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Who can take part?

  1. The competition is only open to persons aged 18 or under on 31 August 2018. We can make an exception for those who are repeating a year or have had an interrupted schooling who are still studying full time for school level or equivalent exams.
  2. Only entrants from the UK who are in full time school-level education in the United Kingdom, the Channel Islands and the Isle of Man are eligible for prizes.  (For the sake of clarity, home-schoolers in these regions do qualify). If you don’t qualify for this or age reasons please tick the “ineligible for prizes ” box when you register, it saves embarrassment!
  3. Entries may be received from teams of any size greater than or equal to 1. Each team has a designated Team Captain who is responsible for recording the team name and submitting solutions. The Captaincy may be delegated to another team member at any time from the current Captain’s account.
  4. We reserve the right to contact anyone registered for the competition via email for any matters  in connection with the competition, including the promotion of next year’s Challenge. Teams must also provide details of a teacher. Parent or Guardian who we can contact if necessary.
  5. In order to qualify for any of the prizes, all entrants, whether solo or part of a larger team agree to their team and school names being used in publicity associated with the competition including publication on the competition web-site. We will publish team member names only with your permission.

Submitting your solutions

  1. Each challenge consists of two parts, part A and part B. You may submit solutions to either or both parts of the current challenge on the entry form.
  2. Only Team Captains, or those with the Team Captain account login, can submit answers for the team.
  3. Rapid fire multiple submissions put an unreasonable load on the servers and make it difficult for others to submit. Anyone who makes an unreasonable number of submissions will be open to disqualification. In the first instance this will mean that anyone who submits more than 20 times in 10 minutes will be disqualified.
  4. A submission will only be deemed to be valid if it is submitted on the entry form and all the instructions on this site are adhered to.
  5. In submitting an entry solo entrants vouch that it is solely their own work and teams warrant that it is solely their own collective work.
  6. In submitting an entry to the competition, all entrants, whether individuals or members of a team, agree to be bound by all the rules of the competition.
  7. Use of spreadsheets, text editors and programmes you write to crack the challenges is not only allowed, it is encouraged, but remember rule 5 above, and rule 2 in the Prizes section below!

Scoring the challenge

  1. For each of the challenges 1 to 8 for which you submit an entry for part B you will be awarded a score, based on the accuracy of your best submission for that challenge and theme at which we receive the submissions. The scores will be used to determine your position on the leaderboard. The scores for Challenges 3B, 4B, 5B, 6B, 7B and 8B will be aggregated to determine the Championship Leaderboard and to decide on the winners of the main prizes, who will be chosen from among those achieving the highest total scores.
  2. A solution will only be deemed to be correct if, disregarding the punctuation [and spacing], the deciphered plaintext (only involving the Roman characters A to Z) is letter perfect as compared to our master solution. UPPER or lower case solutions will be treated the same.


  1. Winners will be notified by email and will be announced on the website. Please ensure that our messages to you are not filtered by your spam filters by adding our email address [email protected] to your address book.
  2. The competition will be judged by the Challenge Committee, whose decision will be final in all matters regarding the competition including the award of prizes. We reserve the right to take into account the methods of solution in judging the final winners, and may ask potential winners for a brief description of their methods and a copy of any programmes they wrote when making the final decision.

Variations in the rules

  1. The organisers reserve the right to change any aspect of the competition at short notice and to split prizes where it is deemed appropriate. Such changes will be announced on the competition web-site as soon as practical.
  2. The Challenge Committee may publish clues on the competition web-site if it considers it appropriate to do so.
  3. If a correct solution of a challenge is not received before the deadline given on the schedule the Challenge Committee will have the discretion to not award the prize or award some or all of it to the entrant or entrants whom it judges to represent the best (partial) solution or solutions.


  1. Anyone posting a solution or partial solution in any public forum before the deadline for the given Challenge will be disqualified and barred from the forums. Please do not publish hints without checking with us first as this may spoil the competition for others.
  2. Entrants who do not abide by the rules will be disqualified from the competition and will not qualify for any of the prizes.
  3. The challenge texts are copyright. You are licensed to use them to participate in the competition but they come with the following restriction: In analysing a Challenge text, or fully or partially deciphering it, you agree not to publish details of the encryption method or key, or to publish any part of the plain text while that Challenge is still live. The live period is published on this website for each challenge. We reserve the right to ask media platforms to remove information published about the challenge in breach of this restriction during the live period for each Challenge. You are however encouraged to discuss the challenges themselves once the final submission deadline is past.

Cookies on the site

  1. We use cookies to anonymously track usage of the website through Google Analytics. No personally identifiable information is recorded by Google Analytics’ cookies.
  2. We also use cookies to keep track of users’ activities when they login in order to facilitate the core functions of the site. We don’t request more information from you when registering for an account than is necessary to administer the competition. 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].
  3. We believe our cookie usage falls under the ‘implied consent’ part of the EU cookie legislation so we haven’t cluttered the site with a warning bar. If you are interested you can read more about the legislation on the Information Commissioner’s website here:

Your data

  1. We collect data about you solely for use in connection with the competition.
  2. We will only share that data with those who need it in order to administer the competition or prizes. This includes the competition staff at the University of Southampton and a small number of staff in the website development team and they are only permitted to use that data in connection with the competition.
  3. We will not sell your data to anyone else.
  4. We will not share your data with anyone else without your consent.
  5. We will delete your data on request, submitted in writing or by email to [email protected]
  6. Unless you ask us not to we reserve the right to contact you using your contact details with information about future challenges.