1. A method of controlling access to a plurality of resources in accordance with a policy, each of the resources being addressable by a set of first identifiers, at least some of the resources being addressable by a set of second identifiers, the method comprising: initializing the resources to a state that does not include any of the resources that a source is not allowed to access under the policy and are not addressable by the source with any of the second identifiers; receiving a request to access one of the resources, the request identifying said one of the resources by one of the second identifiers; determining whether said request is a read request for one of the resources identified by one of the second identifiers; and allowing the request without further evaluation of whether said request is allowable under said policy if, based on the determination, the read request references resources that are included in a list of addressable resources, wherein the request is denied when the request references a first identifier that is determined to be outside of the list of addressable resources.