Interoperability between federated authentication systems

Federated authentication allows users to use their home authentication credentials for gaining access to other institutions services while moving among different institutions. Different federated authentication systems have been designed and implemented. Despite simplified users mobility, one key problem in this area is that different authentication systems do not cooperate. In this paper we propose a protocol for allowing full communication between two federated authentication systems, Shibboleth a de facto standard in this context, and PAPI.