A team of researchers in Sweden has cracked the final cipher set by Simon Singh in "The Code Book" and claimed the £10,000 prize. It took a year and month between publication of the challenge and its completion without the use of a super computer.
Singh set a challenge to would be cryptologists at the end of his book, which catalogues the history and development of ciphers and codes from a mono-alphabetic substitution cipher through to current Internet encryption standards. It was intended to be the toughest public cipher challenge ever set.
A series of ten ciphers were set, in chronological order and hence increasing in complexity. The final stage is similar to the kind of encryption used for internet security and used a 512-bit encryption key. The details of the cipher were checked with Paul Leyland, an encryption specialist working at Microsoft's research Labs in Cambridge.
There are clearly implications for the security of documents sent using similar encryption technologies. Singh's publishers are keen to stress that this deciphering does not imply an inherent weakness, merely serves as a timely reminder that the security of all encryption must be continually monitored.
The original deadline for entries to the contest was the first of January 2010. If no one had claimed the prize by then, the money would have gone to the person who had got the furthest first. ®
We will update this story when we've interviewed the people involved in the challenge.