Program to encrypt and decrypt messages, as well as produce tabula recta using Giovan Battista Bellaso's Vigenère cipher.
https://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher
vigenerator.c is a working version of the program.
Run the program, and it will ask you what you want to do:
Show (T)able,
(E)ncrypt message,
or (D)ecrypt message.
The program will ask you for a key, and message (if encrypting/decrypting). If you are generating a table, it will also ask how large of a table you want.