Skip to main content

National Cipher Challenge 2019

IBM Created with Sketch.
Trinity College Created with Sketch.
GCHQ Created with Sketch.

Cutting Edge Cracking

One of our competitors, Cribbage, from the 2018 competition kindly wrote up how they tackled the final challenge last year. If you are wondering what it takes to decipher a message encrypted with a brand new code then this might give you some idea. The challenges in the early rounds of the of this year’s competition won’t be anything like as difficult, but as for the later ones…

Read more

Rules of Engagement

While we try to keep things simple and friendly, the competition has some rules and you should probably know about them. We think they are clear, and they are certainly tested by time, but if you have any questions about them do contact us and we will try to get back to you within 24 hours. In the meantime you can read them here.

Read more

Programming for Code Breakers

National Cipher Challenge alumnus Julian Bhardwaj wrote a rough guide to computer programming for code breakers which he has kindly allowed us to post here for you. You don’t need to be a world class programmer to do well in the challenge, you can get a long way with a word processor, a spreadsheet and some cunning, but it really helps to automate the routine jobs, and these notes will get you started.

Read more

A free beginner’s guide to code breaking to get you started

Download Now

Anthony Horowitz Tweets

Fetch Tweets: Could not authenticate you. Code: 32



Whether you are a pupil, teacher, parent or school, if you are following along with the cipher challenge and have not signed up, then can we encourage you to do so. It only takes a few minutes and it really helps us to monitor how we are doing with reaching out to everyone across the UK. We won’t use this to spam you and you don’t have to give us loads of info. If you are in a team and … Read on


Intrigued about what a flight to the moon really entails? You are not alone, so was I, so I took a look around the files at NASA and found this copy of the Apollo 11 Flight Plan. Full of detail that you won’t find elsewhere. Enjoy!


Welcome back to the National Cipher Challenge, I can’t believe we are now in the 18th year of the competition. Back in 2005 we travelled with Harry deep under the Arctic to the Lomonosov Ridge, as he worked to recover a Soviet spy satellite that had crashed in the northern waters. The mission took place in 1957 and this year’s competition starts as Harry returned to the US to receive his new assignment. You will be working with him to … Read on


Everyone. Everyone who took part in this year’s challenge, including me. At least, I hope so. It has been a real pleasure watching you all struggle, strive and succeed, and I hope you enjoyed it as much as I did. Of course we do have some prizes to award, so without much further ado, but with a flourish and a fanfare, here they are. The GCHQ Prize of £1,000 is awarded to Claire Carlotti (Kalicali) of Sir Roger Manwood School. … Read on


At 23:00 last night Challenge 9 drew to a close bringing to an end this year’s National Cipher Challenge. I want to give heartfelt thanks to everyone who took part this year: to all the competitors and their supporting teachers and family; to the staff at 10 Degrees who built and managed the website and at OnImpact who designed the poster; to our followers on Twitter who spread the word about the competition, and especially to Tom Keay (@TeaKayB) at … Read on