Provisional Authorizations

Past generations of access control systems, when faced with an access request, have issued a “yes” (resp. “no”) answer to the access request resulting in access being granted (resp. denied). In this paper, we argue that for the world’s rapidly proliferating business to business (B2B) applications and auctions, “yes/no” responses are just not enough. We propose the notion of a “provisional authorization” which intuitively says “You may perform the desired access provided you cause condition C to be satisfied.” For instance, a user accessing an online brokerage may receive some information if he fills out his name/address, but not otherwise. While a variety of such provisional authorization mechanisms exist on the web, they are all hardcoded on an application by application basis. We show that given (almost) any logic L, we may define a provisional authorization specification language pASLL. pASLL is based on the declarative, polynomially evaluable authorization specification language ASL proposed by Jajodia et al. We define programs in pASLL, and specify how given any access request, we must find a “weakest” precondition under which the access can be granted (in the worst case, if this weakest precondition is “false” this amounts to a denial). We develop a model theoretic semantics for pASLL and show how it can be applied to online sealed-bid auction servers and online contracting.