Python Script (Encryption)

Are you able to help me with a little project. What I am after is a python script that enable multiple users to encrypt and decrypt a file with a password. The password must be entered by the user via command line (not stored in the script). The encryption hash used must be SHA256. The script must have the ability to list multiple files in the index. When encrypting a file that is already in the index, have it replace the entry, rather than have duplicates. Finally, provide informative error messages when incorrect password is entered/no suitable entry exists in the index.