Social networking sites enable individuals with common interests or backgrounds to connect and communicate online. Upon joining a social network, users can create personal profiles, create links to other members, and contact each other. Self-managed settings provide users with some control over who is able to view what profile information and contact them.

The explosion in online social networking has given rise to privacy and security concerns. In addition, users are unable to conveniently share their profile and reputation data across networks, and have to manage a different password for each site. Lightweight identity systems raise further privacy concerns and make users vulnerable to man-in-the-middle phishing attacks.

U-Prove can address these social networking challenges:

• Login convenience: By give users multiple U-Prove access tokens that are protected with a single password, users can be given a seamless single sign-on experience without introducing man-in-the-middle phishing attacks.
• Anonymous and pseudonymous identities: With U-Prove, a site can issue access tokens that enable registered individuals to strongly authenticate themselves without being identifiable. The site can control how many "personas" a user can have and can ban users who abuse their privileges.
• Minimal disclosure: U-Prove enables users of social networks to selectively disclose profile and reputation information. Anyone can vouch for profile and reputation data of other users by cryptographically certifying that data; certified data cannot be modified but can be selectively disclosed while retaining anonymity or pseudonymity.
• Cross-network data transfer: U-Prove enables users to port their profile and reputation information across networking sites, in a manner that enables recipients to verify the integrity and source authenticity of the information. Users who port their information can do so selectively and can eliminate unwanted profiling powers across networks, while network providers can retain control over how much information users can share with whom.

Some of these features are demonstrated in our showcase of an online dating portal based on U-Prove.