Decoding the Bombe ~ Bletchley Park

At 9am on a crisp Saturday morning, QMUL History Society met outside Mile End Station to begin our 1st trip of the year to the home of modern computing security.

Bletchley Park, most well-known for its involvement in the Second World War, was developed to its present state by Sir Herbert Samuel Leon who bought the site in 1883. Later bought by Admiral Henry Sinclair, the head of MI6 in 1938, it became the designated home for code-breakers, in the case of war being declared.

Following the release of 2014 film The Imitation Game starring Benedict Cumberbatch and Kiera Knightly, the work of mathematician Alan Turing has been thrust into the spotlight. Turing is most revered for his work in inventing the Bombe, a decoding machine, designed to break the Enigma code in WWII. The Enigma machine, designed by German Arthur Scheribus, provided German officials with triple level encryption for their messages, and they never doubted its security.

The Enigma machine worked by initially swapping two letters, before feeding the letter through to 3 spinning wheels, which would change the letter 3 times. The letter then traveled backwards through the 3 drums, before revealing the letter on a lit keyboard. The catch? Each machine used 3 drums at a time (of a possible 5) set to 1 of 26 positions each. When a letter was fed through, the 1st drum would rotate 1/26 of a rotation; when this drum had completed 1 revolution the next drum would turn 1/26 of a turn and so on. In this way, the set up of the machine changed with every letter typed.

The flaw in the Enigma machine, which the code-breakers at BP exploited, was that Enigma could never code a letter as itself. That is to say A could be coded as B-Z, but never A. This allowed codebreakers, before the Bombe was invented, to estimate codes, whilst looking for frequently used phrases such as ‘wettervorhersage’ meaning weather forecast.

20161022_120659.jpg

Using this knowledge Alan Turing designed his Bombe, which was later modified by Gordon Welchman to vastly improve its efficiency.

Today, Bletchley Park is no longer a hub of military intelligence, having moved to GCHQ and NSA once the war was over. The work at Bletchley remained classified long after the war had ended. The Germans never found out their enigma code had been broken; Only the British and Americans were privy to this information, so when Russia looted their way through Eastern Europe and found a large quantity of Enigma Machines, they didn’t think twice about using them during the Cold War.

When Gordon Welchman was brought in by the NSA during the Cold War to crack Russian codes, he found the work surprisingly similar to his work at Bletchley. Luckily, even after Bletchley had been stripped of any clues to its existence in 1945, several Bombes had been kept, by GCHQ and the NSA, giving the USA a key advantage.

Bletchley Park today highlights and celebrates the works of the code-breakers who worked tirelessly throughout the war, with little to no recognition, to thwart the Germans in a battle of wits.

Initially you’re given a brief introduction to the history of Bletchley and code-breaking before you’re given an audio guide and allowed to explore the grounds at your own pace.

The beautiful, famous manor house (above) shows visitors the scale of the operations at Bletchley before they were upscaled. The initiator of the increase in workforce, Gordon Welchman, is celebrated here too, his work so frequently overshadowed by Turing.

Various huts are open to the public. Hut 9 contains information about the redevelopment of Bletchley, having been left in a state of disrepair when it closed in 1945. This hut explores the archaeological techniques used to understand it’s original appearance, and allow developers to recreate this as accurately as possible.

The other huts take visitors through the various stages of code-breaking,  with interactive activities in various rooms giving people of all ages the chance to try their hand at cracking the Enigma code. All the huts have been restored to their original condition, and some contain audio-visual effects to recreate conditions just over 70 years ago.

Visitors are also able to see the cottages inhabited by the code-breakers, although the interiors aren’t open to the public.

 

In 1995 a group of scientists and enthusiasts headed up by John Harper decided to try and rebuild the Bombe. When Bletchley was decommissioned all traces of the work that had dominated the lives of up to 3000 people for the past 6 years was burned or destroyed, so finding plans for the Bombe seemed impossible. 10 years later, after a decade of hard work, trial and error and sourcing now discontinued materials such as Bakelite they had a working Bombe. Today you can see this in action with demonstrations every half an hour.

 

Beside the rebuilt Bombe sits a beautiful graphite statue of Alan Turing, and the letter of apology from Gordon Brown for his conviction of “debauchery” when it was discovered he was a member of the LGBTQ+ community. Having chosen chemical castration over imprisonment, Turing tragically took his own life in 1954. Given that Turing’s work is said to have shortened the war by up to 2 years, saving potentially hundreds of thousands of lives, the fact it took nearly 50 years to pardon him is downright disgusting. Furthermore Parliament’s decision to overturn a bill which would pardon all those convicted of “debauchery” a few weeks ago shows just how static societies views on the LGBTQ+ community are, despite politicians constantly self-congratulating themselves on how progressive they think they are.

Today a memorial to all those who worked at Bletchley stands outside hut 2 bearing the inscription “We Also Served”. When Bletchley closed all those who worked there were sent away with strict instructions never to speak of their work, and for this reason so many achievements went uncelebrated. Since the Enigma code was declassified many of the men and women who worked there have released memoirs of their time at Bletchley. Most speak of fond memories, and many found love there.

Without the work of the Code breakers, WWII could have had a very different conclusion, with millions more innocent lives lost. It is thanks to their work that we live in the world we do today, and for that we salute them.

Admission to Bletchley Park costs between £14.00 and £17.25 for adults which includes unlimited access to the site for 1 calendar year. English Heritage members also enjoy a further discount.

 

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s