Python script to decrypt file encrypted by Monaca

decrypt.py

# Blogpost: https://rz.my/2020/12/decrypting-monaca-encrypt-plugin.html
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.primitives import padding
from cryptography.hazmat.backends import default_backend
from base64 import b64decode, b64encode
import argparse

def encrypt(key, iv, data):
    cipher = Cipher(algorithms.AES(key), modes.CBC(iv))
    encryptor = cipher.encryptor()
    encrypted = encryptor.update(data) + encryptor.finalize()
    return encrypted

def decrypt(key, iv, data):
    cipher = Cipher(algorithms.AES(key), modes.CBC(iv))
    decryptor = cipher.decryptor()
    plain = decryptor.update(data) + decryptor.finalize()
    return plain

def parsekey(hash):
    key = bytes.fromhex(hash)
    iv = [ord(s) for s in hash[0:16]]
    return key, bytes(iv)

def isEncrypted(data):
    header = [24, 8, 77, 69, 1, 13, 10, 0]

def main():
    parser = argparse.ArgumentParser(description="Decrypt file encrypted by MonacaEncrypt Plugin")
    parser.add_argument("-k", "--key", help="Key Hash", action="store", default=False, required=True)
    parser.add_argument("-f", "--file", help="File to decrypt", action="store", default=False, required=True)
    args = parser.parse_args()
    key,iv = parsekey(args.key)
    with open(args.file, 'rb') as f:
        data = f.read()
    print(decrypt(key, iv, data[8:]).decode("utf-8", 'backslashreplace'))

if __name__ == '__main__':
    main()