Cryptanalysis of an Image Encryption Algorithm Based on Random Walk and Hyperchaotic Systems

Recently, an image encryption algorithm based on random walk and hyperchaotic systems has been proposed. The main idea of the original paper is to scramble the plain image by means of random walk matrix and then to append diffusion. In this paper, the encryption method with security holes is analyzed by chosen plaintext attack. In addition, this paper improves the original encryption algorithm. The experimental and simulation results show that the improved algorithm has the advantages of the original and can improve the ability to resist attack.

A Class of New Correlative and Switchable Hyperchaotic Systems and Their Switch-Synchronization

A new population of correlative and switchable 4D hyperchaotic systems and their switch-synchronization are investigated. First, the switched system with the self-contained subsystems which show some symmetry are constructed. The Lyapunov exponent spectrums and Lyapunov dimensions are displayed to indicate the existence of hyperchaos, and the complex dynamical properties are discussed. Second, its real circuit implement is exhibited for application, and the switching with the flexible and diverse operation assembled can be accomplished randomly by using system selector. Third, nonlinear control strategies are presented to ensure the synchronization stability of the switched system. Simulations are displayed to verify the effectiveness of the control.

Adaptive Terminal Synergetic Synchronization of Hyperchaotic Systems

This research paper introduces an adaptive terminal synergetic nonlinear control. This control aims at synchronizing two hyperchaotic Zhou systems. Thus, the adaptive terminal synergetic control’s synthesis is applied to synchronize a hyperchaotic i.e., slave system with unknown parameters with another hyperchaotic i.e., master system. Accordingly, simulation results of each system in different initial conditions reveal significant convergence. Moreover, the findings proved stability and robustness of the suggested scheme using Lyapunov stability theory.

Interval Type-2 Fuzzy Brain Emotional Control Design for the Synchronization of 4D Nonlinear Hyperchaotic Systems

This research provides a novel intelligent control structure for 4D nonlinear hyperchaotic systems. This is a hybrid design containing a new interval type-2 fuzzy fourfold function-link brain emotional controller and a smooth robust controller. It comprises a fuzzy inference system and three subnetworks. The subnetworks are a new fourfold function-link network, a type-2 fuzzy amygdala network and a type-2 fuzzy prefrontal cortex network that decrease the synchronization errors efficiently, follow the reference signal well and achieve good performance. Two Lyapunov stability functions are utilized to get the adaptive laws, and they are applied to online tune the parameters of the system. The proposed design is used to synchronize two 4D nonlinear hyperchaotic systems and the simulation results are given to demonstrate its superiority and effectiveness.

Text Encryption Method Using multi Hyperchaotic systems

With rapid evaluation of technologies, huge amount of critical information can exchange over unsecure network every day, secure and fast encryption schemes become more and more urgent need to provide the desirable confidentiality and thwart unauthorized access, lately and for many reasons, chaotic based encryption algorithms become more and more popular technique due to exceptionally superior characteristics such as simplicity, resistance attacks and high speed, in this paper the advantages of two nonlinear hyper-chaotic systems will utilized to strength the proposed encryption algorithm, the random sequences generated from systems will used to position scramble and value change of the plaintext, the main features of such method are efficiency, large key space, low computational overhead, and simple design as well as the experimental results demonstrate that the proposed method have more ability to thwart attacks.

Scaling Analysis of an Image Encryption Scheme Based on Chaotic Dynamical Systems

Despite that many image encryption systems based on chaotic or hyperchaotic systems have been proposed to protect different kinds of information, it has been crucial to achieve as much security as possible in such systems. In this sense, we numerically implement a known image encryption system with some variants, making special emphasis when two operations are considered in the scrambling stage. The variants of such an encryption system are based on some hyperchaotic systems, which generated some substitution boxes and the keys of the system. With the aim to have a more complete evaluation, some internal stages of the image encryption scheme have been evaluated by using common statistical tests, and also the scaling behavior of the encrypted images has been calculated by means of a two-dimensional detrended fluctuation analysis (2D-DFA). Our results show that the image encryption systems that include two operations or transformations in the scrambling stage present a better performance than those encryption systems that consider just one operation. In fact, the 2D-DFA approach was more sensitive than some common statistical tests to determine more clearly the impact of multiple operations in the scrambling process, confirming that this scaling method can be used as a perceptual security metric, and it may contribute to having better image encryption systems.