A Review Report on Access Control Policies for XML Documents

1. A Review Report on Access Control Policies for XML Documents Aiman Rasheed Syed Akhtar Ghazi

2. Agenda • Introduction • Access Control Building Blocks • Access Policy • Conflict Resolution Policy • Generating Views for users • Updating XML • Write Access to XML • Conclusion

3. Introduction • Current trend of information sharing and retrieval. • Semi-structured to structured data • A need for generic environment? • Solution: XML • XML • Structured • User-defined Tags

4. Introduction • Access Control Building Blocks • Subject • user or a group • Object • Whole or part of XML document • Authorization Rules • Grant/Deny permissions for subject on objects.

5. /files /record @id= 9203 /member /name /diagnosis /text( ) Jeff Daan /item @id=”daan” /text( ) Pneumonia Introduction

6. Introduction • XML Document <files> <record id=9203> <member id="daan"/> <name>Jeff Daan</name> <diagnosis> <item>Pneumonia</item> </diagnosis> </record> </files>

7. Introduction • Authorization Rules • Grant/Deny permissions for subject on objects. <!-- Rule 1 --> <xas DefaultPolicy=”open" DefaultSubjectsFile="subjects.xss"> <!-- Rule 2 --> <rule <subject>users/member[@id=$user<subject/> <object> record[@id=$user]<object/> <accessmethod>read<accessmethod/> <access>deny<access/> <priority>10<priority/> /> </xas> • Conflict Resolution

8. View Generation • Compute View Algorithm • A subject, main XML doc and Authorization Rules(XAS) are input to the algorithm • Traversal the XML tree • select a node • if there is a rule for the selected node such that the given subject(user) has any permission for it • Apply Conflict Resolution Policy • if the elected rule is a ‘deny’ rule discard the node • otherwise append the node in ListofNodes.

9. Updating XML • MMDOC-QL • Insert INSERT: (<Doctor> WITH Name=%refdoc) BEFORE (<diagnosis> with item=“Pneumonia”) PATTERN: {*[A-Z][ ] /%refdoc}; FROM: hospital.xml CONTEXT: {<diagnosis> with item=“Pneumonia”);

10. Insert /files /record @id= 9203 /member /name /diagnosis /Doctor /text( ) Jeff Daan /item @id=”daan” /text( ) %refdoc /text( ) Pneumonia

11. Write Access to XML • ‘List of Nodes’ = All nodes in INSERT and CONTEXT clauses • For each node in XML tree, label whether the write access is granted or denied. • If all nodes in ‘List of Nodes’ are granted • apply insert • otherwise return error.

12. Conclusion • Discussion of Access control policy in XML • Updating XML document • Write Access policy and authorization in XML

13. Questions and Answers

14. Thankyou