The idea of the Caesar Cipher is to pick an integer and shift every letter of your message by that integer. In other words, suppose the shift is k . Then, all instances of the i-th letter of the alphabet that appear in the plaintext should become the (i+k)-th letter of the alphabet in the ciphertext. You will need to be careful with the case in which i + k > 26 (the length of the alphabet). Here is what the whole alphabet looks like shifted three spots to the right:
Original: a b c d e f g h i j k l m n o p q r s t u v w x y z 3-shift: d e f g h i j k l m n o p q r s t u v w x y z a b c Using the above key, we can quickly translate the message "happy" to "kdssb" (note how the 3-shifted alphabet wraps around at the end, so x -> a, y -> b, and z -> c).
| plaintext | shift | ciphertext |
|---|---|---|
| 'abcdef' | 2 | 'cdefgh' |
| 'Hello, World!' | 5 | 'Mjqqt, Btwqi!' |
| '' | any value | '' |
Note: Python3 only