New Robust Watermarking Scheme for a Distributed Database with Hyperbolic Structure

In this paper we propose a new robust water-marking scheme for medical images stored in a distributed database with a hyperbolic structure. Our approach is to first generate a watermark from the patient information and the statistical parameters of the image. The watermark is then inserted into the image and fragmented before being distributed to different nodes. The repartition is carried out using the hyper-catadioptric projection model in order to guarantee its robustness. The receiver extracts the watermark from the image and look for watermark fragments stored in the nodes before proceeding with a comparison. Simulation results clearly show that any attempt to modify the image or the watermark will be detected. The asynchronous stream cryptography technique has been proposed to restore data in the event of an attack. The implementation of the hyper-catadioptric model enabled us to adapt our watermarking scheme to the structure of the distributed database. Finally, formal analysis and simulations allow us to state that our system is chaotic and therefore robust.