It is a simple text-cypher project. The program encrypt the given text according to given key
The program takes one command-line argument and this is the key you want to use.
./substitution key
Key must be 26 alphabetical characters and character repetition is not allowed.
$ ./substitution VCHPRZGJNTLSKFBDQWAXEUYMOI
plaintext: hello, world
ciphertext: jrssb, ybwsp