Comment on “On the security of a spatiotemporal chaotic cryptosystem” [Chaos 17, 033117 (2007)].

This paper comments on a recent paper by R. Rhouma and B. Safya [Chaos 17, 033117 (2007)]. They claimed to find some security weakness of the spatiotemporal chaotic cryptosystem suggested by G. Tang et al. [Phys. Lett. A 318, 388 (2003)] and proposed a chosen-plaintext attack to analyze this system. We find that in their analysis, called a “chosen-plaintext attack,” they actually act as a legal receiver (with a machine in their hands during the entire decryption process) rather than an attacker and, therefore, the whole reasoning is not valid. [ABSTRACT FROM AUTHOR]