ABSTRACT
Wireless sensor networks (WSNs) are special types of networks. WSNs consist of hundreds or even thousands of small devices, each with sensing, processing and communication capabilities to monitor the real-world environment. They are envisioned to play an important role in a wide variety of areas ranging from critical military surveillance applications to forest fire monitoring and building security monitoring in the near future (Akyildiz et al., 2002). In these networks, a large number of sensor nodes are deployed to monitor a vast field, where the operational conditions are most often harsh or even hostile. However, the nodes in WSNs have severe resource constraints due to their lack of processing power, limited memory and energy. Since these networks are usually deployed in remote places and left unattended, they should be equipped with security mechanisms to defend against attacks such as node capture, physical tampering, eavesdropping, denial of service (DoS), etc. Unfortunately, traditional security mechanisms with high overhead are not feasible for resource-constrained sensor nodes. Moreover, threats to sensor networks are different from threats to mobile ad hoc networks. A traffic model in WSNs is many to one, unlike in mobile ad hoc models where it is many to many. Sensor nodes are prone to failure due to harsh deployment environments. The number of nodes in WSNs can be several orders of magnitude higher than the nodes in the ad hoc network. Sensor nodes may not have global identification.
