Color image encryption using Choquet fuzzy integral and hyper chaotic system

This paper proposes a color image encryption scheme based on Choquet fuzzy integral (CFI) and hyper chaotic system. The major core of the encryption algorithm is a pseudo-random number generator based on the CFI. Before encrypting the color image, the piecewise linear chaotic map (PWLCM) is used to generate the 128-bit secret keys, and the Lorenz system is iterated for limited times to generate the initial parameters of the CFI. The outputs of the CFI are used to confuse and diffuse the three components of the pixel, respectively. Experiment results and security analysis show that the scheme not only can achieve good encryption result and large key space, but also can resist against common attacks, so the scheme is reliable to be adopted for network security and secure communications.     

Cryptanalyzing a novel image fusion encryption algorithm based on DNA sequence operation and hyper-chaotic system

Recently, an image fusion encryption algorithm [Optik 124 (18) (2013) 3596–3600] was proposed based on DNA sequence operation and hyper-chaotic system. The security of this algorithm depends mainly on both five keys as the initial conditions of hyper-chaotic system and a key image. In this paper, we cryptanalyze the algorithm and find that two chaotic keystream determined by the five keys keep unchanged for different image encryption processes. The two chaotic keystream can be revealed and the computational complexity is approximately O(mn), where m and n represent the height and width, respectively. In addition, the key image needs to be changed for each encryption. Finally, experimental results also verify our idea.     

Cryptanalysis on a novel image encryption method based on total shuffling scheme

A novel image encryption method based on a skew tent map is proposed recently. In this paper, some flaws of this algorithm are pointed out and then a chosen plaintext attack against it is presented. Both theoretical analysis and experimental simulation indicate that the plain image can be recovered exactly from the cipher image without the secret key. So it can be seen that this algorithm is not secure enough to be applied in network communication.     

Novel image encryption algorithm based on cycle shift and chaotic system

In this paper, a novel image encryption algorithm is proposed. The cycle shift in bits of pixels and the chaotic system are employed for the encryption of the proposed scheme. For cycle shift operations, random integers with the same size of the original image are produced to scramble the plaintext image. Moreover, the scrambled image effects the initial values of the chaotic system for the further encryption process, which increases the sensitivity of plaintext images of the scheme. The scrambled image is encrypted into the ciphered image by the keys which are produced by the chaotic system. The simulation experiments and theoretical analyses indicate that the proposed scheme is superior and able to resist exhaustive attack and statistical attack.     

Color image encryption using skew tent map and hyper chaotic system of 6th-order CNN

The paper designs a color image encryption scheme based on skew tent map and hyper chaotic system of 6th-order CNN. The essence of the image encryption is to confuse and diffuse the pixels, the skew tent map is applied to generate the confusion sequence, and the hyper chaotic system of 6th-order CNN is applied to generate the diffusion sequence, for 6 state variables in the system, there are total 120 combinations. For each pixel of the plain image, one combination is chosen to encryption the red, green and blue components, and the combination is determined by one of the state variables. Each pixel is encrypted by the cipher value of the previous pixel and the combination value of the CNN system. Experimental results and security analysis demonstrate that the scheme can achieve good encryption result and larger key space, and can resist common attacks, so the scheme can be applied in secure communication to enhance the security of transmitting image.     

An improved image encryption algorithm based on chaotic maps

Recently, two chaotic image encryption schemes have been proposed, in which shuffling the positions and changing the grey values of image pixels are combined. This paper provides the chosen plaintext attack to recover the corresponding plaintext of a given ciphertext. Furthermore, it points out that the two schemes are not sufficiently sensitive to small changes of the plaintext. Based on the given analysis, it proposes an improved algorithm which includes two rounds of substitution and one round of permutation to strengthen the overall performance.     

A novel color image encryption scheme using alternate chaotic mapping structure

This paper proposes an color image encryption algorithm using alternate chaotic mapping structure. Initially, we use the R, G and B components to form a matrix. Then one-dimension logistic and two-dimension logistic mapping is used to generate a chaotic matrix, then iterate two chaotic mappings alternately to permute the matrix. For every iteration, XOR operation is adopted to encrypt plain-image matrix, then make further transformation to diffuse the matrix. At last, the encrypted color image is obtained from the confused matrix. Theoretical analysis and experimental results has proved the cryptosystem is secure and practical, and it is suitable for encrypting color images.     

