KL-51
The KL-51 is an off-line keyboard encryption system that read and punched paper tape for use with teleprinters. In NATO it was called RACE.
It was developed in the 1970s by a Norwegian company, Standard Telefon og Kabelfabrik. It used digital electronics for encryption instead of rotors, and it may have been the first machine to use software based crypto algorithms. KL-51 is a very robust machine made to military specifications.
U.S. National Security Agency bought it in the 1980s to replace the earlier KL-7. As of 2006, the U.S. Navy was developing plans to replace KL-51 units still in use with a unit based on a more modern Universal Crypto Device.
