A novel grayscale image encryption approach based on chaotic maps and image blocks

A novel image encryption scheme comprising of one permutation process and one diffusion process is proposed. In the permutation process, the image sized is expanded to one sized by dividing the plain-image into two parts: one consisting of the higher 4bits and one consisting of the lower 4bits. The permutation operations are done row-by-row and column-by-column to increase the speed. The chaotic generalized Arnold map is utilized to generate chaotic sequence, which is quantized to shuffle the expanded image. The chaotic sequence for permutation process is dependent on plain-image and cipher keys, resulting in good key sensitivity and plain-image sensitivity. To achieve more avalanche effect and larger key space, Chinese Remainder Theorem is applied to diffuse the shuffled image. The key sensitivity and key space of the proposed image encryption have been analyzed as well. The experimental results suggest that the proposed image encryption scheme can be used for secure image and video communication applications.

This paper proposes an image encryption scheme based on chaotic system with changeable parameters depending on plain-image. A generalized Arnold map, whose control parameters are changeable and image-dependent during the iteration procedure, is utilized to generate chaotic orbits applied to permute the pixel positions. A diffusion function is also designed to realize the diffusion effect by piece-wise linear chaotic map. In both the permutation process and the diffusion process, the keystreams generated by chaotic maps are all strongly dependent on plain-image, and thereby can improve the encryption security efficiently. The major merits of the proposed image encryption scheme include a huge key space, good statistical nature resisting statistical analysis attack, differential attack, and good resistance against known-plaintext attack and chosen- plaintext attack, etc. Experimental results have been carried out with detailed analysis to show that the proposed scheme can be a potential candidate for practical image encryption.

In the last decade, the communication of images through the internet has increased. Due to the growing demands for data transfer through images, protection of data and safe communication is very important. For this purpose, many encryption techniques have been designed and developed. New and secured encryption schemes based on chaos theory have introduced methods for secure as well as fast communication. A modified image encryption process is proposed in this work with chaotic maps and orthogonal matrix in Hill cipher. Image encryption involves three phases. In the first phase, a chaotic Henon map is used for permuting the digital image. In the second phase, a Hill cipher is used whose encryption key is generated by an orthogonal matrix which further is produced from the equation of the plane. In the third phase, a sequence is generated by a chaotic tent map which is later XORed. Chaotic maps play an important role in the encryption process. To deal with the issues of fast and highly secured image processing, the prominent properties of non-periodical movement and non-convergence of chaotic theory play an important role. The proposed scheme is resistant to different attacks on the cipher image. Different tests have been applied to evaluate the proposed technique. The results of the tests such as key space analysis, key sensitivity analysis, and information entropy, histogram correlation of the adjacent pixels, number of pixel change rate (NPCR), peak signal to noise ratio (PSNR), and unified average changing intensity (UCAI) showed that our proposed scheme is an efficient encryption technique. The proposed approach is also compared with some state-of-the-art image encryption techniques. In the view of statistical analysis, we claim that our proposed encryption algorithm is secured.

A new image encryption method based on memristive hyperchaos

Image encryption based on chaotic maps is an important method for ensuring the secure communication of digital multimedia on the Internet. To improve the encryption performance and security of image encryption systems, a new image encryption algorithm is proposed that employs a compound chaotic map and random cyclic shift. First, a new hybrid chaotic system is designed by coupling logistic, ICMIC, Tent, and Chebyshev (HLITC) maps. Comparison tests with previous chaotic maps in terms of chaotic trajectory, Lyapunov exponent, and approximate entropy illustrate that the new hybrid chaotic map has better chaotic performance. Then, the proposed HLITC chaotic system and spiral transformation are used to develop a new chaotic image encryption scheme using the double permutation strategy. The new HLITC chaotic system is used to generate key sequences used in the image scrambling and diffusion stages. The spiral transformation controlled by the chaotic sequence is used to scramble the pixels of the plaintext image, while the XOR operation based on a chaotic map is used for pixel diffusion. Extensive experiments on statistical analysis, key sensitivity, and key space analysis were conducted. Experimental results show that the proposed encryption scheme has good robustness against brute-force attacks, statistical attacks, and differential attacks and is more effective than many existing chaotic image encryption algorithms.

A robust and secure chaotic standard map based pseudorandom permutation-substitution scheme for image encryption

The objective of this research is to develop a novel image encryption method that can be used to considerably increase the security of encrypted images. To solve this image security problem, we propose a distributed homomorphic image encryption scheme where the images of interest are those in the visible electromagnetic spectrum. In our encryption phase, a red green blue (RGB) image is first separated into its constituent channel images, and then the numerical intensity value of a pixel from each channel is written as a sum of smaller pixel intensity sub-values, leading to having several component images for each of the R, G, and B-channel images. A homomorphic encryption function is used to separately encrypted each of the pixel intensity sub-values in each component image using an encryption key, leading to a distributed image encryption approach. Each of the encrypted component images can be compressed before transmission and/or storage. In our decryption phase, each encrypted component image is decompressed if necessary, and then the homomorphic property of the encryption function is used to transform the product of individually encrypted pixel intensity sub-values in each encrypted component images, to the encryption of their sum, before applying the corresponding decryption function with a decryption key to recover the original pixel's intensity values for each channel image, and then recovering the original RGB image. Furthermore, a special case of an RGB image encryption and decryption where a pixel's intensity value from each channel is written as a sum of only two sub-values is implemented and simulated with a software. The resulting cipher-images are subject to a range of security tests and analyses. Results from these tests shown that our proposed homomorphic image encryption scheme is robust and can resist security attacks, as well as increases the security of the associated encrypted images. Our proposed homomorphic image encryption scheme has produced highly secure encrypted images.

