Cryptology Goes Public

David Khan

From Foreign Affairs, Fall 1979

Article preview: first 500 of 7,451 words total.

Summary:  In November of 1978 a remarkable conference took place in Germany. It brought together for the first time the Allies? backroom boys of World War II and those whom they had outwitted for nearly six years?the cryptographers of the Third Reich. Together with historians, they discussed what had been the most secret part of the intelligence war. This was the Allied solution of the principal German ciphers and consequent ability to read large segments of high-level military traffic, including the very messages of Adolf Hitler to his generals.

David Kahn is the author of The Codebreakers and Hitler's Spies. He is currently assistant viewpoints editor of Newsday.

In November of 1978 a remarkable conference took place in Germany. It brought together for the first time the Allies' backroom boys of World War II and those whom they had outwitted for nearly six years-the cryptographers of the Third Reich. Together with historians, they discussed what had been the most secret part of the intelligence war. This was the Allied solution of the principal German ciphers and consequent ability to read large segments of high-level military traffic, including the very messages of Adolf Hitler to his generals.

An admiral of the Royal Navy described how his knowledge of U-boat orders enabled him to steer convoys around the wolf packs to help win the Battle of the Atlantic. An American intelligence officer told how foreknowledge of a German attack enabled the Seventh Army to repel it with minimal losses. The Royal Air Force's former scientific intelligence chief recounted how Ultra-as the Allied solutions of German messages were called-gave him the first clues to German V-weapons and enabled the Allies to bomb the research center at Peenemünde and later the launching sites in France. A historian discussed how the American solution of the Japanese diplomatic cipher machine revealed what the Japanese ambassador in Berlin was reporting to Tokyo about his conversations with Hitler-intercepts that became, Chief of Staff George C. Marshall said, "our chief basis of information regarding Hitler's intentions in Europe."

All of this proved too much for one of the Germans. During the war he had repeatedly assured the head of the Kriegsmarine, Grand Admiral Karl Dönitz, that the naval Enigma cipher machine was not being solved by the Allies-when, in fact, they were doing so almost solidly and often instantaneously. "If the Allies could read it all," he asked with some asperity, "why didn't they win the war sooner?" An American historian answered, "They did." And no one in the high-ceilinged university senate room dissented. All agreed that Ultra had shortened the war and saved thousands of lives. Ultra was, one of its veterans has rightly said, "the most important sustained intelligence success in the history of human conflict."

It was typical of the traditions of cryptology that the Ultra secret was withheld, from the Germans as well as from the public, for nearly 30 years after World War II ended. Governments maintain this sort of discretion for a number of practical reasons. To reveal how a cryptogram was solved would enable other countries to strengthen their cryptosystems to prevent such solutions. Even to reveal that a cryptogram had been solved might awaken other nations' cryptographers to the possibility that their ciphers, too, might be broken and so might impel them to change them. Disclosing the details of one's own cipher systems would obviously nullify their ability to keep communications confidential.

Finally, to admit prying into other nations' messages would embarrass a country and so burden its international relations. In only one case, apparently, did a statesman refuse to read other countries' messages not out of fear ...

End of preview: first 500 of 7,451 words total.