A code breaking riddle that offers the chance to win a genuine World War II Enigma machine remains unsolved more than a year after the challenge was first posed.

The chance to own a piece of crypto history is on offer through a code-breaking competition associated with the book Can you crack the Enigma code? by author Richard Belfield.

As part of the book, Belfield worked with a team of boffins from the Information Security Group at Royal Holloway, University of London, to create a challenging collection of interlinked puzzles. These "Enigma puzzles" have been designed in such a way that ingenuity and lateral thinking will be as important as having access to a computer in solving them.

The formidable challenge has withstood the best efforts of numerous would-be code breakers for more than a year since the book was launched in September 2006. Kenny Paterson, one of the team of cryptographers who devised the puzzle, wrote to alert us about the ongoing competition.

Long-term readers may recall our own codebreaker competitions. Given the interest these spurred we're sure many of you will be keen to get stuck in. Getting involved in the competition may lead to hours of frustration but, as Paterson notes, is perhaps better than bidding for an Enigma machine on eBay.

"The competition has been running for over a year and, so far, the puzzles have defied any attempts to break them all. There's been plenty of discussion on the online forum, but so far it seems that only the first three of the six puzzles have been cracked," Paterson writes.

Time to sharpen your pencils and get to work, perhaps?

The competition can be found here.®

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