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NSA Historical Figures

Joseph Desch

2011 Hall of Honor Inductee

Joseph Desch graduated from the University of Dayton in Ohio in 1929 with a degree in electrical engineering.

While working, first for General Motors, then for National Cash Register Company (NCR), he acquired a reputation as an innovative engineer. Among other achievements, early in World War II he helped design a proximity fuse for anti-aircraft artillery shells. He also worked on a high-speed electronic counter that, unknown to him, was used in the Manhattan Project.

From early in World War II, the United States and Great Britain worked to solve the problem of the German Enigma machine. The Enigma machine used a series of rotor wheels and a plug board that theoretically gave the device enciphering capabilities of 3x10114, thus convincing the Germans that the code was unbreakable. The code was eventually broken, and Germany's U-boat commander added another rotor to the machines used in his submarines to increase communications security. The United States and Great Britain then worked on solving the four-rotor Enigma. In December 1942, the British solved the four-rotor problem, allowing them to read messages with moderate delays.

In its efforts to break the four-rotor enciphering code, the U.S. Navy contracted NCR in March 1942 to build its Bombes, which were machines used for processing the German navy's four-rotor Enigma-based messages. NCR selected Joseph Desch, head of its electrical research laboratory, to be the principal engineer on the project. While the British had already solved the four-rotor Enigma in December 1942, the Americans felt they needed a faster machine and continued its efforts.

Mr. Desch, working under a compressed schedule and immense pressure, turned complex cryptanalytic theories into a practical blueprint for constructing a working machine to solve the four-rotor Enigma. To do so, he had to solve many difficult, unforeseen problems. Mr. Desch understood that untold numbers of lives, and possibly the outcome of the war, depended on his work, so he drove himself relentlessly toward designing a device that could solve the four-rotor Enigma. He solved the key problems and drew up a successful design.

He completed his work on prototype four-rotor Bombes by Spring 1943. Despite the haste with which they were designed, the Bombes produced in Dayton were faster and more efficient than any analytic machines before them. The Bombes Mr. Desch designed in Dayton became a vital cryptanalytic tool in the war against Germany's U-boats and an important component of Allied victory in Europe in World War II. The last original four-rotor Bombe resides in the National Cryptologic Museum.

After the war, Mr. Desch served with distinction as a member of NSA Scientific Advisory Board.

Joseph Desch died on August 3, 1987, at age 80.