University of British Columbia Towards Web 2.0 Content Sharing Beyond Walled Gardens San-Tsai Sun Supervisor: Kosta Beznosov Laboratory for Education and Research in Secure Systems Engineering (LERSSE) University of British Columbia

practical problem 2 lack of usable mechanisms for secure Web 2.0 user content sharing across content and service providers (CSPs)

content sharing scenario 3 CCA scouts only Colonial Coast Adventures (CCA) Girl Scouts Alice Jenny Picasa Web Alice’s CCA scout friends in Picasa Web

question 4 how to enable useful sharing of Web 2.0 content across CSPs? can existing technologies enable this type of sharing?

secret-link approach 5 Alice Picasa Web Jenny usable for Web users easy to implement by CSPs Alice does not have control over Jenny’s sharing of secret link with others Alice has to know Jenny’s secret-link

design goals content sharing useful for average users user-centric, i.e., access policy and identity follow the user only use browser, no special software or crypto on the user computer CSPs – separation of content hosting and content sharing – not required to change their existing access- control mechanism 6

approach OpenID extension [1] to enable OpenID IdPs to use as an alternative identifier – vs. policy hosting service – role-based trust-management policy language (RT) for credentials and policies [2] – distributed membership and containment queries 7 [1] B. Adida, “EmID: Web authentication by address,” in The Proceedings of Web 2.0 Security and Privacy Workshop 2008, Oakland, California, USA, [2] N. Li, J. C. Mitchell, and W. H. Winsborough, “Design of a role-based trust-management framework,” in SP ’02 Proceedings of the 2002 IEEE Symposium on Security and Privacy, 2002

sharing scenario 8 CCA Alice Picasa Web policy service Gmail  CCA.scout  CCA.scout  CCA.scout  policy service Yahoo secret-link, memberships secret-link

access scenario 9 Picasa Web policy service Gmail  CCA CCA.scout  CCA.scout  CCA.scout  policy service Yahoo containment Jenny secret-link OpenID AOL yes/no

content sharing scenario 2 10 CCA scouts and their parents only Colonial Coast Adventures (CCA) Girl Scouts Mary Alice Jenny Picasa Web Alice’s scout friends in Picasa Web

sharing scenario 2 11 CCA Alice Picasa policy service Gmail   CCA.scout  CCA.scout  CCA.scout  policy service Yahoo Jenny policy service AOL 

  access scenario 2 12 Picasa CCA CCA.scout  CCA.scout  CCA.scout  policy service memberships secret-link yes/no policy service AOL  containment Jenny secret-link Mary policy service Gmail

progress up-to-date protocols/algorithms for distributed memberships and containment queries preliminary prototype initial performance evaluation 13

open questions what is the expressiveness of sharing control that users need? how to design useable interface for controlled sharing? how to limit transitive trust? – A trusts B  B trusts C  A trusts C how to preserve the confidentiality of credentials and policies? – CCA does not want everybody to know addresses of its scouts 14

future work investigate user needs in controlled sharing design user interface evaluate usability investigate an approach for limiting transitive trust preserve the confidentiality of credentials and policies investigate phishing/spam prevention improve performance 15

San-Tsai Sun 16  San-Tsai Sun and Konstantin Beznosov. Open problems in Web 2.0 user content sharing. Presented at iNetSec Workshop, April 23th  San-Tsai Sun, Kirstie Hawkey, and Konstantin Beznosov. Towards enabling web 2.0 content sharing beyond walled gardens. To be presented at the Workshop on Security and Privacy in Online Social Networking, August 29th 2009

literature review user content sharing practices federated identity management attribute-based access control systems distributed authorization systems current sharing solutions provided by CSPs 17

literature review results (1) is the most commonly used sharing mechanism [Voida 2006, Miller 2007, Whalen 2008] Open ID is an open and user-centric identity solution without pre-trust between CSPs and IdPs 18 S. Voida, W. K. Edwards, M. W. Newman, R. E. Grinter, and N. Ducheneaut, “Share and share alike: exploring the user interface affordances of file sharing,” in Proceedings of the SIGCHI conference on Human Factors in computing systems CHI ’06:. New York, NY, USA: ACM, 2006, pp. 221–230. A. D. Miller and W. K. Edwards, “Give and take: A study of consumer photo-sharing culture and practice,” in Proceedings of the CHI 2007, San Jose, California, USA, April 28 –May , pp. 347–356. T. Whalen, “Supporting file sharing through improved awareness,” Ph.D. Dissertation, Dalhousie University, Canada, D. Recordon and B. Fitzpatrick, “OpenID authentication final,” authentication-2 0.html, December 2007.

literature review results (2) characteristics of attribute-based access control [Li 2002] distributed authority attribute inference attribute-based delegation attribute with fields RT [Li 2002] policy language supports attribute-based credential and policy concise ( 4 types of policy statements) 19 N. Li, J. C. Mitchell, and W. H. Winsborough, “Design of a role-based trust-management framework,” in SP :’02 Proceedings of the 2002 IEEE Symposium on Security and Privacy, 2002c

secret-link approach supported by Google, Yahoo, Facebook, … a hard-to-guess URL that identifies a shared content usable for Web users Alice does not have control over Jenny’s sharing secret link with others no support for attribute-based sharing TBD: Show flicker secret link … 20