Spatiotemporal Chaotic System Research Articles

A new image encryption algorithm based on two-dimensional spatiotemporal chaotic system

In this paper, a new image encryption algorithm based on the two-dimensional spatiotemporal chaotic system is proposed.This system mixes linear neighborhood coupling and the nonlinear chaotic map coupling of lattices, and it has more cryptographic features in dynamics than the system of coupled map lattices does. The two-dimensional coupled map lattices (2DCML) system is only a special case in this chaotic system. In addition, bit-level permutation is employed to strengthen security of the cryptosystem. Simulations have been carried out, and the results demonstrate that the proposed algorithm has properties of large key space, high sensitivity to key, strong resisting attack. So, it is more secure and effective algorithm for encryption of digital images.

An encryption algorithm for user's sensitive information resources in network database

At present, the encryption process of simple one-dimensional chaotic system has limitations, which leads to the poor security of sensitive information in the network database. To solve this problem, in this paper, a secondary encryption algorithm based on NCA mapping was proposed for user’s information resource with spatio-temporal chaotic. By using the sensitivity, scrambling and randomness characteristics of initial value in dual chaotic system which was based on Logistic mapping combined with Henon mapping, the algorithm was applied to the generation of key, to make double encryption of plaintext. The dual chaotic system which combined Logistic mapping and Henon mapping was improved, and a new spatio-temporal chaotic system based on NCA mapping was constructed. NCA mapping was used to control the scrambling process of sensitive information, and the spatio-temporal chaotic sequence was used to change the diffusion process of sensitive information, to complete the encryption of user’s sensitive information resource in network database. The experimental results show that the proposed algorithm can effectively encrypt sensitive information and improve the security of network database operation.

Bit-level plane image encryption based on coupled map lattice with time-varying delay

Most of the existing image encryption algorithms had two basic properties: confusion and diffusion in a pixel-level plane based on various chaotic systems. Actually, permutation in a pixel-level plane could not change the statistical characteristics of an image, and many of the existing color image encryption schemes utilized the same method to encrypt R, G and B components, which means that the three color components of a color image are processed three times independently. Additionally, dynamical performance of a single chaotic system degrades greatly with finite precisions in computer simulations. In this paper, a novel coupled map lattice with time-varying delay therefore is applied in color images bit-level plane encryption to solve the above issues. Spatiotemporal chaotic system with both much longer period in digitalization and much excellent performances in cryptography is recommended. Time-varying delay embedded in coupled map lattice enhances dynamical behaviors of the system. Bit-level plane image encryption algorithm has greatly reduced the statistical characteristics of an image through the scrambling processing. The R, G and B components cross and mix with one another, which reduces the correlation among the three components. Finally, simulations are carried out and all the experimental results illustrate that the proposed image encryption algorithm is highly secure, and at the same time, also demonstrates superior performance.

Hybrid forecasting of chaotic processes: Using machine learning in conjunction with a knowledge-based model.

A model-based approach to forecasting chaotic dynamical systems utilizes knowledge of the mechanistic processes governing the dynamics to build an approximate mathematical model of the system. In contrast, machine learning techniques have demonstrated promising results for forecasting chaotic systems purely from past time series measurements of system state variables (training data), without prior knowledge of the system dynamics. The motivation for this paper is the potential of machine learning for filling in the gaps in our underlying mechanistic knowledge that cause widely-used knowledge-based models to be inaccurate. Thus, we here propose a general method that leverages the advantages of these two approaches by combining a knowledge-based model and a machine learning technique to build a hybrid forecasting scheme. Potential applications for such an approach are numerous (e.g., improving weather forecasting). We demonstrate and test the utility of this approach using a particular illustrative version of a machine learning known as reservoir computing, and we apply the resulting hybrid forecaster to a low-dimensional chaotic system, as well as to a high-dimensional spatiotemporal chaotic system. These tests yield extremely promising results in that our hybrid technique is able to accurately predict for a much longer period of time than either its machine-learning component or its model-based component alone.

