Research On Key Security Issues In Clustered Mobile Ad Hoc Networks

Mobile ad hoc networks (MANETs) are self-organized wireless networks that are formed by mobile nodes through distributed protocols. Although the features of dynamic topology, limited bandwidth and energy, and the non-existence of central facilities ensure their widespread application prospects, these features bring about many new problems and challenges. Among them, the security problem is the biggest challenge, but the hottest spot in these research areas.This dissertation conducts in-depth investigation into the key techniques of MANET security, and proposes algorithms, models and solutions to the key issues, such as security clustering, key & trust management, and security routing protocols, etc. Simulation experiments and performance analysis show that these algorithms, models and solutions can effectively improve the security of MANETs, and are of significant theoretical and practical values. The main research achievements of this dissertation include:1) This dissertation presents a maximum stable link based security clustering algorithm MSLBSCAThis dissertation presents a Maximum Stable Link Based Security Clustering Algorithm (MSLBSCA), which adopts certificate service mechanism to realize the identification of messages and the authentication of authorized nodes during cluster generation. It also adopts the DGKMF group key management framework to generate the same communication key for each authorized node, and thus ensures the privacy of communication messages during clustering, and decreases the encryption/decryption overheads of communication messages. Furthermore, MSLBSCA well takes into account the relative mobility of nodes on the criteria for clusterhead selection. According to intensity variation of the signals which are successively received from neighboring nodes, it decides the directions and velocities of the relative motions between the nodes. In this way, MSLBSCA overcomes the drawbacks of over-idealization assumptions about signal transmission models in similar research, and thus is more applicable to realistic environments. Simulation results show that the MSLBSCA algorithm can generate more stable clustering structure and has lower communication overheads and better fairness, compared with the homologous algorithms.2) This dissertation presents a key management scheme for clustered mobile Ad hoc networks, and designs an encryption authentication-based security routing protocol based on this schemeTo provide comprehensive security assurance for clustered MANETs, this dissertation presents an key management scheme which is suitable for clustered MANETs. The scheme has two cases, i.e., inter-cluster and intra-cluster cases. The inter-cluster case adopts the technique of (k, n) threshold encryption, while the intra-cluster case lets the clusterhead nodes to be responsible for the negotiation and distribution of the keys of the member nodes. This layered management mode significantly reduces the time overheads and bandwidth requirements of the communications. Based on this key management scheme, the dissertation designs an encryption authentication-based security routing protocol CBSRP. CBSRP adopts a combined scheme of certificate signature and encryption to negotiate the sharing of session keys. It uses the session keys to ensure the security of data transmission, and has lower encryption overheads. The security analysis shows that our CBSRP protocol can effectively defend the attacks such as forged routing information and changing path lengths. The simulation results show that, despite a moderate increase of the communication delays caused by this key management scheme, CBSRP has better performances on message delivery rate and routing overheads.3) This dissertation presents a trust management model CMBTM that is suitable for clustered MANETs, and designs a trust-based security routing protocol TBSRP based on CMBTMEncryption authentication-based routing protocols cannot effectively cope with the scenarios when malicious attacks occur after the authorized nodes have been captured or taken over, while trust-based routing protocols can well solve this kind of problems. Inspired by the similarity between MANETs and human society networks, this dissertation presents a centrality measurement-based trust model CMBTM. CMBTM adopts directed graphs and adjacent matrixes to construct the trust relationship models, and it uses distributed iterative algorithms to solve the trust matrixes, and hence get the global trust values of the nodes. Based on these, this dissertation designs a trust-based security routing protocol TBSRP. Simulations and analysis show that the TBSRP protocol has very good performance when it is used to identify and suppress malicious nodes, and to ensure the proper running of the networks.The research of this dissertation is an important part of the Chinese National Science Foundation project Security Issues in Massive Mobile Ad hoc Networks. The results provide important guidelines for ensuring the communication security under opposition environments.