US Patent 7216368 Information processing apparatus for watermarking digital content

This invention relates to an information processing apparatus for managing copyrights under SDMI provisions as well as the copyrights for contents distributed over the Internet. Data Enc(Kc, Content) generated by encrypting a given content using a content key Kc are recorded, along with a header (Header), certificate (Cert), data Enc(KR, Kc) generated by encrypting the content key Kc using a root key KR, and an enabling key block (EKB). The header includes a content ID (CID), a license ID (LID), a URL, and a watermark (WM), supplemented with a header signature Sig(Header). The inventive apparatus is applied to devices that provide contents.