AES Cipher in Python

aes_cipher.py

import base64
import hashlib

from Crypto.Cipher import AES
from django.conf import settings

AES_BLOCK_SIZE = 16
AES_KEY = settings.SECRET_KEY[:32]
AES_MODE = AES.MODE_CBC


def encrypt(plain_text: str) -> str:
    padded_plain_text = _pad(plain_text)
    iv = _get_iv(padded_plain_text)
    cipher = AES.new(AES_KEY, AES_MODE, iv)
    return base64.b64encode(iv + cipher.encrypt(padded_plain_text)).decode()


def decrypt(cipher_text: str) -> str:
    decoded_text = base64.b64decode(cipher_text.encode())
    cipher = AES.new(AES_KEY, AES_MODE, decoded_text[:AES_BLOCK_SIZE])
    return _unpad(cipher.decrypt(decoded_text[AES_BLOCK_SIZE:])).decode()


def _get_iv(string):
    return bytes(hashlib.sha512(string.encode()).hexdigest()[:AES_BLOCK_SIZE], 'utf-8')


def _pad(msg):
    return msg + (AES_BLOCK_SIZE - len(msg) % AES_BLOCK_SIZE) * chr(AES_BLOCK_SIZE - len(msg) % AES_BLOCK_SIZE)


def _unpad(msg):
    return msg[:-ord(msg[len(msg) - 1:])]