The flexible and privacy-preserving proximity detection in mobile social network.

With the popularity of mobile social network, proximity detection has become a fundamental service. For the traditional proximity detection methods, users need to upload their locations to a location server so that they can find their neighbors by calculating relative distances among them. It will cause significant privacy concerns when the location server is an untrusted one. To solve this problem, we propose a proximity detection method which is based on the transfer of neighbor relation. Specifically, each request user in our paper only needs to submit a nearby reference list to the social network server (SNS). After that, the SNS searches the neighbors of the request user by judging whether their nearby reference lists have a common item. Moreover, we present two mechanisms to determine the ways of transmitting signals of beacon nodes, i.e., Beacon Node Rotating Mechanism and Beacon Node Competition Mechanism, respectively. Besides, we experimentally demonstrate the effectiveness and feasibility of the proposed method.