Solving GCHQ’s Christmas nonogram in 0.07 seconds

GCHQ throws down the gauntlet

A while back I found the GCHQ Director’s Christmas card, which came in the form of a nonogram. GCHQ has a history of puzzle setting and even hiring people through puzzles. The WWII codebreakers were hired through crosswords and other puzzles in the newspaper, which was featured in The Imitation Game.

I was new to nonograms, but quickly found out they’re a “paint by numbers” puzzle where hints for rows and columns give you series of segments (of varying lengths) to colour in. Applying all the clues together logically lets you work out whether each cell is filled in or empty progressively until you reach the final solution.

Typically you then have a badly pixelated picture of something and a sense of accomplishment. With GCHQ’s puzzle, you end up with a QR code that leads you to the next puzzle. So the picture is not very pretty and the sense of accomplishment is short lived. Here’s what GCHQ’s best Christmas wishes look like:


And I thought I was bad at Christmas cards.

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