Simple AES cryptography using Python

AES_Cryptography.py

#!/usr/bin/python3
# python AES_Cryptography.py -e/-d <AbsolutePathToFile>
from Crypto import Random
from Crypto.Cipher import AES
import os
import os.path
from os import listdir
from os.path import isfile, join
import hashlib
import sys


class Encryptor:
    def __init__(self, key):
        self.key = key

    def pad(self, s):
        return s + b"\0" * (AES.block_size - len(s) % AES.block_size)

    def encrypt(self, message, key, key_size=256):
        message = self.pad(message)
        iv = Random.new().read(AES.block_size)
        cipher = AES.new(key, AES.MODE_CBC, iv)
        return iv + cipher.encrypt(message)

    def encrypt_file(self, file_name):
        with open(file_name, 'rb') as fo:
            plaintext = fo.read()
        enc = self.encrypt(plaintext, self.key)
        with open(file_name + ".e2nc", 'wb') as fo:
            fo.write(enc)
        os.remove(file_name)

    def decrypt(self, ciphertext, key):
        iv = ciphertext[:AES.block_size]
        cipher = AES.new(key, AES.MODE_CBC, iv)
        plaintext = cipher.decrypt(ciphertext[AES.block_size:])
        return plaintext.rstrip(b"\0")

    def decrypt_file(self, file_name):
        with open(file_name, 'rb') as fo:
            ciphertext = fo.read()
        dec = self.decrypt(ciphertext, self.key)
        print(file_name)
        with open(file_name[:-4], 'wb') as fo:
            fo.write(dec)
        os.remove(file_name)



def driver():
    file_path=sys.argv[2]
    if sys.argv[1] == '-e':
        def startenc(file_path):
            file_name = file_path.split('\\')[-1]
            key=bytes(hashlib.sha256(file_name.encode('utf-8')).hexdigest()[:32], 'utf-8')
            enc = Encryptor(key)
            enc.encrypt_file(file_path)
            print(200,flush=True)
    elif sys.argv[1] == '-d':
        def startdec(file_path):
            file_name = file_path.split('\\')[-1].split('.e2nc')[0]
            key=bytes(hashlib.sha256(file_name.encode('utf-8')).hexdigest()[:32], 'utf-8')
            enc = Encryptor(key)
            enc.decrypt_file(f'{file_name}.e2nc')
            print(200,flush=True)
    else:
        print(404, flush=True)