Defending against Sybil Attacks via Social Networks(Haifeng Yu)

Title: Defending against Sybil Attacks via Social Networks

Speaker: Haifeng Yu, Department of Computer Science, National University of Singapore

Time:June 24, 3:00pm

Place:East Main Building 10-109, Tsinghua University


Peer-to-peer and other decentralized, distributed systems are known to be particularly vulnerable to sybil attacks where a malicious user pretends to have multiple (fake) identities. By controlling a large fraction of the identities in the system, the single malicious user is able to "out vote" the honest users in a wide scope of collaborative tasks.In this talk, I will present SybilLimit, a novel protocol for limiting the corruptive influences of sybil attacks. SybilLimit is based on the social network among user identities, where edges correspond to human-established trust relationship. Malicious users can create many identities but disproportionally-few trust relationships. SybilLimit exploits this observation to bound the number of fake identities, providing strong and provable end guarantees. I will further show that SybilLimits guarantee is at most a log(n) factor away from the optimal. Finally, I will present experimental results from real-world social networks to validate SybilLimits approach. I will also briefly summarize my other research thrusts.(This talk is largely based on a paper in [IEEE S&P08], available at


Haifeng Yu is currently an Assistant Professor at Department of Computer Science, National University of Singapore. Previously he was a Researcher at Intel