Rotation ciphers have a long history, a famous example being the Caesar Cipher (also Caesar’s code or Caesar’s shift), a substitution cipher used to encode messages by substituting letters by other letters a fixed number of positions away in alphabetic location.
Double-encoding ROT13 results in a shift of 26, which is exactly the the original message and is the same as no encoding. This is often humorously termed 2ROT13 or ROT26.
Decrypting a rotationally encrypted message requires no key. It only requires the knowledge that rotational substitution is being used.
Interesting Words in ROT13
|Original Word||ROT13 encrypted|