Chaos-based Image Encryption Algorithm Research Articles

A chaos based image encryption algorithm using Shimizu-Morioka system

Recent research on image encryption schemes has focused on chaotic systems in order to meet the demand for real-time secure image transmission over the Internet. In this paper, we propose a new image encryption scheme based on ShimizuMorioka chaotic system. The scheme consists of two stages: the confusion (mixing) stage and the diffusion stage. In the confusion stage, we utilized the rich chaotic properties of the Shimizu-Morioka chaotic system by solving the system N time’s steps using Euler’s method and scrambled the positions of the pixel values of the image using the randomness of the solutions obtained from the chaotic system. In the diffusion stage, we generate N (where N is the size of image per colour) random integer numbers that is non-periodic and performed MOD and bitXOR operations on the shuffled image using the random numbers to obtain encrypted (diffused) image. The proposed algorithm is tested on a standard RGB image that is of size 256x256 and is stored with TIFF file format. Performance analysis on the proposed scheme such as the statistical analysis and the sensitivity analysis show that the proposed encryption scheme is reliable and strong enough to withstand different attacks.

A chaos based image encryption algorithm using Shimizu- Morioka system

A chaos based image encryption algorithm using Shimizu- Morioka system

Efficient and Secure Image Encryption Algorithm Using a Novel Key-Substitution Architecture

Recently, many chaos-based image encryption algorithms have been proposed. Most of them adopt the traditional confusion-diffusion framework. Multiple encryption rounds or one round of complex encryption is typically executed in these schemes to realize high security. However, these operations will reduce the computational efficiency. To overcome these issues, we propose a novel key-substitution encryption architecture (KSA). Under the proposed KSA, we design a key scheming for updating the initial keys using the plain-image and develop a new substitution method for encrypting various types of images. The simulation results and security analysis demonstrate the superior security and high efficiency of the proposed image encryption algorithm using the KSA (KSA-IEA), which executes only one round of encryption.

Lightweight, dynamic and efficient image encryption scheme

Recently, there has been a growing attention for Chaos-based image encryption algorithms. This class of algorithms relies on embedded chaotic maps to ensure a high security level with minimal performance overhead. One such algorithm, which we refer to as NCIES, was proposed recently, and the authors claimed that the algorithm achieves the required cryptographic properties with just a single round. In this paper, we first assess the performance of the NCIES cipher and we show that a single round is not enough for this cipher to ensure the desired cryptographic properties. In this context, we describe how such a cipher is vulnerable to a chosen plaintext/ciphertext attack. Next, we propose a new lightweight dynamic key-dependent cipher scheme that can address and overcome the issues identified in the NCIES cipher and other recent lightweight image encryption schemes. The proposed cipher is designed in a way to achieve a good balance between the latency, the required resources, and the security level when compared to recent chaotic image cipher schemes.

Chaos-based image encryption algorithm with orbit perturbation and dynamic state variable selection mechanisms

In this paper, we propose a novel chaos-based image encryption algorithm with the orbit perturbation and dynamic state variable selection mechanisms. The two-dimensional logistic-adjusted-sine map is employed to generate pseudo-random numbers. Using an auxiliary variable, the orbit of the chaotic map is perturbed continuously by the previously processed pixel and one of two state variables is selected to generate the keystream. Consequently, the keystream depends on not only the initial condition and control parameter of the chaotic map, but also on the information in the plain and cipher images, and thus, the algorithm is highly sensitive to both the images. A number of simulations were conducted to verify the effectiveness and security of the algorithm. Moreover, the proposed algorithm provides excellent encryption performance in only one round.

A Novel Quasigroup Substitution Scheme for Chaos Based Image Encryption

A During last two decades, there has been a prolific growth in the chaos based image encryption algorithms. Up to an extent these algorithms have been able to provide an alternative to exchange large media files (images and videos) over the networks in a secure way. However, there have been some issues with the implementation of chaos based image ciphers in practice. One of them is reduced/small key space due to the fact that chaotic behavior is only observed for certain range of system parameters/initial conditions of the chaotic system used in such algorithms. To overcome this difficulty, we propose a simple, efficient and robust image encryption algorithm based on combined applications of quasigroups and chaotic standard map. The proposed image cipher is based on the popular substitution-diffusion architecture (Shanon) where a quasigroup of order 256 and chaotic standard map have been used for the substitution and permutation of image pixels respectively. Due to the introduction of quasigroup as part of the secret key along with the parameter and initial conditions of the chaotic standard map, the key space has been increased significantly. The proposed image cipher is very fast due to the fact that the substitution based on the quasigroup operations is very simple and can be executed easily through the lookup table operations on Latin squares (which are Cayley operation tables of quasigroups) and the permutation is performed row-by-row as well as column-by-column using the pseudo random number sequences gener-ated through the chaotic standard map. The security and performance have been analyzed through the histograms, correlation coefficients, information entropy, key sensitivity analysis, differential analysis, key space analysis etc. and the results prove the efficiency and robustness of the proposed image cipher against the possible security threats.

