Efficient support for enterprise delegation policies

Delegation, whereby an entity gives some of its rights to other entities, is considered the cornerstone of decentralized authorization, and many access control frameworks proposed recently make delegation its central tenet. In these frameworks, delegation is commonly viewed as a transfer between two autonomous agents---the grantor and the grantee. But the situation can be considerably more complex, and more challenging, in the case the grantor belongs to an organization. Generally, employees are not autonomous agents, but their actions are subject to the regulations of their enterprise. In particular, if an employee transfers his rights to another agent, this transfer is subject to the enterprise delegation policies.In delegation frameworks, authorizing a request requires finding a valid chain of credentials that delegates the authority from the source (the local policy of the entity that serves the request) to the requester. Unfortunately, chain discovery is a computationally expensive and time consuming task. It was shown that, in the general case, chain discovery is undecidable, and in more restrictive cases, it is polynomial in the number of credentials available to the server. Verifying compliance with the terms of a delegation policy adds a considerable overhead to request authorization.This paper presents a framework that considerably reduces the time required to authorize a request. In this framework, a delegation chain is condensed into a single credential, called chained delegation certificate (CDC). A CDC attests that the owner has a certain right, and serves as proof that every link in the chain complies with the policy governing delegation of the right in question. When CDCs are used for authorization, a server does not need to verify compliance with the delegation policy, nor does it need to perform the chain discovery step, and therefore requests are served considerably faster.