Security analysis of communication system based on the synchronization   of different order chaotic systems
  This work analyzes the security weakness of a recently proposed communication method based on chaotic modulation and masking using synchronization of two chaotic systems with different orders. It is shown that its application to secure communication is unsafe, because it can be broken in two different ways, by high-pass filtering and by reduced order system synchronization, without knowing neither the system parameter values nor the system key. 
G. Alvarez and L. Hernandez and J. Munoz and F. Montoya and Shujun Li