#cryptoctf2021 #!/usr/bin/env python3 from Crypto.Util import number from Crypto.Cipher import AES import os import sys import random from flag import flag def keygen(): iv, key = [os.urandom(16) for _ in '01'] return iv, key def encrypt(msg, iv, key): aes = AES.new(key, AES.MODE_CBC, iv) return aes…