Chaos-based image encryption using vertical-cavity surface-emitting lasers

We study the encryption and decryption processes of color images using the synchronization of polarization dynamics in a free-running vertical-cavity surface-emitting laser (VCSEL). Here, we consider a bidirectional master-slave configuration or two-way coupling with two VCSELs. The latter are shown to exhibit hyperchaos and synchronization with a high level of similarity between their emission characteristics. The coupled VCSELs are then used as a transmitter and a receiver for the communication of image or data. Furthermore, we propose a modified chaos-based image encryption algorithm using the pixel- and bit-level permutations which provides robust, faster and simpler encryption/decryption compared to many other chaos-based cryptosystems. The performances of the new cryptosystem are analyzed and compared with a recently developed scheme [Opt. Laser Eng. 90 (2017) 238–246]. The security analysis and some statistical investigations show that the proposed cryptosystem is resistant to various types of attacks and is efficient for secure communications in nonlinear optical media.

Depreciating Motivation and Empirical Security Analysis of Chaos-Based Image and Video Encryption

Over the past years, an enormous variety of different chaos-based image and video encryption algorithms have been proposed and published. While any algorithm published undergoes some more or less strict experimental security analysis, many of those schemes are being broken in subsequent publications. In this paper, we show that two main motivations for preferring chaos-based image encryption over classical strong cryptographic encryption, namely computational effort and security benefits, are highly questionable. We demonstrate that several statistical tests, commonly used to assess the security of chaos-based encryption schemes, are insufficient metrics for security analysis. We do this experimentally by constructing obviously insecure encryption schemes and demonstrating that they perform well and/or pass several of these tests. In conclusion, these tests can only give a necessary, but by no means a sufficient condition for security. As a consequence of this paper, several security analyses in related work are questionable; further, methodologies for the security assessment for chaos-based encryption schemes need to be entirely reconsidered.

An image encryption algorithm based on substitution technique and chaos mixing

These recent years, countless chaos-based image encryption algorithms have been proposed to meet security needs in real time multimedia communication. However, many of these have exhibited flaws due to the chaotic map inadequacy. In this paper, we proposed a fast and secure image encryption algorithm by using new 1D chaotic systems, with better chaotic properties in the range of their control parameters. These new chaotic systems were obtained from well-known 1D chaotic maps (Logistic, May, Gaussian, Gompertz) with flaws in their chaotic properties. From the chaotic systems designed, we extracted a pseudo random number sequence (PRNS) and generated S-boxes. Then a novel technique of plain image substitution was used to enhance the sensitivity of the original image pixels, followed by a scrambling-masking technique using the generated S-box. Security tests and evaluation metrics confirmed that the proposed cryptosystem was efficient, practicable, and reliable, with high potential to be adopted for network security and secure communications because of its high encryption speed.

A chaotic image encryption algorithm based on 3-D bit-plane permutation

There are two shortcomings existing in the current color image encryption. One is that high correlation between R, G, B components of the original image may be neglected, the other is that the encryption has little relationship with the plain image, and then it is vulnerable to be broken. In order to solve these two problems and present secure and effective image encryption scheme, we introduce a novel chaos-based image encryption algorithm for color images based on three-dimensional (3-D) bit-plane permutation. In the proposed algorithm, the color plain image is firstly converted to 24 bit planes by RGB splitting and bit plane decomposition, next three-dimensional bit-plane permutation is performed on bit planes, position sequences for permutation are obtained from the 3D Chen chaotic system, and then the three confused components are gotten. Secondly, three key matrices are generated by a 1D chaotic system and a multilevel discretization method, and finally, the color cipher image is obtained by diffusing the confused components using key matrices. The SHA 256 hash function value of the plain image is obtained and combined with the given parameters to calculate the parameters and initial values of the chaotic system, so that the proposed scheme highly depends on the plain image and it may effectively withstand known-plaintext and chosen-plaintext attacks. Simulation results and security analyses demonstrate that our algorithm not only has good encryption effect, but can also resist against common attacks, so it is reliable to be applied for image secure communications.

A Symmetric Plaintext-Related Color Image Encryption System Based on Bit Permutation.

