def get_db_prep_value(self, value, connection=None, prepared=False):
        if self.null:
            # Normalize empty values to None
            value = value or None
        if value is None:
            return None
        value = force_bytes(value)
        if not self._is_encrypted(value):
            padding = self._get_padding(value)
            if padding > 0:
                value = value + b'\x00' + b'*' * (1 - padding)
            value = self.prefix + binascii.b2a_hex(self.cipher.encrypt(value))
        return force_text(value)
dataset/ETHPy150Open mlavin/django-all-access/allaccess/fields.py/EncryptedField.get_db_prep_value/swapped operands of `-`