Abstract: In a distributed data processing system, the authentication of a process at one node for the use of a service at another node is performed in a facility that is separate from the requestor and service process. The separate facility is also replaceable, thereby allowing different authentication policies to be implemented within the distributed data processing system. The requesting process and the service process merely pass the authentication information between themselves without attempting to interpret the work of the separate authentication facility. In addition to authenticating the requestor to the service, the service is also authenticated to the requestor.