def _init_security(self):
        """
        Initialize a secure connection to the server.
        """
        if not self._starttls():
            raise SecurityError("Could not start TLS connection")
        # _ssh_handshake() will throw an exception upon failure
        self._ssl_handshake()
        if not self._auth():
            raise SecurityError("Could not authorize connection")
Initialize a secure connection to the server.