Historians prepare for Enigma Challenge take three

Bletchley Park
Bletchley Park

GCHQ Historians will pit their wits against the team behind the Bombe Rebuild at Bletchley Park in the third Enigma Challenge later this month.

The Bombe Team will race against time – just like the real Codebreakers at Bletchley Park during World War Two – to break Enigma coded messages sent by members of GCHQ’s Historical Section.

This time the team will be at The Big Bang Fair at London’s ExCel, a four-day event aimed at young scientists and engineers.

At the X Plus Why? Factor stand at Big Bang, visitors will be able to encrypt a message on a real Enigma machine and send it Bletchley Park. Once at Bletchley, the message will be decrypted using and the original procedures involved along with the reconstructed wartime technology. The decoded message will then be tweeted back to the Big Bang with the whole process shown live on large TV screens at both venues.

Both teams will be as true to the history as they possibly can. The modern-day Codebreakers at Bletchley Park will use the Bombe Rebuild, which is a faithful copy of the original, built as a tribute to those who invented, built and maintained the machines which were crucial to the success of the Codebreakers.

The electromechanical Bombe machine was developed at Bletchley Park to speed up the process of deducing the Enigma machine’s settings. The three rotor machine had approximately 158 million million million possible settings.

The second Enigma Challenge in October 2012 was a huge success, with the Bombe Team beating their own record time for deducing the Enigma settings. The GCHQ Historians were at the Museum of Science and Industry in Manchester, where visitors were able to send their own enciphered messages.

he fastest time in which the Bombe Team deduced the day’s settings was two hours and fifteen minutes. They were then able to decipher messages quickly and tweet the plain text so those taking part could see it had worked. Veteran Wrens who operated the machines during the Second World War recall it took an average of around four hours each night to work out the day’s settings on each German military network, most of which were changed at midnight.