Minutes of XACML TC Meeting of May 1 2003

May 1, 2003 XACML TC Concall Meeting Minutes

Attendees:

(voting members)

Carlisle Adams,

Michiharu Kudo,

Anne Anderson,

Steve Crocker -- scribe,

Simon Godik,

Bill Parducci,

Hal Lockhart,

Steve Anderson,

Daniel Engovatov,

Tim Moses.

(prospective member)

Frank Siebenlist

Quorum was reached. Meeting brought to order.

1) Hal reported on his talk at the Network Applications Consortium

(NAC) Spring Meeting. NAC is a meeting of senior technical people (architects, etc.). Organizations may not join so marketing 'spin' is kept to a minimum. This year's two day meeting was centered around the theme of moving authorization into the infrastructure. Three real world scenarios were posed to six vendors, of which Hal was the one who covered XACML and SAML. The vendors spoke on the topic of how their products would address the three scenarios.

A lot of interest was shown in the standardized access control languages. Some discussion took place on what level of granularity should be covered by WAM (Web Access Method?) products. Vendors tended to a course grain approach, Hal advocated a fine grain use.

Hal reported the Burton Group lead a discussion on standardized API's for authorization at NAC. That led to a brief discussion in our phone meeting on api's. Mention was made of GARP API, the Open Group API, SAML authorization decision request as an API, and the Global Grid Forum. Frank said he worked in the same group as Cliff Newman of the GARP API but more promise now lies with the Global Grid Forum. Frank is going to send pointers and summary information on the Grid api system and its concentration on port types.

In summary, Hal reported that there was a "large appetite" for something like XACML and over the couple few years we can look forward to wide adoption of XACML.

2) Carlisle led us through a run down of the XACML 1.1 work items listed in the April 17th meeting notes.

Item A: Fully specify hierarchical resources

Simon got no feedback yet on his writeup. Comments from Seth

Proctor got waylaid but will be forwarded by Anne. Simon and Hal

clarified that the intended use of hierarchical resources is in the

specification of a policy's target (e.g. this policy applies to all

objects under this node in a tree), not in the specification of a

request (e.g. a single request can not ask for authorization of an

action for all objects under a node in the tree).

Carlisle reminded us we have set a May 29 deadline for agreement on

solutions to the work items.

Item I: Add an ID Attribute so can reference elements easily for

use with Digital Signatures

Simon proposes an XPath ID type as a candidate for this attribute

type. He is proposing changing the an anyURI type to a type ID.

There was some discussion about issues of signing a policy when the

policy contains references to XML.

Item B: Deterministic algorithm for combining obligations

Item G: Obligations in Rule Element

Michiharu-- items B and G are not yet done. On item G, he wants to

hear more on extensions to obligations.

Item E: Condition References

Item F: Properties for Conditions

Michiharu-- first proposals for these items have been posted.

Item C: References to Rules.

Anne will repost the proposal for more comments. It seems to

have been lost in the flurry.

Item H: Define any elements needed in the XACML schema for use by

a Digital Signature envelope for XACML

Anne stated that this is dropped, the SAML attribute is sufficient.

Simon and Anne had a discussion on why then do we need the ID

attribute (Item I)?

Anne-- When you sign the top policy in SAML, you need references to

the policies.

Simon-- The example in the Digital Signature document shows you how to

sign with a manifest.

Anne-- The issue is that when dereferencing a policyID, you may get a

different policy.

Various opinions on whether or not digital signatures were too complex

to be widely adopted and useful were briefly discussed.

3) Work Items beyond XACML 1.1

a) Approaches for Policy combination and compilation.

The comments by Maryann Hondo and Tony Nadalin have not been received.

General consensus (no vote) was obtained that we've agreed to the

high level architecture of his porposal and we'll move forward with

fleshing out the details. Tim discussed his writeup in terms of three

items:

1) version 4 of the use cases.

2) an algorithm for combining/merging policies into one policy.

3) a map from WFDL service or ports to XACML components. (see the

attachment to Tim's mail of 4/22/03.

Tim explained the mapping from WSPL to XACML briefly as summarized

here:

A service on a WSPL port maps to an XACML PolicySet (PS) with a

resource specifying the port and an action specifying the service.

Each aspect of the service on the port maps to a distinct policy under

the PS. E.g. reliable-messaging maps to one policy, cryptographic

security to another policy and privacy to a third policy. These

policies are combined by the PS as a conjuction (by a deny-overrides

algorithm). These policies combine their rules as a disjuction (using

a permit-overrides algorithm). The condition in each rule must be a

conjunction of predicates.

Feedback was it will need to be more readable, perhaps by starting

with an example.

The version of WSPL referenced needs to be clearly stated as the

terminology has changed from version 1.0. This will come out sometime

after 1.1, as a profile for XACML.

A target date was set for when we vote for submission of this spec as

a standard. We'll vote on it at the last general body meeting in September.

Meeting was adjorned.

Next weeks focus group adjenda is a return back to 1.1 work items.

Namely:

1) Hierarchical resources proposal

2) attribute ID's

3) other items.

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