Say Hello Again: Privacy Preserving Matchmaking Using Cloud in Encounter Based Mobile Social Networks

Mobile social networks (MSNs) are getting increasingly popular day by day. With the help of MSNs people can connect with each other online as well as offline. One of the famous applications of MSNs is profile matchmaking in which users share their interests in order to find mutual friends. However, the user of such application can be a victim of various privacy related attacks due to the revelations of user's personal interests during profile matchmaking. More recent dimension of MSN is encounter-based social networks. In this scenario, the users make social contacts while sharing a common location and time. Mobile devices record the encounter information when two users are within physical proximity and at a later time, their encounter history should be matched when they try to find each other again. In this paper, we propose a privacy preserving matchmaking protocol in which users share the encounter information and later utilize a cloud server to post encounter information in order to privately match their profiles with unknowns to whom they shared the encounter. In our protocol, neither the users nor the cloud server is able to discover the interests of either participants during matchmaking. To the best of our knowledge, this approach is the first attempt that combines encounter based social networks and fine-grained profile matchmaking. Towards the end of the paper, we present security analysis as well as performance evaluation that shows the effectiveness and feasibility of our protocol.