Transcript Ontological RBAC - Onto-Med

An Ontological Implementation of a RoleBased Access Control Policy for Health
Care Information
Cristian Cocos and Wendy MacCaull
({ccocos,wmaccaul}@stfx.ca)
Centre for Logic and Information
St. Francis Xavier University, Nova Scotia
Canada
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Introduction
• Currently developing a workflow
management system for community-based
palliative and seniors’ care
• Scheduled to be deployed at several
hospitals in rural Nova Scotia
• The aim: streamlining workflow by
improving process documentation and
communication
• Collaborative project involving healthcare
entities
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Introduction
• Perils: security and privacy
• Idea: use ontological structures to
represent access control policies
• More exactly: use the classes of an
ontology to model roles, and role hierarchy
• Adopt a suitable upper-level ontology: our
choice was BFO
• Other concerns: re-use portions of existing
ontologies: SNOMED-CT, ICNP etc.
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Access control scenario
• Two types of resources in need of access
control
– Informational items
– System actions
• E.g.: database fields (patient ID, patient
name, primary diagnosis etc.) and, resp.,
actions such as form/report printing,
faxing, phoning, appointment scheduling
etc.
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Access control policy
• Roles are organized hierarchically
• Resources are organized hierarchically
• Constraints can be provided for each form
field and action individually
• Allows for disjoint roles
• Database fields can be accessed as both
read only and write
• System users may have multiple roles with
regard to the same patient
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Implementation
• BFO
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Implementation
• BFO:role branch contains the main
mechanism
• Most of the classes that populate this
branch have been imported from
SNOMED-CT
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Implementation
• Core ACO mechanisms reside under the
Clearance-Level0Role and
PermissionLevel0Role:
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Implementation
• ClearanceLevelRole classes are defined
as a union of roles that have a certain
security clearance level
• Similar story goes for
PermissionLevelRole classes
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Implementation
• All ClearanceLevelyRole roles have also
clearance level x for x  y, but not viceversa
• E.g., all information that is accessible to a
community nurse (say) is also accessible
to a clinical oncologist (a
ClearanceLevel0Role role)
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Implementation
• Relations required to tie clearance and
permission level roles with database fields
and system actions respectively
• hasWriteAccessTo and hasReadAccessTo
• writeAccessibleBy and readAccessibleBy
• invokableBy (for actions)
• hasRole/roleOf
• hasClearanceLevel/clearanceLevelOf
• permissionLevelOf
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Implementation
• Classes that represent controlled
information are children of the
BFO:generically_dependent_continuant
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Implementation
• Classes that represent controlled actions
comprise the ACO:SystemProcedure
class, which is a child of BFO:process
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Implementation
• All classes that make the subject of
access control have restrictions outlining
their clearance/permission level
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Implementation
• Finally, the last of the relevant BFO
classes is BFO:object, that contains
SNOMED’s “Homo sapiens (organism),”
which represents the main ACO rolebearer
• ACO expressivity: SROIF
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Workflow interaction
• Access control clearance is checked at
login time, by querying ACO upon user
login
• The query returns a list of GASHA form
fields and reports whose access is
forbidden to the user, and a list of system
actions permitted
• The workflow system acts accordingly, by
blocking access to the requisite actions
and information entities
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Workflow interaction
• Query examples (ALCHO DL):
• not (accessibleBy some (roleOf value
Individual1)); this reveals all the form fields
that are not accessible to Individual1
• invokableBy some (roleOf value
Individual2) returns all system actions that
Individual2 has permission to launch
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Workflow interaction
• The workflow system also uses a
knowledge base for actual palliative and
seniors’ care knowledge
• Also in ontology format (PCSO)
• PCSO will provide logic-based guidance
for the workflow at the decision points
• Decision points = points in the workflow
where it branches, and where palliative
and seniors’ care knowledge is involved in
the decision
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Workflow interaction
• PCSO interaction scenario:
• the workflow reaches a decision point
• PCSO is queried with the patient data
contained in the EHR, and furnishes
information regarding the workflow branch
that the process is recommended to follow
for that particular patient
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Workflow interaction
• PCSO interaction scenario (cont’d):
• The information returned by the query is
analyzed by the responsible physician
• Physician ultimately decides whether the
process should follows the path indicated
by the ontology query
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Future work for ACO
• Add a customization phase
• Requires implementing a workflow
mechanism that queries the patient/client on
specific access control preferences during
several predetermined phases of the
workflow
• Also implement a workflow mechanism that
builds new patient-specific access control
ontologies that will be combined with the
default ACO described above in order to
customize the access control policy for each
patient
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Future work for ACO
• Implement an emergency override
scenario (“break the glass” mechanism)
• Question: can this be implemented using a
DL-based ontology?
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References
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Bittner, T. and Smith, B. (2004) Normalizing Medical Ontologies using Basic Formal
Ontology, in Kooperative Versorgung, Vernetzte Forschung, Ubiquitäre Information
(Proceedings of GMDS Innsbruck, 26-30 September 2004), Niebüll: Videel OHG, pp. 199–
201.
Bouamrane, M.-M., Rector A. and Hurrell, M. (2009) A Hybrid Architecture for a
Preoperative Decision Support System Using a Rule Engine and a Reasoner on a Clinical
Ontology, in Polleres, A. and Swift, T. (Eds.): RR 2009, LNCS 5837, pp. 242–253,
Springer-Verlag Berlin Heidelberg 2009.
Finin, T. et al. (2008), ROWLBAC - Representing Role Based Access Control in OWL, in
SACMAT’08, June 11–13, 2008, Estes Park, Colorado, USA.
Grenon, P., Smith, B. and Goldberg, L. (2004) Biodynamic Ontology: Applying BFO in the
Biomedical Domain. In D. M. Pisanelli (ed.), Ontologies in Medicine, Amsterdam: IOS
Press, 2004, pp. 20–38.
Miller, K. and MacCaull, W. (2009) Toward Web-based Careflow Management Systems,
Journal of Emerging Techniologies in Web Intelligence, vol. 1, no. 2, pp. 137-145.
Tsoumas, B., Dritsas, S. and Gritzalis, D. (2005) An Ontology-Based Approach to
Information Systems Security Management in V. Gorodetsky et al. (eds.): MMM-ACNS
2005, LNCS 3685, Springer-Verlag Berlin Heidelberg, pp. 151 – 164, 2005.
Kazakov, Y. (2008) SRIQ and SROIQ are Harder than SHOIQ, in Baader, F. et al. (eds.),
DL 2008. Vol. 353 of CEUR Workshop Proceedings.
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