Earlier this year, the Bombe rebuild team faced their toughest challenge yet from no less than GCHQ themselves. An Enigma machine was installed at the Cheltenham Science Festival and every day it was configured with new settings, just like in wartime. After a test message was sent, containing a phrase known to the Bombe team (to replicate wartime ‘cribbing’), visitors were invited to encrypt and then send messages to Bletchley Park. In B Block, the Bombe team used the original techniques to break the Enigma settings using ‘Phoenix’, our very own Bombe. Every day brought a new challenge as the Enigma settings were changed. This went on for the course of a week.
They scored 7 for 7. Typically, the correct Enigma settings were known to the team before noon. Conclusive proof of the capabilities of Turing, Welchman and Keen’s formidable machine and a great result for the Bombe rebuilders.
On the Saturday, in a nod to old and new technology, Enigma-encrypted messages were sent to Bletchley Park by morse code. The plaintext replies arrived in Cheltenham by Twitter.
Peter J Davis has uploaded this video of the challenge, it’s well worth a watch.