How to Crack the Nazi Code

In The Imitation Game, Benedict Cumberbatch plays real-life cryptanalyst Alan Turing with single-minded intensity. But almost as captivating is a complex hunk of electromagnetic machinery known as ”the Bombe” — which Turing and a group of British proto-hackers used to break the Nazis’ Enigma code during WWII. Creating a working Bombe, a watershed moment for the Allied cause, became Turing’s obsession — and that of production designer Maria Djurkovic (The Invisible Woman).

The original Bombes were destroyed after the war, but director Morten Tyldum (Headhunters) and his crew studied a replica at the Bletchley Park museum, site of the U.K.’s code-breaking headquarters. ”All the red cables were like blood in veins,” says Tyldum. ”It was like a living thing.”

To build a Bombe, Djurkovic’s team put ads in WWII hobbyist magazines seeking period parts like valves, batteries, and cogs — then spent days assembling the device. The film’s Bombe may look authentic, but it can’t crack any codes. ”That would have been somewhat beyond us!” Djurkovic says. Still, Cumberbatch asked a Bletchley Park expert for a tutorial on how his electronic costar worked. ”You see him sizing you up and realizing you’re not a math Ph.D.,” the actor recalls. ”You see him sigh inwardly, and outwardly he says, ‘Well, you’ve got this system of wheels…’ After about 16 minutes, you know his energy is going into the black hole of your inability to understand.”