Digital images watermarking and partial encryption based on DWT transformation and chaotic maps

In this paper we present a commutative watermarking and partial encryption techniques based on wavelet transformation and chaotic maps. The commutative property of the proposed scheme allows us to cipher a watermarked image without interfering with the embedded signal or to watermark an encrypted image still allowing perfect deciphering. Both operations are performed in a transform domain given by the DWT transform. Level 1 DWT transformation gives four coefficients : One approximation coefficient which contains the most important information of the image, and three details coefficients. The main idea of Our scheme in to hide the approximation coefficient in the details and to encrypt that coefficient considering that it contains the most information of the image, so the encryption of the approximation coefficient leads to the encryption of the whole image.