German man beats WWII Colossus codecracker

German man beats WWII Colossus codecracker

Summary: A rebuilt British cipher-breaking machine used in World War II has been beaten in a codebreaking challenge by a German man who wrote his own software

TOPICS: Security

In an ironic twist, a British team operating a World War II codebreaking computer has been beaten in a cipher-breaking contest by a German.

In the Cipher Challenge, a competition run by the National Museum of Computing on Thursday and Friday, the cipher-breaking computer Colossus had to decode encrypted radio communications intercepted from Paderborn in Germany. Competing against Colossus, which took 14 years to rebuild, were radio enthusiasts from across Europe, who had to beat the WWII codecracker using whatever computing means they had at their disposal.

The winner was Joachim Schüth, from Bonn, who completed the task using software he wrote himself. 

"[Schüth] cracked the most difficult code yesterday," said the museum's spokesperson on Friday. "We're absolutely delighted. He used specially written software for the challenge. Colossus is still chugging away, as we got the signals late. Yesterday the atmospheric conditions were such that we couldn't get good signals."

The team operating Colossus managed to intercept the radio signals early on Friday, before loading the paper tape containing the encoded cipher stream. At the time of writing, the tape was still running, and the team expected to break the cipher later on Friday.

Schüth had "been much quicker and done a stunningly good job", said the museum's spokesperson. Few technical details were available at the time of writing about the systems or software used to break the cipher, although the spokesperson said Schüth had used the Ada programming language. Ada is used for military systems and was created by the US Department of Defense in 1980.

Anthony Sale, the head of the team which rebuilt Colossus, said that the transmitted text had been encrypted using a Lorenz teleprinter cipher machine, the same type of machine which was used by Germany for high-level communications in WWII.

Topic: Security

Tom Espiner

About Tom Espiner

Tom is a technology reporter for He covers the security beat, writing about everything from hacking and cybercrime to threats and mitigation. He also focuses on open source and emerging technologies, all the while trying to cut through greenwash.

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  • Not so much irony as conspiracy lol

    What you fail to mention is the fact that Sch
    Trotskiii (uk)
  • Actually...

    Hello there,

    Thanks for taking the time to post a talkback. I found the story ironic too. However, I did mention that Sch
    Tom Espiner