OASIS ACAL [XACML] TC

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Re: [xacml] request's attribute assertion lifetime?

  • 1.  Re: [xacml] request's attribute assertion lifetime?

    Posted 03-16-2004 01:17
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    Subject: Re: [xacml] request's attribute assertion lifetime?


    Ok - I'm running out of steam here with Daniel, you and me repeating our 
    arguments - I'll give up...
    
    Regards, Frank.
    
    
    Polar Humenn wrote:
    
    >>I tried to argue before:
    >>
    >>"...decisions for a single time T are not very useful in practice and we rely on
    >>unspoken, implicit time-intervals for which we assume the validity of that
    >>decision."
    > 
    > 
    > I'll take issue with the above comment, especially "not very useful in
    > practice".  I might as well go home. Are any other people finding XACML
    > not very useful in this regard?
    > 
    > 
    >>and
    >>
    >>"The PEP actually makes use of that property to note implicitly or explicitly
    >>that the current time is still within an acceptable range compared to the time
    >>for which the decision was evaluated."
    >>
    >>In other words, we are already using time intervals for authorization decisions
    >>and enforcement ... maybe it's time to acknowledge that and formalize it instead
    >>of keeping it fuzzy and under the carpet.
    > 
    > 
    > The only thing that is fuzzy is the specification of the Request Handler,
    > and the PEP-PDP interface. It's fuzzy, because it isn't defined in XACML.
    > Perhaps, it may be defined some where else.
    > 
    > The Request Handler can make sure that all attributes are valid for the
    > period of time necessary to caculate, or retrieve the access decision,
    > deliver it to the PEP and have the PEP enforce the decision within that
    > time. That time interval can even be a parameter to the Request Handler.
    > "You must produce a value by time T and it must last until T+n" This means
    > that all information given to the Reqeust Handler must be valid until T+n.
    > Pretty easy stuff.
    > 
    > Furthermore, if you are looking for validity periods for cached access
    > decisions, the Request/Reply Handler can do that as well as it can
    > calculate the validity periods for all attributes and intersect them
    > together, and place that in something that wraps the decision, such as an
    > Assertion.
    > 
    > Are you looking for the PDP to calculate validity periods throughout the
    > evaluation based on what attributes it may or may look at? That means if a
    > policy doesn't look at an attribute, it's validity time doesn't enter into
    > the validity interval of the decision?
    > 
    > Cheers,
    > -Polar
    > 
    > 
    >>-Frank.
    >>
    >>--
    >>Frank Siebenlist               franks@mcs.anl.gov
    >>The Globus Alliance - Argonne National Laboratory
    >>
    > 
    > 
    
    -- 
    Frank Siebenlist               franks@mcs.anl.gov
    The Globus Alliance - Argonne National Laboratory
    


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