Images are important information carriers in our lives, and images should be secure when transmitted and stored. Image encryption algorithms based on chaos theory emerge in endlessly. Based on previous various chaotic image fast encryption algorithms, this paper proposes a color image sector fast encryption algorithm based on one-dimensional composite sinusoidal chaotic mapping. The main purpose of this algorithm is to improve the encryption and decryption speed of color images and improve the efficiency of image encryption in the big data era. First, four basic chaos maps are combined in pairs and added with sine operations. Six one-dimensional composite sinusoidal chaos maps (CSCM) were obtained. Secondly, select the two best chaotic mappings LCS and SCS. The randomness of these two chaotic mappings was verified through Lyapunov index and NIST SP 800-22 randomness tests. Thirdly, the encryption process is carried out according to the shape of a traditional Chinese fan, and the diffusion and scrambling of each pixel of the image are performed in parallel. This greatly improves encryption speed. When diffusing, changing the value of one pixel can affect the values of multiple subsequent pixels. When scrambling, each pixel changes position with the three pixels before it according to the chaotic sequence. Finally, through many experiments, it is proved that the image encryption algorithm not only greatly improves the encryption and decryption speed, but also improves various indexes. The key space reached 2192, the average information entropy was 7.9994, the average NPCR was 99.6172, and the average UACI was 33.4646. The algorithm can also resist some common attacks and accidents, such as exhaustion attack, differential attack, noise attack, information loss and so on.

The chaos based cryptographic algorithms have suggested some new and efficient ways to develop secure image encryption techniques. A new approach to image encryption based on hyperchaotic map which is called coupled map lattices(CML) is proposed in order to meet the requirements of the secure image transfer. The results of several experimental, analysis of correlation of adjacent pixels and key sensitivity tests show that the proposed image encryption scheme provides an efficient and secure way for image encryption and transmission.

We propose an improved image encryption algorithm based on hyper chaotic system and permutation-diffusion structure. In the permutation process, the algorithm introduces plain-text feedback mechanism that makes the permutation effect not only associated with the chaotic sequences, but also related to plain-text. And in the diffusion process, the algorithm introduces both cipher-text and plain-text feedback mechanisms to diffuse the permuted image. All of these methods make the mapping-relationship between cipher-text and plain-text as well as secret keys more complex. At last, the security analysis such as key space analysis, histograms, correlation coefficients, information entropy, key sensitivity analysis, plaintext sensitivity, speed analysis. We also perform series evaluation experiments, experimental results show that the proposed image encryption scheme is of very good performance on security and reliability, with high potential to be adopted for the secure image communication applications.

A novel devaney chaotic map with uniform trajectory for color image encryption

A novel image encryption algorithm based on a hybrid model of deoxyribonucleic acid (DNA), cellular automata (CA) and chaotic system is proposed. CA due to its complex behavior has several applications such as generating random numbers and cryptography. DNA rules, DNA sequence XOR operator and CA rules are used simultaneously to encrypt the plain-image pixels. To determine rule number in DNA sequence and also CA, a 2-dimension logistic map is employed. Experimental results show that the proposed image encryption scheme has a lot of characteristics, including large key space, low correlation of adjacent cipher pixels, and high security, which can effectively protect the security of the encrypted image.

The rapid development of digital image transmission technology requires a more secure and effective image encryption scheme to provide the necessary security. This paper introduces an improved sine-transform-based chaotic system (ISTBCS). By linearly weighting and nonlinearly multiplying the selected classic maps, the new chaotic maps with more complex dynamics are obtained through sinusoidal transformation. Performance evaluation shows that it has chaotic characteristics such as wide range of chaos, high complexity, and strong non-periodicity. On this basis, an image encryption algorithm that uses bidirectional pixel encoding, displacement and diffusion at the same time is designed. By pixel encoding the plaintext, the small changes in the ordinary image can be propagated to all the pixels of the encrypted image, which greatly improves the ability to resist known plaintext attacks and selected plaintext attacks. Simulation results and performance analysis show that the algorithm has a large key space, strong key sensitivity, strong performance to make the structural data correlation disappear, and then can increase the entropy, has good anti attack ability, and can effectively meet the needs of image encryption.

A novel image encryption algorithm based on polynomial combination of chaotic maps and dynamic function generation

Chaotic systems are widely used in various fields, but under the finite precision device, chaotic systems would fall into a cycle and subsequently the performance degrade. Thus, the suppression method of the dynamic degradation of digital chaos is receiving increasing attention. This paper proposes a new improvement model to suppress the dynamical degradation under finite computing accuracy equipment. By using the difference between two maps of the same type but with different initial values, and the state feedback function to improve the performance of the digital chaotic map and extend the time before the chaotic map enters the cycle. Take the 1D Logistic map and x-dimensional of Baker map as examples to prove the effectiveness of the improvement model. Then we proposed a new key selection method, in what part of information of the image would be selected by using a chaotic map to generate a special value. The special value would be used as part of the key. Based this method, a new image encryption algorithm was proposed. The information entropy of the image encrypted by our encryption algorithm is 7.9972, the NPCR and UACI are 0.996095 and 0.334635, respectively, what both are very close to ideal values. The experimental simulation results show that the image encryption scheme exhibits good performances and high security and effectively resists various attacks.