A privacy-preserving reputation system for participatory sensing

Participatory sensing is a revolutionary paradigm in which volunteers collect and share information from their local environment using mobile phones. The design of a successful participatory sensing application is met with two challenges - (1) user privacy and (2) data trustworthiness. Addressing these challenges concurrently is a non-trivial task since they result in conflicting system requirements. User privacy is often achieved by removing the links between successive user contributions while such links are essential in establishing trust. In this work, we present a way to transfer reputation values (which is a proxy for assessing trustworthiness) between anonymous contributions. We also propose a reputation anonymization scheme that prevents the inadvertent leakage of privacy due to the inherent relationship between reputation information. We conduct extensive simulations using real-world mobility traces and practical application. The results show that our solution reduces the probabilities of users being tracked via successive contributions by as much as 80%. Moreover, this improvement has no discernible impact on the normal operation of the application.