Skip to main content

About the Challenge

Welcome to the National Cipher Challenge, a nationwide, online codebreaking competition, which will run again rom October 4th 2018 to January 9th 2019. The full site will re-open for online registration on September 6th, and when it does you will find an updated set of rules and policies here. For now we would just like to remind you about the data we collect, how we handle it and how it will be used. If you have any questions on this, or any other matters connected with the competition, please contact us at [email protected]

Your data

We are currently inviting you to register for further information about the competition. If you agree to that and submit your contact information we will only use it in connection with the competition. The data will be stored throughout the competition and will be deleted within six months of the competition ending. You can revoke your consent for us to contact you using the provided contact information at any time by sending an email with the subject line UNSUBSCRIBE to [email protected]

It may be necessary to collect additional information about you if you choose to register for the competition in the Autumn. We will not request more information from you when registering for an account than is necessary to administer the competition. We will publish our full policy on collection, storage, use and retention of that data when the site is refreshed in September.  again, if you have questions, concerns or suggestions about this or any other matter then please contact us at [email protected]

Cookies on the site

We use cookies to anonymously track usage of the website through Google Analytics. No personally identifiable information is recorded by Google Analytics’ cookies.

We also use cookies to keep track of users’ activities when they login in order to facilitate the core functions of the site. If you have any questions or concerns about this or any aspect of data security on this site then please do contact us at [email protected].


Before we go here is a reminder of what the competition is about:

The competition is a great extension activity (or a fantastic maths club project) that can be tackled by students in teams or on their own. There is no charge to register or take part, and all you need to get involved is a reasonably modern web browser.

The competition has been running since 2002, and regularly attracts entries from teams at over 700 UK schools and colleges. Long time competitor, Julian Bhardwaj, said of the Challenge

If I were to name one thing which has undoubtedly influenced my academic drive, interests and overall career to date, it would be the National Cipher Challenge. Since being introduced to cryptography and the challenge in Year 8, it has been my one passion and driving force in pursuing further education in maths.

Julian went on to study Discrete Mathematics and made it to the Grand Final of the UK National Cyber Security Championship in 2013, following in the footsteps of the 2008 National Cipher Challenge winner, Jonathan Millican, who was crowned winner of the UK National Cyber Security Championship the previous year.

Our competition has attracted support from a number of people over the years, who have encouraged us by giving up their time to launch the competition, to meet with competitors and to attend the annual prize giving at Bletchley Park. These include the media scientists Adam Hart-Davis and Simon Singh; Newsnight editor Mark Urban who has a passion for military history;  comedy writer James Cary who wrote Bluestone 42 and the Radio 4 comedy Hut 33, and the star of that show (and many others),  Robert Bathurst  whose aunt worked at Bletchley in the war. We have also had the pleasure of introducing the Cipher Challenge team from Saint Anne’s School in Southampton to the Duke of Edinburgh.

Two Foreign Secretaries, Boris Johnson and William Hague have supported the competition (though Boris was London Mayor at the time), and we are also grateful to our sponsors who give time as well as money to support the competition. It is not unknown for our winners to meet members of the secret world of GCHQ at the awards dinner despite their busy schedules.

The competition is structured as a series of encrypted messages which tell a story. That story is, for now, a closely guarded secret. Come back in September to find out about it.

You can download lessons and notes on codebreaking from the resources page on the competition website. This is the competition library and, alongside the materials we have produced you will find links to books,  online videos and help guides that contain everything you need to be a successful code-breaker. You can even build your own cipher machines, including the simple cipher wheel and the more complicated Pringle Can Enigma Machine.

Entrants can take part alone or in teams of any size. To take part you will need to register for an account  the website, and we will ask you for a Nickname (which we will use to identify you on the forum, where you can discuss a whole range of things connected to the competition, and quite a few that are totally unrelated). You will then be asked to create or join a team which you will use to submit your entires. If you ask to join an existing team then we will email your request to the team captain and let you know the outcome. If your request is turned down, don’t worry, you can request to join another team, or set up your own.

If you want others to join your team let them know and they can submit a request through their account page which is linked at the top right of the menu bar.  The names of everyone on a team will be on the certificate and we will publish the team name on the leaderboards so you can see how everyone is getting on.

When setting up the team we ask you to say whether or not you are eligible for a prize. The rules are below. If you are eligible we will ask you for some information about your school, including the name and email address of a teacher contact. We need this in case you win a prize, but please do ask them first. If you are home educated then state that in the School name box and give the name and email address of an adult we can contact if we need to. We will not publish your name or the contact information of your teacher without your (or their) permission, but of course if you win a prize we will want to tell the world about your success!

Competition schedule

Registration will open online on 6th September and the first episode will be published at 3pm on Thursday October 4th. The first three episodes are designed as a warm up, and while we will publish leader boards, the marks for those challenges won’t count towards the final competition standings. There will be a break for half term from and the main competition starts with episode 4 on 1st November, with the remaining challenges published weekly until December 13th



Episode Publication date 15:00 on Solution deadline 23:59 on
1. Practice challenge 04/10/2018 10/10/2018
2. Practice challenge 11/10/2018 17/10/2018
3. Practice challenge 18/10/2018 31/10/2018
4. Competition challenge 01/11/2018 07/11/2018
5. Competition challenge 08/11/2018 14/11/2018
6. Competition challenge 15/11/2018 21/11/2018
7. Competition challenge 22/11/2018 28/11/2018
8. Competition challenge 29/11/2018 05/12/2018
9. Competition challenge 06/12/2018 12/01/2018
10. Competition challenge 13/12/2018 09/01/2019


Points are awarded for speed and accuracy (with accuracy more important) but you do not have to rush to download the first challenges immediately as you have a day or two in which you can still get top marks. In later challenges speed will become important, and the full schedule of marks is published on the Challenge pages so you can see how quickly you will need to get started in each round.

The first three challenges should be thought of as a “warm-up” exercise and will not count in the final leader board rankings or for the award of main prizes, however it is still worth tackling them as they give excellent practice and they do develop the storyline. You will be able to download certificates recording your team’s performance at each stage.

As usual we apologise in advance if your school holidays clash with the schedule. It is impossible to set the schedule to avoid them all, but there is nothing to stop you doing the challenge during the break, you only need a web browser and your brain!


To take part you will need to register for the competition on our registration page:

Owing to changes in dataa protection regulations we are currently reviewing our data policies. Updated information will appear here in due course.