Research On Neighbor Query Technology In Location Privacy Protection

With the continuous development of mobile Internet and spatial positioning technologies,Location-Based Services(LBS)has become more and more widely used.The LBS server provides users with a variety of services based on the location information provided by the user,which greatly facilitates the work and life of the user.LBS also brings the risk of privacy leakage while providing convenience services for people.As users pay more and more attention to personal privacy security,how to provide good location-based services under the premise of ensuring the privacy of users is a hot topic in the field of location privacy protection.In order to ensure the privacy of users' location,the researchers proposed a variety of location privacy protection methods such as false location method,space conversion method and spatial anonymity method.However,these methods still have some shortcomings,such as inaccurate query results,too heavy LBS server calculations,and so on.This paper has conducted in-depth research on location privacy protection in LBS.The research results obtained are as follows:1.Aiming at the problem that the third-party anonymous server is insecure and easily becomes the system bottleneck,a privacy protection method based on the proximity query location of the third-party anonymous server that can be controlled by the user is proposed.The method uses the GeoHash algorithm to encode the precise position coordinates of the user,and converts the latitude and longitude coordinates into a string representing the anonymous area of the rectangle where the user is located;the LBS server performs the GeoHash-encoded string by constructing the index data structure based on the Trie tree.Query operations to obtain a POI result set.The method achieves the purpose of protecting the privacy of the user's location by using space generalization,and improves the efficiency of the query by designing indexes and caching methods.2.A privacy protection method for the nearest neighbor query location that is not subject to the third party anonymous server controlled by the user is proposed.The method uses Hilbert space filling curve to perform Hilbert coding on the user's precise position coordinates;the LBS server forms the nearest neighbor query result set by constructing Voronoi polygon and Hilbert coding.The key of the result set is the index of the Hilbert coded cell,and the value is the primary key value of the POI data in the database.Reduce memory usage by using two-dimensional variable length arrays.This method uses spatial anonymity technology to protect the user's location privacy.Since the result set is constructed offline and stored in memory,the search efficiency is improved.3.The GeoHash-based neighbor query location privacy protection system is designed and implemented.By adopting the strategy of read-write separation,the performance of the database is improved.In order to solve the problem of high concurrency and high availability,the load balancing algorithm for GeoHash coding is designed.The distributed cache based on Redis is used to improve the query efficiency of the whole system.