Research On Security System Of Wireless Sensor Networks

Wireless sensor networks (WSNs) consist of a large number of small cheap tiny-sized sensor nodes which possess self-organizing capabilities and are densely deployed in the environment. The primary mission of wireless sensor network is to detect the events occurring in the range of sensor networks and then to report them to users.Wireless sensor network can be widely used, and its applications include environmental monitoring, home application, agriculture, building safety, earth-quake monitoring, human health monitoring, and many military applications. Security is critical for a variety of WSNs applications, such as home security monitoring and military deployments. Traditional security techniques used in traditional networks cannot be applied directly due to each node's cost and energy limitation, wireless communication, and exposed location. This dissertation addresses the security problem of WSNs, and the main contributions are shown as below:1. A security system architecture is presented for wireless sensor networks based on current works, and each module's function of the system, significance and the relations among them are dispicted, which provide academic support for the following research.2. A novel pairwise key pre-distribution scheme based on deployment knowledge was proposed (KPSBM). In KPSBM, the sensor nodes are divided into some groups, inner group pairwise keys are set up by a group key and intergroup pairwise keys are established by Blom's key pre-distribution scheme. We describe the details of the algorithm and compare it with other proposed schemes. Comparison and theory analysis show that the proposed scheme achieves better performance in terms of wireless sensor networks security, efficiency and key connectivity.3. According to the characteristics of Wireless Sensor Networks and the defects in current key management schemes, a key management scheme based on deployment knowledge (KMSBDK) is presented using identity-based cryptography (IBC). Then, the scheme is analyzed from security, key connectivity, scalability and efficiency. Compared with some current popular schemes, KMSBDK achieves better performance, and is fit for high security wireless sensor networks.4. The security problem at MAC layer in wireless sensor networks is considered. The security defects in current works on MAC protocols are analyzed, and then a intrusion detection system(IDS) on MAC layer based on D-S evidence theory is presented for the condition that current security system was broken down. In the IDS, the collision ratio, data packet's waiting time, RTS packets arrival ratio and the other nodes'alarms are selected as evidences to detect the attacks such as collision attack, unfairness attack and exhaustion attack. This IDS can be used in S-MAC, IEEE820.15.4, et al. directly. To evaluate the performance of the system, we analyzed the IDS with NS-2, the results show that the IDS can detect attacks on MAC layer, and guarantee the wireless sensor networks work well with the help of other security modules.5. The secure routing problem in wireless sensor networks is studied. According to the characteristics of WSN, a secure routing algorithm based on hypergraph theory (SRAHT) is presented. In SRAHT, some cryptography technologies are used to guarantee the data integrity, data freshness, data confidentiality and data authenticity; the technology of multi-path routing is adopted to promote the intrusion-tolerant ability of WSN; credit mechanism is introduced into SRAHT to detect the malicious nodes. The simulation results and theory analysis show that SRAHT is highly efficient, highly secure and attack-tolerant, and therefore is fit for large-scale wireless sensor networks.