Cryptanalysis of a color image encryption algorithm based on chaos

A novel image encryption algorithm based on logistic map is proposed recently. In this paper, a chosen plaintext attack on this algorithm is presented and some other flaws of the algorithm are pointed out. Theoretical analysis and experimental simulation indicate that the plain image can be recovered exactly from the cipher image without secret key. Therefore, this algorithm is not secure enough for practical applications. An improvement is proposed to enhance the security of the original algorithm. Simulation results and theoretical analysis show that the improved scheme has expected cryptographic properties and is more secure than the original algorithm.     

A novel hybrid color image encryption algorithm using two complex chaotic systems

Based on complex Chen and complex Lorenz systems, a novel color image encryption algorithm is proposed. The larger chaotic ranges and more complex behaviors of complex chaotic systems, which compared with real chaotic systems could additionally enhance the security and enlarge key space of color image encryption. The encryption algorithm is comprised of three step processes. In the permutation process, the pixels of plain image are scrambled via two-dimensional and one-dimensional permutation processes among RGB channels individually. In the diffusion process, the exclusive-or (XOR for short) operation is employed to conceal pixels information. Finally, the mixing RGB channels are used to achieve a multilevel encryption. The security analysis and experimental simulations demonstrate that the proposed algorithm is large enough to resist the brute-force attack and has excellent encryption performance.     

Cryptanalysis and improvement of a digital image encryption method with chaotic map lattices

A digital image encryption scheme using chaotic map lattices has been proposed recently. In this paper, two fatal flaws of the cryptosystem are pointed out. According to these two drawbacks, cryptanalysts could recover the plaintext by applying the chosen plaintext attack. Therefore, the proposed cryptosystem is not secure enough to be used in the image transmission system. Experimental results show the feasibility of the attack. As a result, we make some improvements to the encryption scheme, which can completely resist our chosen plaintext attack.     

A novel bit-level image encryption algorithm based on chaotic maps

Recently, a number of chaos-based image encryption algorithms have been proposed at the pixel level, but little research at the bit level has been conducted. This paper presents a novel bit-level image encryption algorithm that is based on piecewise linear chaotic maps (PWLCM). First, the plain image is transformed into two binary sequences of the same size. Second, a new diffusion strategy is introduced to diffuse the two sequences mutually. Then, we swap the binary elements in the two sequences by the control of a chaotic map, which can permute the bits in one bitplane into any other bitplane. The proposed algorithm has excellent encryption performance with only one round. The simulation results and performance analysis show that the proposed algorithm is both secure and reliable for image encryption.     

Comment on “Image encryption with chaotically coupled chaotic maps”

This paper studies the security of a recently proposed chaos-based cryptosystem. It is shown that the encryption architecture of this cryptosystem exhibits some important problems related to its implementation and its robustness against noise. Some security problems are also highlighted.     

A fast image encryption method by using chaotic 3D cat maps

An image encryption method using a chaotic 3D cat map is presented in this paper. The process of the proposed algorithm contains the simultaneous operations of pixels’ locations permutation and pixels’ values substitution at every iterative step of the chaotic map, which making the forward and reverse encryption needs only one traverse of the image pixels. Moreover, a perturbation is introduced to eliminate the undesirable finite precision effect of computer in realization. The main advantages of such a secure method are the simplicity and efficiency. Both simulations and analysis show the proposed algorithm can produce a large key space and resist the common existing cipher attacks. These good cryptographic properties make it suitable for image applications.     

Comment on ‘A technique for image encryption using digital signature’

The security of a recently proposed technique for encryption images by Sinha and Singh [A. Sinha, K. Singh, Opt. Commun. 218 (2003) 229], based on the use of digital signatures and error correcting codes, is analyzed. The proposed cryptosystem is shown to have some weakness. In fact, the secret key and the original image can be recovered efficiently by a brute force attack.     

