Section 0.2. Roadmap

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0.2. Roadmap

Subject Matter

The material in this book is organized into three broad categories:

Cryptology: This is the study of techniques for ensuring the secrecy and/or authenticity of information. The two main branches of cryptology are cryptography, which is the study of the design of such techniques; and cryptanalysis, which deals with the defeating such techniques, to recover information, or forging information that will be accepted as authentic.

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Network security: This area covers the use of cryptographic algorithms in network protocols and network applications.

Computer security: In this book, we use this term to refer to the security of computers against intruders (e.g., hackers) and malicious software (e.g., viruses). Typically, the computer to be secured is attached to a network and the bulk of the threats arise from the network.

The first two parts of the book deal with two distinct cryptographic approaches: symmetric cryptographic algorithms and public-key, or asymmetric, cryptographic algorithms. Symmetric algorithms make use of a single shared key shared by two parties. Public-key algorithms make use of two keys: a private key known only to one party, and a public key, available to other parties.

Topic Ordering

This book covers a lot of material. For the instructor or reader who wishes a shorter treatment, there are a number of opportunities.

To thoroughly cover the material in the first two parts, the chapters should be read in sequence. With the exception of the Advanced Encryption Standard (AES), none of the material in Part One requires any special mathematical background. To understand AES, it is necessary to have some understanding of finite fields. In turn, an understanding of finite fields requires a basic background in prime numbers and modular arithmetic. Accordingly, Chapter 4 covers all of these mathematical preliminaries just prior to their use in Chapter 5 on AES. Thus, if Chapter 5 is skipped, it is safe to skip Chapter 4 as well.

Chapter 2 introduces some concepts that are useful in later chapters of Part One. However, for the reader whose sole interest is contemporary cryptography, this chapter can be quickly skimmed. The two most important symmetric cryptographic algorithms are DES and AES, which are covered in Chapters 3 and 5, respectively. Chapter 6 covers two other interesting algorithms, both of which enjoy commercial use. This chapter can be safely skipped if these algorithms are not of interest.

For Part Two, the only additional mathematical background that is needed is in the area of number theory, which is covered in Chapter 8. The reader who has skipped Chapters 4 and 5 should first review the material on Sections 4.1 through 4.3.

The two most widely used general-purpose public-key algorithms are RSA and elliptic curve, with RSA enjoying much wider acceptance. The reader may wish to skip the material on elliptic curve cryptography in Chapter 10, at least on a first reading. In Chapter 12, Whirlpool and CMAC are of lesser importance.

Part Three and Part Four are relatively independent of each other and can be read in either order. Both parts assume a basic understanding of the material in Parts One and Two.