German beats Colossus codecracking computer

In an ironic twist, a team from the UK 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 last week, 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.

The museum's spokesperson said: "[Schüth] cracked the most difficult code yesterday. 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 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.

Tom Espiner writes for ZDNet.co.uk