Anonymous fingerprinting with direct non-repudiation

Abstract

Fingerprinting schemes support copyright protection by enabling the merchant of a data item to identifythe original buyer of a redistributed copy. In asymmetric schemes, the merchant can also convince an arbiter of this fact. Anonymous fingerprinting schemes allow buyers to purchase digital items anonymously; however, identification is possible if theyre distribute the data item. Recently, a concrete and reasonably efficient construction based on digital coins was proposed. A disadvantage is that the accused buyer has to participate in any trial protocol to deny charges. Trials with direct nonrepudiation, i.e., the merchant alone holds enough evidence to convince an arbiter, are more useful in real life. This is similar to the difference between “normal” and “undeniable” signatures. In this paper, we present an equallye fficient anonymous fingerprinting scheme with direct non-repudiation. The main technique we use, delayed verifiable encryption, is related to coin tracing in escrowed cash systems. However, there are technical differences, mainlyt o provide an unforgeable link to license conditions.