IEEE Communications Surveys & Tutorials • 2nd Quarter 2006 2dvances in wireless communication and electronics have enabled the development of low-cost, lowpower, multifunctional sensor nodes. These tiny sensor nodes, consisting of sensing, data processing, and communication components, make it possible to deploy Wireless Sensor Networks (WSNs), which represent a significant improvement over traditional wired sensor networks. WSNs can greatly simplify system design and operation, as the environment being monitored does not require the communication or energy infrastructure associated with wired networks [1].WSNs are expected to be solutions to many applications, such as detecting and tracking the passage of troops and tanks on a battlefield, monitoring environmental pollutants, measuring traffic flows on roads, and tracking the location of personnel in a building. Many sensor networks have mission-critical tasks and thus require that security be considered [2,3]. Improper use of information or using forged information may cause unwanted information leakage and provide inaccurate results.While some aspects of WSNs are similar to traditional wireless ad hoc networks, important distinctions exist which greatly affect how security is achieved. The differences between sensor networks and ad hoc networks are [4]: • The number of sensor nodes in a sensor network can be several orders of magnitude higher than the nodes in an ad hoc network.• Sensor nodes are densely deployed.• Sensor nodes are prone to failures due to harsh environments and energy constraints.• The topology of a sensor network changes very frequently due to failures or mobility.• Sensor nodes are limited in computation, memory, and power resources.• Sensor nodes may not have global identification.These differences greatly affect how secure data-transfer schemes are implemented in WSNs. For example, the use of radio transmission, along with the constraints of small size, low cost, and limited energy, make WSNs more susceptible to denial-of-service attacks [5]. Advanced anti-jamming techniques such as frequency-hopping spread spectrum and physical tamper-proofing of nodes are generally impossible in a sensor network due to the requirements of greater design complexity and higher energy consumption [5]. Furthermore, the limited energy and processing power of nodes makes the use of public key cryptography nearly impossible. While the A YONG WANG, GARHAN ATTEBURY, AND BYRAV RAMAMURTHY UNIVERSITY OF NEBRASKA-LINCOLN
ABSTRACTWireless Sensor Networks (WSNs) are used in many applications in military, ecological, and health-related areas. These applications often include the monitoring of sensitive information such as enemy movement on the battlefield or the location of personnel in a building. Security is therefore important in WSNs. However, WSNs suffer from many constraints, including low computation capability, small memory, limited energy resources, susceptibility to physical capture, and the use of insecure wireless communication channels. These constraints ...