OASIS eXtensible Access Control Markup Language (XACML) TC

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RE: [xacml] another small time/date issue

  • 1.  RE: [xacml] another small time/date issue

    Posted 08-12-2003 19:47
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    Subject: RE: [xacml] another small time/date issue


    >We already require these values be provided, so there's no
    >complication in keeping them constant, and this certainly isn't out of
    >scope of XACML since it defines how a standard attribute should be
    >handled during policy evaluation. This has nothing to do with
    geographic
    >location or accuracy.
    
    But what if the evaluation is distributed?  It should be possible.
    Also, it may be a problem to keep them constant - PDP may not have the
    caching of data, and PIP may not be aware of the duration of the
    evaluation session.
    I do not think we should specify the architecture of PIP and for data
    paths provided from the virtual context - things like caching, sessions
    etc. are too specific to a particular implementation.
    Yes, that means that a time-based policy is not 100% portable, but
    nothing that rely on an external information source is 100% portable.
    For 100% portability this attribute has to be specified in the request,
    and is such a case we already state (do we ?) that it will be constant
    for the duration of the evaluation, and no further clarifications are
    needed.
    
    >If you refer to current-time twice in a policy where the value is being
    >supplied by the PDP, one implementation might return two slightly
    >different values while another might return the same value twice. This
    >is not likely to be a huge problem, but it does represent different
    >behavior across different applications, and it can be addressed without
    >too much difficulty.
    
    That's what I am not sure about.  Why XACML should address the value of
    time?  If it is the accuracy that you are worried about - then we have
    to specify the expected accuracy.
    
    >I'm not sure what adjusting clocks has to do with this...
    
    If your PDPs are on different machines, they may have different clocks.
    I think we should not be in the business of synchronizing them.
    
    Daniel.
    
    


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