The UK's national security agency, GCHQ, is currently conducting an online treasure hunt, the starting point of which is a set of codes. It is presented as part of a recruitment drive to fill open positions that require problem solving skills.

GCHQ (Goverment Communications Headquarters) is one of those places you won't find on Google earth. It is the UK's listening agency, which with the US National Security Agency, has been gaining negative publicity for the degree to which it eavesdrops on online traffic.

It recently launched a new Can you find it? website offering prizes for those who can solve five codes that have been hidden around the web which is open to UK residents aged 18 and over.

This is not the sort of cypher you'll crack in a matter of minutes - the closing date is October 21st so there's still more than a month to attempt it. The codes have been created by a GCHQ team of top mathematicians and a similar campaign last year was cracked by just 170 people out of 3.2 million who visited the website.

If you have the ability to crack the codes that provide the starting point for this "treasure hunt" you might go on to win a Google Nexus 7 (5 on offer) or a Raspberry Pi (100 available). However the real prize could be a job opportunity. According to Jane Jones, Head of resourcing at GCHQ, the challenge has been designed to identify the right people to help protect the UK. She said:

 "The 21st century is confronting us with online threats that are difficult and dangerous, so we want employees who have evolved with the ever-changing digital world and therefore have the right skills to combat these challenges. It's a puzzle but it's also a serious test – the jobs on offer here are vital to protecting national security."

A range of jobs are on offer with starting salaries from £26,000 to £60,000 and the codes are intended to identify candidates who might be suitable by virtue of their interest in both  problem solving and computer technology.

"They set a high bar for recruiting curious, tenacious and creative candidates who have the intellectual ability, though not necessarily the practical experience or qualifications, to join GCHQ and support the Government's national cyber security agenda."

So crack a code and get a job. It could also be a good way of getting a double agent inside.