PPLS: a privacy-preserving location-sharing scheme in mobile online social networks

The recent proliferation of mobile devices has given rise to mobile online social networks (mOSNs), an emerging network paradigm that uses social networks as its main design element. As one of the most critical components in mOSNs, location sharing plays an important role in helping users share information and strengthen their social bonds, which however may compromise users’ privacy, including location information and social relationship details. To address these challenges, some solutions have been proposed. However, none of them considers the privacy of inter-user threshold distance, which effectively can be used to identify users, their friends, and location information, by malicious or undesired elements of the system. To overcome this limitation, we propose a secure distance comparison protocol. Furthermore, we present a privacy-preserving location-sharing scheme (PPLS), which allows users to build more complex access control policies. The safety of our scheme is validated by the security analysis and the experimental results demonstrate the efficiency of PPLS scheme.