A Mechanism for Privacy-preserving Concurrent Collaborations in Distributed Environment∗

Several challenges come to fore while realizing collaborations among independent administrative domains in a distributed setup. Interoperability of access control models, deployed in respective collaborating domains, is one such challenge. Collaborating domains may have heterogeneous types of access control models that need to be interoperable in order to accommodate each other’s collaborating users and resources. Even, a collaboration among homogeneous access control models is not straight-forward due to the incompatible security orderings they might employ. Manageability of resulting post-collaboration domain is another challenge. Manageability and simplicity of collaboration facilitating mechanism in order to give a clear understanding of authorization flows across domains to domain administrators is important. The modifications to the pre-collaboration internal functionality of a domain should be at the minimum possible so that in case of an ephemeral/unsuccessful collaboration pre-collaboration functionality can be restored quickly. The privacy of collaboration agreement clauses is crucial for modern day globalized business environment of outsourcing and collaboration. We introduce a new mechanism to address all of the above challenges. Central to our mechanism is an overlay formation mechanism that allows domain administrators to map their collaborating entities into a new collaboration specific security ordering that is agreeable to the peer collaborator. Collaborators use overlays as interoperation interfaces. By digitally signing each other’s overlays, organizations enter into collaboration. Overlays are collaboration specific and are capable of capturing context of collaboration. A domain can enter into concurrent collaborations by defining separate overlays for each collaboration instance. This feature of concurrency leads us to ask interesting questions like; can visiting users of a collaborating domain take part in that domain’s other collaboration instances, if yes under what context? The facility of delegation provided under our mechanism allows a resulting postcollaboration domain to form further overlays, comprising entities from domains that constituted the post-collaboration domain, and enter into new collaborations.