# How do you determine the recorded value of a cipher when using the shift key?

I am taking a cryptography class and having a hard time understanding how to utilize Ceasar Cipher and how to determine the shift key values. Is it based on many characters are in the cipher or is it something different?

• The mathematical formula is $c = p + key \bmod n$. Here the $n$ is the size of the alphabet, $p$ is a character from the alphabet and as one can see the $c$ is also another one that $p$ is mapped. The $key$ is 3 is Caesar cipher and it can be any value between 0 and $n-1$, of course 0 means no encryption. Note that the letters of the alphabet are numbered from 0 to n-1. – kelalaka Jun 22 at 16:10