level through M-cut requirement. Last, two methods of constructing the cloaked spatial region are provided in our research, namely Random Selection and Junction Sharing. These algorithms support path privacy and also take system computation and communication overhead into consideration.