Location Privacy Protection Research Towards Mobile Location Service

With the rapid development of mobile Internet,especially the large-scale popularity of mobile terminal devices,location-based services are widely used in certain fields,such as tourism services and vehicle navigation,etc.,which has brought major changes to people's daily lives.Location-based service is becoming more and more popular.In the process of LBS,the user needs to submit an accurate location to obtain the corresponding service,people enjoy the great convenience of location service while also suffering the risk of location privacy leakage.Therefore,the privacy protection of the user's location is an important issue to be solved in the process of mobile location service.This thesis firstly introduces the current research status of location privacy protection at home and abroad in detail,deeply analyzes the system architecture and technical means related to location privacy protection,and points out their respective advantages and disadvantages.Then we focus on the research on the problems towards location privacy protection and seek to accurately assess the privacy threats faced by users in a typical application scenario,thereby achieving full protection of the users,location and finally achieving a balance between location privacy and service quality.The main research work and contributions of this thesis are summarized as follows:(1)The thesis firstly proposes a scheme on location privacy protection based on query cloaking region construction,named as QCRC-LocPriv,which uses a trusted third-party anonymous server model and combined spatial anonymity method with k-anorxymity.In QCRC-LocPriv,the trusted anonymous server has a shared location database,which can reduce the overhead of the system.In order to meet the users' different privacy anonymity requirements,k initial sub-cloaking regions satisfying k-anonymity are generated according to the privacy demand.In the process of spatial anonymity,circular regions are used to generate their corresponding query regions and the cloaking regions are reconstructed.Finally,the cloaking regions are submitted to the location service provider without reducing the privacy protection level of the user,which can reduce the query cost of LSP and improve the location service quality.Through the theoretical analysis and experimental verification,QCRC-LocPriv can well protect the privacy of the user's location,while ensuring a high quality of service.(2)The thesis secondly introduces a scheme on a differential privacy model,named DPTD-LocPriv,which is proposed to defense against background knowledge attacks and deal with server security problems on the trusted third-party anonymous server based on the QCRC-LocPriv.In DPTD-LocPriv,differential privacy is suitable for location privacy protection due to its insensitivity to background knowledge and has a good protection effect.At the same time,the main realization mechanism of differential privacy:Laplace Mechanism and Exponential Mechanism,which are based on a solid foundation of mathematics.And the privacy protection degree can be expressed by assigning a privacy budget,which is more reliable and rigorous.In addition,a tree structure is used to represent the distribution of location data according to the characteristics of location data and the degree of difficulty in retrieval,which solved the problem that location data is difficult to express because of its discreteness and sparsity.Through theoretical analysis and experimental verification,DPTD-LocPriv can well protect the privacy of users and maximize the utility of data,and effectively ensure the quality of location services in mobile location services.