Chapter 39 – Public Key Infrastructure

This chapter will explain the cryptographic background that forms the foundation of PKI systems, the mechanics of the X.509 PKI system (as elaborated by the Internet Engineering Task Force), the practical issues surrounding the implementation of PKI systems, a number of alternative PKI standards, and alternative cryptographic strategies for solving the problem of secure public key distribution. PKI systems are complex objects that have proven to be difficult to implement properly. This chapter aims to survey the basic architecture of PKI systems, and some of the mechanisms used to implement them. It does not aim to be a comprehensive guide to all PKI standards or to contain sufficient technical detail to allow implementation of a PKI system. These systems are continually evolving, and the reader interested in building or operating a PKI is advised to consult the current work of standards bodies referenced in this chapter.