Online social networks have revolutionized the way we interact and share information over the Internet, and social networking applications such as YouTube, Flickr, MySpace, Facebook, etc., have millions of active users. While already being enormously popular, these applications only scratch the surface of online social networking possibilities. The goal of this research project is to investigate and find new and creative ways of how to make use of social networking applications to enrich people's everyday lives. Answering this question poses challenging and fascinating research problems that require both creativity and rigorous mathematical analysis. As part of the project, we are developing novel mathematical models of how online social networks are formed, and are trying to find creative ways to use the resulting network topologies to efficiently share/distributed information. While our work focuses on online social networks, our models and results also provide surprising insights into how and why the social networks that we form and use in our everyday life are so important and efficient.

One drawback of current online social networking applilcations is that sharing personal content online is surprisingly hard despite the recent emergence of a huge number of content sharing systems and sites. These systems suffer from several drawbacks: they each have a different way of providing access control which cannot be used in other systems; moving to a new system is a lengthy process and requires registration and invitation of all the friends to the new system; and the rules for access control are complicated and become more so as our networks of online friends grow.

We present the design of an access control scheme that makes sharing personal content easy. We have deployed this schme on BitTorrent and Flickr, two popular systems for sharing content online. Our scheme is based on a simple insight -- we must decouple content delivery and sharing from managing social networking information. Our scheme lets people manage their social networks themselves (e.g., through their personal address books) while letting Web sites and Internet systems deliver content. For this, we introduce two new concepts -- social attestations and social access control lists (ACLs). At a high-level, a social attestation is a small piece of meta-data issued by one person to another encapsulating a social relationship. The recipient can use this attestation to prove the social relationship to any online site or to any other user. People exchange these attestations once while reusing them to gain access to their friends' personal content scattered across different sites and systems.