Wednesday, November 4, 2009

Social Tagging to Verify Identity

Because the anonymity of the web might allow a major chunk of social network users to be dishonest, an algorithm being developed by a Duke graduate student is trying to estimate a given user's credibility by asking their friends if they're legit.

Michael Sirivianos, a PhD student in Computer Science presented FaceTrust in a talk on Tuesday.

It's a unique system he and his fellow researchers developed that uses a person's Online Social Network (OSN) and reputation among friends to verify how trustworthy they may be. He calls it "relaxed and attribute-based credentials."

In the talk entitled "On the Internet, 'Am I really not a dog?' " Michael explained the complete concept behind their system and how it could be an essential step in assessing the personality of users on social networks.

"An online world without identity credentials makes determining who to believe very difficult," Michael said.

Sites like Amazon, eBay, dating sites, Craigslist etc., might "simply ask you a question, like, if you are over 18 or not, and if you say yes, there is no other checking mechanism to determine if you are speaking the truth or not," Michael said.

The approach that Michael and his team took in solving this problem is inspired by the wisdom of crowds-- the power of user feedback. FaceTrust employs "crowd vetting," i.e., using feedback from friends to determine whether an online user's statement or assertion may be credible.

"Online Social Network users tag/vote for their friends' verifiable identity assertions. These OSN providers issue credentials on the user's assertions," Michael explained.

"We do tagging using a concept called social tagging. Currently, we use Games With a Purpose to assess the credentials. Basically, a combination of fun and serious (useful) assertions are presented to the user's friend, and they vote for a yes or no," Michael added.

Since FaceTrust utilizes OSN and friend feedback as reliable sources, it is successful in providing probabilistic assurances of a user's credibility.

"Of course a number of concerns come up- there can be dishonest users, credentials can be forged, and maybe the users don't even tag at all. Also, we need to preserve the privacy of taggers and preserve anonymity of users that present credentials."

To ensure that the feedback from only honest users is weighted in the algorithm, only friends of that user on that network can tag a user. Friending can be seen as a form of trust with high probability.

The algorithm also assumes that most honest users have friends who will not tag their honest assertions about themselves as false.

"To further ensure the fact that the feedback we collect over a large range is reliable, we employ trust transitivity via a method called Trust Inference. We use history to determine similarity. It is observed that honest friends have a history of tagging attributes about a person similarly," Michael explained.

The complete paper, entitled "FaceTrust: Assessing the Credibility of Online Personas via Social Networks" can be found here.

Michael Sirivianos completed his B.S. in Electrical and Computer Engineering at the National Technical University of Athens, and M.S. in Computer Science and Engineering at UCSD. His other projects include Free-riding in BitTorrent networks, Loud and Clear(L&C), and Dandelion.

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