code: def _create_cipher(self, password, salt, IV):
          
          from Crypto.Protocol.KDF import PBKDF2
          from Crypto.Cipher import AES
          pw = PBKDF2(password, salt, dkLen=self.block_size)
          return AES.new(pw[:self.block_size], AES.MODE_CFB, IV)
docs: Create the cipher object to encrypt or decrypt a payload.