Colossus Back to Crack Codes After a 60-Year Absence

Colossus, the code-breaking computer used to decipher German messages during World War Two, has been put back together. Over six decades after the 10 truck-sized devices were dismantled, one has been rebuilt. Today, two teams of code-breakers, one using the Colossus, another using modern technology, are going head-to-head as they attempt to unscramble messages sent from Paderborn, in Germany.

Tony Sale, the man behind Colossus' restoration, had just a few old photos to go on when he started on the project 14 years ago. One of the reasons that the machine, which contains over 2,000 valves, is so fast, is because it was a single-purpose processor rather than one with multiple uses, like modern computers. Of the two teams, he is unsure which one will win the Cipher Challenge.

Colossus Back to Crack Codes After a 60-Year Absence

"A virtual Colossus written to run on a Pentium 2 laptop takes about the same time to break a cipher as Colossus does," he said. The original machine could break codes in a matter of hours, and was instrumental in the Allies' eventual victory, shortening the war by an estimated 18 months.

"It was extremely important in the buildup to D-Day," reckons Mr Sale. "It revealed troop movements, the state of supplies, state of ammunition, numbers of dead soldiers—vitally important information for the whole of the second part of the war." Today's messages will be scrambled using a Lorenz SZ42 machine, the same used by German high command back in the '40s. [BBC News and 24 Hour Museum]