The Codebreakers: The Comprehensive History of Secret Communication from Ancient Times to the Internet

This massive, exhaustively-researched book by David Kahn examines the HISTORY of cryptography from the dawn of civilization to the darkness of the Cold War. He starts an introductory bow to capture readers' attention with the Magic story (American decryption of Japanese WWII codes). Then, Kahn traces the cryptologic developments from the early most rudimentary monalphabetic substitution systems to polyalphabetics, codes, transposition ciphers, enciphering devices (e.g. checkerboards, grille ciphers, one-time pads, one-time tapes, ciphering cylinders, voice modulators, etc.), deciphering systems, and all the governmental organizations devoted to enciphering and deciphering activities. His investigations cover Babylonian cuneiform, Roman cipher systems (e.g. the famed Caesar cipher), an entire host of Renaissance cryptographers and systems, Englightenment-era black chambers, British amateur contributions (e.g. Playfair cipher), American Civil War transposition systems, telegraphic codes, French military ciphers, and the communication cipher used during the Dreyfus affair. The book then devotes about 2/3 of the book to modern cryptographic systems used from 1914 to 1965 (the book was published in 1967). Some of the WWI-era subjects treated in this section are Britain's WWI Room 40, the unusual ADFGVX German cipher, WWI battlefield cipher and code systems. Between the wars, Kahn describes the American Black Chamber, the advent of rotor machines (e.g. Engima, Hagelin, Hebern), the rise of mathematical/statistical analysis, the US Magic decryption program, the extraordinarily successful Soviet cipher systems, and quite a thorough examination of all WWII-era cryptographic activities. The last few chapters of the book are devoted to describing the NSA, the chimeric search for Shakespearean hidden messages, pigpen ciphers, Prohibition-era rumrunners, numbers runners, visual telegraphy, the decryption of Linear B/hieroglyphics, potential SETI coding systems, and a very short brief on DES. Bar none, this is the one book to own on cryptographic history up to 1965. (This is not a cryptology textbook, however.) Kahn's writing style and subjects are always engaging and packed full with comprehensive information. Kahn reveals that almost every cipher system ever invented (with the significant exception of one-time pads/tapes) has been broken - most surprisingly quickly. This is a lesson that any organization using radio (including mobil phones) and public facilities (e.g. internet, PSTN) to communicate definitely ought to realize. This is a must read for anyone interested in cryptologic history. Outstanding!

As a historian, with a particular interest in other than "American History", I found this book particularly compelling. I read the Earlier edition at least three times. Yes, I found that, at times, the text gets bogged down in minutae that may not appeal to a particular reader, but in a volume of this magnitude, with this scope, and this ambition, that is virtually a lock.What many of the reviewers don't seem to realize that the book was written in the context of the 1960s and that not only the writing, but also events described must be put into context. David Kahn does an excellent job of doing just that. To illustrate, I might simply point out his portrait of Herbert O. Yardley. One only has to read Yardley's "Education of a Poker Player" to understand just how accurate Kahn was in describing Yardley and his role. Like all history books of a more specialized nature, there is a serious advantage to having enough background information to understand where events, people, and technology fit into the puzzle.If you are seriously interested in what went on "behind the scenes" in much of the historical events of the 19th and 20th centuries, this book provides information that is an essential part of the puzzle.

This book is not intended to teach the reader how to design or cryptanalyze codes and ciphers; it is a history book, and a really great one. However, the reader should be aware of a couple of things that may not be apparent.First, the 1996 "revised edition" differs from the 1967 first edition only in the addition of a final chapter to cover what Kahn didn't know (or didn't choose to include) in the 1967 edition. The first 26 of 27 chapters, and the references and bibliography associated with them, are essentially identical to those of the 1967 edition. This means that a number of statements and passages in the first 26 chapters, although correct in 1967, are misleading if one assumes they were written in 1996. I recommend that the reader skim Chapter 27 quickly before reading the rest of the book, so as not to misunderstand any of what's in earlier chapters.Second, keep in mind that in 1967 Kahn was essentially an outsider so far as the intelligence community was concerned, but by 1996 he was definitely regarded as an insider. Hence, the new final chapter is written with complete respect for the sensitivities of the intelligence community, which the original book was not. I was surprised to see one particular statement in the last chapter until I realized that NSA wants to correct a misapprehension widely held outside the community. Much more important, Kahn now knows a great deal that he has chosen to omit from the last chapter, including much that's unclassified but still regarded by somebody as sensitive for one reason or another. He even omits certain material that he made publicly available some years ago in his written testimony to a Congressional subcommittee. So the reader should understand that this book says less than it might about various aspects of the history of cryptology and its impact dating back as far as World War II. Whether this is good or bad depends on where one sits; if one is concerned about the sensitivities of various governments, it's good; if one wants to know as much as one can about the history of cryptology since 1940 that's not still clasified, it's bad.

David Kahn's newest book updates his previous work, which sits on every Cryptographer's, Cryptanalyst's, and government Special Intelligence officer's bookshelf in the entire world. If you REALLY want to how ciphers, codes, and systems are broken, Kahn is the author who tells you. Any person knowledgable in the field of Cryptology or Intelligence will tell you that Kahn' book has never been equalled. It is known as "The Bible of Cryptology" within the field.From early Sparta and Rome to the present day, the strengths and weaknesses of systems and devices are presented in clear, concise terms -- occassionally with a bit of levity, where appropriate. Novices in the field will find much useful -- and highly interesting -- information. Professionals always find reminders of the fallability of "unbreakable" systems.Kahn's writing style is clear, concise, and analytical. It is never boring.I was employed by a maker of Cryptographic equipment, and was authorized to discuss key generator and cipher system issues with the heads of national governments. A copy of "Codebreakers" was our most requested -- and welcomed gift. That speaks more eloquently than any words I might craft.

This massive volume is the final word on the history of classical (non-computer) ciphers, codes, and secret writing. The book is carefully researched: 153 of its 1164 pages are endnotes. But Kahn's writing is very readable, and includes many human interest stories in addition to historical and technical treatments of his topics. Crypto buffs have never been able to understand why this 1967 book keeps going out of print. (Don't let the 1983 reprint date fool you; the book leaves off in the mid-60's. Also, don't be confused by the paperback version, which is much shorter than the hardcover version.)