Partial identification of Lorenz system and its application to key space reduction of chaotic cryptosystems

In this brief, we present a novel adaptive method to synchronize with a partially known Lorenz chaotic system. The method exploits a novel expression of the Lorenz system to design a parameter identifier for its unknown parameter. We also apply the result to investigate the security of a cryptosystem previously proposed in the literature and show that the method can be used to eavesdrop on an encrypted communication channel. Numerical simulations are presented to illustrate the results.