AES-CBC cryptor implemented in Python.

aes-cbc-cryptor.py

#!/usr/bin/env python3

'''
Install dependencies:
$ python3 -m venv env
$ source env/bin/activate
$ python3 -m pip install -U pip pycryptodome

Usage:
$ python3 aes_cryptor.py e web.config
qhoLTUH0ah0tz6a2MFvXPQ%3D%3D
$ python3 aes_cryptor.py d qhoLTUH0ah0tz6a2MFvXPQ%3D%3D
web.config
'''

from base64 import b64encode, b64decode
from sys import argv
from urllib.parse import quote, unquote

from Crypto.Cipher import AES

key     = bytes(range(32))
mode    = AES.MODE_CBC
iv      = bytes(range(16))
cryptor = AES.new(key, mode, IV=iv)

action = argv[1]  # Pass "e" to encrypt, or "d" to decrypt.

# Encrypt a plaintext string.
if action == 'e':
    plain          =  str(argv[2]).encode()
    pad_len        =  16 - (len(plain) % 16)
    plain          += bytes([pad_len]) * pad_len
    cipher         =  cryptor.encrypt(plain)
    cipher_b64     =  b64encode(cipher).decode()
    cipher_b64_url =  quote(cipher_b64)
    print(cipher_b64_url)

# Decrypt a Base64- and percent-encoded ciphertext string.
elif action == 'd':
    cipher_b64_url = str(argv[2])
    cipher_b64     = unquote(cipher_b64_url).encode()
    cipher         = b64decode(cipher_b64)
    plain          = cryptor.decrypt(cipher).decode()
    print(plain)