Signatures of Reputation: Towards Trust Without Identity

Reputation systems have become an increasingly important tool for highlighting quality information and filtering spam within online forums. However, the dependence of a user's reputation on their history of activities seems to preclude any possibility of anonymity. The authors show that useful reputation information can, in fact, coexist with strong privacy guarantees. They introduce and formalize a novel cryptographic primitive they call signatures of reputation which supports monotonic measures of reputation in a completely anonymous setting.