Abstract
In recent years, thanks to technology advances in low-power wirelessly networked systems and, we have witnessed the emergence of Wireless Sensor Networks (WSNs) and embedded computing technologies in many fields of our life; which range from military to medical applications and from industry to home appliances. Although most of researchers focus on designing protocols that maximizes both the processing capabilities and energy reserves, many of these protocols pay little attention to securing this WSNs. Nowadays, security goal is vital for ensuring the performance and the acceptance of the wireless sensor networks in many recent applications. This goal is still a challenge on account of the constraint resources of these wireless sensor nodes. This chapter givesan overview of the desired security services required for the WSNs, their threats model and finally the chapter presents in details different pairwise key distribution security techniques for distribution WSNs.