1 / 35

DSybil: Optimal Sybil-Resistance for Recommendation Systems

DSybil: Optimal Sybil-Resistance for Recommendation Systems. Ennan Zhai Peking University enzhai@pku.edu.cn. What is the Sybil Attack ?. Sybil Nodes. Honest Nodes. How about the Current Work ?. SybilGuard SybilLimit DSybil SumUp Approach using Puzzles.

sloan
Download Presentation

DSybil: Optimal Sybil-Resistance for Recommendation Systems

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. DSybil: Optimal Sybil-Resistance for Recommendation Systems Ennan Zhai Peking University enzhai@pku.edu.cn

  2. What is the Sybil Attack ? Sybil Nodes Honest Nodes

  3. How about the Current Work ? • SybilGuard • SybilLimit • DSybil • SumUp • Approach using Puzzles

  4. Let’s recall SybilGuard … … • SybilGuard: • Bounds the number of sybil nodes accepted; • Guarantees are with high probability; • Approach: Acceptance based on random route intersection between verifier and suspect.

  5. SybilGuard Basic Insight • Undirected graph • Nodes = identities • Edges = strong trust E.g., colleagues, relatives

  6. sybil nodes SybilGuard Basic Insight Sybil Nodes may collude – the Adversary honest nodes attack edges malicious user

  7. sybil nodes SybilGuard Basic Insight But cannot search for such cut brute-force… honest nodes

  8. Normal Random Walk f a e b d c pick random edge d pick random edge e pick random edge c

  9. Random 1 to 1 mapping between incoming edge and outgoing edge Random Route f a e b d a  d d  e c randomized routing table e  d b  a c  b f  f d  c Using routing table gives Convergence Property: Routes merge if crossing the same edge

  10. Intersection Verifier Suspect Honest Nodes Sybil Nodes

  11. Intersection Verifier Suspect same intersection Sybil Nodes Honest Nodes

  12. Intersection Verifier for a given intersection

  13. The Lack of SybilGuard ? Is SybilGuard so perfect ? What is the lack of the approach ? … … … …

  14. SybilLimit SybilLimit is a novel protocol which leverages the same insight as the SybilGuard but offers dramatically improved and near-optimal guarantees. Based on the large real-world social networks, SybilLimit has been proved by the first evidence that real-world social networks are indeed fast mixing.

  15. How about DSybil ? This work aims to answer the question: Is it possible to sufficiently diminish the influence of ( a potentially unlimited number of ) sybil identities based on historical behavior ?

  16. DSybil’s Contributions ? • Defend against unlimited num of sybil; • The loss is limited; • Work proved the last optimal system; • Provide a growing defense.

  17. DSybil’s Target Scenarios ? • Recommendation Systems: • Credence: recommends content items; • Digg: recommends stories. Votes: A vote claims a certain object to be good, and this is the only kind of vote DSybil uses.

  18. Leveraging Trust The Obvious, the Subtle and the Challenge … …

  19. DSybil • Two Key Algorithms Details: • Assumes the total number of sybil identities is M (Alg-A); • Improves the algorithm so that it can tolerate an unlimited number of sybil identities, as long as the number of sybil voters on any given object is bounded within M (Alg-B).

  20. Design (Alg-A) At Most M Sybil Identities Total

  21. Design (Alg-A) Overwhelming: An object is overwhelming, if the total trust of the identities voting for the object is at least some constant c, where c > S.

  22. Example

  23. Example

  24. Discussions (Alg-A) Some Intuition about the first algorithm of DSybil … …

  25. Guarantees (Alg-A)

  26. Guarantees (Alg-A)

  27. Design (Alg-B) How about M Sybil Voters on each object ?

  28. Design (Alg-B)

  29. Discussions (Alg-B) Some Intuition about the second algorithm of DSybil … …

  30. Guarantees (Alg-B)

  31. Guarantees (Alg-B)

  32. A Growing Defense A salient property of DSybil is that its defense against attacks grows over time. The growing defense comes from 3 factors … …

  33. The Rest of DSybil Some further extensions and deeper look are in the technical report. Loosely Bounding M can also be seen in the paper and report … …

  34. My Discussions • The Sybil Attack; • Defense Mechanisms; • Future Works.

  35. Thanks !

More Related