Research On Privacy-preserving Range Query Mechanism For Location-based Services

Location-based service(LBS)is the services that employ Positioning System to obtain users' location information and provide users with traffic guidance,location inquiries,business network inquiries and many other location-related services.With the pervasiveness of location-aware mobile electronic devices and the advances of wireless communication,location based services,which can help people enjoy convenient life,has attracted considerable interests recently.Although LBS can benefit people by providing convenient lifestyle,the privacy issues of LBS are still challenging today.For example,LBS providers can gain a lot of users' sensitive information(such as location,interest,etc.)through analyzing the user's current location and request information.In addition,it's a trend that LBS providers outsource LBS data to cloud services.However,in outsourced LBS environment,the privacy of LBS provider,LBS users and cloud server is crucial and the performance of the LBS privacy protection in the application environment is one of the important factors for the development and flourish of the LBS system.In this paper,aiming at the challenges about privacy and efficiency of LBS,we propose secure and efficient privacy-preserving polygon and circular spatial query schemes for LBS.With the schemes,LBS provider can provide accurate and efficient LBS without divulging users' query data and LBS provider's LBS resources in outsourced environment with high efficiency and security.Specific work is as follows:Firstly,design a polygon range query scheme for location-based service.Aiming at the privacy-preserving and high computation and communication overhead,an efficient and privacy-preserving polygons spatial query scheme is proposed and an efficient special polygons spatial query algorithm over ciphertext is constructed,based on an improved homomorphic encryption technology over composite order group.The LBS provider outsources the encrypted LBS data to cloud server,and the registered user can query any polygon range to get accurate LBS results without divulging his/her query information to the LBS provider and cloud server.The proposed scheme can search outsourced encrypted LBS data in cloud server by the encrypted request,and respond the encrypted polygons spatial query results accurately and guarantee the privacy of LBS provider's data resource and users' query locations.Then,design a circle range query scheme for location-based service.Based on an improved homomorphic encryption technology over composite order group,the proposed scheme can achieve location privacy preservation and confidentiality of LBS data.Specifically,for an LBS query request from a registered user,the LBS query execution is directly performed over ciphertext on the cloud server without decryption,and the result of LBS query can only be decrypted by the registered user.Thus,the user can get accurate LBS query result without divulging his/her location information.Through detailed security analysis,the proposed scheme can resist various security threats.Finally,the proposed two schemes are implemented on a smart phone and workstations in a wireless network with real LBS data to test the efficiency and accuracy of schemes.Extensive simulation results further demonstrate that the proposed schemes have lower computation and communication overheads.Thus,the proposed schemes can efficiently provide accurate LBS and guarantee the privacy of users' query and LBS resource.