Can you crack the code for GCHQ's Christmas card puzzle?

  • GCHQ
The GCHQ Christmas brainteaser Credit: GCHQ

Britain's intelligence agency GCHQ has decided to release a Christmas card with a difference. This year, instead of the usual festive greeting it features a brainteaser, can you work it out?

The Puzzle

How to play

  • Players must complete a grid-shading cryptographic puzzle with a black pen to reveal a picture.

  • Once the first puzzle has been completed it will lead to "increasingly complex" challenges.

  • After completing all stages of the challenge participants can then submit their answer to GCHQ via email by 31 January.

  • The winner will then be drawn from all the successful entries.

  • Full instructions can be found on the agency's website.

GCHQ said: "In his Christmas card this year, director GCHQ Robert Hannigan has included a cryptographic challenge that should exercise the grey matter over the festive season".

Those taking part are invited to make a donation to the NSPCC children's charity.