Try Hitler's 'unbreakable' cipher: Germany's WWII Lorenz crypto machine is now online

The Virtual Lorenz machine lets you try a replica of the cipher system Hitler used to communicate in secret with his top generals.
Written by Liam Tung, Contributing Writer

When you visit the Virtual Lorenz machine online, you should be prepared for the original sound effects.

Image: ​The National Museum of Computing

An online version of Hitler's "unbreakable" messaging encryption machine is now available for anyone to try.

The UK's National Museum of Computing (TNMC) has unveiled the Virtual Lorenz machine to commemorate the centenary of Bill Tutte, the Bletchley Park mathematician who reverse-engineered the German High Command's Lorenz SZ42 cipher system, allowing the Allies to unscramble top-secret messages.

"Tutte's work, often regarded as the greatest intellectual feat of the war, shortened the conflict by enabling the decryption of the enemy's strategic messages on a regular basis -- and very rapidly with the help of Colossus computers," The National Museum of Computing says.

Tutte and fellow codebreaker John Tillman figured out how the 12-rotor Lorenz worked over a three-month period. They achieved this feat without having seen the machine, which was considered more complex than the better-known Enigma cipher machine.

As per an account by fellow codebreaker Tony Sale, the codebreakers named the Lorenz machines and their traffic after fish, which in Lorenz's case was Tunny, or tuna fish. Although they broke Tunny, initially it took six weeks to decrypt messages. Colossus would help cut message-breaking time to hours.

The online Lorenz replicates the high-pitched industrial sound of the real Lorenz SZ42, as well as the sound of the machine crunching through messages being exchanged.

Martin Gillow, who created the Virtual Lorenz, says the inspiration for the project was a Virtual Colossus, which was built by the late Sale. Gillow has created an updated version of that, too.

"As a programmer, I was fascinated by the rebuild of the Colossus computer when I first saw it at The National Museum of Computing. Tony Sale, who led the rebuild team, had also created a Virtual Colossus for the web, but I discovered that it would only run on old browsers. Since Tony Sale had passed on, it was likely to become inaccessible and lost forever as web technologies progress," he said.

"So, I decided to recreate the Virtual Colossus -- and then a Virtual Lorenz to accompany it. It took months of work in my spare time, and revealing it to the audience at the museum was a real thrill."

The Virtual Lorenz isn't straightforward to use, but TNMC assures that it's easier than the wartime original.

Gillow has provided detailed tutorials explaining how to use the machine to exchange encrypted messages with others, or you can set the machine to auto type. Text can be input via the keyboard typed into an input field.

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