Location Privacy Protection Algorithm And Its Application In Medical Query Scenarios

With the continuous development of wireless communication and positioning technology,and the increasing intelligence of mobile terminal devices,the Location-based Service(LBS)has been increasingly widely applied.However,users will continue to expose their location information while enjoying the convenience of LBS,which has caused more and more attention to location privacy protection.This thesis focuses on the location privacy protection algorithm in application scenarios where users need to query private places such as hospitals based on LBS.The main research work of the thesis is as follows:(1)Based on extensive tracking and research on the structure of domestic and foreign common location privacy models and commonly used location privacy methods,this thesis analyzes their advantages and disadvantages in depth.After that,the thesis summarizes the main challenges faced by location privacy protection technologies.(2)The method of location privacy protection based on dummy locations is researched.Aiming at the problem that clients may choose dummy locations in unreasonable places such as rivers and lakes,a method for selecting dummy locations based on the distribution density of historical users is proposed,making the dummy locations selected by the client able to resist background information attacks and obtaining higher privacy entropy.Then,considering the user’s personalized privacy needs,this paper proposes a method that can assign the appropriate location privacy protection level to users according to their privacy preferences.(3)Location privacy protection ideas based on location interference and cryptography are also studied.And this paper proposes a privacy query algorithm that takes into account the privacy of the user’s location and query contents.The client and the server provider(SP)each hold a pair of keys.The real location and query keywords are encrypted,and an anchor point is selected instead of the user location to initiate a query request to the SP.And then the server provider can use its own private key to decrypt the user’s query keyword ciphertext,and the user’s location ciphertext serves as a reference for screening the query results of nearest neighbors.The algorithm can not only provide users with stronger location privacy protection,but also screen out more accurate nearest neighbor results for users.