First version of the current generation sensor devices was introduced in mid 1990s with Wireless Integrated Network Sensors (WINS) at the University of California, Los Angeles UCLA). As computation power, communication range, and lifetime of the devices have increased, the node sizes have significantly decreased. These changes have led to better performance of WSN devices resulting in better performance of existing applications as well as possible exploration of new application areas. In 2003, MIT’s Technology Review had included Wireless Sensor Network (WSN) technology in its annual list of the ten most important technologies that will change the world (Huang, 2003). With new application areas and developments in wireless technologies, WSNs will gain more popularity and take more roles in our everyday lives.
WSNs are often deployed in areas where constant power is not available and recharging of batteries is not an option. Hence, the most important design aspect of a sensor network is its energy efficient operation to provide a long network lifetime. At present, with a pair of AA batteries a sensor node can operate several years. This comes at the cost of very constrained resources. Protocol designs in WSNs have to consider many constraints of the sensing devices such as limited battery power, memory size, and computing capacity. This makes a WSN more vulnerable to attacks than a wired or less energy constraint wireless network such as a Wireless Local Area Network (WLAN) or a Mobile Ad-hoc Network (MANET). On the other hand, the ever-increasing computational power of personal computers and laptops along with better performing decryption algorithms pose greater threats to wireless communication. For instance, various sniffing and wireless key hacking software is freely available on the Internet.
The objective of this book chapter is to make practical information on security in resource constrained wireless sensor networks available to a wide audience, ranging from practitioners to academic researchers. We explain security associated terms with respect to WSNs and present security relevant services. As the focus of the chapter, we thoroughly describe the characteristics of attacks and their countermeasures in WSNs. We qualitatively analyze and illustrate the multi-dimensional relationship of the discussed attacks. This allows a simplified comparison of relevant properties such as the effectiveness of a particular attack, the resources needed by the adversary to mount it, and the cost for the network to counter this attack.