Physical Sciences and Mathematics Commons^™

Cryptanalysis Of Two Anonymous Buyer-Seller Watermarking Protocols And An Improvement For True Anonymity, Bok-Min Goi, Raphael C. W. Phan, Yanjiang Yang, Feng Bao, Robert H. Deng, M. U. Siddiqi

Research Collection School Of Computing and Information Systems

By combining techniques of watermarking and fingerprinting, a sound buyer-seller watermarking protocol can address the issue of copyright protection in e-commerce. In this paper, we analyze the security of two recent anonymous buyer-seller watermarking protocols proposed by Ju et. al and Choi et. al respectively, and prove that they do not provide the features and security as claimed. In particular, we show that i) the commutative cryptosystem used in Choi et. als protocol fails to prevent the watermark certification authority (WCA) from discovering the watermark (fingerprint) chosen by the buyer; ii) for both protocols, the seller can discover the watermark …