Location Privacy in Buildings: A 3-Dimensional K-Anonymity Model

Privacy protection has recently received considerable attention in location-based services. In this paper, we show that most of the existing k-anonymity location cloaking algorithms are concerned only and cannot effectively prevent location-dependent attacks when users' locations have height information. Therefore, adopting the three dimensional location information, we propose a new clique-based cloaking algorithm, called 3d Clique Cloak, to defend against location leaks in indoor environment. The main idea is to expand the MBV (minimum bounding volume) to a three-dimensional space, thus for a user who initiated location services can find k-anonymity cloaking set in the three-dimensional space. The efficiency and effectiveness of the proposed 3d Clique Cloak algorithm are validated by series of carefully designed experiments.