Simple code that implements basic Vigenère Cipher alghoritm in Rust

It is built using a simple pseudo-code example for implementing Vigenère cipher alghoritm. You can see it below:

m <-- length of key
for index, character in plaintext:
    ciphertext[index] <-- (character + key[index % m]) % 26
return ciphertext

However, it is made more complex in order to not encrypt the spaces and by doing so, to make encryption of whole sentences possible. Since the v0.2.0 decryption is also supported.

This program is a very simple example of Vigenère cipher alghoritm, so it takes only uppercase English letters and spaces for plaintext or ciphertext and uppercase English letters for a key. Any other symbol will not be encrypted correctly.

Plaintext: HELLO WORLD
Key: KEY
Ciphertext: RIJVS UYVJN
Decrypted ciphertext: HELLO WORLD

To change the values and the output, clone this repo and change the main function as you want in main.rs.