Watermark embedding processing method, watermark embedding processing system, the service provider device and customer equipment, as well as program

摘要

PPROBLEM TO BE SOLVED: To allow a watermark to be embedded while keeping a watermark embedding function, a content, etc. secret. PSOLUTION: A service provider device holds a watermark embedding function A(x, y), and a client device holds a content C and watermark information I. The function A(x, y) takes C and I as input and outputs a content with watermark C'=(C, I) wherein I is embedded into C. The service provider device converts the function A(x, y) to a function B(x, y) in preprocessing. The function B(x, y) cannot obtain C' by input of C and I but outputs C' by input of CSP-/SPand I. The service provider device transmits the function B to the client device in response to a request for watermark embedding from the client device. Hereafter, 2-party protocols are executed between both of them, and the client device obtains CSP-/SPwhile keeping C secret from the service provider device and inputs CSP-/SPand I to the function B(x, y) to execute C'=B(CSP-/SP, I). PCOPYRIGHT: (C)2008,JPO&INPIT