On Fri, Jul 4, 2014 at 1:26 PM, Matt Oliveri <[email protected]> wrote:

> On Fri, Jul 4, 2014 at 3:16 PM, Jonathan S. Shapiro <[email protected]>
> wrote:> Ah! We're hung up on the distinction between permission and
> authority.
>
> Really? Is it that important to distinguish the two? What I ultimately
> care about is authority, and whether I analyze that in terms of
> permissions or with more general-purpose semantic techniques shouldn't
> matter.


The part that's important is getting it into the programmer's head that
choosing the interface specifications in a way that yields the right
transitive reflexive closure of reachable operations is the essence of
interface-based security. Since that TRC is (by definition) the difference
between permission and authority, yes, it's an important thing to consider.

And yes, it's a static approximation to controls you might do with more
general semantic techniques, but my experience is that the more general
techniques are both hard to explain and hard to understand. In the right
place, sure. But the simplest answers to manage are going to be the
conservative ones, because they are simpler to explain.


shap
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