A secure and robust digital watermarking technique by the block cipher RC6 and secure hash algorithm

Digital watermarking has been proposed for copyright protection of multimedia data. Most current researchers focus on the robust watermarking techniques to embed a perceptually invisible watermark in the image without considering the multiple ownership deadlock problem of the watermarked image. We propose a digital watermark technique to resolve the rightful ownerships of a digital image. The original image is processed by a standard hash algorithm to generate a hash value, which can be viewed as the fingerprint of the image. The hash value is used as a secret key for a standard encryption algorithm such as data encryption standard (DES) or the advanced encryption standard. (AES). A meaningful watermark is then encrypted by the standard encryption algorithm We then develop a robust technique based on wavelet transform to embed the encrypted watermark in the image. In our simulation, we use the secure hash algorithm SHA and the block cipher RC6, which was a candidate of the AES, to encrypt the watermark. Experimental results shows that the proposed method can be effective and robust to resolve the rightful ownerships of digital images.