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How to make and use a Caesar Wheel

Thu, 9 Apr 2020
Learn how to make and use a Caesar Wheel to encrypt messages

A Caesar wheel is a simple substitution cipher. Caesar wheels are an easy way to encrypt and decrypt messages. If you are taking part in #TheBletchleyParkChallenge, you will find the template for your Caesar wheel at the bottom of this page.

What is the Caesar cipher?

The Caesar cipher is one of the earliest known and simplest ciphers. It is a substitution cipher which means that each letter in the plaintext (original message) is ‘shifted’ a certain number of places down the alphabet. So for example with a shift of one, A would become B, B would become C and so on. It is also known as a shift cipher. It isn’t difficult to break like Enigma messages, so this is a great introduction to cryptography for new codebreakers!

Did you know? The cipher is named after Julius Caesar who is said to have used it to communicate with his generals.

The Caesar Wheel

You can create your own Caesar wheel using our template below which is a simple way to send an encrypted message to your friends. Here is a quick how-to guide for making your own Caesar wheel.

How to make a Caesar Wheel

You will need:

  • A print out of the template below
  • Scissors
  • A pen or pencil
  • Split pin
  • A friend or family member to send your secret message to (If they don’t live with you, it might be useful to send them this blog post so they can make their own Caesar wheel to decode your message!)

How to build your Caesar wheel

  1. Write the letters A-Z (capitals) clockwise in order in the boxes around the outside of the larger circle.
  2. Write the letters a-z (lower case) clockwise in order in the boxes around the outside of the smaller circle.
  3. Cut out the two circles.
  4. (Carefully!) poke a hole through the dot in the centre of each wheel.
  5. Place the smaller circle over the larger circle so that the holes line up, and join them together using a split pin. If you don’t have a split pin you can be inventive with a piece of string or a paperclip.
  6. The two circles should be able to rotate around this centre hole with respect to each other.

To find out how to use your Caesar wheel to encipher and decipher messages, download the template below.

Share your Caesar wheels with us on social media – Use the hashtag #TheBletchleyParkChallenge and tag us so we can share your creations. Good luck!

Caesar Wheel Template and Instructions