Research On Some Key Issues Of Security For Mobile Peer-to-Peer Networks

Mobile Peer-to-Peer (MP2P) technology has been increasingly attracting more and more attentions from academic and industry. Nowadays, there are many world-renowned research institutes and enterprises who have been studying MP2P key issues. Their researches have covered mobile topology discovery, mobile data retrieval, security, MP2P application systems and other aspects, where MP2P network security is a key issue. Because MP2P networks are essentially different from P2P networks, such as the frequent topological changes and the constraints of the limited resources, in particular that of the energy, of the mobile nodes, traditional P2P networks security techniques cannot be applied to MP2P networks. Therefore, to address this need, it becomes necessary to deeply study MP2P network security issues.First of all, the states of P2P and MP2P networks research and application are given in this dissertation. Then, we compare P2P networks security with MP2P networks security. Later, we summarize the existing security issues over the MP2P networks. Finally, we deeply study the secure network topology construction issue, the trust management issue, the access control issue and the mutual anonymity issue. The main contributions of the dissertation are shown as follows.(1) Secure network topology can fundamentally guarantee the security of MP2P applications. In this dissertation, we propose an adaptive MP2P network security topology construction protocol based on Bayesian game (AMPSTP). Firstly, the Fortune algorithm is used to divide a large geographical region into some small sub regions. Secondly, the temporary anchor node selection strategy based on queuing theory and the anchor node scheduling policy based on traffic prediction are presented. Thirdly, the cross-layer MP2P overlay network routing discovery algorithm and the mobile node selection mechanism based on Bayesian game are successively proposed. Finally, both the theoretical analysis and the simulation results show that compared with similar protocols, AMPSTP protocol not only can guarantee the network security and improve network performace, but also greatly reduce the extra communication overhead.(2) Trust is a key issue for trusted MP2P networks construction. As the MP2P networks and the P2P networks environments are fundamentally different, the existing trust models for P2P networks are not suitable for MP2P networks. In this dissertation, we propose a dynamic secure trust model for MP2P networks (DSTM_MP2P). DSTM_MP2P is comprised of two schemes. One is node type-identifying mechanism based on node behavior under the situation of the known or part of the known trust information of the nodes. And the other is node probability selection strategy based on Bayesian game under the situation of the unknown trust information of the nodes. The theoretical analysis and experimental results show that whatever MP2P network environment is, a request node under the direction of the DSTM_MP2P is always first to connect the safe and reliable nodes, which greatly increases the downloading success rate. In addition, it is theoretically proved that the control overhead of DSTM_MP2P is constant degree, which can ensure the scalability of the system.(3) Access control is a key issue to guarantee the security of mobile nodes and their resources. In this dissertation, we propose a secure access control model (SACM) for MP2P networks. SACM contains two different strategies, which are a trust and risk assessment-based access control strategy and a Bayesian game-based access control strategy. Both the two strategies adopt two-way authentication, namely the resource peer selection and the request resolution. The trust and risk assessment-based access control model is enabled when the peers in the networks are the nodes with full or partial previous experience information. Otherwise, the Bayesian game-based access control model is enabled when the peers in the networks are the nodes with no previous experience information. Both the theoretical analysis and the simulation results show that no matter how the MP2P networks environments change, with the help of the SACM, the request peers always give first priority to connecting the secure resource peers and the resource peers always give first priority to authorizing the trusted request peers, which can greatly improve the download success rate. Besides, SACM has lower communication control overhead than other access control models, which can ensure the scalability of the system.(4) Mutual anonymity is a key issue to protect the privacy of users over MP2P networks. In this dissertation, we propose a network coding-based mutual anonymity communication protocol (NMA). The contributions of this part are described as below. Firstly, a network coding scheme which can defend against various omniscient adversary attacks is presented. Secondly, in order to achieve the mutual anonymity between the resource requestor and the resource providers, the network coding scheme is used in the MP2P file-sharing entire process, including the resource searching, the resource requesting, response and the file download. Our simulations results show that when there are less than 50% malicious nodes in the network, NMA not only can protect the normal MP2P applications, but also can hide the identities and privacy information of the initiator and the responder.(5) The implementation of the secure MP2P file-sharing system is the verification of the feasibility of the proposed theories and models in the dissertation. The main work of this part is designing and implementing a secure MP2P file-sharing system on the platform of the Symbian Series 60 simulator. Both the CPPUNIT unit test and the system test show that the logic functions of the system are normal and the system can stably run.