中文摘要：

提出了一种新颖的用于盗版追踪的买方卖方水印协议．在此协议中，引入的水印认证授权中心WCA，它能为买方一次生成多个数字水印，从而不需要参与买卖双方的每次数字产品交易．为了保证买方的匿名，WCA还对买方的数字证书加密，并通过买方把加密的数字证书传给卖方．此外，该水印协议还能很好地解决消费者权益、水印绑定、买方匿名、共谋、争论等问题．分析表明：提出的协议是安全有效的．

英文摘要：

In this paper, a novel buyer-seller watermarking protocol is proposed for piracy tracing. In the proposed proto- col, a Watermark Certification Authority （WCA） is introduced, that can produce many watermarks for a buyer at a time and is not required to participate in each transaction of digital content between the buyer and seller. In order to guarantee the anonymity of the buyer, the WCA also can encrypt the digital certificate of buyer and hand over the encrypted message to seller via the buyer. In addition, the proposed protocol also can resolve other problems, such as the customer right problem, the binding attack problem, the anonymity problem, the digital conspiracy problem, the dispute problem. The analyses indicate that the proposedprotocol is secure and practical.