公开(公告)号：GB2358313A

公开(公告)日：2001-07-18

申请号：GB0029073

申请日：2000-11-29

Applicant: IBM

Inventor： BELLWOOD THOMAS ALEXANDER ,  DUTTA RABINDRANATH ,  EILBOTT SETH AARON ,  LITA CHRISTIAN ,  RUTKOWSKI MATTHEW FRANCIS ,  STERLING MERLE DOUGLAS

IPC: G06T1/00 ,  H04N1/32

Abstract: Upon receiving a request for a document, recipient- specific identifying information for the requester is secured, including at least the TCP/IP address(es) of the client being utilized by the requester and the proxy, if any, transmitting the request from the client, and optionally including client authentication information such as userid and password or HTTP request header information such as authorization header information, "From" header information, proxy-authorization information, and user-agent header information. The recipient-specific identifying information is then compared to a watermark database for the requested document. If a match is found, the associated unique watermark is retrieved from the database. If no match is found, a unique watermark is generated for the document and associated with the recipient-specific identifying information in a new entry within the watermark database for the document. The watermark is employed to generate a uniquely watermarked version of the requested document, with the watermarked version being returned in response to the request. Subsequently, when an infringing copy of the document is located, the infringing copy is compared to the original, unwatermarked version of the document to extract the watermark. The extracted watermark is then looked up in the watermark database for the document to determine the "original" copyright infringer, and the associated recipient identifying information is retrieved.