Caesar Cipher & ROT13

What is the Caesar Cipher?

The Caesar cipher is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For example, with a left shift of 3, D would be replaced by A, E would become B, and so on.

What is ROT13?

ROT13 ("rotate by 13 places") is a special case of the Caesar cipher where the shift is exactly 13. Because the English alphabet has 26 letters, a shift of 13 means that encoding and decoding use the exact same algorithm. It is frequently used in online forums as a means of hiding spoilers, punchlines, puzzle solutions, and offensive materials from the casual glance.