Efficient Anonymous Fingerprinting with Group Signatures

Abstract

Fingerprinting schemes enable a merchant to identify the buyer of an illegally distributed digital good by providing each buyer with a slightly different version. Asymmetric fingerprinting schemes further prevent the merchant from framing a buyer by making the fingerprinted version known to the buyer only. In addition, an anonymous fingerprinting scheme allows the buyer to purchase goods without revealing her identity to the merchant. However, as soon as the merchant finds a sold version that has been (illegally) distributed, he is able to retrieve a buyer's identity and take her to court. This paper proposes a new and more efficient anonymous fingerprinting scheme that uses group signature schemes as a building block. A byproduct of independent interest is an asymmetric fingerprinting scheme that allows so-called two-party trials, which is unmet so far.