Rating: 
Summary: Absolutely THE definitive history of Cryptology
Review: .. .Kahn's book was the second book I read on the history of cryptology, Simon Singh's "The Code Book" being the first. Without a doubt, you will get the whole knowable history of cryptology in Kahn's book. But don't make the mistake that some other readers obviously did. . .Kahn's book does NOT give a technical explanation of cryptanalysis, nor does he make such a claim. This is a history book pure and simple. If you want a more technical treatment, look up the books in his bibliography.Kahn's book can be tough in some areas, such as the telegraph codes and similar systems, where he seems to keep explaining each individual business codebook or system, but the true cryptography sections are a delight to read. You may want to try Singh's "The Code Book", as it is a much easier (and cheaper) read, to see if it piques your interest. Then, do like I did, and devour every crypto book you can find, reading this one second! It truly is an epic work.
Rating: 
Summary: excellent informative tells all in an interesting way
Review: . This book is excellent. It gives the history of cryptography from ancient times up to recent events. Clearly the most recent info is obviously still kept under wraps by the NSA, CIA, KGB, mossad, et al. What the book covers is done with an interesting style and enough detail to be educational. Combined with the techniques are the usages and stories behind the usage of crypto. This is the only history book that I ever found to be worth reading. Kahn is accurate, complete, and interesting. He tells all but omits the usual history book tedium and boring factoids strung together with a verb (usually is or was), a noun, and the word "the". This is more like a novel than a textbook. David is an authority in the subject area. I met him at an ACA convention and again at the NSA museum where he was doing research. He has some supplemental books that bring this one more up to date with newer info that has become available but this one is still the classic and should be the start for anyone interested in either the techniques, usage, or the historical implications of crypto. This book is most highly recommended. Buy it, read it, enjoy it, re-read it again because it is so interesting you will rush through it to see what is next and not pick up on many details the first time through. This is the definitive book and is a classic. Ten Stars is the real rating but Amazon does not let me go that high.
Rating:
Summary: excellent informative tells all in an interesting way
Review: . This book is excellent. It gives the history of cryptography from ancient times up to recent events. Clearly the most recent info is obviously still kept under wraps by the NSA, CIA, KGB, mossad, et al. What the book covers is done with an interesting style and enough detail to be educational. Combined with the techniques are the usages and stories behind the usage of crypto. This is the only history book that I ever found to be worth reading. Kahn is accurate, complete, and interesting. He tells all but omits the usual history book tedium and boring factoids strung together with a verb (usually is or was), a noun, and the word "the". This is more like a novel than a textbook. David is an authority in the subject area. I met him at an ACA convention and again at the NSA museum where he was doing research. He has some supplemental books that bring this one more up to date with newer info that has become available but this one is still the classic and should be the start for anyone interested in either the techniques, usage, or the historical implications of crypto. This book is most highly recommended. Buy it, read it, enjoy it, re-read it again because it is so interesting you will rush through it to see what is next and not pick up on many details the first time through. This is the definitive book and is a classic. Ten Stars is the real rating but Amazon does not let me go that high.
Rating:
Summary: Truly a History
Review: 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.
Rating:
Summary: Truly a History
Review: 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.
Rating:
Summary: Truly a History
Review: 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.
Rating:
Summary: The definitive book on Cryptography.
Review: 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.
Rating:
Summary: Excellent book
Review: Definitely one of those books that will lead to a month or two of *excellent* reading. Kahn covers a mountainload of material, all at a light-to-medium depth, enough to wet your appetite, and with some of the systems and attacks described, enough that you need to spend a couple hours on a whiteboard to understand them, but not so much that it takes away from the historical aspect of the book. I definitely recommend this book for anyone wanting some very enjoyable medium-to-heavy reading. The last chapter, though, was a huge disappointment -- the publisher made a huge mistake in coercing Kahn into releasing a new edition of this book when he was in the middle of another project. The added chapter is a short 15 pages that gives only a cursory overview of the last 30 years... it really would have served better as an addendum or as part of the preface, and can hardly justify a new edition. Its content was very weak compared to the rest of the book, and hinted at some misleading assertions without qualifying them. I was very disappointed reading it as the last chapter of such an excellent book. As Kahn is definitely considered an insider during the last several decades, its understandable that he would choose not to write as in-depth on matters with which he may or may not have been exposed to in his professional dealings with the agencies and companies that have heavily influenced the cryptography community in the last 30 years. But it seems that there is a ton of additional information has been made publicly available since the first edition was published, much of it in the last decade, regarding the time periods already covered in this book, that could have greatly improved existing chapters or led to new chapters. Hopefully some day Kahn will have the time and inclination to return and do a new edition of this book, but until then, the first edition is just as good as this one and probably available at your local university library.
Rating:
Summary: CRYPTO HISTORY
Review: Having read both the title and the synopsis above (which both clearly state that this is an history), you should not be expecting an how-to book. There are plenty of those out there (good and bad). If you want a couple of good ones, start with Military Cryptanalytics, Parts I & II by Friedman and Callimahos. If you want the definitive history of cryptography, then you are in the right place and in for a treat. You can really sink your teeth into this book. I'm glad that David Kahn has taken the time to update this valuable tome. I need to get this edition myself as I have the 4th edition (1968) and an old abridged paperback version (full of just stories, no technical stuff, covering about a 1/3 of the hardback). This would make a great present for someone you know (especially if they are a recent T9 graduate). Do them (or you) a favor and buy this book.
Rating: 
Summary: Don't bother if you have the first edition
Review: I agree entirely with bruen@mit.edu. I am giving this book a "5" because it's a must-have 10 if you don't already have a copy of the first edition, and a worthless 1 if you do. I haven't examined my 2nd edition copy thoroughly, but a quick comparison shows the text to be identical to the first, even down to the pagination
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