FADBM: FrequencyAware DummyBased Method in LongTerm Location Privacy Protection With the rapid usage of locationbased services (LBSs), protection of location privacy has become a significant concern. Existing dummybased methods mainly consider generating dummies in continuous queries, which neglects the fact that the user would launch queries in a frequent region(e.g., home), resulting in privacy disclosure in a longterm period (i.e., more than 30 days). To solve this problem, we propose a method which generates dummy frequent regions, and make dummies locate in these dummy regions as far as possible. Compared with other methods, evaluation based on realworld dataset shows that the proposed method can reduce the ratio of recognized dummies and restored trajectory in a longterm situation.

An Approach Based on Customized Robust Cloaked Region for Geographic Location Information Privacy Protection Locationbased services (LBS) have gained huge popularity because of the easy availability of modern mobile devices and the fast development of geographical information science (GIS). However, the lack of protection for private user positions might give rise to privacy concerns. This kind of problem is especially serious in mobile application environment because many mobile applications tend to use LBS. In this paper, we propose a new privacy preserving approach using customized robust cloaked region (RCR), depending on a peertopeer structure and the premise that users do not trust each other when sharing their geographical locations. Two algorithms are used to generate the RCR with high user density. The area of the RCR is controlled by the userxe2x80x99s demanded degree of protection. To enhance the resistance to regional background knowledge attack, we incorporate a location semantic value into each unit of the user map. According to extensive simulations, our method can effectively obfuscate a userxe2x80x99s geographical location into a highly indistinguishable region because of the disturbance of nearby users and different equally possible locations.