From cryptic Christmas cards to mysterious coded baubles, GCHQ's festive puzzles have always been brutally difficult to solve.
This year's challenges have been announced today, prompting thousands of Brits to get to work to solve the problem.
Among the tests are a quiz about clocks, a word hidden in a series of musical notes and a clue in the form of a photo of the Second World War code-breaking headquarters Bletchley Park in winter.
Last year's test included the question: 'If a French ailurophile feels like chatting, what does a Polish cynophile feel like?'
And in 2021 – the first time GCHQ released a puzzle designed for children – the centerpiece was a Christmas tree filled with glowing nodes linked to a series of questions.
Below, MailOnline reveals this year's challenge, along with previous festive puzzles dating back to 2020. Below are the answers to the questions.
TO ASK
2023
This year's challenges have been announced today, prompting thousands of Brits to get to work to solve the problem
This year there are seven questions that become increasingly difficult.
Each of the questions has a one-word answer that can follow the word “Christmas.”
To discover the final festive answer, children should look at the design on the front of the card, which features a rare 1940 image of a snow-covered Bletchley Park, taken before a photography ban was introduced at the manor.
The image was found in the personal family album of codebreaker Joan Wingfield, a talented cryptographer who worked on breaking Italian naval codes and who later married Arthur Bonsall, the seventh director of GCHQ.
The challenge is designed to test a range of problem-solving skills and high school students may have to work together to reveal the final festive message.
This year there are seven questions that become increasingly difficult. Each of the questions has a one-word answer that can follow the word “Christmas”
The architect of the quiz, known only as Colin, has set up a final test for students to find a hidden word in his quote: 'Christmas is a great opportunity for GCHQ to get young people involved, hence our annual Christmas Challenge.
'Our mission is aimed at helping people think differently and find inventive ways to tackle challenges.
'Like the work at GCHQ, solving the puzzles on the map requires a mix of minds, and we want to show young people that thinking differently is a gift.
'To read the final message, these different approaches must be brought together, demonstrating the value of teamwork as the final piece of the puzzle.
'With the Christmas Challenge we not only want to introduce young people to the way we work at GCHQ, but we also want it to be fun!'
To discover the final festive answer, children should look at the design on the front of the card, which features a rare 1940 image of a snow-covered Bletchley Park, taken before a photography ban was introduced at the manor.
2022
In last year's test, students were challenged to solve a series of seven puzzles based on the image of the Christmas tree on the front of the card.
There was also a special twist to challenge high school students in lateral thinking, ingenuity and perseverance.
Once they solved the puzzles, the ambitious young James Bonds had to look to the Christmas card design for the answer.
Six of the puzzles had one-word answers.
In last year's test, students were challenged to solve a series of seven puzzles
Using the design on the front of the map, wannabe sleuths had to arrange these words to form two what3words addresses – using the online geocoding system designed to identify each location with a resolution of around three meters.
The remaining puzzle contained a third address.
Once the locations were found, children had to take one word from each address and put them together to discover the secret GCHQ message.
Using the design on the front of the map, wannabe sleuths had to arrange these words to form two what3words addresses – using the online geocoding system designed to identify each location with a resolution of around three meters
2021
Also in 2021, the first year that the puzzles were designed for children, there were seven questions.
In addition to an image of a Christmas tree made of glowing nodes, there were questions for children aged 11 to 18.
Below that was a Harry Potter-themed question, along with a number grid that, when solved, revealed a four-letter word.
Also on the list of questions were a mnemonic and a Venn diagram hiding a six-letter word.
The final question for the oldest students was a code hidden in a series of letters.
Also in 2021, the first year that the puzzles were designed for children, there were seven questions. In addition to an image of a Christmas tree made of glowing nodes, questions were asked for children aged 11 to 18
Among the questions was a Harry Potter-themed test, along with a number grid that, when solved, revealed a four-letter word
2020
The front of the 2020 Christmas card featured a circuit board pattern in the shape of a Christmas bauble, with room for nine answers.
There were nine strings of letters on the inside of the card that had to be entered into the decoration to reveal a message.
The front of the 2020 Christmas card featured a circuit board pattern in the shape of a Christmas bauble, with room for nine answers
There were nine strings of letters on the inside of the card that had to be entered into the decoration to reveal a message
2019
The 2019 test came in the form of a snowflake made of hexagons with a series of letters and different colors.
Participants had to color the image so that each circle of six hexagons surrounding a gray hexagon used each of the colors once.
The 2019 test was in the shape of a snowflake made of hexagons with a series of letters and different colors
ANSWERS
2023
2022
2021
2020
2019