Original URL: http://www.theregister.co.uk/2007/11/16/german_code_breaker_defeats_colossus/

German amateur code breaker defeats Colossus

Reversal of fortune

By John Leyden

Posted in Security, 16th November 2007 12:32 GMT

Updated An amateur cryptographer from Germany has beaten Colossus, the world’s first programmable digital computer, in a code-breaking challenge.

The original machine was developed at Bletchley Park to crack encrypted German messages during World War II. After years of painstaking restoration work a recreation of machine returned to action on Thursday to mark the launch of the first part of the fledgling National Museum of Computing.

A recreation of the venerable machine was put up against PCs in a code-breaking challenge on Thursday. The match is not as unequal as it may first seem as Colossus was a single function device whose speed at breaking codes rivals that of modern PCs, at least in theory.

The rebuilt Colossus Mark II is being put to work deciphering a teleprinter message transmitted by radio from Paderborn in Germany, after it was first encrypted by one of the original Lorenz cipher machines used by the German High Command during the war. Other amateur code breakers were also invited to join the challenge to intercept the transmission and to try to beat Colossus in cracking the 1938 Lorenz SZ42 encrypted message.

As previously reported, interference hampered the efforts of code-breakers at Bletchley Park to intercept the message on Thursday. They deliberately used wartime radio equipment to intercept the messages in an effort to make the exercises as authentic as possible. Bletchley Park was unable to get a good copy of the signal until 4.30pm on Thursday, about two hours after an amateur cryptographer in Germany had intercepted and decoded the most heavily encrypted of three messages that featured in the challenge.

A spokesman for the National Museum of Computing confirmed early reports on German website Heise that Joachim Schüth of Bonn had won the challenge.

Schüth wrote specialist software in the tricky language of Ada after learning of the challenge in September, allowing him to uncrack the message in the most difficult of the three challenges in less than two hours on Thursday afternoon.

"He's succeeded in beating Colossus after cracking the hardest challenge. We are delighted for him, he did a fantastic job," the spokesman said.

Over at Bletchley Park the team is not expecting a result until Friday lunchtime after loading tape representing the encoded message onto Colossus for deciphering this morning at 9.05am. The message itself is about the Heinz Nixdorf Museum in Germany, which assisted the National Museum of Computing in running the challenge.

The code-breaking challenge marks the completion of the successful rebuild of Colossus and the start of a major fundraising drive for the fledgling National Museum of Computing. It's the first time Colossus has been used since then Prime Minister Winston Churchill ordered the destruction of the top-secret machine following the end of World War II.

The recreated Colossus is on public display at The National Museum of Computing at Bletchley Park, Buckinghamshire, following a 14-year rebuilding project led by Tony Sale, a founder of the emerging museum. The trustees of the museum hope to raise £6m in investments in order to fully establish and run the facility.

Donations to this worthy cause can be made online at the Museum's website here. ®

Updated

The team at Bletchley Park correctly deciphered the message at 1.15pm on Friday, after a run-time of three hours and 35 minutes (excluding 45 minutes for an injured valve). The code-challenge marks the first time the rebuilt Colossus was run since a test run on a real German wartime messages, after it was first put together, 18 months ago.

Splendid work, chaps.