Configures the engine to require/request client authentication. Following are the options :

NONE - No client authentication is requested or required.

REQUEST - Accept authentication if presented by client. If this option is set and the client chooses

  not to provide authentication information about itself, the negotiations will continue.

REQUIRED - Require client to present authentication, if not presented then negotiations will be declined.

Created by manishk on 10/2/2015.