A Secure Watermarking Scheme for Buyer-Seller Identification and Copyright Protection

A buyer-seller protocol for content rights protection deters dishonest buyers from illegally distributing bought content. This can be achieved by giving the seller the capability to trace and identify these buyers, while also allowing the seller to prove illegal acts to a third party. Many protocols have been proposed, one of the most recent being the protocol of Ahmed et al. in the EURASIP Journal on Applied Signal Processing in 2006. This protocol is interesting in that it uses a new design method, but we show that its claims of copyright infringement protection and buyer-seller identification can be defeated. We remark that the main reason for the security flaws is due to the misinterpretation of the design principles of a buyer-seller protocol, in which we give a brief definition, and further suggest a way forward in designing protocols of this nature.