SIGABA was an electromechanical rotor-based cipher machine developed in the late 1930s in the United States (US) as a joint effort of the US Army and US Navy [1]. At the time it was considered a superior cipher machine, intended to keep high-level communications absolutely secure. It was used throughout WWII and was so reliable that it was used well into the 1950s, after which it was replaced by newer machines like AFSAM-7 (KL-7). As far as we know, SIGABA was never broken.