Random strings for enciphering messages
One-time pads are a type of encryption that can only be decrypted by someone who has the same key. They have been used for special purposes since the early 20th century. For example, the German diplomats used them to communicate secretly in 1923. The Soviets also adopted one-time pads after their codes were cracked by the British around 1930. Some KGB agents still used one-time pads with pencil and paper in modern times.
Many countries have relied on one-time pads for their sensitive messages. The British Special Operations Executive used them in World War II to encode their communications with their offices. They also introduced one-time pads for their agents abroad later in the war.
The U.S. Army Special Forces used one-time pads in Vietnam. They combined them with Morse code and continuous wave radio transmission to achieve both security and reliability.