A spatiotemporal chaotic image encryption scheme based on self adaptive model and dynamic keystream fetching technique

This paper proposes a block chaotic image encryption algorithm based on self-adaptive and dynamic key stream fetching technique (DKSFT) which makes use of a non-adjacent spatiotemporal chaotic system coupled with Tent-Sine system (NASC-TSS) for the chaotic orbit generation. The chaotic dynamics of NASC-TSS has incredible cryptographic properties contrasted with the existing 1D chaotic map. Firstly, a bit-level permutation strategy based on circular-shift operation is suggested which focuses to lessen the implications propelled by the classical permutation architectures. Finally, in the block based diffusion phase, a control parameter is designed to update the initial condition of the employed chaotic system. Subsequently, a unique keystream is generated for various plain-image processing which in turn elevates the complexity of breaking the proposed algorithm under known attacks. Furthermore, the pixel handling in both the permutation and the diffusion stages are done with DKSFT in which the keystream selection corresponds to the pixel position of the permutated-image. The adopted strategies such as self adaptive model and DKSFT can keep up the characteristics of the keystream fluctuating and dodge different sorts of attacks, undoubtedly the known-plaintext and chosen plaintext attacks. The investigation outcomes against a series of rigorous security analysis shows that the strong execution of the proposed cryptosystem against various attacks. These highlight an appealing security level with just a single round of encryption operation, making the algorithm impeccably appropriate for some unique interactive media applications.

Bit-level image cryptosystem combining 2D hyper-chaos with a modified non-adjacent spatiotemporal chaos

A novel bit-level image cryptosystem is proposed by introducing a new coupled map lattices (CML). The modified non-adjacent spatiotemporal chaotic system with good dynamic performance is constructed by coupling the piecewise-linear chaotic map (PWLCM) in a non-adjacent manner. In the proposed bit-level image cryptosystem, the binary plain image is scrambled globally by a 2D hyper-chaos system. And the confused image is then diffused via the pseudo-random sequences produced quickly and efficiently from the fabricative CML. After converting the diffused binary matrix into its homologous decimal matrix, the cipher image is achieved. Computer simulations and performance comparisons with recent image encryption algorithms demonstrate the superior performance and high security of our proposed cryptosystem.

Chaotic image cryptosystem using DNA deletion and DNA insertion

By combining chaotic system and DNA sequence operations, an image cryptosystem is proposed. To generate sequences with better chaotic characteristics, a new spatiotemporal chaotic system is constructed by employing the Logistic-Sine system (LSS) in the coupled map lattice (CML). In the cryptosystem, the original image is firstly diffused through exclusive or with a key image transformed from the constructed spatiotemporal chaotic sequences. Furthermore, DNA deletion and DNA insertion pseudo-operations are used to confuse the DNA-encoded diffused image under the control of the key streams. The encrypted image is obtained after decoding the confused DNA image. Experimental results and performance analysis demonstrate that the proposed image cryptosystem has acceptable speed, good robustness and outperforms some existing image encryption schemes to counteract the recognized attacks.

Finding equilibrium in the spatiotemporal chaos of the complex Ginzburg-Landau equation.

Equilibrium statistical mechanics allows the prediction of collective behaviors of large numbers of interacting objects from just a few system-wide properties; however, a similar theory does not exist for far-from-equilibrium systems exhibiting complex spatial and temporal behavior. We propose a method for predicting behaviors in a broad class of such systems and apply these ideas to an archetypal example, the spatiotemporal chaotic 1D complex Ginzburg-Landau equation in the defect chaos regime. Building on the ideas of Ruelle and of Cross and Hohenberg that a spatiotemporal chaotic system can be considered a collection of weakly interacting dynamical units of a characteristic size, the chaotic length scale, we identify underlying, mesoscale, chaotic units and effective interaction potentials between them. We find that the resulting equilibrium Takahashi model accurately predicts distributions of particle numbers. These results suggest the intriguing possibility that a class of far-from-equilibrium systems may be well described at coarse-grained scales by the well-established theory of equilibrium statistical mechanics.

