Location-Sharing Systems With Enhanced Privacy in Mobile Online Social Networks

Location sharing is one of the critical components in mobile online social networks (mOSNs), which has attracted much attention recently. With the advent of mOSNs, more and more users' location information will be collected by the service providers in mOSN. However, the users' privacy, including location privacy and social network privacy, cannot be guaranteed in the previous work without the trust assumption on the service providers. In this paper, aiming at achieving enhanced privacy against the insider attack launched by the service providers in mOSNs, we introduce a new architecture with multiple location servers for the first time and propose a secure solution supporting location sharing among friends and strangers in location-based applications. In our construction, the user's friend set in each friends' query submitted to the location servers is divided into multiple subsets by the social network server randomly. Each location server can only get a subset of friends, instead of the whole friends' set of the user as the previous work. In addition, for the first time, we propose a location-sharing construction which provides checkability of the searching results returned from location servers in an efficient way. We also prove that the new construction is secure under the stronger security model with enhanced privacy. Finally, we provide extensive experimental results to demonstrate the efficiency of our proposed construction.