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Seizing the Enigma : The Race to Break the German U-Boat Codes 1939-1943 (10 1 1/2 cassettes)

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David Kahn's Seizing the Enigma is a detailed effort to tell the story of how the German naval code was broken. Though that intelligence breakthrough of WWII is widely known, little is known of how complicated the effort was. It required the effort of brilliant mathematicians working the theoretical side and the bravado of British naval and intelligence officers who literally risked their lives to obtain the information and equipment needed to crack the code. Kahn gives a very detailed story and it is at times a bit thick and difficult to follow. This is only because the theory behind the enigma was so complex and a complete history of the saga requires at least some examination of the intriguing, yet, sometimes confusing mathematical concepts. In all, a good read. John Kidd

This book deals with the German code machine the Enigma; How it was developed, how it was used and finally how its code was broken. This book is very well researched and was very interesting to read with no slow spots.

The most interesting point I got out of this book was the Enigma machine was very well designed and if properly used its code was unbreakable. The trouble was that lazy German code operators often broke the security rules regarding the enigma (the most blantant of these was sending the same message in an inferior code(the british easily broke this) and the same message enciphered in Enigmna. With the one message easily deciphered the British were able to break the Enigma one. German code operators made a number of other mistakes due (cutting corners) regarding the keys which made these codes possible to break.

THe author also gave a great deal of credit to the Polish code breakers (Rejewski, etc) as being the first to crack the Enigma. Most other histories/documentaries neglect this important aspect which made it possible for the British get Bletchley Park up and running. THe Poles gave the British & French a great deal of their research info regarding Enigma after Poland was overun.

The narratives of the British boarding German weather ships and U-boats were quite exciting to read with the author writing in a manner that made you feel you were with the boarding party.

Good book through and through, excellent read!

The year is early 1941, and the Battle of Britain is intensifying. The Kriegsmarine submarines, organized in groups - wolf packs - are trying to cut the life-line the British defense depends on - the convoys which supply Britain with food, military supplies and raw materials. And they are pretty much successful in it, sinking more ships each month than Britain and United States can build. Meanwhile, a group of mathematicians, linguists and other odd characters located a top-secret base in Bletchley Park, Buckinghamshire, is trying in frenzy to decode the German naval code, Enigma...

David Kahn has produced a well researched and clearly written book on this segment of naval history, which has long remained classified. The story of Enigma is traced from the Arthur Scherbius's design, through the first successful decoding made by Marian Rejewski's group in Poland, and finally to Alan Turing and the Hut 8 staff in Bletchley Park. We learn that while direct attack on the cipher was mindbogglingly impossible, the chances for decoding being 150 million million million to one, the Brits had to find bypasses, raiding German boats for the on-board code books, employing "kisses" (identical messages transmitted in two different cryptosystems), and finally mechanising the solution finding with the "bombes".

The emphasis of the book is more on the naval war than on the cryptology. Although the operation of Enigma machine is described to some extent, you will not be able to fully understand its workings from it alone. Singh's Code Book, for instance, has a much better introduction to it. It also limits its scope quite narrowly, not spending one single word on the fact that while Hut 8 was busy solving naval Enigma, some hundred yards away the world's first electronic computer - Colossus - was built in attempt to solve the German Lorenz cipher.

The book comes with an exhaustive list of notes, an excellent bibliography and a useful index. There are also over thirty b/w documentary photographs.

I thoroughly enjoyed this book which focuses on an important yet frequently ignored piece of WWII history. The book is more engaging than a textbook, but at the same time less so than a novel. It contains a lot of fascinating insights into this "war within a war" which make it a wonderful book for anyone intesrested in the subject.

The book's focus is much more on the history of Enigma than on the technical aspects of Enigma or cryptography in general. However, There is also a lot of general "best practices" information to be gleaned from this book. (Admittedly, a background in cryptography or information security will help). Principles such as protecting the cipher, security through obscurity, brute forcing, key rotation, and others are all dealt with, although they are rarely called by those titles.

Overall this book is a very good look into some of the early history of modern cryptography.

Kahn hits it out of the park again with this look at the race to break the German Enigma cypher during WWII. The strategy and success of the Third Reich -- particularly the Kriegsmarine -- rested on the infallability of the code.

While Hitler's tank-based blitzkrieg gets the most credit for his effective rampaging across the European continent, Doenitz's u-boats played an equally important role in the initial victories of the fatherland. How was it possible that so many u-boats could sink millions of tons of allied shipping every month, in the most coordinated fashion, with the allies virtually helpless to stop it?

