A CODED festive greeting sent out by GCHQ spies is a real Christmas hard.
The front features a circuit board pattern set inside a bauble with space for nine answers.
Recipients turn inside to find nine letter sequences.
They are told to find the next letter and put it in the correct order on the bauble to reveal a hidden message.
The quiz was designed by Cheltenham-based spooks, led by director Jeremy Fleming, and sent to UK staff plus allies in the US and Canada.
The snooping agency said: “Taking on this Christmas cracker gives puzzlers an insight into the skills you need to be a GCHQ analyst.”
An intelligence source added: “Problem solving is at the heart of what we do.”
Most read in News
YOU BETTER WATCH OUT
Can you solve this puzzle and find Santa's items in his workshop
Children 'washing their hands more than ever' during Covid pandemic
Moment red squirrel bites baby rat before throwing it to its death in turf war
KYLE SHOW TRAGEDY
Ex-Jeremy Kyle producer hanged herself after losing job when show axed
Dad who butchered wife & daughter after suspecting cheating found guilty
Missing Brit hiker 'may not be found for 5 YEARS if she fell on glacier'
GCHQ has previously put puzzles in newspapers as a talent-spotting exercise.
The agency oversees the National Cyber Security Centre which protects the UK from digital crime.
It is also a partner of the National Cyber Force, created this year to attack “hostile” states such as China, Russia and Iran.