Chapter 3 - Working with Asymmetric Ciphers and Key Agreement Protocols

Abstract

Public-Key Cryptography is a common term used to describe asymmetric ciphers; the terms are interchangeable. Key agreement protocols explicitly rely on the design characteristics of asymmetric ciphers. In each situation, two keys are required to successfully employ a round trip cryptographic operation. The two keys are appropriately named “public key” and “private key,” and often they are collectively referred to as a “key pair.” Asymmetric ciphers depend heavily on extremely large prime numbers that have been randomly generated. Every asymmetric cipher requires a pair of keys before any cryptographic operation can be performed. The responsibility for key generation falls to an engine class, java.security.KeyPairGenerator. Asymmetric key pairs are actually composed of sets of related numbers that are plugged into advanced mathematical formulas. The cipher class serves as the entry point into all of the Java Cryptography Extension (JCE) cipher algorithms, relying on the use of the standard pair of engine factory methods. The chapter includes some code examples involving key exchange to establish a secure channel.