Slide 1Sybil AttackSybil Attack Domains and SolutionsSybilGuardRandom RouteRandom Route IntersectionBounding Number of Sybil GroupsBounding Size of Sybil GroupsDiscussionSybil AttackHyeontaek Lim15-744November 12, 2010Sybil Attack•Generates multiple false identities to attack systems relying on identity•Example - Product rating–a_honest_user: 2 stars. “Not worth the money.”–another_honest_user: 1 star. “DOA.”–john: 5 stars. “Highly recommended.”–bob: 4 stars. “Well done.”–sam: 5 stars. “Excellent!”–Average: 3.4 stars (should be 1.5 stars)2051015202530Sybil Attack Domains and Solutions•Domains–Mobile networks–Auditing–Cash economics–Reputation systems•No solution applies to every caseBrian Neil Levine, Clay Shields, N. Boris Margolin. A Survey of Solutions to the Sybil Attack. 2006.SybilGuard CAPTCHA3SybilGuard•Use social network to defend against Sybil attack•No extra links btw honest nodes and sybil nodesDiagrams from authors’ slides4Random Route•1:1 mapping from incoming edge to outgoing edge–Convergent & back-traceable5Random Route Intersection•Verifier and suspect use fixed-length random route•Random routes from honest verifier & honest suspect are highly likely to intersect at some point6Bounding Number of Sybil Groups•Routes traversingsame edge traverse same intersection point•# of sybil groups <= # of attack edges7Bounding Size of Sybil Groups•Accept ~[route length] nodes per intersection point•Size of sybil group <= [route length]8Discussion•Validity–Side effects of using random routes–No real world evaluation•Limitations from using social network–Privacy concerns–Ambiguous notion of trust–Compromised nodes•Performance–High-degree
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