Research On Key Management Schemes In Wireless Sensor Networks

Wireless sensor networks (WSNs) are ideal candidates to monitor the environment such as military surveillance, forest fire monitoring. In some WSNs military application scenarios, if a sensor is compromised or captured, the information on the sensor is disclosed to the adversary, and then its operation may be manipulated by the adversary. Therefore, security becomes one of the main concerns. However, providing security services in such networks turns out to be a challenging task due to the resource constraints on sensors and the sensor compromise attacks. These features and challenges motivate the research on security services such as encryption and authentication for sensor networks.Encryption and authentication are the most important modules in the security framework, especially encryption messages among sensors. Due to resource constraints, some key management schemes, such as the key distributed center scheme and the public key scheme, are not suitable for WSNs. Key pre-distribution schemes whose keys are pre-installed into sensors have been studied for a few years. However these schemes can not take application scenarios such as irregular deployment regions and energy-balancing into consideration. Thus, this paper studies how to achieve the key management schemes' performances including connectivity, security, and memory usage/computational capabilities from deployment information, energy-balancing and irregular deployment regions.The main conclusions are as follows:1) After establishing direct-keys between neighbor sensors, sensors in the network are different in energy consumption. Thus they can bring bad effects to the network. We propose an energy-balancing key management scheme in distributed sensor networks in order to improve network energy balance. This scheme establishes energy-based sensor-disjoint paths and then chooses a good sensor-disjoint path by which two sensors negotiate an indirect key according to the Min-Max energy method. Compared with the conventional proposals, the proposed scheme provides good energy balance while still maintaining high network resilience.2) There is a contradiction between security and local connectivity in the proposed schemes using a priori area deployment information. Thus, we study a location-based key management (LKM) scheme. In this scheme, we separate the network into core groups which select keys from neighbor core groups and non-core groups which select keys from neighbor core groups. We take the LKM scheme and the LKM-Polynomial (LKM-P) scheme which keys are generated by polynomials into analysis and simulation. Simulations show that these two schemes achieve a high local connectivity, and enhance the network resilience against sensor capture.3) Many sensors are deployed over a vast terrain, such as a canyon and a fjord. Some proposed schemes using deployment information are difficult when there are obstacles and holes in the network topology and can not deal with the problem of boundary regions. We discuss how to exchange messages among sensors in the irregular sensor networks, and analyze the whole network local connectivity in details. Theoretical and experimental analysis demonstrates that our method effectively resolves the exchange messages among sensors in the irregular region.4) The various key management schemes have focused on different aspects and applications. How to select a good scheme among them becomes a key for the applications of WSNs. We propose an effective system that is constructed by four performances to evaluate those key management schemes.