"Since the Allies did not know the Germans' daily rotor selections, several Bombes worked on the same message. Each Bombe tested a different sent of wheel orders. The Bombes usually found two sets of possible rotor settings on each run, but only one solution on one Bombe was the correct wheel order and rotor position used by the Germans for that day. After the Bombe completed a run, a Wave supervisor checked the printed results on this M-9 machine. She checked each result looking for the correct one. Once she found the results, she used the M-9 to fill in any missing plugboard positions. The Bombes could find only a portion of the Stecker positions because the menus were between 13 and 16 letters long, too short to find all the plugboard connections. Having found the correct wheel order, rotor position, and Steckers, the supervisor then sent the results back to the library where Waves and cryptanalysts used an analog machine and decrypted the message. Short messages could be decrypted directly on the M09 and Waves in the library also used the M-9 to work against messages that had other problems, such as garbles."
Click here to read the related story on the National Cryptologic Museum, and click here to check out the entire Road Trip 2010 package.
August 6, 2010 4:00 AM PDT
Photo by: Daniel Terdiman/CNET
| Caption by: Daniel Terdiman
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