by Rudolf Kippenhahn. The Overlook Press 1999.
283 pages. Index, bibliography, four short appendices. $29.95.
ISBN 0-87951-919-3. LoC Z103.K56
The translation from the German by Ewald Osers to the English edition involved more work than usual because the many examples of code breaking required English language examples. Breaking codes has certain underlying techniques that apply to all situations, but there are significant differences, for example, in the frequency of letters within each language. The extra work has paid off quite well, the examples work wonderfully.
Code Breaking, as the subtitle suggests, is both a history of code breaking and an exploration on how it is done. Although much shorter than the bible in the field (David Kahn's The Code-Breakers, 1181 pages) it reads smoothly from start to finish. Modern topics, such as PGP (Pretty Good Privacy) and the use of computers are integrated and not just added on at the end, with the result that the transition from the Enigma to prime numbers does not seem contrived.
Not surprisingly, the majority of the book is spent around World War I and World II, but there is plenty of material on Edgar Allen Poe, Sherlock Holmes, Caesar and early European history. The impact of various players throughout history are brought out with the appropriate important attached, such as the execution of Mary Stuart by Queen Elizabeth after the decipherment of her encoded message that proved her intentions. Thomas Jefferson invented an encryption device that was used in a modified form by the US military as late as 1920.
The explanations of how the various methods of encryption work are some of the best I have seen. The detail is presented in a step by step approach written for the nonprofessional, but without skipping over anything. Moreover, as the book progresses through history, the readers is given the modifications that results in new improvements. Starting with the monoalphabetic substitution of the Caesar cipher through polyalphabetic techniques and keys is done in well connected style. The chapters on how to break these codes is also a step by step approach that serves as good teaching model for anyone who wants to understand the basics about encryption and decryption.
The discussion of how DES works is limited when compared to the rest of the book. It seems that the book Cracking DES from O'Reilly was not taken into consideration when the DES chapter was prepared. There is some of the history of the development of DES that is interesting, but the difficulty of keeping up with currents changes is apparent. A good explanation of how prime numbers work with public key encryption stands alone without mention of the new algorithms or the search that is underway to find the successor to DES. I would suggest that a second edition ought to be in progress.
Code Breaking is recommended for those interested in the history of the field and for those who need a clear introduction to the breaking of codes. The math is simplified and the techniques well presented, preparing the novice for the more difficult modern world.