Research On Privacy Protection Towards Continuous Query In Location-based Services

With the rapid development of mobile Internet and positioning devices in recent years, the popularity of location-based services has been promoted. Mobile users can enjoy location-based services provided by location service provider anytime. Users who enjoy the services will need to submit their precise locations and query contents to the location service providers, therefore it will reveal the users’ personal information since the location service providers are not reliable and the communication channels are insecure. How to guarantee high quality of services under the premise of protecting users’ privacy has become an urgent topic and the problem is also the key aspect of the research on privacy protection in location-based services. There are instantaneous query privacy protections and continuous query privacy protections in privacy protection in location-based services currently.Existing solutions to continuous query attacks mostly assume that the attackers have already known the corresponding relationships between the anonymous region and continuous query users, however, in reality it is not always easy for the attackers to obtain this correspondence. In this situation, we research the existence of continuous queries attacks, and propose solutions for continuous query attack under the background. The main contents of this paper are as follows.If the attackers know the user’s positioning distribution and every moment anonymous query request sets of continuous query, we propose an optimal matching algorithm based on weighted bipartite graph, which treats anonymous query request as the vertex of figure and the possible relations between anonymous query as the edges of figure then constructs a relational graph between anonymous query, the simulation results show that the algorithm can determine the correspondence of continuous query anonymous sets between different time with a high probability. In order to prevent the continuous query attacks effectively, we propose a continuous query privacy protection algorithm based on user’s movement speed, the simulation results demonstrate the feasibility and effectiveness of the algorithm.A more general algorithm is proposed in this paper when the attackers’ background knowledge relaxes further. If the attacker knows every query user’s movement speed and every moment query requests anonymity set in continuous query, a matching algorithm based on critical edge of bipartite graph is proposed,which treats anonymous query requests as the vertex of figure and the association between anonymous query as the edge of figure.The simulation results demonstrate that the algorithm can determine the correspondence of continuous query anonymous sets between different time with a high probability. In order to prevent the continuous query attacks effectively, we propose a continuous query privacy protection algorithm based on intersection degree of anonymity area which increases the size of correspondence between anonymous quest by extending the anonymous area, the simulation results show the feasibility and effectiveness of the algorithm.