An Efficient Anonymous Buyer-Seller Watermarking Protocol

Abstract

In order to deter unauthorized duplication and distribution of multimedia content, the seller can insert a unique watermark with respect to each buyer into a copy of the content. Then the seller can find out the original buyer of unauthorized copies using the corresponding watermark detection or extraction algorithm. However, the accused buyer can claim that the found unauthorized copies are created and distributed by the seller herself because the watermark is embedded solely by the seller. In this paper, a watermarking protocol is proposed to make the seller embed the watermark into a copy to be sold in encryption domain so that she cannot glean the watermarked copy exactly. This prevents the buyer from claiming that an unauthorized copy may have originated from the seller. In comparison with previous solutions, the proposed scheme is more convenient for buyers as they only have to interact with one party, the seller, each time they want to buy something. Besides, the proposed scheme enables buyers to buy multimedia content anonymously. However, upon finding an unauthorized copy at a later point in time, the seller can find the related record by detecting the embedded watermark in that copy and then provide this evidence to the judge to identify the cheating buyer in the trial.