Editing NSA encryption systems (section)

=== First generation: electromechanical ===

[[File:KL-7 from front.jpg|thumb|[[KL-7]] at NSA Museum]]

First generation NSA systems were introduced in the 1950s and were built on the legacy of NSA's [[World War II]] predecessors and used rotor machines derived from the [[SIGABA]] design for most high level encryption; for example, the [[KL-7]]. Key distribution involved distribution of paper key lists that described the rotor arrangements, to be changed each day (the ''[[cryptoperiod]]'') at midnight, [[GMT]]. The highest level traffic was sent using one-time tape systems, including the British [[5-UCO]], that required vast amounts of paper tape keying material.<ref name=boaklectures />{{rp|p. 39 ff}}