1. A Conceptual Framework for Group-Centric Secure Information Sharing Ram Krishnan (George Mason University) Ravi Sandhu, Jianwei Niu, William Winsborough (University of Texas at San Antonio) ASIACCS 2009, Sydney, Australia

2. Secure Information Sharing (SIS) A fundamental problem in cyber security – Share but protect Current approaches not satisfactory Classic models (DAC/MAC/RBAC) do not work Recent approaches Proprietary systems for Enterprise Rights Management Many solutions: IBM, CA, Oracle, Sun, Authentica, etc. Interoperability is a major issue Many languages have been standardized XrML, ODRL, XACML, etc. Primarily, dissemination or object centric 2

3. Dissemination Centric Sharing Attach attributes and policies to objects – Objects are associated with sticky policies – XrML, ODRL, XACML, etc. provide sticky policies 3 AliceBobCharlieRaviShashi Attribute + Policy Cloud Object Attribute + Policy Cloud Object Attribute + Policy Cloud Object Attribute + Policy Cloud Object Dissemination Chain with Sticky Policies on Objects Attribute Cloud

4. Group Centric Sharing (g-SIS) Advocates bringing users & objects together in a group – In practice, co-exists with dissemination centric sharing 4 Never Group Subject Leave Current Group Subject Past Group Subject Join Never Group Object Remove Current Group Object Past Group Object Add Two useful metaphors – Secure Meeting/Document Room Users’ access may depend on their participation period E.g. Program committee meeting, Collaborative Product Development, Merger and Acquisition, etc. – Subscription Model Access to content may depend on when the subscription began E.g. Magazine Subscription, Secure Multicast, etc.

5. Core g-SIS Properties JoinAdd Authz AddJoin Authz 1. Provenance: Authorization can only originate during a simultaneous period of membership 2. Bounded Authorization: Authorization cannot grow during non- membership periods 3. Persistence: Authorization cannot change if no group event occurs

6. g-SIS Operation Semantics 6 6 GROUP Authz (S,O,R)? Join Leave Add Remove Subjects Objects GROUP Authz (S,O,R)? Strict Join Strict Leave Liberal Add Liberal Remove Liberal Join Liberal Leave Strict Add Strict Remove Subjects Objects

7. Operation Semantics (Continued) 7 Strict Join (SJ): Only access objects added after Join time Liberal Join (LJ): Also access objects added before Join time Strict Leave (SL): Lose access to all objects Liberal Leave (LL): Retain authorizations held at Leave time

8. Operation Semantics (Continued) 8 Strict Add (SA): Only existing subjects at Add time are authorized Liberal Add (LA): No such restrictions Strict Remove (SR): All subjects lose access Liberal Remove (LR): Subjects who had authorization at Remove time can retain access

9. Family of g-SIS Models 9 Most Restrictive g-SIS Specification: Traditional Groups: Secure Multicast:

10. Conclusion & Future Work Group-centric Vs Dissemination-centric Focus on group operation semantics Lattice of g-SIS models Ongoing Work – Extension to other operations such as write, etc. – Multiple groups Investigate information flow Compare with Lattice Based Access Control models – Attribute Based Access Control in g-SIS 10

11. Thank You! 11 Comments & Questions Email: rkrishna@gmu.edurkrishna@gmu.edu Web: http://mason.gmu.edu/~rkrishnahttp://mason.gmu.edu/~rkrishna

12. Backup 12

13. Presentation Outline Secure Information Sharing (SIS) – Dissemination Vs Group Centric Group Centric SIS (g-SIS) g-SIS Core Properties g-SIS Operation Semantics Family of g-SIS Models Usage Scenarios Conclusions 13

14. g-SIS (continued) Never Group Subject Leave Current Group Subject Past Group Subject Join Never Group Object Remove Current Group Object Past Group Object Add Subject Membership States Object Membership States

15. Operation Semantics (Continued) 15

16. Re-visiting Metaphors Program Committee Meeting – Committee members initially enter room with LJ – Exit room with LL – Re-admitted with SJ if no access allowed to conversations during periods of absence LJ, on the other hand, will allow access Objects added with SA are accessible to existing members in the room 16