Patent ID: 7024017

Claim:
An information system for processing digital information including contents information inserted with a digital watermark information and identification information for the contents information, said information system comprising: a first verification device which detects said digital watermark information from said digital information, and verifies validity of use of said contents information when the digital watermark information is detected; a registration device which registers the identification information for said contents information whose validity has been confirmed by said first verification device, wherein said registration device associates and registers, in a table, said identification information, a random number value for randomly designating sector information included in the contents information corresponding to the identification information, and the sector information; and a second verification device which verifies the validity of the use of said contents information by using the identification information when the validity is confirmed by the first verification device, and verifies the validity of said contents information with respect to the contents information corresponding to the identification information registered by said registration device instead of said first verification device.