Cryptanalysis of a new image encryption algorithm based on hyper-chaos

This Letter proposes two different attacks on a recently proposed image based on hyper-chaos. The cryptosystem under study proceed first by shuffling the image rows and columns to disturb the high correlation among pixels by iterating the logistic map. Second, a keystream is generated to mix it with the pixels of the shuffled image using hyper-chaos. These two processes in the encryption stage present weakness, and a chosen plaintext attack and a chosen ciphertext attack can be done to recover the ciphered-image without any knowledge of the key value. It just demands three couples of plaintext/ciphertext to break totally the cryptosystem.     

Cryptanalysis on an image block encryption algorithm based on spatiotemporal chaos

An image block encryption scheme based on spatiotemporal chaos has been proposed recently.In this paper,we analyse the security weakness of the proposal.The main problem of the original scheme is that the generated keystream remains unchanged for encrypting every image.Based on the flaws,we demonstrate a chosen plaintext attack for revealing the equivalent keys with only 6 pairs of plaintext/ciphertext used.Finally,experimental results show the validity of our attack.     

A novel image encryption method based on total shuffling scheme

In this paper, a novel image encryption method based on skew tent chaotic map and permutation-diffusion architecture is proposed. In the proposed method, the P-box is chosen as the same size of plain-image, which shuffles the positions of pixels totally. The keystream generated by skew tent chaotic map is related to the plain-image. Statistical analysis, information entropy analysis, and sensitivity analysis to plaintext and key on the proposed scheme are provided in this paper. It can be seen that this algorithm is efficient and reliable, with high potential to be adopted for network security and secure communications.     

对一类超混沌图像加密算法的密码分析与改进

对一种超混沌图像加密算法及其改进版进行了安全性分析, 结果表明该类算法的置乱过程都是与混淆过程相脱离的, 且混淆过程的加密公式简单; 因此都不能抵抗选择明文和选择密文攻击. 进而提出了一种改进的加强型超混沌图像加密算法; 改进算法包含两轮像素值替代加密操作, 并使得密文与明文、密钥之间的关系更复杂. 安全性分析和实验测试表明, 改进算法不仅克服了原算法不能抵御选择明文和选择密文攻击的缺陷; 而且具有时间开销更小和抗差分攻击性能更好的优势.     

Encrypting the compressed image by chaotic map and arithmetic coding

Due to the efficient and secure requirements of image transmission, a number of research works have been done to encrypt the compressed image. Inspired by the arithmetic coding and chaotic map which are used to compress and encrypt image, respectively. In this paper, a scheme is proposed to encrypt the compressed image by chaotic map and arithmetic coding. This scheme compresses the image row by row which is firstly permuted by two logistic maps before arithmetic coding. It not only enhances the security of arithmetic coding, but also improves the compression ratio. To further improve the security of binary data which has been compressed, we use the chaotic maps to encrypt the data, and set different parameters and initial value for chaotic maps. In order to possess high sensitivities of key and plain-image, the keys that are employed to determine the parameter and initial value of chaotic maps are related to the plain-image. The experimental results validate the effect of the proposed scheme and demonstrate that the compressed and encrypted image is secure and convenient for transmission.     

Double-image encryption based on discrete fractional random transform and chaotic maps

A novel double-image encryption algorithm is proposed, based on discrete fractional random transform and chaotic maps. The random matrices used in the discrete fractional random transform are generated by using a chaotic map. One of the two original images is scrambled by using another chaotic map, and then encoded into the phase of a complex matrix with the other original image as its amplitude. Then this complex matrix is encrypted by the discrete fractional random transform. By applying the correct keys which consist of initial values, control parameters, and truncated positions of the chaotic maps, and fractional orders, the two original images can be recovered without cross-talk. Numerical simulation has been performed to test the validity and the security of the proposed encryption algorithm. Encrypting two images together by this algorithm creates only one encrypted image, whereas other single-image encryption methods create two encrypted images. Furthermore, this algorithm requires neither the use of phase keys nor the use of matrix keys. In this sense, this algorithm can raise the efficiency when encrypting, storing or transmitting.