Cryptologic Bytes

"On This Date in History" Calendar

1930: Abraham Sinkov reported to work at SIS.

Thursday, April 11, 2024

11 April 1930: Abraham Sinkov reported to work for William Friedman at SIS, becoming one of the original four - with William Friedman, Solomon Kullback, and Frank Rowlett. Sinkov was inducted into the NSA/CSS Cryptologic Hall of Honor in 1999. Read the full entry regarding his career and accomplishments via the link below. In the photo: The Signal Intelligence Service about 1935. Seated: Louise Newkirk Nelson. Standing, left to right: Herrick F. Bearce; Solomon Kullback; Capt. Harold G. Miller, U.S. Army; William F. Friedman; Abraham Sinkov; Lt. L. T. Jones, United States Coast Guard; and Frank B. Rowlett.

In 1930, William Friedman, a senior civilian in the Army's Signal Intelligence Service (SIS) was authorized to hire three civilians, at $2,000 per year -- a fairly good salary in the early period of the Great Depression. On April 1, Frank Rowlett, a mathematics teacher from Virginia, reported for duty. Later that month, two mathematics teachers from Brooklyn came to Washington to work as cryptanalysts, Abraham Sinkov and Solomon Kullback. In addition to his successes with SIS and also with the Central Bureau, in 1954, Dr. Sinkov became the second NSA official to attend the National War College (the first was Dr. Louis Tordella). Upon his return, he became Deputy Director for Production, effectively swapping jobs with his old colleague Frank Rowlett. Dr. Sinkov retired from NSA in 1962.


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