The use of public key algorithms to sensor networks brings all merits of these algorithms to such networks: nodes do not need to encounter each other in advance in order to be able to communicate securely. However, this will not be possible unless “good” key management primitives that guarantee the functionality of these algorithms in the wireless sensor networks are provided. Among these primitives is public key authentication: before sensor nodes can use public keys of other nodes in the network to encrypt traffic to them, they need to make sure that the key provided for a particular node is authentic. In the near past, several researchers have addressed the problem and proposed solutions for it as well. In this chapter we review these solutions. We further discuss a new scheme which uses collaboration among sensor nodes for public key authentication. Unlike the existing solutions for public key authentication in sensor network, which demand a fixed, yet high amount of resources, the discussed work is dynamic; it meets a desirable security requirement at a given overhead constraints that need to be provided. It is scalable where the accuracy of the authentication and level of security are merely dependent upon the desirable level of resource consumption that the network operator wants to put into the authentication operation.
