Secure Digital Signal Transmission by Multistep Parameter Modulation and   Alternative Driving of Transmitter Variables
  The idea of secure communication of digital signals via chaos synchronization has been plagued by the possibility of attractor reconstruction by eavesdroppers as pointed out by Perez and Cerdeira. In this Letter, we wish to present a very simple mechanism by which this problem can be overcome, wherein the signal is transmitted via a multistep parameter modulation combined with alternative driving of different transmitter variables, which makes the attractor reconstruction impossible. The method is illustrated by means of the Lorenz system and Chua's circuit as examples. 
P. Palaniyandi and M. Lakshmanan (Centre for Nonlinear Dynamics)