The design of code and cipher systems has undergone major changes in modern times. Powerful personal computers have resulted in an explosion of e-banking, e-commerce and e-mail, and as a consequence the encryption of communications to ensure security has become a matter of public interest and importance. This book describes and analyses many cipher systems ranging from the earliest and elementary to the most recent and sophisticated, such as RSA and DES, as well as wartime machines such as the ENIGMA and Hagelin, and ciphers used by spies. Security issues and possible methods of attack are discussed and illustrated by examples. The design of many systems involves advanced mathematical concepts and this is explained in detail in a major appendix. This book will appeal to anyone interested in codes and ciphers as used by private individuals, spies, governments and industry throughout history and right up to the present day.

Contents

1. Introduction
2. From Julius Caesar to simple substitution
3. Polyalphabetic systems
4. Jigsaw systems
5. Two-letter ciphers
6. Codes
7. Ciphers for spies
8. Producing random numbers and letters
9. The ENIGMA cipher machine
10. The Hagelin cipher machine
11. Beyond the ENIGMA
12. Public key cryptography
13. Encipherment and the Internet

Appendix