About the competition

A web based national schools competition designed to stretch the ingenuity of the UK's young mathematicians.

The fourth University of Southampton National Cipher Challenge is a cipher cracking competition which consists of a sequence of 8 enciphered messages to be published on this web site between September 29th and December 8th 2005. For each part A challenge there will be a variety of small prizes awarded: we will select a number of winners drawn at random from among those submitting a correct entry for that challenge. Speed of submission is not important in the consideration of these awards. If your first submission for either part A or part B contains a mistake don't worry, you can try again. For the part B Challenge speed and accuracy are vital, with an emphasis on accuracy. For each part B Challenge you will be awarded a score will be based on the speed of your most accurate entry. So if you submit two solutions to Challenge 1B and your second entry is more accurate than your first then the time of submission of the second entry will be used to calculate your score, whereas (and it does happen) if your first entry was more accurate we will use the time of your first entry. At the end of the competition the individual or team with the highest score will be declared the National Cipher Challenge Champions for 2005 and they will win the Championship prize. Other prizes may be announced later. See more details below. The schedule for the publication of messages, the solution deadlines and a list of the prizes can be found below; note that all challenges will be published at 4pm on a Thursday, here and at EducationGuardian.co.uk. The enciphered messages correspond to a series of encrypted messages passing between the protagonists in our tale of espionage, based at the dawn of the space age in the late 1950's. Throughout the adventure you will be travelling on the Michael5, a submarine patrolling the waters of the arctic ocean, in the company of Harry Schultz Vandiver, a mathematician, cryptographer, secret agent and private eye. Harry will act as your guide. His notebook, the boat's log, will contain hints about how to tackle the challenges as well as news about the challenge and links to the Honours board where we will list all the correct entries. The part A challenges and the early part B challenges are very straightforward, and you can find help with their decryption in the Teachers' Notes which you can download in PDF format. Some of the messages give clues to the ciphers used in subsequent messages, but it is not necessary to solve all the messages. Solutions to messages will appear as the competition proceeds, and you will find links to the solutions in the boat's log. The competition, is open to students attending full-time education in schools in the UK (together with the Channel Islands), who will be 18 years or under on 31 August 2006 . In order to take part you will need to register on our registration page. You will be asked for your age, the name of your school and an email address where you can be contacted. You will also be asked to provide a username and password for submitting entries to the competition. If you do forget your password, you can ask for it to be resent by email.

Information for teachers

The competition is designed so that participants on the Cipher Challenge trail will learn not only about ciphers but also some mathematics, science and engineering and the social and cultural context of the time. However to colour the story there are a few anachronisms and historical inconsistencies, so watch out! Our teachers pack includes an introduction to substitution ciphers together with three lesson plans which may be useful in helping you to explore the understanding of simple encipherment and decryption techniques with interested pupils. We have set the release time for each challenge to 4pm on a Thursday in the hope that pupils will be able to use School IT resources at that time. If you have a Maths Club already perhaps they could be organised into teams to tackle the challenges, and if not this might be a good project for a short term Cipher Club. Bruce Schneier and Niels Ferguson, two of the world's top cryptographers have described cryptography as "Just about the most fun you can have with mathematics " and we are inclined to agree with them. We hope that this competition will help you in the task of enthusing students. If it does let us know, and if it doesn't let us know that too. We are always looking for ways to improve the competition.

Why should we take part?

Because it is fun? Because it is stimulating? Because it really works? Last year the competition attracted entries from over 3,000 students at over 300 UK schools. They didn't all finish the Challenge, but feedback from competitors, parents and teachers was extremely enthusiastic about the Challenge. It can really grip the imagination and reveals a dedication to problem solving that Maths teachers don't always see in their pupils, sometimes in the least likely cases. If you want to hear more we have a couple of case studies for you to look at, one concerning a group in Nottingham, and another from a school in Southampton which will be published on the web site soon.
Teacher's Pack — notes and lesson plans for use in the class or after school.

About the Challenges

The part A challenges will consist of encrypted messages from the crew of the Michael 5. These might consist of a letter from the commander of the boat to Harry containing information about their orders, or it might be a briefing note from Harry to you about the latest Challenge. It is always possible that the part A challenge contains information that will help you crack the part B challenge. Since the part A challenge is only transmitted onboard the Michael5 security is not a serious concern and these messages will be lightly encrypted.
The part B challenges will consist of intercepts, either messages overheard by headquarters monitoring surface traffic and transmitted to the boat using a secure channel, or a signal intercepted by the boat's radio room. These messages will be encrypted using a more secure system, then transmitted in morse code, so it might pay for you to examine morse code, though in fact it is not necessary in the early stages if you don't mind tackling frequency analysis of morse signals. On the other hand it can't hurt!

The story so far ...

It is late 1959 and the space race has begun. Both the Russians and the Americans have successfully launched satellites into earth orbit and the competition to build a network of spy satellites has begun in earnest. Despite superior resources the American programme is hampered by internal politics and the US team is anxious to discover as much as possible about the technology of their Soviet rivals. Against this background the Michael5 receives a signal to investigate the wreckage of a fallen soviet satellite which is believed to have been ejected from an R7 rocket which exploded soon after launch. A US navy reconnaissance pilot who viewed the crash has given search coordinates and reported soviet naval activity in the region. As the only US covert ship in the region the Michael5 is ordered to investigate and to recover as much data concerning the satellite as possible without revealing US involvement.
The signals officer on board the Michael5 is Harry Schultz Vandiver. It is his job to monitor the soviet communications as they too hunt for the downed satellite, and to decipher their messages. Harry needs your help ...

Tips and tricks

One of the most arduous tasks in code breaking is the writing out of the broken message while you are cracking the cipher. Even if you don't know any programming you can easily use a computer to help with this. The idea is to use a word processor like Word or Text Edit to replace symbols from the ciphertext with their plaintext counterparts using search and replace. One way of doing this is as follows:
Paste the ciphertext into a new document and if it is not already in capital letters change the case so it is. Now suppose that you know that the plaintext letter e is represented by the ciphertext character V. Do a global search and replace on the document to replace every uppercase (capital) letter V with a lower case letter e. Make sure that the search and replace is case sensitive! Now if you know that the plaintext s is represented by the ciphertext Q replace all occurrences of Q by s and so on. This can be automated using scripts in Excel or another spreadsheet, or if you might want to try and use a programming language to write a simple programme to make the changes for you. In the past competitors have used Visual Basic, C and Perl to speed up their decryptions this way. Note that this method only works (in this simple way) for monoalphabetic ciphers like the Caesar shift or the affine shift ciphers, but if you are lucky they may play a role, at least in the early stages of the competition!