ABSTRACT
There are mainly two types of cryptographies: symmetric and asymmetric. In Symmetric Key Cryptography (SKC), the sender and the receiver of a message share a single, common key for encryption and decryption of the message, whereas in asymmetric key cryptography (also known as PKC), the key (public key) used to encrypt a message differs from the key (private key) used to decrypt it. These two keys are mathematically related to each other. For managing security issues in WSNs, among the two types of cryptographies, SKC has been preferred over PKC from the very beginning stage because of its low-resource requirements. The use of PKC in WSNs was totally ruled out for a long time with the idea that PKC is energy-inefficient, slow, and computationally complex; thus not at all suitable for resource-constrained devices such as sensors. More or less this was the commonly held belief of the researchers until late 2004 when some courageous researchers came up with positive results about the feasibility of PKC in WSNs. From that time up to today a good number of works have proved the suitability of PKC with practical and experimental validations. The intent of this chapter is to present a survey on these notable implemented works. Our focus is to get a lucid picture of the current status of practical achievements, challenges, and future hopes of harnessing the benefits of PKC in low-resource sensor network environment. With the survey of various notable works, we also present an overview of PKC, analyze its necessity for WSNs, and the hurdles to implementing it in WSNs. We conclude the chapter with a summary of proven facts and future expectations of exploiting PKC in WSNs.
