A privacy-preserving proximity friend notification scheme with opportunistic networking

Recently, smartphones have revolutionized mobile and pervasive computing around the world, and many smartphone-based applications have been developed to enrich our daily lives, such as location-based application which offers various useful services to its users based on users´ current locations like Google Latitude. However, the attractive features of smartphone-based applications inevitably incur higher risks for abuse if such applications and services do not take security and privacy consideration into account prior to it being widely deployment. In this paper, to simultaneously find the proximity friends and protect smartphone users´ identity privacy, we utilize the opportunistic networking to propose an efficient privacy-preserving proximity friend notification (PFN) scheme. Specifically, by combining the Bluetooth and 3G techniques of smartphones, a smartphone user can first send his privacy-preserving friend notification packet in a physical proximity area, then once a friend nearby receives and identifies the packet with opportunistic networking, the friend can directly phone back to the user. Detailed security analysis with provable security technique demonstrates the security of the proposed PFN scheme. In addition, extensive simulations have also been conducted to examine its effectiveness in terms of friend notification delay.