The goal of the Authorization Interoperability activity is providing interoperability between middleware and authorization infrastructures. This is achieved by designing and implementing an authorization protocol common to OSG VO services, EGEE, Globus, and Condor. This protocol is based on the SAML profile of XACML v2.0 [XACML]. The C library that implements the profile is provided by the Globus Toolkit security group; the JAVA library by the SWITCH group of EGEE.

The authorization protocol is used by Policy Enforcement Points (PEP), i.e. resource gateways, to interact with Policy Decision Points (PDP), i.e. repository of authorization policies. For each access request, the PDP informs the PEP on whether access is granted or denied and the conditions to be enforced if access if granted. These conditions are expressed in the form of XACML Obligations and are the mechanism to restrict privileges at Grid resources.