A privacy-preserving Proximity Detection Method in social network

Proximity detection is a fundamental service in social network. Most of traditional proximity detection methods need users' locations for location server to find their neighbors by calculating relative distance among them. However, this mechanism has caused similarly serious concerns on the potential privacy leakage if server is untrusted. To solve this problem, we propose a proximity detection method which is based on wireless APs (Access Point). Each request user only needs to submit a nearby AP list to social network server, which called SNS in this paper. After that, the SNS finds neighbors of request users by judging whether their nearby AP lists have a common item. In addition, since most existing APs may be uneven distribution and have risks of the location leakage, we also present a distributed Beacon Node Rotating Mechanism---each user acts as a beacon node, which is similar to AP to be a reference of neighbor discovery in proximity detection. Our method works well without requiring user's location information, which enhances the security of location privacy. Finally, we experimentally demonstrate the effectiveness and feasibility of the method.