The Research On Key Management Protocols For Hierarchical Wireless Sensor Networks

Hierarchical wireless sensor network (HWSN) is a kind of sensor networks in which mass of nodes are distributed in hiberarchy. Providing secure in-network processing and passive participation is most important for hierarchical wireless sensor networks. Owing to HWSNs'restricted resources, many secure mechanisms, which base on public keys or highly complicated symmetric keys such as Kerberos, cannot be directly applied to them, and the random key predistribution schemes are not suitable for them because of difficult cluster keys establishment. Based on the pre-share and dynamic negotiation model, which is usually adopted in existing researches on key management protocols in HWSNs, this paper outspreads the research in respects of power consumption, security and scalability. The main research results are listed below:Firstly, a security model for HWSNs (HSM) is established on the basis of analysising the features of HWSNs. In the guidance of HSM, a key management model for HWSNs (HKMM) is proposed by investigating existing based-HWSNs protocols and the demand of the functions of key management and the security of HWSNs.Secondly, according to HKMM, some solutions aimed at the defects of existing protocols are presented, such as lowing the power consumption by equipped with communication key, by negotiation model without response and by negotiation with only one packet; enhancing the security by using Hash function or MAC and by randomizing the memory; improving the scalability with effective solution of motes addition; etc. At last a hierarchical key management protocol (HKMP) is designed base on these ideas. The theory analysis and experiment results show that HKMP is more energy-efficient, securer and more scalable than LEAP, which shows the effectiveness of HKMM and the methods proposed.Finally, the implementation and simulation of key management protocols in TinyOS are researched. A TOSSIM-based solution for the simulation of heterogeneous sensor networks, namely ETOSSIM, is proposed. The influences of link status in wireless sensor networks on key negotiation and repetitious negotiation are also discussed. The simulation experiments bring out the following results: the scalable simulation of heterogeneous sensor networks in TOSSIM is possible; although the probability of successful key negotiation in WSN is lower than ordinary networks, the secure connectivity would be better if the distance between nodes accounts for about two fifths of the longest communication distance, and 3 to 4 times'repetitious key negotiations are more suitable for higher secure connectivity.