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Budgets are tight for everyone so we get asked this a lot. The good news is it still costs nothing. For seventeen years we have been lucky to have several generous sponsors, and the running costs of the competition are covered by the School of Mathematical Sciences at the University of Southampton.

Registration opens on September 21st. The first part of the competition will be published at 3pm on Thursday October 4th. There is no need to rush to download it as you have one or two days in which to submit to achieve full speed marks. Often the website is overloaded for the first half an hour or so, and it probably pays to wait out the rush. The part B prizes will be allocated based on performance in rounds 4-10 so if you miss the first couple of challenges it won’t matter too much.

The challenges are published on Thursdays at 3pm. There are 8 rounds and they are scheduled as follows:

ChallengePublication Date
15:00 on
Final submission deadline
23:59 on
Challenge 0This is an introduction to the
story and not a challenge
Not applicable
Practice Challenge 14/10/201810/10/2018
Practice Challenge 211/10/201817/10/2018
Practice Challenge 318/10/201831/10/2018
Competition Challenge 401/11/201807/11/2018
Competition Challenge 508/11/201814/11/2018
Competition Challenge 615/11/201821/11/2018
Competition Challenge 722/11/201828/11/2018
Competition Challenge 829/11/201805/12/2018
Competition Challenge 906/12/201812/12/2018
Competition Challenge 1013/12/201809/01/2019


NOTE: all times stated on the site refer to current UK time. The clocks change back from British Summer time to GMT at around 2am on Sunday October 28th and our competition clock resets with that.

Please also note that Challenge 3 lasts two weeks, not because it is harder than all the others, but to accommodate as many half terms as possible (and to give you all a rest before the main competition starts)! We know that not all schools have the same dates, and it is impossible to accommodate them all, we hope you understand. It is possible for Team Captains to submit their solutions from anywhere with internet access so they should still be able to take part if their school is not open, and the Team Captain can always delegate that role (using the team page) if they are going to be away. In the past Challenges 6 or 7 have often also lasted two weeks, but having extended the competition to ten rounds this year we have made them just one week long. You still have a month for the Mega Challenge, round 10.

The final deadline for each Challenge is 11.59pm on the day before the next Challenge is published, The number of points you score in part B depends on how early you submit your best attempt, but your score for part A is not time dependent. The points schedule for each challenge is linked from the Challenge page.

Principally this is an extension activity for older pupils, but the early stages of the competition are aimed at a wide audience and there is something for everyone. We have had bright year 6 pupils do well on early rounds and this prepares them for further achievement in future competitions, though the challenge is definitely not designed or intended for the junior school age group. Many pupils return year after year as they try to improve on the number of stages they can successfully complete, and the staged certificates give everyone an incentive to keep going as long as possible.

Certainly. The entire math club could enter as a team or you could divide up into smaller groups and use the math club meetings to discuss techniques and strategies. The Resources page is full of useful materials for a Maths or Codebreaking club.

Yes, we get many solo entrants and teachers do not have to be involved, but we do ask for the contact details of a teacher or Parent/Guardian contact for prize administration.

No, in the past we have had several teams made up of members of different schools and colleges, and this is great. We do ask for the name of at least one of the schools and a teacher contact for prize administration, and, for now at least, the team captain’s school will get all the credit!

No, we do not split the competitors by age group and mixed age groups can work well with the older team members training up the younger ones for future success.

No, but everyone can have one! If you are taking part on your own you only need to register and create a team of 1 with you as Captain.

If you want to enter as a group the Team Captain should sign up for an account. Team members should then register for accounts and select “Join an existing team”.

If you need or want to change your team you can do so, but you will not take your score with you. That remains with your original team and you will become part of the new team with its existing score.

The website is stocked with information about the competition, including this FAQ,  the About the Challenge page, the Rules and Regulations, and our news on the Stay up to Date page.

There is more infomation on our Resources page including notes on codebreaking, some class materials and a guide to programming for codebreakers.

It is also worth taking part in the forums, which we will monitor and where we will publish occasional updates and answers to common questions. Be kind to the Elves who staff the Forum. They work very hard to support you and can’t always answer queries immediately (it is, in elf terms,  getting close to Christmas and the sleigh needs packing).

If you are a teacher who is registering in order to keep an eye on the forum, or a Cipher Challenge alumnus who is now too old to take part but just can’t keep away, or ineligible for some other reason, then please tick this box so that the computer doesn’t award you a prize by mistake! It is embarrassing for us to have to ask for it back. Thanks.

