| Location-Based Service(LBS)in mobile terminal apps provides great convenience to people’s daily life.Before mobile users can enjoy location-based services,Mobile Application Service Providers(MASPs)of the apps need to obtain users’ location information.However,malicious MASPs may abuse the privilege granted by users to access their location information that exceeds that required for providing services,which poses a huge risk to users’ location privacy.Distributed location privacy protection is achieved through the collaboration of multiple nodes,among which there may exist untrustworthy behaviors.On the one hand,collaborating nodes may have malicious behaviors,such as not willing to provide their accurate locations.Therefore,the queried nodes may receive false positions from them.On the other hand,requesting nodes may have malicious behaviors,such as leaking the location information of collaborating nodes for personal gain.All these malicious behaviors will affect the effectiveness of users’ location privacy protection.Aiming at the problem of MASP abusing user authorization and nodes doing evil in the distributed location privacy protection structure,this paper proposes two solutions: a mobile user location privacy protection scheme based on multi-level authorization and a blockchain-based mobile user location privacy protection scheme,the scheme is a pair of hierarchical authorizations for different APPs,so that they can use permissions reasonably,and the scheme two formulates a reward and punishment mechanism to manage node behavior,effectively protecting the location privacy of mobile users.The main research content and achievements of the paper are as follows:(1)A privacy-preserving scheme for mobile user location based on multi-level authorization is proposed to address the issue of MASP’s abuse of user permissions to collect location information.In this scheme,PKI issues privacy level certificates for the app based on its service type before the app is officially released.When MASP obtains the user’s location information,the mobile terminal will apply the corresponding level of kanonymity protection to the user’s location information based on the certificate and the user’s selection,preventing MASP from obtaining user location information that exceeds the precision required to provide the service.At the same time,MASP location access duration is set to ensure that MASP cannot continue to obtain the user’s location information when the user does not need location-based services but has not turned off location permission,thus ensuring user privacy and security.Experimental results show that the scheme achieves more secure mobile user location privacy protection while reducing communication overhead.(2)In distributed structure location privacy protection,a blockchain-based mobile user location privacy protection scheme is proposed to address the problem of dishonest behavior among mutually cooperating nodes.Under the multi-level authorization-based mobile user location privacy protection architecture described above,the scheme uses the immutability and transparency properties of the blockchain to write smart contracts that constrain the behavior of nodes,thereby achieving mobile user location privacy protection.The contract constrains nodes in the blockchain network in two ways: on one hand,it rewards cooperative nodes that actively participate in location anonymity and behave honestly;on the other hand,it punishes malicious nodes that harm the location privacy of other nodes.Experimental results show that the scheme more effectively protects the security of mobile user location privacy under limited computational delay and communication overhead. |
