Chapter 10. The Theory of Cryptography

One of the essential ingredients of e-business and enterprise computing is cryptography. Cryptography plays a critical role in J2SE and J2EE security, as Part IV of this book demonstrates .

This chapter explains the theory of cryptography that will be used in Chapters 11, 12, and 13. First, this chapter describes secret-key cryptographic systems, as they are at the heart of most cryptographic services, including bulk-data encryption, owing to their inherent performance advantage. Next is an overview of public-key encryption, which is essential for conducting e-business, particularly across public networks, because of the relative ease of distributing cryptographic keys. In Chapter 11, secret- and public-key cryptography services are described in the context of the standard Java APIs: the Java Cryptography Architecture and the Java Cryptography Extension.

For readers who may feel intimidated by the mathematical jargon associated with cryptography, we have tried to explain the mathematics associated with cryptography in a clear and simple way. Our intent is to demystify the concepts and terms surrounding cryptography.