Abstract
[Display omitted]
•Using circle as a cloaking region and explain how to compute a circle region.•Proposing an algorithm for server to find the kNNs of the circle region.•Performing an experiment on WeChat data to study the effectiveness and efficiency of the proposed method.
With the development of mobile Internet technology, location-based services (LBS) has been widely used in social networks, such as WeChat. A user of WeChat can discover people nearby with the help of LBS. However, users need to send their current locations to get the service, which may lead to the leakage of their location privacy. An effective way to protect the user's location privacy is using an imprecise location, such as a region to replace his real location. When processing continuous queries, the user need to transmit the region to the server continuously and an attacker is able to infer the real location from the overlapping regions. In this paper, we use circle as the query region and describe how to form a circle region. Then we study the overlapping circle attack and design a method to avoid this attack by changing the confidence level to a fixed value. We also propose an algorithm EPPINQ for the server to process a kNN query while protecting user's location against the attack. Experimental results show that our algorithm is more effective and efficient than the existing algorithm.