A new simple digital image cryptography technique based on multi-scroll chaotic Delay Differential Equation

A new simple digital image cryptography technique based on multi-scroll chaotic Delay Differential Equation (DDE) is presented. The proposed cryptography technique realizes a XOR operation between separated planes of binary gray-scale image and a shuffled multi-scroll DDE chaotic attractor image. The security keys are parameters in DDE, including initial conditions, time constants, and simulation time that sets final states of an attractor. Experimental results are performed in MATLAB. Nonlinear dynamics of DDE are described in terms of equilibrium points and an infinite-dimensional system of Ordinary Differential Equation (ODE) with demonstrations of 3-scroll attractors in both time and phase-space domains. Encryption and decryption security performances of a gray-scale Lena image with 512x512 pixels are evaluated through histograms, 2-dimensional power spectrums, image correlation plots and coefficients. Demonstrations of wrong-key decrypted image are also included. The proposed technique offers a potential alternative to simple-but-highly-secured image transmissions in information privacy protection applications.