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Subject: RE: [xacml] Draft BTG Profile

(Note—I don’t think this comment will reach the list as I am an observer, not a member.  If one of you--John/David—is a Member an wants to forward this message to the list, please do so.)


In the contexts that we (in my part of DHS) have been considering similar issues, we would basically agree that there are two important “use cases” to cover, but we use slightly different terms, i.e.,


1.  Some access attributes may allow the requestor to assert them (perhaps from a pick list of “authorized purposes” for the info may be sought; perhaps with a warning (“You are asserting an authorized purpose for accessing this info.  Your access may be audited and legal action taken if it is determined that the use was fraudulent or unauthorized.”)   For the BTG scenario, the assertion of  “FIRE!” may be the ONLY access attribute required, but of course the asserted “authorized purpose” attribute might also be only one of several required attributes:  “JobRole=PassportOffice Clerk AND AuthorizedPurpose=”Validating Application”.

2.  Access may also be conditional on some environmental attribute obtained by the PDP or whatever at rule-evaluation time (and not associated with or provisioned from the requestor’s credentials or the requested resource’s metadata or value.)   Examples:  “CurrentThreatLevel; “EmergencyDeclared”.





Martin F. Smith
Director, National Security Systems
US Department of Homeland Security
NAC 19-204-47
(202) 447-3743 desk
(202) 441-9731 mobile
(800) 417-6930 page

From: xacml-return-2257-martin.smith=dhs.gov@lists.oasis-open.org [mailto:xacml-return-2257-martin.smith=dhs.gov@lists.oasis-open.org] On Behalf Of Davis, John M.
Sent: Tuesday, November 23, 2010 2:49 PM
To: David Chadwick; xacml
Subject: RE: [xacml] Draft BTG Profile




1. BTG is a common healthcare concept.  The Draft BTG profile seems to describe a concept somewhat different.  I've included a short paper which provides definitions, descriptions and requirements for BTG and "emergency access" as two distinct and different concepts within the healthcare domain.  Here is a short description from HL7's Access Control Service Functional Model:


"Break‐glass is named after the glass panel that protects a fire alarm. Everyone in the building is authorized to use the fire alarm to report a fire, but the ramifications of misuse are substantial. The fragile glass panel is sufficient to avoid accidental triggering, and it forces the user to stop and think

before acting. In the context of this document, a “Break Glass” scenario involves a situation where the access control policy will authorize the user to access certain information or functionality, but only after the user attests that one or more relevant conditions exist."


2.  As described in the draft profile, the most important concept is that the profile requires a BTG permission.  This does not match the notion of BTG as used in healthcare which is much more like a user controlled "gateway" much such as a fire alarm.  I'll explain by means of a use case:


In this healthcare scenario, a user is authorized to access patient records (has appropriate permissions).  Some records (e.g., VIP) are sequestered behind a BTG barrier.  A user attempting to access a VIP record will be presented with a warning banner indicating that the record is protected and that access will subject the user to increased auditing (and perhaps other controls such as notifications to system admins).  In any case, the requester has two options; 1) abort or 2) continue.  If 2) is chosen the record is presented.  The distinguishing characteristic is that no elevation of user permissions and no special "BTG permission" is required, the user is already in the "clinician" group authorized to view records.  This is analogous to students in a high school.  They are all members of a group who are "authorized" to pull the fire alarm.  Doing so falsely will subject the student to discipline but the student does not need the teachers authorization to pull the alarm when conditions warrant.


This is distinguished from emergency access of the first kind (normal emergency room operations).  In emergency access #1, the context of the emergency (significant harm or risk of death to the patient) needs to be presented so that the access control system evaluates the appropriate policy set (e.g. A clinician at one hospital may not be authorized access to records at another under normal conditions of “treatment”).  In emergency access #1, the XSPA SAML attribute assertion profile provides an "Emergency Access" purpose of use attribute.  This purpose of use allows the PDP to select and evaluate the appropriate policy for the "emergency" condition as opposed to normal "treatment".  Again, it is not the user permissions that are evaluated but the fundamental context of the policy environment.


There is emergency access of the second kind which is a variation of emergency access #1.  In emergency access #2, the requester makes the request for information under the purpose of use of treatment and clinical role.  Authorization to view the record under these conditions is denied (perhaps an underlying privacy policy is being enforced).  In response the clinician responds by elevating permissions by asserting the “emergency role” in the XSPA SAML Assertion profile thereby elevating privileges under the same POU of “treatment” and overriding the original policy decision. In our work in HL7 we have found the “emergency” role/permission unnecessary as POU has the added benefit of putting in place (and managing) an emergency context vice a simple role.  Emergency #2 is probably closer to what is intended by the Draft BTG profile but is significantly different from what is described above.


I believe additional discussion is warranted on the fundamental concepts of the Draft BTG profile, first to ensure common understanding of the different forms of access, the uses of policy, purpose of use and permission and second to establish sound use cases that will sufficiently clarify the purpose and conditions under which use of such a profile is warranted.   




Regards, Mike Davis, CISSP

Department of Veterans Affairs

Office of Health Information

Security Architect



-----Original Message-----
From: David Chadwick [mailto:d.w.chadwick@kent.ac.uk]
Sent: Tuesday, November 23, 2010 9:07 AM
To: xacml
Subject: [xacml] Draft BTG Profile


Dear List


about a year ago we discussed the standardisation of the Break The Glass response (see Seth Proctor's message of 17 Dec 2009) and decided that a profile to standardise the BTG response would be useful. Unfortunately Seth left Sun before we got around to writing it.


Consequently Stijn Lievens and myself from Kent have produced a first version (attached) for your consideration. I know its not in the correct format yet, but we can fix that once the technical content has been agreed.


Comments appreciated









David W. Chadwick, BSc PhD

Professor of Information Systems Security School of Computing, University of Kent, Canterbury, CT2 7NF Skype Name: davidwchadwick

Tel: +44 1227 82 3221

Fax +44 1227 762 811

Mobile: +44 77 96 44 7184

Email: D.W.Chadwick@kent.ac.uk

Home Page: http://www.cs.kent.ac.uk/people/staff/dwc8/index.html

Research Web site: http://www.cs.kent.ac.uk/research/groups/iss/index.html

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