Research on public-key digital watermarking system

Digital watermarks are signals embedded in multimedia data to allow copyright enforcement or to distinguish copies of the document and it's still a novel study area. While a public-key watermarking system allows two parties who have never met or exchanged a secret to send hidden messages over a public channel so that an adversary cannot even detect that these hidden messages are being send, and in copyright protection, everybody who owns the public key can detect and verify the authenticity of watermarking information but can't alternate or remove it. In this work, we propose a public-key watermarking method, where combined a public/private key cryptographic method with a digital watermarking technique together, which is suitable for protection of the copyright as a fragile watermarking method. The embedding method based on wavelet transform and RSA encryption algorithm. The use of a public/private key cryptographic system guarantees anybody with the public-key can detect the embedding information. So it can be used for copyright protection of DVD system and other digital works.