David Sheldon Boone (born August 26, 1952) is a former U.S. Army signals analyst who worked for the National Security Agency and was convicted of espionage-related charges in 1999 related to his sale of secret documents to the Soviet Union from 1988 to 1991. He is currently serving a prison sentence of 24 years and four months. Boone's case was an example of a late Cold War U.S. government security breach.