The National Museum of Computing has challenged members of the public to take on a rebuilt version of Colossus, the world's first programmable digital computer.

Colossus was developed at Bletchley Park to decipher German messages during World War II.

A working replica of the code-breaking device will return to active service as part of the Cipher Challenge on 15 November to mark the launch of the National Museum of Computing.

Two groups of amateur code breakers will be invited to crack transmissions encrypted by one of the original Lorenz cipher machines used by the German High Command during World War II.

The encrypted teleprinter message will be transmitted by radio from colleagues in Paderborn, Germany, and intercepted at Bletchley Park by the two code-breaking groups, one using modern PCs and the other using the newly rebuilt Colossus Mark II.

"Colossus marked the beginning of the modern age of computing, a heritage that we are planning to preserve by raising £6m to establish a world-class facility at Bletchley Park," said Tony Sale, co-founder of the National Museum of Computing.

"Witnessing Colossus Mark II in action is a chance to relive and admire the historic breakthrough made by Bletchley Park code breakers during World War II. "

The original 10 Colossus Mark II machines provided the Allies with vital information on enemy plans, helping to save thousands of lives by shortening the war by several months.