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Subject: RE: XACML TC Charter Revision - Strawman

Sorry to be slow on this, but there is another issue I think we need to
consider and include or explicitly reject. I will describe this informally
because it is easier to express that way and I hope will be easier to
understand. If we get some consensus we can worry about more precise

Since this bears on the use of XACML by SAML, I have cross posted this.

As I understand it the current scope of the XACML schema is to express:

1. Some policy is "this".

SAML is interested in using XACML as a means of expressing a Authorization
Policy Decisions. In other words something like:

2. The result of evaluating "this" is TRUE (or FALSE)

It seems to me that under the current charter for XACML, this should work.

However, in order to do this, SAML needs to be able to make a request for
this to be done. Presumably, making the request does not require knowing
what policies apply. Therefore it needs to be possible to say:

3. Please evaluate the policies that apply to target X. Here are some inputs
that may be needed for this decision. [The PDP will fill in any missing
values, either by observing them for itself (e.g. date/time) or by using
default values (e.g. unauthenticated subject).]

It seems to me that XACML could help with this. For example, XACML will
certainly have to define a generalized syntax for expressing the name of a

Also, if you can say:

a) True if signinglimit > $5000

Then similar syntax could be used to express:

b) Current value of signinglimit = $10,000

Any opinions?


> -----Original Message-----
> From: Damodaran, Suresh [mailto:Suresh_Damodaran@stercomm.com]
> Sent: Wednesday, June 06, 2001 7:45 PM
> To: 'xacml@lists.oasis-open.org'
> Subject: RE: XACML TC Charter Revision - Strawman
> Here is the revised TC Charter - from the lack of email on this thread
> in the past few days, I am assuming that all the comments are 
> already in.
> Notes: 
> 1. Changes from previous version: 
> 	a) "subject" has been replaced by "target"
> 	b) "CORBA CSIv2" replaced by "LDAP"
> 2. Charter is silent on the mechanisms for executing the 
> policy (PDP and
> PEP). 
> 3. Non-goals  of XACML are missing (if any of you want to 
> take a stab at it,
> please do)
>  Please send your comments.
> --------------------------------------------------------------
> --------------
> ---------------
> Product of TC
> XACML TC will define a core XML schema for representing
> entitlement policies, also called XACML
> Policy Target
> The target of a policy (hereafter referred to as "target") 
> can be any object
> that can be referenced in XML.
> Protocols and bindings
> XACML TC will define new protocols or identify bindings
> to existing protocols (e.g., XPath, LDAP) intended as means 
> of accessing and
> communicating the policies
> Scope
> XACML is expected to address fine grained control of
> authorized activities, the effect of characteristics of
> the access requestor, the authorization protocol over
> which the request is made, authorization based on classes
> of activities, and content introspection (i.e. authorization
> based on both the requestor and potentially attribute
> values within the target where the values of
> the attributes may not be known to the policy writer)
> Extensibility
> XACML core schema is extensible for as yet unknown features
> Interoperability
> XACML TC will define interoperability of XACML core schema
> with other standards.
> Simon Blackwell
> Suresh Damodaran
> Fred Moses

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