Merry Christmas from the British GCHQ

David

The Government Communications Headquarters (GCHQ) is a British intelligence and security organisation responsible for providing signals intelligence (SIGINT) and information assurance to the British government and armed forces.[2] Based in "The Doughnut", in the suburbs of Cheltenham, it operates under the formal direction of the Joint Intelligence Committee (JIC) alongside the Security Service (MI5), the Secret Intelligence Service (MI6) and Defence Intelligence (DI). GCHQ is the responsibility of the UK Secretary of State for Foreign and Commonwealth Affairs, but it is not a part of the Foreign Office and its Director ranks as a Permanent Secretary.

A Christmas card with a cryptographic twist for charity

News article - 7 Dec 2015​

This year, along with his traditional Christmas cards, Director GCHQ Robert Hannigan is including a brain-teasing puzzle that seems certain to exercise the grey matter of participants over the holiday season.

The card, which features the 'Adoration of the Shepherds' by a pupil of Rembrandt, includes traditional Christmas greetings from Director on behalf of the department. However, unlike previous years, the 2015 card will contain a grid-shading puzzle and instructions on how it should be completed. By solving this first puzzle players will create an image that leads to a series of increasingly complex challenges.

Once all stages have been unlocked and completed successfully, players are invited to submit their answer via a given GCHQ email address by 31 January 2016. The winner will then be drawn from all the successful entries and notified soon after. Players are invited to make a donation to the National Society for the Prevention of Cruelty to Children, if they have enjoyed the puzzle.

People who enjoy puzzles, but who are not yet on Director's Christmas card list, need not worry. The first puzzle can be seen below.

Getting started

In this type of grid-shading puzzle, each square is either black or white. Some of the black squares have already been filled in for you.

Each row or column is labelled with a string of numbers. The numbers indicate the length of all consecutive runs of black squares, and are displayed in the order that the runs appear in that line. For example, a label "2 1 6" indicates sets of two, one and six black squares, each of which will have at least one white square separating them.

Click on image for a downloadable version.

Complete the grid carefully with a black pen and check your answer is complete and correct before proceeding.