def __repr__(self):
        return "<Requirements({})>".format(self.filename.name or "")
def decrypt(self, enc):
        # enc = base64.b64decode(enc)
        iv = enc[:AES.block_size]
        cipher = AES.new(self.key, AES.MODE_CBC, iv)
        return self._unpad(cipher.decrypt(enc[AES.block_size:])).decode('utf-8')