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Reputation System Fights P2P Junk

Posted by ryuzaki0 on from the and-not-every-country-song-is-johnny-cash dept.

yeejiun writes "Many of the files that are shared on p2p networks tend to be junk. Organizations such as the RIAA and music labels regularly pollute these networks with nonsense files masquerading as real music/video files. These junk files make it difficult for users to find what they want on such p2p networks. Some researchers at Cornell University have developed a reputation system called Credence, that works on the Gnutella network, allowing users to tell the good files from the bad ones."

4 of 338 comments (clear)

  1. eDonkey by mnemonic_ · · Score: 5, Informative

    Doesn't the eDonkey2000 network already have a system like this? Users identify fakes and report them, then the phony file information propagates throughout the network and the fake file dies.

    1. Re:eDonkey by mnemonic_ · · Score: 4, Informative

      Ah, found it: donkey-fakes. eMule automatically downloads the fakes list upon startup, and prevents the files from spreading.

  2. rtfa, sucka. by knowles420 · · Score: 5, Informative

    7. Can a group of spammers game the Credence algorithm by voting thumbs-up for each others' spam ?

    No. The trustworthiness computation is designed to preclude such attacks.

    8. What happens when a large number of spammers vote each others' spam up ? Can they fool the reputation system ?

    No. Credence's reputation computation is similar to Google's PageRank, but is more general - every node computes a different rank based on its own votes. Reputation flows from a given good node along trust edges towards other nodes. Spammers can create tight cliques in which everyone votes on each others' spam, but the entire clique will be deemed untrustworthy. And if anyone in the spammer clique does a search, they will see each others' spam ranked high.

    or, just do whatever you want.
    --
    -knowles
    1. Re:rtfa, sucka. by PylonHead · · Score: 5, Informative

      No, the pot smoker is right. Your brain is too small to absorb their goodness.

      In their system there is no single "high reputation" metric. Everyone had a different reputation to each other. Three people, A, B and C. A may have a high reputation as far as B is concerned, but C thinks A has a low reputation.

      They do this by grouping people who vote the same way. So you trust the people that vote like you do.

      Assuming that you vote good files up and bad files down, you will be grouped with people who do the same. At some point, the spammers have to start voting differently than you do.. voting their spam up. This will distance them from your trust network, and cause you to value their opinion less.

      --
      # (/.);;
      - : float -> float -> float =