Cryptanalytic Bombe

This is a U.S. Navy cryptanalytic bombe. Bletchley Park analysts worked on British-built bombes.

The machines "worked primarily against the German Navy's four-rotor Enigmas. Without the proper settings, the encrypted messages were virtually unbreakable," according to the National Cryptologic Museum. "The bombes took only 20 minutes to complete a run, testing each of the 456,976 possible rotor settings within one wheel order. Different bombes tried different wheel orders, and one of them would have had the final correct settings. When the various U-boat settings were found for the day, the bombe could be switched over to work on the German Army and Air Force three-rotor messages."