A national codebreaking competition has been won by an extremely bright team of four students from a London school.
Samson Danziger, Daniel Hu, Anthony Landau and Charlie Hu from City of London School took 44 hours and 20 minutes to crack the Trifid code in the National Cyber Challenge. Altogether, 6,268 pupils from 725 British schools took at the end of last year.
The challenge, which ran over two months at the end of last year, was organised by Southampton University, supported by GCHQ and commercial partners. 1,600 teams signed up, but only 30 managed to complete every level.
Codes issued to the teams periodically on the internet became harder and harder as the competition progressed.
The organiser is Prof Graham Niblo, the University's Head of Mathematics. "We started with a Caesar cypher, which is the most basic cypher that everybody learns at school. We ended with a Trifid cypher – the most difficult one this year," he said. In a Caesar cypher, the letters in a code are substituted for others further down the alphabet. A Trifid cypher is a complex combination of both an advanced version of the Caesar cypher and anagrams.
Niblo continued: "It is the longest it has ever taken for the winners to decode any of our cyphers. This year they had to think quite hard about it. The last cypher was not a standard cypher, and we modified it so they couldn't use any standard decryption software." The kids couldn't put one past the organisers either. "We did catch a couple of people trying to get help online. We tracked them down and warned them off," recalls Niblo.
The winning team gets £1,000 prize from GCHQ, and the top 50 runners-up receive Raspberry Pis. Second place went to Andrew Carlotti from Sir Roger Manwood's School in Kent and a team from King Edward VII School in Sheffield finished third.
The National Cypher Challenge is now in its 11th year. The 2012 challenge was kicked off by William Hague at Bletchley Park in October, as part of three GCHQ schemes aimed at attracting youngsters into maths and computer science.
