Re: [xacml] Agenda for November 15 Telecon...

[bill parducci <bill@parducci.net>]

here is a repost of pierangela's document in pdf format.

b

Pierangela Samarati wrote:

> Hi
> 
> as mentioned in the concall today al the last policy committee
> call we discussed the issue of positive (meaning permissions; e.g.,
> "this principal can access this resource") and negative authorizations
> (meaning denials: "this principal cannot access this resources").
> While it is true that you cannot do with permissions alone (many cases
> call for more flexibility), it is also true that having denials
> complicates the framework (mostly also since when you start having denials
> you start thinking of the different semantics that they can carry - and
> that who specified the rule may have intended).
> 
> i had proposed an alternative solution inspired by a recent work, which
> goes as follows. Distinguish two kinds of rules:
> 
> 1) the ones that specify sufficient conditions (which are the permissions
> above)
> 
> 2) the ones that specify necessary conditions.
> 
> instead of repeating descriptions and examples here, i am attaching you a
> file of that work where the two forms of rules are introduced (Section
> 4.2). Of course our language is different as more expressive; but that
> gives the idea.
> 
> only one thing, what i call "subject"
> there is our "principal", what i call "object" is our "resource"
> 
> pls just send me email (or post the group) for any clarification that may
> be needed, and any comments.
> 
> best
> -p

sec2001.pdf