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Advances in Multimedia
Volume 2008, Article ID 905065, 7 pages
Research Article

A Lightweight Buyer-Seller Watermarking Protocol

1Information Security Laborator, Institute for Infocomm Research, 21 Heng Mui Keng Terrace, Singapore 119613
2School of Information Systems, Singapore management University, Singapore 178902

Received 4 March 2008; Revised 3 June 2008; Accepted 6 June 2008

Academic Editor: Chiou-Ting Hsu

Copyright © 2008 Yongdong Wu and Hweehua Pang. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The buyer-seller watermarking protocol enables a seller to successfully identify a traitor from a pirated copy, while preventing the seller from framing an innocent buyer. Based on finite field theory and the homomorphic property of public key cryptosystems such as RSA, several buyer-seller watermarking protocols (N. Memon and P. W. Wong (2001) and C.-L. Lei et al. (2004)) have been proposed previously. However, those protocols require not only large computational power but also substantial network bandwidth. In this paper, we introduce a new buyer-seller protocol that overcomes those weaknesses by managing the watermarks. Compared with the earlier protocols, ours is times faster in terms of computation, where is the number of watermark elements, while incurring only times communication overhead given the finite field parameter . In addition, the quality of the watermarked image generated with our method is better, using the same watermark strength.