Rudimentary text file encryption / decryption utility using a version of the vigenère cipher.
usage: ruby encrypto.rb {option | filename | keyword}
option: 0 for decrypt, 1 for encrypt
filename: name of text file to encrypt or decrypt
keyword: the keyword used to encrypt the file
If encrypting the file, the output file will be called "encrypted.txt"
If decrypting the file, the output file will be called "decrypted.txt"