PEER-TO-PEER FILE SHARING WITH INCENTIVES  Instructor: Dr.Saleh Yosefi  Student: Amir Maboudi  maboudi.amir@yahoo.com  Urm...
PEER-TO-PEER FILE SHARING WITH INCENTIVES  Discussion: Security issues  Incentives for cooperation when uploadingPEER-TO-P...
Security issues •    Security expert Bruce Schneider is often quoted as claiming that “Security is a      process.” •    C...
Security issues • P2P applies at the several levels:        Network level:           try to break routing system        ...
Security issues • The querying process        Misforwarding queries (or responses)        Phony queries • The downloadin...
Incentives for cooperation when uploading • Monetary systems based on a global currency. • Systems based on cumulative rep...
Cumulative reputation system• Avoid interactions with nodes that do not behave.• Information about an actor that can aid i...
Cumulative reputation system• Definitions• π j > 0 is the propensity to cooperate of peer j.•    Rij is the reputation of ...
Cumulative reputation system   • Mean value of Ri :PEER-TO-PEER FILE SHARING                             22   7WITH INCENT...
Cumulative reputation system (Simulation)                                     D                                           ...
Cumulative reputation systemPEER-TO-PEER FILE SHARING                             22   9WITH INCENTIVES - 22slides
Cumulative reputation system (Theorem)PEER-TO-PEER FILE SHARING                             22          10WITH INCENTIVES ...
Cumulative reputation system (Simulation)PEER-TO-PEER FILE SHARING                             22             11WITH INCEN...
Cumulative reputation system (Simulation) Reputation of a specificMean reputation of anode j from i’sspecific node jpoin...
Cumulative reputation system (Simulation)  Individual increases indicate successful transaction for which   j was provide...
Cumulative reputation system    • Sybil Attack    • It is named after the subject of      the book Sybil    • a fictional ...
Cumulative reputation system• Sybil Attack       Also known as pseudospoofing,       An attacker acquires multiple ident...
Cumulative reputation system (Sybil Attack)                 A and B select the broadcasts advertisementmalicious node C to...
Cumulative reputation system (Sybil Attack)                             Another example for Sybil attackPEER-TO-PEER FILE ...
Cumulative reputation system (Sybil Attack)   • Preventing “Sybil attacks” :          One approach is to have a trusted a...
Trust groups• Based on trust groups• Lightweight message authentication       In the presence of both lying and spoofing ...
Trust groups (Simulation)PEER-TO-PEER FILE SHARING                             22   20WITH INCENTIVES - 22slides
Trust groups•One group’s reputation from the point of view of another.•Intra-group transactions were more frequent than in...
Game-theoretic models of P2P systems• Involve end users that behave in a rationally selfish  manner.• Peers may modify the...
References1. An introduction to communication network analysis ,    George Kesidis, 2007 , Wiley.2. Peer-to-Peer Security ...
Questions                  Thank you for your considerationPEER-TO-PEER FILE SHARINGWITH INCENTIVES - 22slides
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Peer to-peer file sharing with incentives

  1. 1. PEER-TO-PEER FILE SHARING WITH INCENTIVES Instructor: Dr.Saleh Yosefi Student: Amir Maboudi maboudi.amir@yahoo.com Urmia university course: Performance EvaluationPEER-TO-PEER FILE SHARINGWITH INCENTIVES - 22slides
  2. 2. PEER-TO-PEER FILE SHARING WITH INCENTIVES Discussion: Security issues Incentives for cooperation when uploadingPEER-TO-PEER FILE SHARINGWITH INCENTIVES - 22slides
  3. 3. Security issues • Security expert Bruce Schneider is often quoted as claiming that “Security is a process.” • Centralized or decentralized security administration . • There is a significant overload for performance in p2p. Decentralized : Very hard to manage. Centralized : single point of failure. PEER-TO-PEER FILE SHARING 22 1 WITH INCENTIVES - 22slides
  4. 4. Security issues • P2P applies at the several levels:  Network level:  try to break routing system  Block access to information by impeding queries  Partitioning the network  Application Level:  Attempt to corrupt or delete data stored in the system or in transit  User Level:  The users themselves can be the subject of attacks PEER-TO-PEER FILE SHARING 22 2 WITH INCENTIVES - 22slides
  5. 5. Security issues • The querying process  Misforwarding queries (or responses)  Phony queries • The downloading process  Content pollution (Malwares, Spam)  Worm spread through P2P file-sharing systems  Erroneous information  Discarding queries (or responses) PEER-TO-PEER FILE SHARING 22 3 WITH INCENTIVES - 22slides
  6. 6. Incentives for cooperation when uploading • Monetary systems based on a global currency. • Systems based on cumulative reputations and trust groups • Rule-based systems with memoryless "tit-for-tat" transactions – Typically involve chunk swapping rather than single-chunk (i.e., client-server) transfers. – The peer arrival rate has exponential growth . – Dealing with free riders is important . – The rule is “ tit – for - tat” . PEER-TO-PEER FILE SHARING 22 4 WITH INCENTIVES - 22slides
  7. 7. Cumulative reputation system• Avoid interactions with nodes that do not behave.• Information about an actor that can aid in the prediction of future behavior .• As transactions occur, these reputation states will change. • It serves two complementary purposes:  Guide a decision maker’s choice in selecting transaction partners  It can act as an incentive for good behavior for those who fear acquiring bad reputations. • Consequences  Bad reputation : punishment or reduced privileges and isolation.  Good reputation : motivating factor for good behavior.PEER-TO-PEER FILE SHARING 22 5WITH INCENTIVES - 22slides
