GCHQ Director Robert Hannigan must be feeling pretty smug right about now. The spy master's Christmas puzzle was deemed the 'hardest puzzle in the world' and indeed after 30,000 entries, not one person has got it right. Not one.
The spy agency's director Robert Hannigan posted a puzzle in his annual Christmas message, giving recipients till 31 January 2016 to send their answers in.
While many were able to solve this first puzzle what they found was that it actually revealed a QR code, one that could be scanned by a smartphone or tablet.
What you are essentially seeing is a QR code, which can be scanned by a mobile phone, moving the code-cracker to the next stage of the puzzle.
Other questions in this category included:
"I was looking at a man on top of a hill using flag semaphore to send a message, but to me it looked like a very odd message. It began "ZGJJQ EZRXM" before seemingly ending with a hashtag. Which hashtag?" The options? #SGM #SEM #SEN #SGN #TEN
Getting the right answers then unlocks part 3:
If you're still keen to power through the rest of the brain teasers, parts 4 and 5 look like this:
GCHQ reportedly told the Telegraph that the puzzle is most definitely not impossible, but the bad news for anyone attempting it is that it was created by the spy agency's top cryptographers.
While that's bad news enough, Hannigan also pointed out that there's an added element of difficulty which is that typically cryptographers think differently to the rest of us mere mortals.