Encoding messages using chaotic synchronization

We discuss a general approach for chaotic synchronization of dynamical systems that is based on an active-passive decomposition (APD) of given dynamical systems. It is shown how this approach can be used to construct high-dimensional synchronizing systems in a systematic way using low-dimensional systems as building blocks. Furthermore, two methods for encoding messages are considered that are both based on synchronization. Using these methods the quality of the reconstructed information signal is higher and the encoding is more secure compared to other encryption methods based on synchronization. The main ideas are illustrated using experimental and numerical examples based on continuous and discrete dynamical systems.