Cryptology ePrint Archive: Report 2000/032

Anonymous Fingerprinting with Direct Non-Repudiation

Birgit Pfitzmann, Ahmad-Reza Sadeghi

Abstract: Fingerprinting schemes support copyright protection by enabling the merchant of a data item to identify the original buyer of a redistributed copy. In asymmetric schemes, the merchant can also convince an arbiter of this fact. Anonymous fingerprinting schemes enable buyers to purchase digital items anonymously; however, identification is possible if they redistribute 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 non-repudiation, 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 equally efficient 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, mainly to provide an unforgeable link to license conditions.

Category / Keywords: cryptographic protocols /

Date: received 26 Jun 2000, revised 26 Jun 2000, revised 26 Jun 2000

Contact author: sadeghi at cs uni-sb de

Available format(s): Postscript (PS) | Compressed Postscript (PS.GZ) | BibTeX Citation

Version: 20000626:212237 (All versions of this report)

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