def get_server_key(self):
try:<EOL><INDENT>return self.server_key_dict[self.host_key_type]<EOL><DEDENT>except KeyError:<EOL><INDENT>pass<EOL><DEDENT>return None<EOL>
Return the active host key, in server mode.  After negotiating with the
client, this method will return the negotiated host key.  If only one
type of host key was set with `add_server_key`, that's the only key
that will ever be returned.  But in cases where you have set more than
one type of host key (for example, an RSA key and a DSS key), the key
type will be negotiated by the client, and this method will return the
key of the type agreed on.  If the host key has not been negotiated
yet, ``None`` is returned.  In client mode, the behavior is undefined.

:return:
    host key (`.PKey`) of the type negotiated by the client, or
    ``None``.