def _seal_message(self, message):
encrypted_message = self.outgoing_handle.update(message)<EOL>return encrypted_message<EOL>
[MS-NLMP] v28.0 2016-07-14

3.4.3 Message Confidentiality
Will generate an encrypted message using RC4 based on the
ClientSealingKey

:param message: The message to be sealed (encrypted)
:return encrypted_message: The encrypted message