Solomon Kullback (April 3, 1907 – August 5, 1994) was an American cryptanalyst and mathematician, who was one of the first three employees hired by William F. Friedman at the US Army's Signal Intelligence Service (SIS) in the 1930s, along with Frank Rowlett and Abraham Sinkov.

His father Nathan had been born in Vilna, Russian Empire, (now Vilnius, Lithuania) and had immigrated[1] to the US as a young man circa 1905, and became a naturalized American in 1911.

[citation needed] At the suggestion of Abraham Sinkov, who showed him a Civil Service flyer for "junior mathematicians" at US$2,000 per year, he took the examination.

For several summers running, the SIS cryptanalysts attended training camps at Fort Meade until they received commissions as reserve officers in the Army.

Afterward, Kullback rediscovered a love of teaching; he began offering evening classes in mathematics at George Washington University from 1939.

Using the talents of linguist John Hurt to translate text, SIS started issuing current intelligence to military decision-makers.

Kullback supervised a team of about 60 people, including such innovative thinkers in automated data processing development as Leo Rosen and Sam Snyder.