Copyright protection protocols based on asymmetric watermarking

Traditional watermarking systems require the complete disclosure of a watermarking key in the watermark verification process. In most systems, an attacker is able to remove the watermark completely once the key is known. We propose the use of public-key watermarking systems, systems in which a watermark is inserted using a private key but checked with a public key. A construction of such a scheme is given, which uses scrambled documents and so-called ownership tickets in the watermark verification process.