This is revised version of Caesar cipher with English Alphabet letters was designed to use for GenCyber summer camp participants. 

Older version can be found here: https://www.printables.com/model/4764-caesar-cipher-decoder-ring-english-alphabet-letter

It was used with high school students to reinforce the concept of symmetric cryptography.

The following Introduction to Caesar Cipher was borrowed from the GenCyber curriculum.

Introduction to Caesar Cipher
The Caesar cipher is one of the simplest forms of cryptography. It encrypts messages by shifting the alphabet between 1 and 25. It can’t go any higher since there are only 26 letters in the alphabet.

The direction of an alphabet shift in the Caesar cipher does matter. For example, in the chart shown below, is the cipher a left shift of 3 or a right shift of 23?

Plain: ABCDEFGHIJKLMNOPQRSTUVWXYZ
Cipher: XYZABCDEFGHIJKLMNOPQRSTUVW

Both can be correct, but if you only said “a shift of 3,” there would be confusion on which way to go. For simplicity, we will handle everything as a shift to the right.

Known Key Decryption
We will use the Ceaser cipher ring to decrypt a message.
With any type of cryptography, the key is very important. It is the key to decrypting the message. In this type of cipher, the key will determine how many spaces the ring shifts.

1.) Let’s start with a simple shift of 1. To decrypt the message, shift the top of the ring 1 space to the right; you will change the bottom letter into the top letter.
Your cipher ring should look like this:

Ciphertext: HFODZCFS Key: Rotate 1 Answer: _____________________

2.) Not too bad, right? Let’s try a harder one. This one has a shift of three. Your cipher ring will look a bit different.
Your cipher ring should look like this:

Ciphertext: GR RU GR QRW WKHUH LV QR WUB Key: Rotate 3 Answer: ___________________________________

More lab examples and copy of multi-color for Prusa MMU2S files are available upon request.