This method is called when a client passes authentication data for this
scheme. The authData is directly from the authentication packet. The
implementor may attach new ids to the authInfo field of cnxn or may use
cnxn to send packets back to the client.
This method is used to check if the authentication done by this provider
should be used to identify the creator of a node. Some ids such as hosts
and ip addresses are rather transient and in general don't really
identify a client even though sometimes they do.