Improvement of cryptosystem based on iterating chaotic map

In this letter we demonstrate that the improvement of cryptosystem based on iterating chaotic map proposed by Yong in 2007 are weak and this cryptosystem can be easily broken using chosen plaintext attack. Then, we give novel improvements to the proposed chaotic cryptosystem. We choose image as plaintext, some experimental tests like sensitivity on initial condition and correlation between two adjacent pixels are presented to show the performances of the new cryptosystem.