Abstract

We open the new academic year with Haifeng Yu’s article on overcoming sybil attacks using social networks. In a sybil attack, a malicious user assumes multiple identities, and uses them to pose as multiple users. Sybil attacks are a threat of the new millennium – they arise in Internet-based distributed systems with a dynamic user population. Indeed, such attacks were not a concern in traditional distributed systems, where the set of participating processes was statically pre-defined. Sybil attacks are inherently difficult to deal with in systems where users do not wish to disclose binding private information, like credit card numbers. A recent popular approach for overcoming sybil attacks is using social networks. Intuitively, even if a malicious user can create many identities, he will have a hard time getting many honest users to befriend all of them in a social network. Thus, the graph structure of a social network can assist in revealing sybil nodes. In this column, Haifeng Yu presents a tutorial on how social networks can be leveraged to defend against sybil attacks, and a survey of recent suggestions employing this approach. Though Haifeng tackles the problem from a theoretical standpoint, (proving formal bounds etc.), this direction has garnered more attention from the systems community, perhaps because sybil attacks are perceived as a real threat for which social networks can provide a viable solution. Yet it appears that much theory for sybil defense using social networks

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