def _get_signature(self, message):
signature = calc_signature(message, self.negotiate_flags,<EOL>self.outgoing_signing_key,<EOL>self.outgoing_seq_num, self.outgoing_handle)<EOL>self.outgoing_seq_num += <NUM_LIT:1><EOL>return signature.get_data()<EOL>
[MS-NLMP] v28.0 2016-07-14

3.4.4 Message Signature Functions
Will create the signature based on the message to send to the server.
Depending on the negotiate_flags set this could either be an NTLMv1
signature or NTLMv2 with Extended Session Security signature.

:param message: The message data that will be signed
:return signature: Either _NtlmMessageSignature1 or
    _NtlmMessageSignature2 depending on the flags set