A Trustless Broker Based Protocol to Discover Friends in Proximity-Based Mobile Social Networks

Due to the rapid growth of online social networking and mobile devices, proximity based mobile social networks (PMSN) are gaining increasing popularity. PMSN refers to the social interaction among physically proximate mobile users where they directly communicate through Bluetooth/Wi-Fi. In PMSN, while making friends, users match their profiles in accordance with their interests. In this regard, preserving a user’s privacy is crucial during profile matching. Users use their profiles for matching. An attacker in user’s near proximity can learn these profiles’ values. This poses significant threat to a user’s privacy. In this regard, we propose a protocol to preserve user’s sensitive information. During discovery of friends in our protocol we use a broker that is an intermediate entity between interacting mobile users. Our protocol does not require trustworthy broker and hence no valuable information is given to broker that can cause a privacy threat. For secure computations paillier encryption has been used in our protocol. Furthermore, we implement and analyze our protocol to show its acceptable computational and communication cost.