A Hybrid Watermarking Technique to Resist Tampering and Copy Attacks

Digital watermarking is an efficient method to protect multimedia documents. Robust watermarks, which survive to any change or alteration of the protected documents, are typically used for copyright protection. Fragile watermarks, which are vulnerable to a little alteration, are typically used for content authentication. In the paper, we propose a hybrid watermarking method joining a robust and a fragile watermark, and thus combining copyright protection and content authentication. As a result this approach is at the same time resistant against tampering and copy attacks. Our contribution is setting up the relationship between fragile watermark and robust watermark. We make use of DCT coefficients to embed watermark information. The experimental results show that the proposed method can resist tampering and copy attacks at the same time.