Abraham Sinkov
American cryptanalyst who carried a PURPLE replica to Bletchley Park in 1941.
Sinkov (1907–1998) was among Friedman's first hires in 1930. In February 1941, ten months before Pearl Harbor, he was one of four Americans who travelled to Bletchley Park with a reconstructed PURPLE machine in their luggage. The exchange laid the groundwork for the Anglo-American signals intelligence partnership.
For the rest of the war he ran cryptanalysis at Central Bureau in Brisbane, MacArthur's codebreaking unit in the Pacific. After his NSA years he taught at Arizona State and wrote Elementary Cryptanalysis (1966), a slim book still used to teach classical ciphers with nothing more than high-school maths.