Abstract
Since the release of the first 3D watermarking algorithm, several approaches have grown up with a diversity of techniques used during the embedding of information into meshes. The main objective is always to secure data shared by remote users. The originality of the present work is issued from combining encryption and hybrid watermarking algorithm to secure 3D multiresolution meshes. The new crypto-watermarking system is composed of three parts: the first part is said watermark preparation and it aims to prepare data to be inserted. During this step, the logo (which refers to copyright information) is encrypted using RSA (Rivest, Shamir,Adleman) algorithm and then encoded by applying a convolutional encoder to the encrypted logo already transformed into a binary sequence. As for the second part, it is called mesh preparation and it consists on decomposing the 3D multiresolution mesh by applying wavelet transform to generate wavelet coefficient vector. Finally, the third part of our algorithm, called hybrid watermarking, occurs to insert encrypted logo and RSA keys into both multiresolution and spatial presentations of the mesh. In fact, the encrypted logo is inserted into resulting wavelet coefficients after applying the transformation to spherical coordinate system, modulation and demodulation. As for RSA key, it is inserted into the mesh resulting from the first watermarking around by modifying geometric information of vertices. Found results prove that we are able to insert a high amount of data without influencing the mesh quality. The application of the most popular attacks does not prevent a correct extraction of data already inserted which is justified by the use of the RSA to encode the watermark and the convolutional error correcting code to retrieve the corrupted information. Our algorithm is, then, robust against these attacks.