Friday, November 16, 2007

Colossus Breaks Code, But Loses Race

Having finally intercepted the radio messages (we know how poor conditions are in solar minimums), the Bletchley Park museum staff put the rebuilt Colossus computer to work on them, while also giving them to a Colossus emulator programmed on a common laptop PC.

The PC beat the 2000-tube, paper-tape-based Colossus, but not by much. Actually, though, another crypto type who'd written his own software already had them both beat.

Still, the clunky replica machine, which fills a large room, was able to break a long message in a complex RTTY Baudot encipherment scheme in about 4 hours, 20 minutes. Not too shabby for vacuum tubes, even though a couple of "valves" blew out toward the end.

It was the timeliness of the decipherment which made these machines so important in shortening World War II. In particular, it gave planners of the D-Day invasion useful information about German defense preparations.


Last Updated: Friday, 16 November 2007, 13:43 GMT

Colossus loses code-cracking race

By Mark Ward

Technology Correspondent, BBC News website

An amateur cryptographer has beaten Colossus in a code-cracking challenge set up to mark the end of a project to rebuild the pioneering computer.


At the same time as Colossus cranked through the messages a separate team used a virtual Colossus on a laptop to read the scrambled messages. That too beat Colossus and deciphered the message mid-morning on Friday.


The ciphertext from the messages will also be placed on the museum's website so amateur code-crackers who do not have access to radio can have a go at breaking the signals.