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Subject: [xacml] Obligations
I don't like the proposal that if the PEP cannot perform all intended obligations on a Permit that the access decision should be "Deny". It really begs the question of the PDP knowing what the PEP can or cannot fulfill in its policy evaluation, because it implies that if the obligation cannot be fulfilled by the PEP, that according to the proposal, it is actually really a Deny. Even leaving the PDP out of it, the PEP may not know if it could fulfill any operations until the PEP actually tries it. In simplist scenario, the obligation may not even terminate, or may be something like "delete record after 60 days" as has been pointed out. I think there may solution for that problem which is illustrated in a paper by Nafty Minsky. It's quite old, 1985, but might be to the point. The citation is below. I'll put the approach in our context: Since the PDP is asked by the PEP for a specific access request, we might want the PEP (or some other entity under control of the PEP) to keep track of enacted obligations and make sure that they are fulfiled. Obligations have the form of a triple of (deed,deadline,saction) where the semantics are to the PEP: The obligation says that the deed must be fullfilled by the deadline, or else the sanction will be executed (i.e. rectifying the situation). No, the sanction cannot be "deny". You have to take the following philosophy: Access has been granted with certain obligations and if obligations are not fullfiled (by the deadline), then something is done to rectify the situation, i.e. possibly: for being granted access some punishment is upon you for not fullfilling the obligations. This approach allows the PDP to tell the PEP what to do in the event that the PEP cannot enforce the obligations to be met, within some time frame, instead trying to figure out whether obligations like (delete record in 60 days) can be fullfiled. The Citation. It is avalable off of the ACM Portal. Proceedings of the 8th international conference on Software engineering 1985 , London, England Ensuring integrity by adding obligations to privileges Authors Naftaly H. Minsky Abe D. Lockman Sponsors IEEE-CS : Computer Society SIGSOFT : ACM Special Interest Group on Software Engineering Publisher IEEE Computer Society Press Los Alamitos, CA, USA Pages: 92 - 102 Proceeding-Article Year of Publication: 1985 ISBN:0-8186-0620-7 Cheers, -Polar
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