ROT-13

ROT-13 is a substitution cypher where each letter is replaced with the letter after 13 positions in the alphabet. Similar to the Caesar Shift the encryption can be written as

\begin{eqnarray*} l_{c} &=& (l_{p}+13)\mod{26} \end{eqnarray*}

and the decryption, for 26 letter alphabets is homomorphic to the encryption.

Implementations