Small-world: Secure friend matching over physical world and social networks

The explosive growths of Social Networks and smart devices over the past decade have redefined the way people interact with their friends and build social connections with physical-proximate others. Unfortunately, increasing backbone network traffic and privacy concerns of the information leakage during the friend matching process limit the expansion of users' friend circles. To address the problem, we propose Small-World, which aims to achieve secure friend matching over physical world and social networks simultaneously. Specifically, we design a physical proximity module, which is based on a novel weight aware spatiotemporal similarity function with considering a set of factors such as hot zones for each user, the distribution of Point of Interests and users' whereabouts. Then we build a Katz score-based social strength proximity module, which is a bidirectional and social strength-aware similarity function, to calculate the similarity between social network users. We design an El Gamal cryptosystem-based solution, termed Protocol I, to realize secure 2-hop social strength matching and further extend it to Protocol II, which aims to establish multi-hop (4-hop at most) social connection chain between two users. Finally, we design a weight assigning function based on the linear regression to evaluate the importance of the physical proximity module and it of social strength proximity module. Thorough security analysis and performance results indicate the effectiveness and efficiency of our proposed scheme. (C) 2016 Elsevier Inc. All rights reserved.