Recently, a variety of chaos-based image encryption algorithms adopting the traditional permutation-diffusion structure have been suggested. Most of these algorithms cannot resist the powerful chosen-plaintext attack and chosen-ciphertext attack efficiently for less sensitivity to plain-image. This paper presents a symmetric color image encryption system based on plaintext-related random access bit-permutation mechanism (PRRABPM). In the proposed scheme, a new random access bit-permutation mechanism is used to shuffle 3D bit matrix transformed from an original color image, making the RGB components of the color image interact with each other. Furthermore, the key streams used in random access bit-permutation mechanism operation are extremely dependent on plain image in an ingenious way. Therefore, the encryption system is sensitive to tiny differences in key and original images, which means that it can efficiently resist chosen-plaintext attack and chosen-ciphertext attack. In the diffusion stage, the previous encrypted pixel is used to encrypt the current pixel. The simulation results show that even though the permutation-diffusion operation in our encryption scheme is performed only one time, the proposed algorithm has favorable security performance. Considering real-time applications, the encryption speed can be further improved.

Colour image encryption algorithm using one‐time key and FrFT

A novel chaos-based colour image encryption algorithm is proposed, which adopts a one-time key mechanism based on message-digest algorithm 5 ( MD5 ) value of the input plain image. The algorithm combines several key technologies including fractional Fourier transform (FrFT), MD5 , and global scrambling. Using fast digital discrete FrFT, the algorithm develops the complex data manipulating potentials of FrFT efficiently; meanwhile, keeps the size of the cipher image un-changed, thus eliminates the requirement on double storage space to store complex values of cipher image. Exploiting the intrinsic robustness of FrFT, the algorithm achieves high robustness to pixel errors and noise attacks. Experimental results show that the algorithm achieves better pixel change rate and unified average change intensity, and is efficient, effective, and robust to attacks.

Optimizing chaos based image encryption

Due to its inherent properties such as sensitivity to initial condition, ergodicity and systematic parametrization chaos systems have been extensively used in image encryption. However, one needs to optimize the chaos for each image being encrypted to provide high quality encryption. Features such as high entropy or low pixel correlation are measures of interest in image encryption. In this paper, we propose a novel technique to optimize a chaos based image encryption algorithm. The image is confused using logistic map as chaos function and diffused by modified Knuth shuffling algorithm. We use the logistic map parameters as encryption key. We then harness TLBO and GSA evolutionary algorithms to speed up the optimization process of these parameters. The optimization method yields parameters that lead to lowest correlation among adjacent pixels or highest entropy. We compare the quality and security of our cryptosystem with some famous image encryption methods in the literature.

Brief review on application of nonlinear dynamics in image encryption

Chaos-based cryptology has become one of the most common design techniques to design new encryption algorithms in the last two decades. However, many proposals have been observed to be weak against simple known attacks. However, security of proposals cannot be proved. An analysis roadmap is needed for the security analysis of new proposals. This study aims to address this shortcoming. Analysis and test results show that many chaos-based image encryption algorithms previously published in the nonlinear dynamics are actually not as secure as they are expressed although these algorithms do pass several statistical and randomness tests. A checklist has been proposed to solve these problems. The applications of the proposed checklist have been shown for different algorithms. The proposed checklist is thought to be a good starting point for researchers who are considering to work in chaos-based cryptography.

Cryptanalysis of a chaotic image encryption scheme based on permutation-diffusion structure

Chaos-based image encryption algorithms have been widely studied since the permutation-diffusion structure (PDS) was proposed. However, the PDS is not secure from attacks, which may lead to security vulnerabilities of PDS based chaotic cryptosystems. In this study, the security problems of PDS are investigated. Then, a new PDS based chaotic image encryption scheme is cryptanalyzed. In the original scheme, a 3D bit matrix permutation was used to address the intrinsic deficiencies of traditional pixel/bit level permutation of image encryption. The double random position permutation provides a high security level. However, it is not unattackable. In this study, a novel attack method will be introduced where all the chaotic mappings or parameters which are functionally equivalent to the keys used in the permutation and diffusion stages of the original cryptosystem can fully be revealed. The encrypted images can then be completely recovered without knowing the secret keys. Both mathematical analysis and experimental results are given to illustrate the effectiveness of the proposed method.

Cryptanalyzing and Improving a Novel Color Image Encryption Algorithm Using RT-Enhanced Chaotic Tent Maps

In recent years, chaos-based image encryption algorithms have aroused extensive research interest. However, some image encryption algorithms still have several security defects, and the research on cryptanalysis is relatively inadequate. This paper performs the cryptanalysis of a newly proposed color image encryption scheme using RT-enhanced chaotic tent map. By using chosen-plaintext attacks, the equivalent keys of the cryptosystem are successfully broken, so that the target ciphertext image can be decoded. Based on the cryptanalysis, we then proposed an improved encryption algorithm. A new logistic-tent map is proposed and applied to the improved encryption algorithm, and a parameter related to the SHA-3 hash value of the plaintext image is introduced as a secret key parameter so that the improved algorithm can resist chosen-plaintext attacks. The security analysis and experimental tests for the improved algorithm are given in detail, which show that the improved algorithm can significantly increase the security of encryption images while still possessing all the merits of the original algorithm.

