Lesson 1, the Caesar shift cipher and pattern detection
The simplest cipher, but a great introduction to both the implementation and cracking of a code.Powerpoint slides
Lesson 2, frequency analysis
Cracking substitution ciphers depends on finding hidden patterns in the text. Frequency analysis is your friend and is where the mathematics begins.Powerpoint slides
Lesson 3, the affine shift cipher
This is an introduction to modular arithmetic and builds on the first two lessons.Powerpoint slides
Lesson 4, breaking the affine shift cipher using modular inverses
A look at the mathematics behind the cipher, how to solve equations in modular arithmetic, and how that helps us break the affine shift cipher using inverses in modular arithmetic.Powerpoint slides
Lesson 5, the keyword cipher
Examines how to implement a much richer family of field ciphers based on an agreed keyword, and considers how to crack one in which the word structure is given, using cribs.Powerpoint slides
Lesson 6, cracking a keyword cipher using frequency analysis and cribs
This lesson takes what we know about frequency analysis and cribs and uses it to crack a much harder example of a keyword cipher in which the word structure is hidden.Powerpoint slides
Simon Singh's Black ChamberA rich technical resource for beginners
On the state of being stuckBen Orlin muses (with Andrew Wiles!) on the natural state of a mathematician
How to crack Challenge 10B of The Kompromat FilesShow me!
Programming for cryptologists, 101
A fantastic short introduction to programming for beginners interested in using computers to break codes and ciphers.
Julian Bhardwaj, long time participant in the National Cipher Challenge and finalist in the UK Cyber Security Championship, wrote these notes and kindly offered them to us.
Download programming guide
There is a rich a variety of careers for mathematicians in just about every aspect of the economy. Here are a few that might appeal to you if you have enjoyed the Challenge
The history of the National Cipher ChallengeGet a glimpse of what you missed, or remind yourself of adventures past
The Lost Legion - National Cipher Challenge 2017Last year's challenge