  8. 8. Cumulative reputation system• Definitions• π j > 0 is the propensity to cooperate of peer j.• Rij is the reputation of j from i’s point of view.• All reputations are normalized at each node.• Gj(π j , R̄ i) is the probability that j responds positively to i’s query.• The response function has the following properties:  G is nondecreasing in both arguments  G(π, R̄) = 0 and π > 0 imply R̄ = 0  G(π,R̄) ≤ π j for all R̄ ∈ [0, 1].PEER-TO-PEER FILE SHARING 22 6WITH INCENTIVES - 22slides
  9. 9. Cumulative reputation system • Mean value of Ri :PEER-TO-PEER FILE SHARING 22 7WITH INCENTIVES - 22slides
  10. 10. Cumulative reputation system (Simulation) D C B A H E F GPEER-TO-PEER FILE SHARING 22 8WITH INCENTIVES - 22slides
  11. 11. Cumulative reputation systemPEER-TO-PEER FILE SHARING 22 9WITH INCENTIVES - 22slides
  12. 12. Cumulative reputation system (Theorem)PEER-TO-PEER FILE SHARING 22 10WITH INCENTIVES - 22slides
  13. 13. Cumulative reputation system (Simulation)PEER-TO-PEER FILE SHARING 22 11WITH INCENTIVES - 22slides
  14. 14. Cumulative reputation system (Simulation) Reputation of a specificMean reputation of anode j from i’sspecific node jpoint of viewβ = 0.15β= 0.95 0.95N= 100 Nodes PEER-TO-PEER FILE SHARING 22 12 WITH INCENTIVES - 22slides
  15. 15. Cumulative reputation system (Simulation) Individual increases indicate successful transaction for which j was provider. Reduction in sample path occur upon successful transaction for which node j was not involved. As expected, reputation converge to the nodes’ propensity to cooperate.PEER-TO-PEER FILE SHARING 22 13WITH INCENTIVES - 22slides
  16. 16. Cumulative reputation system • Sybil Attack • It is named after the subject of the book Sybil • a fictional case study of a woman with multiple personality disorder. • The name was suggested in or before 2002 by Brian Zill at Microsoft Research.PEER-TO-PEER FILE SHARING 22 14WITH INCENTIVES - 22slides
  17. 17. Cumulative reputation system• Sybil Attack  Also known as pseudospoofing,  An attacker acquires multiple identifiers in the system to undermine some function of the system.  if a single faulty entity can present multiple identities it can control a substantial fraction of the system.PEER-TO-PEER FILE SHARING 22 15WITH INCENTIVES - 22slides
  18. 18. Cumulative reputation system (Sybil Attack) A and B select the broadcasts advertisementmalicious node C to Malicious node C non-existent positions of messages of invented Nodes A and B want to send their data towards the Sink. forward their messages. Node C (yellow nodes) non-existent position of nodes overhear s them.PEER-TO-PEER FILE SHARING 22 16WITH INCENTIVES - 22slides
  19. 19. Cumulative reputation system (Sybil Attack) Another example for Sybil attackPEER-TO-PEER FILE SHARING 22 17WITH INCENTIVES - 22slides
  20. 20. Cumulative reputation system (Sybil Attack) • Preventing “Sybil attacks” : One approach is to have a trusted agency certify identities. The system must ensure that distinct identities refer to distinct entities.PEER-TO-PEER FILE SHARING 22 18WITH INCENTIVES - 22slides
  21. 21. Trust groups• Based on trust groups• Lightweight message authentication  In the presence of both lying and spoofing of reputation referrals.• Peer registration mechanismsPEER-TO-PEER FILE SHARING 22 19WITH INCENTIVES - 22slides
  22. 22. Trust groups (Simulation)PEER-TO-PEER FILE SHARING 22 20WITH INCENTIVES - 22slides
  23. 23. Trust groups•One group’s reputation from the point of view of another.•Intra-group transactions were more frequent than inter-groups.•group reputation sample path appears smoother and has a shorter transient phase than the•Depicts an reputation node’s path. individual individual sample mean reputation (within group)•Decreases in the sample path occur less frequently than in non-hierarchical system counterpart because inter-group transactions had no effect (i.e., a lower transaction rate). Reputations fluctuate about their expected mean cooperation value as in the non-hierarchical experiments. PEER-TO-PEER FILE SHARING 22 21 WITH INCENTIVES - 22slides
  24. 24. Game-theoretic models of P2P systems• Involve end users that behave in a rationally selfish manner.• Peers may modify their own "default" cooperation level.• Achieve a desired utility from the system .• At the end of each round, peers evaluate their success rate and adjust their uplink rate accordingly to maximize their net utilityPEER-TO-PEER FILE SHARING 22 22WITH INCENTIVES - 22slides
  25. 25. References1. An introduction to communication network analysis , George Kesidis, 2007 , Wiley.2. Peer-to-Peer Security - Allan Friedman, Harvard University - L Jean Camp, Harvard University3. The Sybil Attack , John R. Douceur , Microsoft Research , johndo@microsoft.com4. Cumulative Reputation Systems for Peer-to-Peer Content Distribution ,B. Mortazavi and G. Kesidis,CS&E and EE Depts,The Pennsylvania State University , University Park, PA, 16802 mortazav@cse.psu.edu and kesidis@engr.psu.edu also a member of technical staff at Verizon Wireless5. And some other Papers and websites like WikiPedia .PEER-TO-PEER FILE SHARINGWITH INCENTIVES - 22slides
  26. 26. Questions Thank you for your considerationPEER-TO-PEER FILE SHARINGWITH INCENTIVES - 22slides

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