About this Masterclass

Cryptography is a fascinating topic that makes today’s world possible. The techniques we use to keep messages secret have improved significantly over millennia, moving from very simple ideas to increasingly complex and computationally difficult as we get better at cracking codes and ciphers. Working out how to crack encryptions and read secret messages is a skill which has always been in high demand and is a very interesting career for many mathematicians.

This workshop encourages students to think strategically and logically to solve problems as they go through the basics of encryption and decryption. Focusing on transposition and substitution ciphers, where each letter is replaced or moved to create an encrypted message, we will create our own ciphers and work together to crack each other’s.

Length: 2 hours (see the session leader notes for ideas on how to shorten the Masterclass).

Resources needed

  • Copies of worksheets, as detailed in Session Leader Notes 
  • Optional: copies of student take-home activity with guidance for extension activities
  • Fixed Caesar wheel templates: 0-25, 3 and Blank. Printed from templates, as detailed in Session Leader Notes 
  • Optional: split-pins, paperclips and rotating wheel template to replace fixed wheels
  • Computer and data projector

Worksheets

01 Route cipher encryption 02 Route cipher decryption 03 Route cipher extra activities 04 Caesar shift cipher 05 Extension activity - unbreakable route cipher 06 Take-home activity - rail fence

Codewheel templates

01 0 to 25 shift wheel 02 3 shift wheel 03 Blank wheel 04 Optional: rotating wheel

Solutions

01 Solutions to worksheets 1 – 4 02 Solutions to worksheets 5 – 6

Supporting documents

Session leader notes Session slides
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