The answer: Doenitz, master strategist, centrally controlled all u-boats via radio communications. For this to work, those communications needed to be encrypted in an unbreakable manner. The admiral had such a device in the Enigma machine -- until, that is, the best Polish, British, and American minds began to make progress against it....

In the same tradition as his masterpiece, The Codebreakers, Kahn presents audiences with as much technical detail as possible without deterring any one of them. Readers cannot escape the nail-biting prose that educates us despite ourselves.

I have read a lot in the past about the Enigma machines, the Battle of the Atlantic, and some of the operations in this book (e.g. the Lofotens raid). Even so, I found many new details which I'd never seen before. This is also an excellent book for those who know nothing of the cryptography battles of WW2. Just writing this has made me want to read it again!

Information contained in the book remained classified for a long time. We came to know that Allies read German Enigma ciphers with the publication of F.W.Winterbotham's book Ultra Secret.This made it indispensible for the historians to re-interpret the History of world war Two , particularly Battle of Atlantic.

Undoubtedly Ultra was the biggest secret of World War Two. Some portions of the book is very technical. I feel the reader not having scientific , mathematical background may have to peruse it couple of times before he could hope to understand complexties of the German enigma machine cipher narrated in the book.

Be that may ,benefitting from the experience of World war One the Kriegsmarine took extraordinary precautions to make its crypto systems foolproof.Communications formed the core of Admiral Doenitz's U-boat wolf-pack warfare.An U-boat after spotting a convoy shadowed its quarry calling other U-boats to the scene.Movements of several U-boats towards the scene were controlledby U-boat HQs at Lorient at the Biscay coast.Attack commenced only when the converging U-boats had formed a pack.This strategy of co-ordinated attack can succeed only if Kriegsmarine had access to secure communications.The German naval Enigma provided such communication.

Unlike Germany's other military ciphers[Army, Airforce]the naval version defied cryptanalysis for a long time.why? Unlike the standard Army Enigma[which had a choice of 3 scramblers out of possible 5]the naval Enigma had 4 scramblers out of possible 8.This increased the number of scrambler arrangements 6 times,correspondingly increasing the number of scrambler substitutions for a cryptanalyst to check.The other difference concerned the reflector responsible for returning the signal through scramblers.Standard Enigma reflector was fixed in one particular orientation but naval enigma reflector can be fixed at any one of the particular orientations.This increased the number of possible keys by a factor of 26.

In short extra scramblers,variable reflector new systems of exchanging message keys,non-stereotypical messages combined to make German naval communications impenetrable.Naval Enigma had pseudonyms Hydra,Triton.
Where ever intellectual endeavour fails to obtain keys other measures had to be resorted to:theft,espionage.Combination of technical wizardry ,shrewd guess work,lucky breaks[pinching navalEnigma scramblers, cipher materials from seized German trawlers,weatherships,U-boats]the British were able to make inroads into the U-boat communications.

Their labour further simplified by some careless mistakes made by German Enigma operators.The book is replete with technical jargons such as Hernivel, Tip,Crib.All of them represented different meathods conceived by British to narrow down the number of possibilities to be tested for determining the correct scrambler settings.

Reader will find in this book personal profiles of Britain's leading codebreakers.Polish contribution in the struggle to break Enigma has also not been ignored by the author.

Cracking U-boat codes helped mitigate disastrous shipping losses as the Allied navies were able to determine the patrol lines formed by U-boats.Bylate 1943 more and more convoys were steered away from the waiting U-boat packs.

Besides cutting shipping losses Enigma decrypts also served as a force multiplier.Ultra guided escort carriers and hunter-killer groups towards U-boats instead of having to search for them over a large area.

It sounds ironical,Kahn after writing a fine book,in the final count,has belittled the the role of Ultra in the Battle of Atlantic.Kahn says Ultra or not the Allies were bound to win.However I disagree with author's optimism in this regard.If the German naval Enigma had not been cracked the number of U-boats would have multiplied.By this time new Electro boats would have come into action.Type XXI class was a full-fledged submarine,had snorkels coated with radar absorbing material,torpedoes that zig-zagged ,guided to the targets helped by soundplots without exposing their periscopes.Then boats stealthily moved away from the scene of action running on silent motors making it difficult for hydrophones to detect.The outcome of this form of struggle hard to predict.

Besides a new naval Enigma was about to enter service when war came to close.Allies obtained technical details of new German submarine after decrypting messages sent to Tokyo by the japanese naval attache in Berlin.

Finally, another statement I find difficult to concur with is what Kahn calls as functional attributes of intelligence:A country defending its freedom is only in need of good intelligence.I wish to modify it by saying that a country embarking on a war with its neighbours also is in need of good intelligence.

