It is envisioned that soon there will be more things connected to the Internet than there are people who are connected. The emergence of this Internet of Things creates many new exciting possibilities, but it can only deliver on its promises if it is reliable and trustworthy. This book addresses the security of the weakest link in this global system – the security of a Wireless Sensor Network (WSN). As the WSN applications mature the need for reliable security mechanisms grows significantly and justifies the use of strong cryptographic protocols. This book shows that solutions based on elliptic curve cryptography and pairing-based cryptography can provide practical security mechanisms for wireless sensor networks. The book presents the material in a very accessible manner covering topics ranging from the deep mathematical theory underlying cryptographic applications to the engineering aspects of embedded system software implementation in constrained computing environments. Any engineer or computer scientist commencing research in these areas would benefit from reading this book due to the comprehensive analysis of the topics.