Punched tape

Punched tape is a medium for data storage. It is made of a long strip with holes in it. The holes are used to represent information. The principle is the same as that of a punched card, except that the length is variable. Punched tape was widely used in the 1950s and 1960s, but was later replaced by other media. Punched tape was first used to program looms, in the 18th century. Similar looms are still used for weaving Tartans, but the punched tape is made of metal platelets today. Another use of punched tape is in barrel organs.

20th century teleprinters also use punched tape. Herman Hollerith used punched tape for a census, in 1890. Gilbert Vernam, a telecommunication engineer developed the Vernam cipher in 1917. This cipher could be used with punched tape. Vernam combined a character of the punched tape, with one of a key, to give the encoded character. Combining the ecoded character with the key again gives the plain text. This is in fact an exclusive disjunction, even though Vernam used a different name. It was an automated one-time pad. The NSA has called this patent "perhaps one of the most important in the history of cryptography."^[1]

1. ↑ Klein, p. 3 "Vernam had invented the unbreakable cipher: "one-time tape" (OTT) for on-line TTY encryption. In 1919 he was granted a patent, perhaps one of the most important in the history of cryptography."