1. XACML Briefing for PMRM TC Hal Lockhart July 8, 2014

2. What is XACML? n XML language for access control n Coarse or fine-grained n Extremely powerful evaluation logic n Ability to use any available information n Superset of Permissions, ACLs, RBAC, etc n Scales from PDA to Internet n Federated policy administration n OASIS and ITU-T Standard

3. OASIS XACML Standard specifies: n An Architecture l Aka: Attribute-based Access Control (ABAC) n A Policy Language l Format and Evaluation Semantics n Request Formats l XML/SOAP l JSON/REST l Programatic (OpenAz Project)

4. XACML Architecture PDP Decision Application Administration Policy Repository PEP Enforcement Client Authorities Attribute Repositories PDP Resources

5. Powerful Policy Expression n “Anyone can use web servers with the ‘spare’ property between 12:00 AM and 4:00 AM” n “Salespeople can create orders, but if the total cost is greater that $1M, a supervisor must approve” n “Anyone view their own 401K information, but nobody else’s” n “The print formatting service can access printers and temporary storage on behalf of any user with the print attribute” n “The primary physician can have any of her patients’ medical records sent to a specialist in the same practice.”

6. Key XACML Features n Federated Policy Administration l Multiple policies applicable to same situation l Combining rules to resolve conflicts n Decision may include Obligations and Advice l More than just Permit or Deny l Obligation can specify present or future action l Examples: Log request, require human approval, delete data after 30 days n Protect any resource l Web Server, Java or C++ Object, Room in building, Network Access, Web Service, Geographic Data, Health Records, etc.

7. XACML Benefits n Standard Policy Language l Investment protection l Skills reuse n Leverage XML tools n Policy not in application code l Reduce cost of changes l Consistent application l Enable audit

8. Policy Evaluation in Brief - 1 n Attribute-based access control (ABAC) n Attributes associated with Subject(s), Action, Resource or Environment n Attributes may represent static (Group) or dynamic (# of accesses) properties n PDP is stateless

9. Policy Evaluation in Brief - 2 n Policies contain Boolean expressions n If false, policy is not applicable n If true, Effect (Permit or Deny) is returned

10. Policy Evaluation in Brief - 3 n Combining Algorithms resolve conflicting policy results l Typical: Deny Overrides n Obligations which are associated with final Effect are also returned n Policies are tree structured to simplify management

11. XACML Concepts PolicySet Policies Obligations Rules Target Obligations Condition Effect Target

12. XACML Policy Tree Policy Set PolicyPolicy Set Policy Rule

13. Decision Request Interfaces n Abstract Interface defined in XML l Profiled as real protocol over SOAP l Programmatic Interfaces permitted, but unspecified n Javascript Object Notation (JSON) format l Functionally equivalent to XML/SOAP format l xacml+json MIME type approved by IANA n REST-based communications l Can carry JSON or XML format requests

14. Prior XACML Privacy work n Privacy Profile l Defines 2 Attributes – “Purpose” Category = Action or Resource l Rule to match Purposes n XSPA XACML Profile l OASIS Standard in 2009 l Based on prior work at HL7 l Defines 53 Attributes (14 Normative) l Several public interops l New Profile in progress

15. Referencing XACML in other Standards n Attributes n What ones may be needed n Category (Subject, Resource, etc.) n Precise semantics (data-type, legal values) n Policy l Agreed upon policies – normative l Example policies – illustrate potential use of attributes

16. Useful Links n XACML core specification http://docs.oasis-open.org/xacml/3.0/xacml-3.0-core-spec-os-en.doc n Privacy Profile http:// docs.oasis-open.org/xacml/3.0/privacy/v1.0/xacml-3.0-privacy-v1.0.doc n XSPA Standard http:// docs.oasis-open.org/xacml/xspa/v1.0/xacml-xspa-1.0-os.doc n Interop Policies https://www.oasis-open.org/committees/download.php/28030/XACML-20-RSA-Interop- Documents-V-01.zip https://www.oasis-open.org/committees/download.php/32225/HIMSS-OASIS-Interop- documents.zip

17. Discussion