On December 3, 1941, officers of the U.S. Army Signal Intelligence Unit decoded a message sent from Tokyo to the Japanese embassy in Washington, ordering embassy staff to destroy its code books and other sensitive material. This, the officers determined, meant that Japan was preparing to break off diplomatic relations with the United States and go to war. When, they could not say; to gain a precise date, they would have had to break the Japanese naval codes. Therein, writes Stephen Budiansky
in Battle of Wits
, lay the rub: "Since mid-1939, America had not read a single message in the main Japanese naval code on the same day it had been sent. For most of the period from June 1, 1939, to December 7, 1941, the [U.S.] Navy was working on naval messages that were months, or even over a year old."
For all their lack of preparedness and occasional inefficiencies, and for all the disdain with which some Allied ground commanders held the work of military intelligence, writes Budiansky, Allied cryptographers were of critical importance in determining the outcome of World War II. The decoding of Japanese and German encryption engines, for instance, helped the Allied navies gain victory in the battles of the Atlantic and Midway, while the translation of secret German railroad schedules allowed Winston Churchill to warn Josef Stalin that the German army was about to invade the Soviet Union--though Stalin refused to take the warning seriously. The codebreakers, in short, "averted disasters that would have been terrible setbacks to the Allied cause," and they almost certainly saved a considerable number of lives as they labored to crack such profound puzzles as Enigma and Purple.
Budiansky's narrative is strong on the science of cryptography--so much so that readers without a background in mathematics and logic may have trouble following the arcana of key squares, bigrams, and all the other trade secrets of cryptanalysis. Readers willing to brave matters technical, however, will find Budiansky's comprehensive account to be the best single book on the subject, and one well worth their attention. --Gregory McNamee
From Publishers Weekly
In February of 1926, German codes, long intercepted and analyzed by Polish cryptanalysts, abruptly became impenetrable. As BudianskyDan Atlantic Monthly correspondent, applied math degree-holder and former congressional fellowDnotes in this penetrating, edgy study, the wary Poles suspected that these new, seemingly unbreakable codes had been generated by a machine. How the Allies' mathematicians and cryptanalysts later deciphered nearly every top-level code produced by that machine, called EnigmaDwhose internal rotors could be wired in 10 to the 80th power (1 followed by 80 zeroes) waysDand by other machines in Axis use is a story already covered by David Kahn's classic The Codebreakers and many other books. Budiansky's bibliography reflects a reliance on those sources, deploying them along with a wealth of archival material; unlike Codebreakers, this book foregrounds the role of cryptanalysis in fighting the war, rather than treating the war as background to cryptanalysis. Readers of a technical bent will be particularly drawn to the meticulous explanations and diagrams depicting trial-and-error code breaking at work. Doling out a consistent measure of beautifully turned observations ("No matter how elaborate a scheme was used to scramble and disguise the original text, its ghost always shone through"), Budiansky is a master at interweaving the science of code breaking within its cultural and historical contexts. He depicts with clarity how the World War II-era code breakers struggled to halt German aggression at a time when the role of signals intelligence in heightening the impact of force was little understood, and delineates the remarkable achievement of those who recognized that the minutiae of enemy communications are well worth knowing. This book gives a fascinating impression of just how crucial these efforts were. (Oct.)
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