DIGITAL WATERMARK SYSTEM, DIGITAL WATERMARK KEY GENERATION DEVICE, DIGITAL WATERMARK EMBEDDING DEVICE, DIGITAL WATERMARK DETECTION DEVICE, DIGITAL WATERMARK REMOVAL DEVICE, FUNCTION EXECUTION DEVICE, DIGITAL WATERMARK METHOD AND PROGRAM

摘要

PROBLEM TO BE SOLVED: To perform embedding, detection, and removal of a digital watermark to a lossy trapdoor function.SOLUTION: A digital watermark key generation device 10 generates a vector space parameter, a public key, a secret key, an embedding key, a detection key, a removal key, an injection key, a lossy key, and an inverse function key. A digital watermark embedding device 20 embeds a digital watermark to an embedding object function key input using the embedding key, and outputs a function key with a watermark. A digital watermark detection device 30 detects whether or not the digital watermark is embedded in a detection object function key input using the detection key. A digital watermark removal device 40 removes the digital watermark from a removal object function key input using the removal key to output a removed function key. A function execution device 50 calculates information y from information x using the function key with the watermark, and moreover, performs inverse calculation of the information x from the information y using the inverse function key.