Lightweight chaotic image encryption algorithm for real-time embedded system: Implementation and analysis on 32-bit microcontroller

The scintillating technological advancements have redefined the process of communication around the world. Banking, purchases, investments, emails, bill payments, etc. are being managed through online communications and needless to mention the linkage of these internet serves with embedded gadgets. A microcontroller being the low-cost solutions for real-time embedded applications has to handle rigid security algorithms for information security paradigm. The high level of sensitivity in chaos-based systems is highly suitable for the design of encryption schemes due to the randomness offered by them. The minimal memory resource and speed are the factors restricting the use of microcontrollers for implementing chaotic schemes that encrypt image data. This paper presents the design of a chaos-based image encryption algorithm with lightweight properties and its optimised implementation on a 32-bit microcontroller. This work also includes parameters related to the analysis of the security level and performance of the microcontroller that was missed to concentrate by the authors on their similar schemes reported in the literature. The level of safety of the proposed algorithm has been analysed via key sensitivity analysis, encryption quality analysis, randomness analysis, differential analysis, statistical analysis, visual analysis and attack analysis. Additionally, the results of performance analysis regarding smaller memory footprint and better throughput of proposed algorithm guarantee its suitability for real-time embedded applications.

Cryptanalysis of a DNA and chaos based image encryption algorithm

A robust encryption algorithm using DNA and chaotic logistic maps was recently proposed, which can resist exhaustive attack, statistical attack and differential attack. The security of this encryption algorithm depends on the initial conditions of 1D and 2D logistic chaotic maps, which include the front and latter pixel sum of plain image. However, this scheme is not secure enough because the front half and latter half pixel sum can be known to the attacker. According to this security weakness the encryption algorithm is completely cracked by a novel chosen-plaintext attack scheme. Experiments and analysis verify our approach.

An image encryption scheme based on three-dimensional Brownian motion and chaotic system**Project supported by the National Natural Science Foundation of China (Grant Nos. 41571417 and 61305042), the National Science Foundation of the United States (Grant Nos. CNS-1253424 and ECCS-1202225), the Science and Technology Foundation of Henan Province, China (Grant No. 152102210048), the Foundation and Frontier Project of Henan Province, China

At present, many chaos-based image encryption algorithms have proved to be unsafe, few encryption schemes permute the plain images as three-dimensional (3D) bit matrices, and thus bits cannot move to any position, the movement range of bits are limited, and based on them, in this paper we present a novel image encryption algorithm based on 3D Brownian motion and chaotic systems. The architecture of confusion and diffusion is adopted. Firstly, the plain image is converted into a 3D bit matrix and split into sub blocks. Secondly, block confusion based on 3D Brownian motion (BCB3DBM) is proposed to permute the position of the bits within the sub blocks, and the direction of particle movement is generated by logistic-tent system (LTS). Furthermore, block confusion based on position sequence group (BCBPSG) is introduced, a four-order memristive chaotic system is utilized to give random chaotic sequences, and the chaotic sequences are sorted and a position sequence group is chosen based on the plain image, then the sub blocks are confused. The proposed confusion strategy can change the positions of the bits and modify their weights, and effectively improve the statistical performance of the algorithm. Finally, a pixel level confusion is employed to enhance the encryption effect. The initial values and parameters of chaotic systems are produced by the SHA 256 hash function of the plain image. Simulation results and security analyses illustrate that our algorithm has excellent encryption performance in terms of security and speed.

A hyper-chaos-based image encryption algorithm using pixel-level permutation and bit-level permutation

Recently, a number of chaos-based image encryption algorithms that use low-dimensional chaotic map and permutation-diffusion architecture have been proposed. However, low-dimensional chaotic map is less safe than high-dimensional chaotic system. And permutation process is independent of plaintext and diffusion process. Therefore, they cannot resist efficiently the chosen-plaintext attack and chosen-ciphertext attack. In this paper, we propose a hyper-chaos-based image encryption algorithm. The algorithm adopts a 5-D multi-wing hyper-chaotic system, and the key stream generated by hyper-chaotic system is related to the original image. Then, pixel-level permutation and bit-level permutation are employed to strengthen security of the cryptosystem. Finally, a diffusion operation is employed to change pixels. Theoretical analysis and numerical simulations demonstrate that the proposed algorithm is secure and reliable for image encryption.