An image encryption scheme based on the MLNCML system using DNA sequences

We propose a new image scheme based on the spatiotemporal chaos of the Mixed Linear–Nonlinear Coupled Map Lattices (MLNCML). This spatiotemporal chaotic system has more cryptographic features in dynamics than the system of Coupled Map Lattices (CML). In the proposed scheme, we employ the strategy of DNA computing and one time pad encryption policy, which can enhance the sensitivity to the plaintext and resist differential attack, brute-force attack, statistical attack and plaintext attack. Simulation results and theoretical analysis indicate that the proposed scheme has superior high security.

A Novel Image Encryption Algorithm Based on DNA Encoding and Spatiotemporal Chaos

DNA computing based image encryption is a new, promising field. In this paper, we propose a novel image encryption scheme based on DNA encoding and spatiotemporal chaos. In particular, after the plain image is primarily diffused with the bitwise Exclusive-OR operation, the DNA mapping rule is introduced to encode the diffused image. In order to enhance the encryption, the spatiotemporal chaotic system is used to confuse the rows and columns of the DNA encoded image. The experiments demonstrate that the proposed encryption algorithm is of high key sensitivity and large key space, and it can resist brute-force attack, entropy attack, differential attack, chosen-plaintext attack, known-plaintext attack and statistical attack.

Breaking an image encryption scheme based on a spatiotemporal chaotic system

In this paper, we describe a cryptanalysis of image encryption scheme recently proposed by Chun-Yan Song, Yu-Long Qiao, and Xing-Zhou Zhang. The scheme is based on a spatiotemporal chaos with a dynamic keystream generator, and its security is claimed to rely in utilized the plainimage in the keystream generation process to obtain a different keystream for every plainimage/cipherimage pair. However, two flaws are investigated and prove that the security of the proposal against chosen plaintext attack is groundless. Simulations conducted demonstrate that the plainimage can be recovered under partial attack with an acceptable perceptual quality. Moreover, a total break is possible, but a large number of plain-image/cipher-image pairs is needed.

A Colour Image Encryption Scheme Using Permutation-Substitution Based on Chaos

An encryption scheme for colour images using a spatiotemporal chaotic system is proposed. Initially, we use the R, G and B components of a colour plain-image to form a matrix. Then the matrix is permutated by using zigzag path scrambling. The resultant matrix is then passed through a substitution process. Finally, the ciphered colour image is obtained from the confused matrix. Theoretical analysis and experimental results indicate that the proposed scheme is both secure and practical, which make it suitable for encrypting colour images of any size.

Parallelization of an Encryption Algorithm Based on a Spatiotemporal Chaotic System and a Chaotic Neural Network

Abstract In this paper the results of parallelizing a block cipher based on a spatiotemporal chaotic system and a chaotic neural network are presented. A data dependence analysis of loops was applied in order to parallelize the algorithm. The parallelism of the algorithm is demonstrated in accordance with the OpenMP standard. The efficiency measurements of a parallel algorithm working in standard modes of operation are shown.

A new algorithm of image compression and encryption based on spatiotemporal cross chaotic system

This paper proposes a new image compression and encryption scheme based on the nearest-neighboring coupled-map lattices (NCML) and Non-uniform Discrete Cosine Transform (NDCT). A new cross chaotic map proposed based on Devaney's theory is used as the local map of NCML, which is called spatiotemporal cross chaotic system. The algorithm adopts Huffman coding and NDCT which carries out transformation of image data to compress image data. In this system, there are two layers of encryption protection. The compression data are packed into blocks, and permutation between blocks and diffusion in blocks are done simultaneously. The parameters produced by spatiotemporal cross chaotic system are used to control the non-uniformity of the NDCT, which has also played a role in encryption. The security test results indicate the proposed methods have high speed, high security and good compression effect.

Chaotic image encryption based on circular substitution box and key stream buffer

A new image encryption algorithm based on spatiotemporal chaotic system is proposed, in which the circular S-box and the key stream buffer are introduced to increase the security. This algorithm is comprised of a substitution process and a diffusion process. In the substitution process, the S-box is considered as a circular sequence with a head pointer, and each image pixel is replaced with an element of S-box according to both the pixel value and the head pointer, while the head pointer varies with the previous substituted pixel. In the diffusion process, the key stream buffer is used to cache the random numbers generated by the chaotic system, and each image pixel is then enciphered by incorporating the previous cipher pixel and a random number dependently chosen from the key stream buffer. A series of experiments and security analysis results demonstrate that this new encryption algorithm is highly secure and more efficient for most of the real image encryption practices.

