Pseudo-Location Updating System for privacy-preserving location-based services

With the rapid development of location-aware devices such as smart phones, Location-Based Services (LBSs) are becoming increasingly popular. Users can enjoy convenience by sending queries to LBS servers and obtaining service information that is nearby. However, these queries may leak the users´ locations and interests to the un-trusted LBS servers, leading to serious privacy concerns. In this paper, we propose a Privacy-Preserving Pseudo-Location Updating System (3PLUS) to achieve k-anonymity for mobile users using LBSs. In 3PLUS, without relying on a third party, each user keeps pseudo-locations obtained from both the history locations and the encountered users, and randomly exchanges one of them with others when encounters occur. As a result, each user´s buffer is disordered. A user can obtain any k locations from the buffer to achieve k-anonymity locally. The security analysis shows the security properties and our evaluation results indicate that the user´s privacy is significantly improved.