Best to let them answer that! Julian Bhardwaj took part for many years, going on the study Discrete Mathematics at University and to be a finalist in the UK Cyber Security Championship. He said of the competition:

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.

Naomi Andrew first tried her hand at the Challenge in year 8, and kept at it until she was too old.

It was fun seeing a different side of maths to what I was learning in class, and the elation of finally understanding a difficult cipher is a feeling that’s hard to beat. The challenge was my first taste of how much there is to maths, and more than 10 years later the subject continues to amaze and excite me!

Naomi did her Undergraduate degree in Mathematics at Southampton and has stayed on to do a PhD, while keeping her hand in by helping out with the Cipher Challenge in the little spare time that she still has!

Not all of the competitors like to work alone and teacher Claire West from Peter Symonds College saw the benefit of team work

As a teacher, I see the students form themselves into successful teams; with self-elected leaders who are responsible for organising their group after identifying their member’s individual strengths.  In our college, the challenges are worked on entirely by the groups alone as they use our library to work past the usual college close time.  I am so proud of them.

One of her team members said:

You can take it as far as you want. I loved it and read books about ciphers got addicted to solving the challenges. It builds up to the more complex challenges so every week you know you’ll get stretched just a little bit more. I went back multiple years to try and beat my score from the year before. It was great fun, solving the challenges as a team and actually applying the mathematical skills you learn in maths. I loved it and I’m sad I can’t do it again next year!

If you are taking part on your own you need to register and create a team that will have just you in it. The team name can be set on this page:

If you want to enter as a group the Team Captain should register first and create a new team. The Team Captain can then send the team members a link to their team from this page: Team members can then use that link to request to join the team. The Team Captain will receive an email on each request and they can then accept or decline invitations from the team tab on the Team Captain’s account page. The team name can be set by the Team Captain editing the name on the Team page under your account.

If you wish to join a team after you have already registered then you will need to change your team. Do this by using the “Change Team” form on this page: Your new Team Captain will need to accept the invitation.

Use the answer boxes on the Challenge page. You will only see this if you are the Team Captain, as only they can submit your answer. If you are not the Captain you will see a reminder of this. If your Captain is not going to be available to post the team submission for a particular round they can either delegate another member of the team as Captain, or give a deputy the Captain’s login username and password so they can submit instead. If you think you might need to do that there are things to be aware of. The erstwhile Captain cannot just take the Captaincy back, they need the new Captain to delegate it back to them. And if you share your account details then whoever knows them can post on the Forum as you.

Email us at [email protected]

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Post a query on the forum

You don’t, you have the option to say “Neither”, or “Prefer not to say” and we are happy with that. We use this data to get a picture of what the National Cipher Challenge community looks like and don’t store it with your registration info. We recognise that “Neither” could look a bit dismissive and we did consider a range of other options, but in practice we don’t need to know so probably shouldn’t be asking, though that might change in the future.

Anyone who has been following the National Cipher Challenge since it started will realise that either Harry is very, very old (and surprisingly sprightly for his age) or he has a time machine. Possibly both. He also has a PhD in Mathematics which makes him feel rather a lot like the Doctor, a comparison he does nothing to discourage. The Elves who run the forum however, violently reject the idea that they are in any sense “Companions”, and anyone who has seen an Elf fighting their way through a horde of Orcs will know that it is never wise to anger one. If you want to meet Harry you could try coming to a University of Southampton Open Day(we have one on October 13th) and identifying yourself as a Cipher Challenge fan!

The Team Captain (or anyone in the team using the Team Captain account) can submit solutions to either Part A or Part B at any time during a round by typing them into the submissions page. If you need to resubmit (because you found a mistake, or because we pointed one out to you) you can use the same form. Just paste your entry as text in the appropriate box on the form. It doesn’t matter how you format your answer with or without punctuation and spaces and whether or not you use capital letters, however you must only type or paste in the exact text of a decrypt of the message. It is a good idea to use a simple text editor to type up your solution (rather than something like Word) as the spell checker sometimes tries to change what you are typing and any “mistake” in the text might be deliberate. Don’t try to correct any errorsyou think we have made, always type in an exact decryption of the text. Don’t try to tell us what cipher we used, or to ask us a question, or to say how you solved the cipher in the entry form, we don’t read it and it will be marked as an error in the solution. If you need to get hold of us you can post a message on the forum or send us an email at

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