This software is an accurate simulation of the TSEC/KL-7 ADONIS & POLLUX, an off-line rotor cipher machine, developed in the late 1940s by the American Armed Forces Security Agency (AFSA) and introduced by the National Security Agency (NSA) in 1953. The KL-7 served in the United States and all NATO countries.

The KL-7 simulator provides authentic handling with its hands-on approach. All switches, buttons and even the sounds are exactly like the real KL-7. Its rotor and cage wiring are fully customizable. With most surviving KL-7’s sanitized, this simulator is the only remaining way to actually work with this beautiful machine and to keep its history alive.

The simulator is based on the most recent information on the KL-7 and developed in collaboration with Crypto Museum. It's principles of operation and technical details are known but the internal wiring of the ciphering rotors, which was considered part of the secret key settings, is still classified. The KL-7 simulator operates with exactly the same cryptographic principles as the real KL-7 but consequently uses its own rotor wiring.

The TSEC/KL-7 simulator comes with an extensive 20-page manual that includes the technical details, its history and sample messages. More technical information is found on the KL-7 webpage. All feedback, comments or questions are most welcome by e-mail or by visiting the Guestbook.

Runs on all Windows™ versions and with Wine on Linux or Parallels Desktop on MAC. There's also a Java version available.

Download the simulator

Download the TSEC/KL-7 Simulator v5.0.1 (Zip 2.69 MB)
Download Java KL-7 Simulator v5.0 (5,99 MB) Uri Blumenthal from MIT Lincoln Laboratory wrote a JAVA version of my KL-7 sim (requires Java Version 8)
Please check the readme file before installation!
Check the integrity of the downloaded software with SHA-256.

Discover also the Enigma, US M-209 and Hagelin BC-52 cipher machine Simulators!

Updates for this Simulator

Help File Edition 2023-01 This version is not included in the installation file! To add to the installed KL-7 Sim, right-click link and save manual in KL-7 installation folder (usually "C:\Program Files (x86)\KL-7") without changing the file name. This manual contains the updated contact information and links.

More About KL-7 on this Site

• U.S. TSEC/KL-7 ADONIS & POLLUX All technical details and the history of this fascinating cipher machine.
• Operation Tinker Bell Decipher a series of KL-7 messages and join the hunt for a KGB defector

The KL-7 on SIGINT Chatter (opens in new tab)

• KL-7 Sim on SIGINT Chatter All posts and history on the KL-7, updates and the evolution of the KL-7 simulation,