I recently came across this article discussing the privacy implications of a Facebook’s general search tool.  The tool comes into play when someone searches the name of a Facebook user using a general search engine like Google or Yahoo.  Facebook then randomly links the person being searched to eight randomly chosen “Friends” of theirs.  In addition if someone searches the name of one of your Facebook friends, there is a chance that your profile will come up if you are one of these eight friends.

It is interesting to look at this idea in terms of concepts that relate to the global friendship network and social graph theory.  If Facebook randomly generates a list of eight friends, it is more or less a random sampling of nodes from one’s social graph.  Researchers have come to show that this list of only eight friends can allow outside parties to reconstruct a person’s social graph fairly accurately and “allow marketers, governments and even criminals to understand the private relationships between different people.”

The Facebook privacy settings have been updated to allow people to opt out of being globally searchable, but I had difficulty finding out if that would prevent you from coming up as a friend in a search for someone else.   It’s scary to think that so much information could be leaked about you to the general public by just showing eight people  you interact with online. 

The article also explains how if you keep searching different listings and aggregating data, then you can approximate the entire network (something that could potentially mimic the global friendship network) fairly well.  When one considers triadic closure, it’s not hard to imagine this phenomenon of information inference. 

http://www.securecomputing.net.au/News/141835,facebook-hit-by-new-security-concerns-over-privacy-settings.aspx