Resilient Privacy Protection for Location-Based Services Through Decentralization

Location-based Services (LBSs) provide valuable features but can also reveal sensitive user information. Decentralized privacy protection removes the need for a so-called anonymizer, but relying on peers is a double-edged sword: adversaries could mislead with fictitious responses or even collude to compromise their peers' privacy. We address here exactly this problem: we strengthen the decentralized LBS privacy approach, securing peer-to-peer (P2P) interactions. Our scheme can provide precise timely P2P responses by passing proactively cached Point of Interest (POI) information. It reduces the exposure both to the honest-but-curious LBS servers and peer nodes. Our scheme allows P2P responses to be validated with very low fraction of queries affected even if a significant fraction of nodes are compromised. The exposure can be kept very low even if the LBS server or a large set of colluding curious nodes collude with curious identity management entities.