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Manipulation-Resistant Reputation Systems #21

Closed jghms closed 6 years ago

jghms commented 6 years ago

Part of larger book on algorithmic game theory. This explains in detail the role of the Sybil- and Whitewashing attack in reputation systems and some possible ways of dealing with them.

jghms commented 6 years ago

Manipulation-Resistant Reputation Systems

jghms commented 6 years ago

An effective way to deal with the threat of whitewashing is to require newcomers to "pay-their-dues" and given them a initial distrust. In the example of the prisoner's dilemma veterans would defect against newcomers on the first term, and afterwards play tit-for-tat. However the overall system is less efficient than without the possibility of whitewashing. The only other way is to make it harder for veterans to obtain new pseudonyms, for example by having a neutral entity check the identity of people and only provide one free psuedonym.

jghms commented 6 years ago

One large problem in real-world reputation systems is that raters are not honest. For example on ebay rater's may not give a negative rating because they fear retaliation from the other party. Also with manual feedback there is no real incentive to provide feedback.

jghms commented 6 years ago

Two different version of sybilproofness: value-sybilproof and rank-sybilproof. The first one means that no node can increase it's reputation and the latter means that no node can obtain a higher rank than a node that has a higher ranking in the graph without sybils.