XML Access ControlXML Access ControlC. Farkas, V. Gowadia, A. Jain

University of South Carolina, ColumbiaC. Farkas, V. Gowadia, A. Jain

University of South Carolina, Columbia

Research Objectives

• Research and Prototype Access Control Models that– Capture semantics of data– Provide flexible security granularity– Provide flexible conflict resolution– Provide secure document updates preserving document integrity– Provide protection against illegal inferences

• Prove security of access control models developed• Provide complexity analysis of algorithms developed

Example Approach

• RDF-based XML Access Control Language (RXACL)• RXACL Framework defines two types of protection objects:

• Simple security Objects• Association Objects

• Layered Access Control Model• User queries and data returned to user are logged in history file• Tree extension algorithms uses XML-keys to combine information viewed

by user

MedicalDb

Patient*

Allergies

Allergen*

Phone

Birthdate

Name

SSN

Race

DateDiagnosis

Physician

Prescription

*

Comments

Patient

Phone

Name

Patient

Birthdate

Race

DateDiagnosis

Comments

DTD of Patient Health Record

++

-

++

+

Node levelclassification

Object - Association levelclassification

Functional Architecture Layered Access Control

RXACL model allows enforcement of access control on association between personal information and medical information of patients.However, it allows users to access parts of association separately.

RDF-based XML Access Control Language

rxacl:Association-A0

/MedicalDb/Patient/

meddb:Association-A0

rdf:Bag

name

diagnosis

rxacl:AsscRoot

rxacl:includes

rdf:type

rdf:type

rxacl:relpath

rxacl:Rule-R0

-read

meddb:Association-A0

Alice

rxacl:Rule

rdf:type

rxacl:object

rxacl:user

rxacl:accesstype

Example: RDF representation of Rules

Example: Association Object representation

Association objects cannot be expressed at node-level, and represent a new layer (association-level) for defining access control. Note that, nodes contained in explicitly defined associations have two classifications assigned to them.

1. Query

3. Answer

5. Security notviolated

7. Returntrees

10. Return answer

2, 5, 8. Reject Query

Check securityviolations

Securitypolicy XML

Store

Tree Extension

Update History

HistoryFile

9.

6.

4.

Securityviolated

8. Security

not violated

Queryscreening

2.