High Quality Content by WIKIPEDIA articles! The KL-51 (RACE) is an off-line keyboard encryption system that read and punched paper tape for use with teleprinters. It was developed by the U.S. National Security Agency in the 1980s to replace the earlier KL-7, but used digital electronics for encryption instead of rotors. 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.