Former must know the strengh and weakness of opponent's armed forces,psychological profile of latter's militaryleadership,terrain,weapons and doctrine guiding its employment,number of reserves at its disposal.For instance Hitler and his Generals seriously underestimated Red Army ,especially the number of divisions it could bring from the hinterland.

RedArmy had immense reserves totalling 200-300 divisions.It frustrated,though at a great cost, the German drive to capture Moscow.

Let us recall what the great Chinese military thinker SunTzu said centuries ago"Know your enemy and know yourself and you can fight hundred battles without defeat".

This book is very interesting, and relates the struggle to break the German WWII Enigma code that sent information about Allied convoys to the wolfpacks. With some interesting pictures.

In contrast to some English-language books on this subject, Kahn gives credit squarely where it is due. He emphasizes the fact that the Poles cracked the German Enigma code, and that "Poland did what no other country had done--and what the Germans believed impossible." (p. 67). Kahn recognizes the fact that Polish mathematician Marian Rejewski was the "solver of ENIGMA." (p. 323). He even calls Rejewski one of the "greatest cryptanalysts of all time". (p. 66).

Kahn emphasizes the codes used by the German Navy, but also touches on other aspects of WWII. He notes the Katyn massacre, wherein the Soviets murdered tens of thousands of disarmed Polish officers and intellectuals. He points to the irony of the Germans exploiting this tragedy for propaganda purposes while at the same time having killed many more Poles and Jews.

Kahn believes that the ULTRA was the greatest WWII secret after the atom bomb. However, he rejects the premise that the cracking of the "invincible" German codes by the Allies enabled them to win the war. Instead, he supposes that the Allied victory in the European theater would have been delayed by about a year, and with much greater casualties, had the Allies not broken the German ciphers.

This 1991 book tells about the secret history of the Battle of the Atlantic, between Allied shipping and Nazi submarines. The German Navy used a version of Enigma that defied code breakers in the early years of the war. After key documents were captured by the British, they were able to decode the messages. This book tells this story in about 360 pages, with an index and bibliography. The 'Preface' lists the acknowledgments. The Battle of Britain failed to defeat the British, next came the Battle of the Atlantic to destroy supply ships. The British used ASDIC and RADAR to detect submarines, but this had a limited range. Only decoded German naval messages would locate the submarines, and allow a convoy to avoid them. The U-boats were controlled by radio from France with constant communication. When a damaged U-boat surfaced, the captain of the attacking British destroyer decided to board it and capture its codebooks.

Chapter 3 tells of the history of the Enigma cypher machine. Necessity is the mother of invention. Chapter 4 tells how this perfectly unbreakable system began to be broken: it use by imperfect men (p.69). The prohibition against keys with repeated letters provided a guide to cryptanalysts (p.70)! Chapter 7 reminds us that intelligence is secondary to strength (p.91). The sinking of U-33 led to the recovery of three rotors (p.111). Since small German ships did not use Enigma but a code known to the British, the latter were used to decode the former (p.144). The capture of the U-110 and its Enigma, ocean charts, and coding keys was priceless (Chapter 13). The capture of a weather ship brought a new supply of key settings (Chapter 14). Warnings of U-boats saved convoys (Chapter 15). Capturing a cipher book from the U-559 allowed breaking the new four-rotor code (Chapter 19). Chapter 20 tells how one convoy evaded U-boats. The cavity magnetron allowed ultra-high frequency radar which could not be detected by U-boats (Chapter 21). The Nazis believed this explained the Allies' success (p.261).

The operational efficiency of U-boats was improved by having them resupplied at sea by special submarine tankers (Chapter 22). Sinking one reduced the effectiveness of many U-boats. The use of escort carriers allowed active attacks on U-boats, not just defensively (p.267). Sinking these supply ships and U-boats won the Battle of the Atlantic. ULTRA was the greatest secret of World War II (p.276). It could both avoid the enemy, and lead to an attack, with a minimal force. Another important factor was the huge production from American shipyards and aircraft factories. [Unmentioned is the war on the Eastern front, which required most Nazi military forces.] The British and Americans used a five or ten rotor machine with a more complex motion; and total censorship of this (p.279). The motivation for intelligence is described on pages 280-281. Another factor for efficiency was that American and British forces cooperated, while Germany had seven major code-breaking agencies that operated separately. A similar comparison could be made to the intelligence agencies. The British were unified, the Germans had competitive agencies. This book provides a short history, but I think it omitted areas for space considerations.