Computer Security Handbook, Fifth Edition

CHAPTER 7

ENCRYPTION

Stephen Cobb and Corinne LeFrançois

7.1 INTRODUCTION TO CRYPTOGRAPHY

7.1.1 Terminology

7.1.2 Role of Cryptography

7.1.3 Limitations

7.2 BASIC CRYPTOGRAPHY

7.2.1 Early Ciphers

7.2.2 More Cryptic Terminology

7.2.3 Basic Cryptanalysis

7.2.4 Brute Force Cryptanalysis

7.2.5 Monoalphabetical Substitution Ciphers

7.2.6 Polyalphabetical Substitution Ciphers

7.2.7 The Vigenère Cipher

7.2.8 Early-Twentieth-Century Cryptanalysis

7.2.9 Adding Up XOR

7.3 DES AND MODERN ENCRYPTION

7.3.1 Real Constraints

7.3.2 One-Time Pad

7.3.3 Transposition, Rotors, Products, and Blocks

7.3.4 Data Encryption Standard

7.3.5 DES Strength

7.3.6 DES Weakness

7.4 PUBLIC KEY ENCRYPTION

7.4.1 Key-Exchange Problem

7.4.2 Public Key Systems

7.4.3 Authenticity and Trust

7.4.4 Limitations and Combinations

7.5 PRACTICAL ENCRYPTION

7.5.1 Communications and Storage

7.5.2 Securing the Transport Layer

7.5.3 X.509v3 Certificate Format

7.6 BEYOND RSA AND DES

7.6.1 Elliptic Curve Cryptography

7.6.2 RSA Patent Expires

7.6.3 DES Superseded

7.6.4 Quantum Cryptography

7.6.5 Snake Oil Factor

7.7 FURTHER READING

7.8 NOTES

7.1 INTRODUCTION TO CRYPTOGRAPHY.

The ability to transform data so that they are accessible only to authorized persons is just one of the many valuable services performed by the technology commonly referred to as encryption. This technolosy has appeared in other chapters, but some readers may not be familiar with its principles and origins. The purpose of this chapter is to explain encryption technology ...