Network Security: Private Communication in a Public World, Second Edition

2. Introduction to Cryptography

2.1. What Is Cryptography?

The word cryptography comes from the Greek words κρυπτο (hidden or secret) and γραφη (writing). So, cryptography is the art of secret writing. More generally, people think of cryptography as the art of mangling information into apparent unintelligibility in a manner allowing a secret method of unmangling. The basic service provided by cryptography is the ability to send information between participants in a way that prevents others from reading it. In this book we will concentrate on the kind of cryptography that is based on representing information as numbers and mathematically manipulating those numbers. This kind of cryptography can provide other services, such as

• integrity checking—reassuring ...