%A Anna C. Squicciarini %A Mohamed Shehab %A Federica Paci %T Collective Privacy Management in Social Networks %X Social Networking is one of the major technological phe- nomena of the Web 2.0, with hundreds of millions of people participating. Social networks enable a form of self expres- sion for users, and help them to socialize and share content with other users. In spite of the fact that content sharing represents one of the prominent features of existing Social Network sites, Social Networks yet do not support any mech- anism for collaborative management of privacy settings for shared content. In this paper, we model the problem of collaborative enforcement of privacy policies on shared data by using game theory. In particular, we propose a solu- tion that offers automated ways to share images based on an extended notion of content ownership. Building upon the Clarke-Tax mechanism, we describe a simple mechanism that promotes truthfulness, and that rewards users who pro- mote co-ownership. We integrate our design with inference techniques that free the users from the burden of manually selecting privacy preferences for each picture. To the best of our knowledge this is the first time such a protection mechanism for Social Networking has been pro- posed. In the paper, we also show a proof-of-concept appli- cation, which we implemented in the context of Facebook, one of today?s most popular social networks. We show that supporting these type of solutions is not also feasible, but can be implemented through a minimal increase in overhead to end-users. %C Madrid, Spain %D 2009 %P 521-521 %L www200953