I Was Confused: Robust Accountability for Permission Delegation in Cloud Federations

Cloud federations allow cloud providers to mitigate the limitation of local resources, enabling service provision for more customers. They allow a provider to either share its unused resources with providers of other clouds or request resources from them when its own resources are not enough to respond to customer demand. Thus, access control is required to manage access to those shared resources. The service provider determines who can access cloud resources by delegating permissions for that purpose. Breakdown in accountability can occur in delegation of permissions among multiple clouds because of ambiguity regarding the interpretation of permission specifications. This paper discusses the breakdown in accountability for delegated permissions in cloud federations, and then demonstrates a trust model to achieve breakdown-robust accountability.