DPM TEM XACML Slide Content

I just got approval to post the DHS slide content presented at the NSA sponsored Digital Policy Management (DPM) Technical Exchange Meeting (TEM) last Aug 21^st regarding the use & assessment of XACML (see below).

DHS gave an unclassified briefing to DPM TEM on NIEM Cyber Information Sharing. The briefing outlined the "Use of XACML Standard for Policies" as follows:

· XML Access Control Mark-Up Language (XACML) is key standard for interoperability

§ Version 3.0 expands the capabilities of XACML with new functions, new combining algorithms, and a new mechanism for user feedback (i.e., "advice”)

§ 2.0 policies can be translated to 3.0 policies, but the reverse is not guaranteed (in cases where new 3.0 features are used, there is no translation)

· Limited Vendor Support

§ Most vendors do not natively support XACML; Vendors that claim "XACML compliance" are typically able to communicate via the XACML request/reply messages

§ Not all vendors that claim "XACML compliance" are able to read/write XACML policies (which can seriously impact any centralized distribution of XACML policies)

§ 3.0 is relatively new, so there is no standard request/reply transport protocol (the SAML 2.0 profile for XACML 2.0 has not been updated for 3.0)

§ Conformance testing performed to-date has exposed significant shortfalls in support for the required features of the XACML policy language

§ While there are optional features of the XACML policy language that are extremely attractive (e.g., XPath attribute selectors are a perfect fit for tagged XML data), to-date support for these optional features has been found to be even more spotty than for the required features

- Richard

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