Virtual private social networks

Social Networking Sites (SNSs) are having a significant impact on the social life of many people - even beyond the millions of people that use them directly. These websites usually allow users to present a profile of themselves through a long list of very detailed information. However, even when such SNSs have advanced privacy policies, users are often not aware of their settings and, on top of that, users cannot abstain from sharing a minimum set of information (e.g. name and location). Such a small set of information has been proven to be enough to completely re-identify a user [22, 25].