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MobiRate [Ubicomp 2008]

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To share services, mobile devices may need to locate reputable in-range providers and, to do so, …

To share services, mobile devices may need to locate reputable in-range providers and, to do so,
they may exchange ratings with each other. However, providers may well tweak ratings to their own advantage.
That is why we have designed a new decentralized mechanism (dubbed MobiRate) with which mobile devices
store ratings in (local) tamper-evident tables and check the integrity of those tables through a gossiping protocol.
We evaluate the extent to which MobiRate reduces the impact of tampered ratings and consequently locates
reputable service providers. We do so using real mobility and social network data. We also assess computational
and communication costs of MobiRate on mobile phones.

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Transcript

  • 1. U C L (daniele quercia)
  • 2. I’m finishing my PhD @
  • 3. U niversity C ollege L ondon
  • 4. <My Research>
  • 5. Ratings on ...
  • 6. Ratings on phones
  • 7. MobiRate: how mobiles collect & store ratings
  • 8. Why ratings on mobiles?
  • 9. Daniele Quercia Situation : People exchange digital content
  • 10. drowning user (content overload) help! who will come to the rescue?
  • 11. Proposal: Accept content only from reputable people
  • 12. how mobiles collect & store ratings
  • 13. collect > store > use
  • 14. Ignorant Forgers Liars collect > store > use
  • 15. Ignorant Forgers Liars [Suspected]
  • 16. Ignorant Forgers Liars [Suspected] [Exposed]
  • 17. Ignorant Forgers Liars [Suspected] [Exposed] [Filtered Out]
  • 18. Ignorant Forgers Liars [Suspected] [Exposed] [Filtered Out] Work done: AAAI,KDD, ICDM,...
  • 19. Ignorant Forgers Liars [Suspected] [Exposed] [Filtered Out] Work done: AAAI,KDD, ICDM,... ~ø ~ø
  • 20. Ignorant Forgers Liars [Exposed] [Filtered Out] Work done: AAAI,KDD, ICDM,... MobiRate collect > store
  • 21. How to collect & store ratings?
  • 22. 1.Log (credentials) 2. Gossip (to check each credential)
  • 23. 1.Log (credentials) 2. Gossip (to check each credential)   Impractical 
  • 24. Idea behind MobiRate
  • 25. Let’s make it practical...
  • 26. 1.Sealed Log (of credentials) 2. Gossip (to check seals only)
  • 27. 1.Sealed Log (of credentials) 2. Gossip (to check seals only)    Practical
  • 28. 1.Sealed Log (of credentials) entry (rating) “ seal” (for the entry)
  • 29. 1.Sealed Log (of credentials) entry (rating) “ seal” (for the entry) “ hash chain” binding whole table
  • 30. Assumption ID is a unique public key
  • 31. Gossiping: To whom?
  • 32. To witnesses [slow down]
  • 33. Audit! [slow down] What witnesses do
  • 34. Audit! [slow down] What witnesses do Why?
  • 35. If one is ignorant If one is a forger [Suspected] [Exposed]
  • 36. Who are my witnesses Those who will share content with me
  • 37. . Who are my witnesses Like-minded familiar strangers
  • 38. 1.Sealed Log (of credentials) 2. Gossip (to check seals only)    Practical
  • 39. Does MobiRate work?
  • 40. Mobility Traces AND Social Networks Reality Mining
  • 41. Does MobiRate work?
  • 42. Does MobiRate work? <1> Is it robust to malicious individuals? <2> Does it run on phones?
  • 43. <1> robust The f factor
  • 44.  
  • 45.  
  • 46. MobiRate Oracle
  • 47. MobiRate reduces f!!!
  • 48. <2> run
  • 49. “ heaviest” protocol runs < 2sec
  • 50. “ longest” protocol completed in 2.5ms (if Bluetooth 100kb/s)
  • 51. MobiRate works  robust  runs on phones
  • 52. Ignorant Forgers is a step towards...
  • 53. … rescuing drowning user help!
  • 54. Daniele Quercia All this on … mobblog mobirate
  • 55.  
  • 56. Assumption ID is unique public key
  • 57. If not unique  Sybil attacks!
  • 58. Ignorant Forgers Liars [Exposed] MobiRate (eg, Sybils) collect > store > use
  • 59. Ignorant Forgers Liars [Exposed] Filtered Out by [ICDM07] MobiRate (eg, Sybils) collect > store > use [ICDM07] Lightweight Distributed Trust Propagation

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