Expressive rating scheme by signatures with predications on ratees

Abstract

Reputation boards are popular tools because of their useful information of products for consumers. In this paper, we propose a rating scheme for the reputation boards. The feature of our rating scheme is that it enables users to rate not only products but also their providers expressively by using digital signatures with predications on ratees. First, we define a syntax of such an expressive rating scheme. Then, we provide a generic conversion of a cryptographic primitive called an attributebased signature scheme (ABS) into an expressive rating scheme. Using a boolean formula on attributes of ratees, signatures with predications on ratees are generated, which we call expressive ratings. Public linkability of ABS is effectively used to prohibit double ratings. Also, employing an ABS scheme of the Fiat-Shamir type, we construct a concrete efficient expressive rating scheme.