Atbash Cipher

A folding cipher where the mappings are done by "folding the alphabet." This way, "a" maps to "z", "b" maps to "y", "c" maps to "x", and so on.

https://en.wikipedia.org/wiki/Atbash

Plain:    abcdefghijklmnopqrstuvwxyz
Cipher:   zyxwvutsrqponmlkjihgfedcba

Example usage:

"hello" => "svool"

"peter" => "kvgvi"

Further

Implement decode funcionality.

Further

Prompt the user for input and encode that input.

Further

Prompt the user for input and then see if they want to either encode or decode that input.

Further

The cipher assumes a character set of just letters. It doesn't include number characters.

Create the ability for the user to input their own charaacter set, abcdefghijklmnopqrstuvwxyz1234567890 for example. Then process that input so that you can encode a cipher. (reverse the order) Ask the user for some input to encode.