Text Encrypter

This program was made to explore ways that data might be encrypted. To use it, you can build the code with this command:
gcc -o enc main.c
The usage is as follows:
./enc -d/e (-p [password] -i [input file] -o [output file]) [input]
To encrypt the string "A little piece of text." with the password "pswd", you can use the following command:
./enc -ep "pswd" "A little piece of text."
It produces this string:
&X8eA?uk;LTHPkd~{Y-aWqH
To decrypt it again, you can run this command:
./enc -dp "pswd" "&X8eA?uk;LTHPkd~{Y-aWqH"