The number of letters shifted functions as the secret key. When we encrypt something in this way, we are using what is called a Caeser cipher. Then, each letter of the encrypted message should be replaced with the letter on the outer dial that lines up with it as found on the inner dial. One would rotate the outer dial so that 'C' on the inner dial is lined up with the 'A' on the outer one. Replacing each letter of our intended message 'AWESOME' with its outer-ring counterpart, we arrive at the encrypted message: 'CYGUQOG'Дecrypting is just as easy.

( note: the shift forward will always be one less than the number shown in the window) For letters 'Y' and 'Z', since we don't have enough letters to go 'forward 2' without surpassing the end of the alphabet, so we wrap around to the beginning, matching 'Y' with 'A' and 'Z' with 'B'. Upon inspection, we can see that almost every letter of the inner ring is now paired with a letter on the outer ring that is 2 letters 'forward' in the alphabet. In this particular model, one can also see a small '3' in the window below the inner ring's 'A', since 'A' is lined up 'C' and 'C' is the third letter of the alphabet. In the ring shown, we see this is the letter 'C'. To do this with the secret decoder ring shown below, we would turn the outside ring by some amount, noting the letter on the outer ring that then matches up with the letter 'A' on the inner ring. Secret Decoder Rings and the Caeser CipherA secret decoder ring is a device which allows one to encrypt or decrypt a message using a simple Caeser cipher.ДЄs an example, suppose you wanted to encode the word 'AWESOME'. Secret Decoder Rings and the Caeser Cipher

Shifted code decoder