Signals Intelligence Service

The Signals Intelligence Service (SIS) was the United States Army codebreaking division, headquartered at Arlington Hall. It was a part of the Signal Corps so secret that outside the office of the Chief Signal officer, it did not officially exist. William Friedman began the division with three "junior cryptanalysts" in April of 1930. Their names were Frank Rowlett, Abraham Sinkov, and Solomon Kullback. Before this, all three of them had been mathematics teachers with no cryptanalysis background. Besides breaking foreign codes, they were responsible for just about anything to do with the War Department's code systems. The SIS initially worked on an extremely limited budget, lacking the equipment it needed to even intercept messages to practice decrypting.

Related Topics:
United States Army - Codebreaking - Arlington Hall - William Friedman - Frank Rowlett - Abraham Sinkov - Solomon Kullback

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In 1943, the Army Signal Intelligence Service (later the Army Security Agency) began intercepting Soviet intelligence traffic sent mainly from New York City?assigning the code name VENONA to the project. By 1945, some 200,000 messages had been transcribed, a measure of Soviet activity. On 20 December 1946, Meredith Gardner made the first break into the VENONA code, revealing the existence of Soviet espionage at the Los Alamos National Laboratory.

Related Topics:
VENONA - Meredith Gardner - Los Alamos National Laboratory

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