Editing Punched tape (section)

=== Cryptography ===
[[File:Paper Tape Canister, Tampered With.jpg|thumb|This secure paper tape canister shows evidence of tampering]]
[[Gilbert Vernam|Vernam ciphers]] were invented in 1917 to encrypt [[teleprinter]] communications using a key stored on paper tape. During the last third of the 20th century, the [[National Security Agency]] (NSA) used punched paper tape to distribute [[key (cryptography)|cryptographic keys]]. The eight-level paper tapes were distributed under strict accounting controls and read by a [[fill device]], such as the hand held [[KOI-18]], that was temporarily connected to each security device that needed new keys. NSA has been trying to replace this method with a more secure electronic key management system ([[EKMS]]), but {{as of|2016|lc=y}}, paper tape was apparently still being employed.<ref name="taleoftape"/> The paper tape canister is a [[tamper-resistant]] container that contains features to prevent undetected alteration of the contents.