oleg - Peer-to-Peer Systems Direct Reciprocity Incentives...

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Unformatted text preview: Peer-to-Peer Systems Direct Reciprocity Incentives Reputation Systems Incentives in Peer-to-Peer Systems Oleg Naroditsky and Weiyu Zhang December 1st, 2009 Naroditsky,Zhang P2P Incentives Peer-to-Peer Systems Direct Reciprocity Incentives Reputation Systems Outline 1 Peer-to-Peer Systems 2 Direct Reciprocity Incentives 3 Reputation Systems Naroditsky,Zhang P2P Incentives Peer-to-Peer Systems Direct Reciprocity Incentives Reputation Systems What is Peer-to-Peer? Peer-to-Peer (P2P) is a network architecture allowing network nodes (peers) to share resources (such as files) by making part of their resources available to other nodes. Each node is both a client and a server. Management can be cetralized or decentralized. Connection pattern may be structures (DHT) or unstructured (arbitrary connections). Naroditsky,Zhang P2P Incentives Peer-to-Peer Systems Direct Reciprocity Incentives Reputation Systems Example of a Peer-to-Peer System The Gnutella network introduced in March 2000. Millions of individuals participated. Six months later 2/3 users are free riding*. * E.Adar and B.A. Huberman. Free Riding on Gnutella. First Monday , Oct. 2000. Naroditsky,Zhang P2P Incentives Peer-to-Peer Systems Direct Reciprocity Incentives Reputation Systems Issues with P2P Systems The Gnutella experience lead to push in incentive systems. These systems try to address the following issues: Anonymous, on-time interactions. Free-riding (leeching) problem. Hidden actions (undetectable defections). Naroditsky,Zhang P2P Incentives Peer-to-Peer Systems Direct Reciprocity Incentives Reputation Systems Incentives in P2P Systems Possible incentive strategies proposed for P2P networks: Direct reciprocity Barter (BitTorrent) Reputation (KaZaA) Currency (MojoNation, Karma) Naroditsky,Zhang P2P Incentives Peer-to-Peer Systems Direct Reciprocity Incentives Reputation Systems Attacks Against Reputation Systems Possible strategies agaist incentive systems: Cybil attack (multiple personalities) Whitewashing attack (leech, flee, repeat) Naroditsky,Zhang P2P Incentives Peer-to-Peer Systems Direct Reciprocity Incentives Reputation Systems P2P System as a PD Game With one time interactions between strangers, there is no incentive to cooperate. Cooperate Defect Cooperate Defect C l i e n t Server s c R R / s c S T / s c P P / s c T S / Figure 2: Payoff matrix for the Generalized Prisoners Dilemma. T, R, P, and S stand for temptation, reward, punishment and sucker, respec- tively. 2.3 Generalized Prisoners Dilemma The Prisoners Dilemma, developed by Flood, Dresher, and Tucker in 1950 [22] is a non-cooperative repeated game satisfying the so- cial dilemma requirement. Each game consists of two players who can defect or cooperate. Depending how each acts, the players re-can defect or cooperate....
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oleg - Peer-to-Peer Systems Direct Reciprocity Incentives...

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