It took the Swedes the equivalent of 70 years of computer time to decipher 10 increasingly difficult codes set by author Simon Singh in his international bestseller "The Code Book."
"It is the toughest code that has ever been cracked," Singh said on Thursday before handing over the first prize check for 10,000 pounds ($15,000) to the team headed by Fredrik Almgren.
Schoolboys to professors
Almgren works on Internet security. He solved the puzzle with software developer Torbjorn Granlund and a trio of computer buffs from the Royal Institute of Technology in Stockholm.
The challenge had obsessed thousands of codebreakers around the world. They even set up their own web site, which attracted 2,500 fans, from a 14-year-old schoolboy to math professors.
Singh, believing that the ultimate prize was out of their reach, had already given a 1,000-pound prize to two computer buffs who had cracked the first nine codes. But then the Swedes came through with the solution to the final "512 bit" code.
Singh, who has a doctorate in physics from Cambridge University, took two years to create the brain teasers with Dr. Paul Leyland, who works for Microsoft in Cambridge.
They worked in total secrecy. "I regularly went into my little garden, dipped the relevant papers in molten wax and set them alight," Singh told Thursday's Daily Telegraph.
A hard grind
Almgren admitted that it was a long, hard grind and the Swedish team was tempted to abandon ship at times.
"The first stages were very simple, but at one point we thought we wouldn't get any further than stage eight," he told BBC radio.
"When you do come to the 10th stage, it is a question of heavy mathematics and rather difficult algorithms that I don't even claim to understand myself."
"It is the sort of thing that some people do use on the Internet for Internet security," Singh said.
"That doesn't necessarily mean that Internet security is invalid because it took a year for a team of Swedes to crack this with some very sophisticated computers."