On Mon, Jul 16, 2012 at 6:36 PM, James A. Donald <[email protected]> wrote:
> To prevent the sybil attack, to prevent the attacker from creating very > large numbers of sybils at low cost, it must be costly to create sybils. > For it to be costly to create an identity allowed to contribute to the > reputation system, that identity first needs to provide significant > services to those already entitled to contribute to the reputation system > before it is allowed to contribute to the reputation system. > To actually trick a collaborative filtering algorithm that's looking for self-similarity, a "Sybil" (I'm not even sue if that word makes sense in this context) would need to participate in the network as a good-faith peer. After earning the network's faith, it could turn malicious, e.g. refuse to participate in the DHT, or selectively block access to an ID it has gone out of its way to cluster around. You might call that "the long con", and while I can't think of a defense against it, that's a lot of effort to go through (and you'd have to farm multiple Sybils around a particular ID in order to perpetrate an effective DoS) -- Tony Arcieri
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