Abraham Sinkov was a US cryptanalyst. An early employee of the U.S. Army's Signal Intelligence Service, he held several leadership positions during World War II, transitioning to the new National Security Agency after the war, where he became a deputy director. After retiring in 1962, he taught mathematics at Arizona State University.

Cryptanalysis refers to the process of analyzing information systems in order to understand hidden aspects of the systems. Cryptanalysis is used to breach cryptographic security systems and gain access to the contents of encrypted messages, even if the cryptographic key is unknown.