An Improved Ikeda System and Its Application in Image Encryption

Based on the enhanced Ikeda time delay system derived from modified nonlinear function, a multi-rounds image encryption scheme is proposed. It is constructed by adding arctangent functions to nonlinear terms. Not only is the stability condition of the improved system analyzed theoretically, but also the stability and chaos characteristics of the system are studied from the aspects of solution response, phase diagram by using numerical analysis method. And then, the current time response sequence and delay time sequence are used to scramble and replace the pixel sequence of the plain image, respectively. As a characteristic of encryption algorithm, when multi-rounds encryption is carried out, it is necessary to use the pixels of the previous encrypted image to update the control parameters of the system dynamically. Simulation results show that the cryptosystem has excellent encryption performance, and can resist various attacks.