Research On Users Privacy Protection Based On Service In Mobile Networks

With the popularity of mobile devices and wireless networks, the way of using mobile devices to get services becomes increasingly common. It becomes more and more popular that a user uses a mobile terminal to access a server to obtain services. At the same time, more and more private information will be obtained from a server which is always conducted under the condition that the user is not informed. Therefore, how to protect the confidentiality of sensitive user data and provide a secure, reliable and convenient service is a hot topic of our study.Individual users accessing servers to obtain the required information may cost a lot, while the way that people collaborate to obtain the information together would be relatively cost-effective. However, the issue of privacy disclosure of user identity information and service information would possibly arise during the interaction of mobile devices of users with servers due to the openness of wireless networks. Attribute-based encryption mechanism is one of public key encryption mechanism that is capable of implementing fine-grained access control and supporting one-to-many encryption, which, compared with the traditional public key encryption mechanism, has unparalleled advantages:firstly, the encryptor can encrypt the message without any public key certificates of the decryptor; secondly, the attribute encryption corresponds to multiple decryptors, rather than just a single decryptor, but for the encryptor, the data may be completely encrypted without multiple encryptions; and finally, the attribute encryption algorithm has flexible access policies, and the algorithm realizes access control to unauthorized users.Many of the information resources in servers may be obtained free, but at the same time sensitive user data, such as users’identity information, location information, request type and other information may be disclosed. Homomorphic encryption-based methods have a good protective effect when used in the field of information encryption, which can effectively realize k-anonymous and 1-diversity. Placement of cache information in actual base stations can effectively reduce times that users access the server, allowing sensitive user data to be protected effectively.In this thesis, problems arisen in obtaining required information of mobile devices accessing the server are studied in a deep going way, wherein the primary work is as follows:Firstly, the current common method of protecting privacy is introduced, and a study overview based on attribute encryption mechanism and homomorphic encryption scheme is analyzed in detail.Secondly, studied Ciphertext-Policy Attribute Based Encryption (CP-ABE) used for multiple users accessing the server together to obtain service information, so each user can access the server with a reduced cost of service. To solve this problem, the server adopts ciphertext policy attribute encryption to send a service request result to users, which is more efficient compared with traditional encryption methods. While pseudonyms methods are applied to achieve multi-user jointly requesting the server for one or more services, which can not only achieve privacy protection, but also reduce the cost of service of users. The analysis shows that the mechanism can protect the privacy of user identity, enabling secure mobile device communication, reducing the cost of computing and communication cost on the server side.Thirdly, the problem of privacy protection arisen in multi-user services implemented based on homomorphic encryption is studied. A user service privacy protection scheme based on homomorphic encryption is proposed based on applying the existing knowledge of homomorphic encryption schemes and base station to models in the mobile network. Homomorphic encryption algorithms are used to enable multi-user aggregated access to achieve k-anonymous and l-diversity; where in the base station facility is used to store related shared service information, and the frequency that users access the service provider is reduced, therefore reducing the risk of user privacy disclosure. The simulation results show that the frequency that mobile users access the service information from the service provider is greatly reduced with time; at the same time, with the user cooperation time increased, user privacy become securer.Finally, important issues existed during the interaction of mobile devices with servers are analyzed and summarized, and the future research direction is raised.