The U.S. Army Signals Intelligence Service personnel pose in front of their vault, ca. 1935. From left to right: H. Frank Bearce, Solomon Kullback, U.S. Army Capt. Harrod Miller, William Friedman, Abraham Sinkov, U.S. Coast Guard Lt. L.D. Jones, Frank Rowlett. Sitting: Louise Newkirk Nelson. Solomon Kullback, Abraham Sinkov, and Frank Rowlett were the first cryptanalysts of the Signals Intelligence Service. They were recruited by William F. Friedman. NSA photo An M-138, a strip cipher device, that allowed the use of multiple alphabets to decrypt and encrypt messages. The M-138 used a sliding metal bar moving across a tablet with two metal alphabets. NSA photo Arlington Hall personnel at work during World War II. President Franklin D. Roosevelt authorized women for noncombatant roles, and eventually thousands of women contributed to the cryptologic efforts of the U.S. during World War II. NSA photo Fleet Radio Unit Pacific (FRUPAC) operators work on JN-25, the principal Japanese navy encryption system, Pearl Harbor, Hawaii. FRUPAC was the U.S. Navy's signals monitoring and cryptographic intelligence unit based at Pearl Harbor during World War II. NSA photo A Bombe operator during World War II. Bombes were designed to break German messages that were encrypted on Enigma machines. Manufactured by National Cash Register, the Bombe eliminated all possible encryptions from intercepted messages until it arrived at the correct solution. NSA photo Gen. Dwight D. Eisenhower visits Arlington Hall, Va. William F. Friedman is standing on the far right. Friedman went on to become the chief cryptologist of the NSA in 1952. NSA photo A segregated office during World War II. William Coffee, standing, was the first African-American supervisor in the U.S. Army's cryptologic organization. Like the larger U.S. military, the intelligence services were also segregated. NSA photo The SIGSALY voice security system, used during World War II for the highest-level communications between the Allies. NSA photo The site of the future NSA headquarters at Fort Meade, Va. The nine story headquarters building opened in 1963. NSA photo Lt. Gen. Ralph J. Canine, USA, receives his three-star flag, March 17, 1953. Canine served as the first director of the NSA from 1952-1956. NSA photo “Meade Mobile” provided information on relocating to the Fort Meade, Va., area for potential employees. Fort Meade was chosen for the headquarters of the NSA because it was far enough away from Washington, D.C., to survive a nuclear strike, but allowed employees to stay in the D.C. area without moving their families. NSA photo Contestants in the Miss NSA Pageant, held annually in the 1950s and early 1960s. NSA photo The direct communication link between the U.S. and Soviet Union, the so-called Moscow–Washington hotline. The first message sent was, "the quick brown fox jumped over the lazy dog's back 1234567890." That message was a pangram of all letter and numbers in the Latin alphabet, and served to make sure all keys on the teletype were functional. NSA photo Lt. Gen. Marshall Carter, Director of the National Security Agency, observes a class at the National Cryptologic School, Linthicum, Md., ca. 1967. The National Cryptologic School provides training to members of the NSA. NSA photo NSA employees in front of a supercomputer in the 1970s. NSA photo