The KL-7 simulator provides authentic handling with its hands-on approach. All switches, buttons and even the sound function exactly like the real KL-7. Its rotor and cage wiring are fully customizable. With most surviving KL-7s sanitized, this simulator is the only remaining way to actually work with this beautiful machine and the simulator serves as an attempt to keep this machine and its history alive. The simulator comes with an extensive 20 page manual (view here ) that includes the use of the simulator, the KL-7's technical details, its history and sample messages.
The development of this simulator is based on publicly available information on the KL-7. It's principles of operation and most of the technical details are known. However, the internal wiring of the ciphering rotors, which is considered part of the secret key settings, is still classified. The KL-7 simulator operates with the same cryptographic principles as the real KL-7 but consequently uses its own rotor and stepping wiring.
Runs on Windows™ and on MAC with CrossOver, Parallels Desktop or WINE (open source).
Download the simulator
Download the TSEC/KL-7 Simulator v5.0.1 (Zip
Download Java KL-7 Simulator v5.0 (5,99 MB) Uri Blumenthal from MIT Lincoln Laboratory has written a JAVA version of the KL-7 simulator for non-Windows users. This software requires Java Version 8.
Updates for this Simulator
Please uninstall any previous version through configuration screen/software and remove 'KL-7' before installing the new version!
MAJOR UPDATE 5.x.x (22 May 2013) added option to save and load keys in txt file format, Rotor Set Mode for quick and easy preset of the rotor positions and Zeroize button. Changes according recently declassified KAO-41C/TSEC: changes in notch ring set-up against alphabet ring, added 13th rotor core, rotor core selection also possible for 4th rotor, settable wide ring for 4th rotor, renamed parts according official documents, complete rewrite of the help file pages on message procedures. Warning: version 5.x.x key set-up and saved key file format are not compatible with previous versions!
Help File Edition 501-07 Right-click link and save in the KL-7 sim installation folder (by default "C:\Program Files\KL-7") without changing its name. This file contains the manual, latest information on the KL-7, its technical details and procedures.
More About the KL-7