A symmetrical image encryption scheme in wavelet and time domain

There has been an increasing concern for effective storages and secure transactions of multimedia information over the Internet. Then a great variety of encryption schemes have been proposed to ensure the information security while transmitting, but most of current approaches are designed to diffuse the data only in spatial domain which result in reducing storage efficiency. A lightweight image encryption strategy based on chaos is proposed in this paper. The encryption process is designed in transform domain. The original image is decomposed into approximation and detail components using integer wavelet transform (IWT); then as the more important component of the image, the approximation coefficients are diffused by secret keys generated from a spatiotemporal chaotic system followed by inverse IWT to construct the diffused image; finally a plain permutation is performed for diffusion image by the Logistic mapping in order to reduce the correlation between adjacent pixels further. Experimental results and performance analysis demonstrate the proposed scheme is an efficient, secure and robust encryption mechanism and it realizes effective coding compression to satisfy desirable storage.

A symmetric image encryption algorithm based on mixed linear–nonlinear coupled map lattice

We propose a new image encryption algorithm based on the spatiotemporal chaos of the mixed linear–nonlinear coupled map lattices. This spatiotemporal chaotic system has more outstanding cryptography features in dynamics than the logistic map or the system of coupled map lattices does. In the proposed image encryption, we employ the strategy of bit-level pixel permutation which enables the lower bit planes and higher bit planes of pixels permute mutually without any extra storage space. Simulations have been carried out and the results demonstrate the superior security and high efficiency of the proposed algorithm.

Design of pseudorandom-number generator based on spatiotemporal chaos

The spatiotemporal chaotic system has good cryptographic properties,while the efficiency of the existing pseudorandom number generators based on this model is low. A new scheme to generate pseudorandom numbers with high efficiency based on a spatiotemporal chaotic system was proposed. In the process of generating pseudorandom numbers,the time-consuming operations were replaced by some fast ones and the iteration of the spatiotemporal chaotic system was reduced as possible,which made the generator own faster speed. The cryptographic performance of the pseudorandom sequences generated by this scheme was tested. The results show that the proposed scheme not only owns fast running speed and good cryptographic properties,but also has good cryptographic properties.

Chaos-based image encryption with total shuffling and bidirectional diffusion

This paper proposes a chaos-based image encryption method with permutation–diffusion architecture, in which a spatiotemporal chaotic system modeled by coupled map lattices is used to generate random sequences. In the permutation step, the permutation is generated of the same size as the plain image, which shuffles the positions of image pixels totally. In order to effectively generate this large permutation, we present a fast method to construct permutation by combining several small permutations, where small permutations are directly generated by a chaotic system. In the diffusion step, bidirectional diffusion is used to diffuse each pixel to all other pixels of the image. A key stream buffer is utilized to cache the random numbers generated by the chaotic system, and each pixel is ciphered by a random number chosen from the key stream buffer according to its previous pixel. The experimental results and analysis by using several security measures show that the proposed image encryption scheme has high security and efficiency.

A Robust Secondary Secure Communication Scheme Based on Synchronization of Spatiotemporal Chaotic Systems

This paper deals with the synchronization of spatiotemporal chaotic systems and presents a new robust secondary chaotic secure communication system for digital signal transmissions which can recover digital signal even though the transmitted signal is influenced by limited noise. The transmitter terminal and the receiver terminal both contain a spatiotemporal chaotic system and a hyperchaotic system. The asymptotic convergence of the errors between the states of the transmitter terminal and the receiver terminal has been proved based on the Lyapunov stable theory and active-passive decomposition (APD) method. Moreover, a random digital signal and a binary Lena image are encrypted and decrypted successfully to verify the efficiency of the proposed robust secure communication system.