Electronic Thesis and Dissertation Repository


Master of Science


Computer Science


Sylvia Osborn


The recent emergence of online social networks (OSNs) has changed the communication behaviors of thousand of millions of users. OSNs have become significant platforms for connecting users, sharing information, and a valuable source of private and sensitive data about individuals. While OSNs insert constantly new social features to increase the interaction between users, they, unfortunately, offer primitive access control mechanisms that place the burden of privacy policy configuration solely on the holder who has shared data in her/his profile regardless of other associated users, who may have different privacy preferences. Therefore, current OSN privacy mechanisms violate the privacy of all stakeholders by giving one user full authority over another’s privacy settings, which is extremely ineffective. Based on such considerations, it is essential to develop an effective and flexible access control model for OSNs, accommodating the special administration requirements coming from multiple users having a variety of privacy policies over shared items.

In order to solve the identified problems, we begin by analyzing OSN scenarios where at least two users should be involved in the access control process. Afterward, we propose collaborative access control framework that enables multiple controllers of the shared item to collaboratively specify their privacy settings and to resolve the conflicts among co-controllers with different requirements and desires. We establish our conflict resolution strategy’s rules to achieve the desired equilibrium between the privacy of online users and the utility of sharing data in OSNs. We present a policy specification scheme for collaborative access control and authorization administration. Based on these considerations, we devise algorithms to achieve a collaborative access control policy over who can access or disseminate the shared item and who cannot. In our dissertation, we also present the implementation details of a proof-of-concept prototype of our approach to demonstrate the effectiveness of such an approach. With our approach, sharing and interconnection among users in OSNs will be promoted in a more trustworthy environment.