Plaintext Image Research Articles

An Image Encryption Algorithm Based on Hyperchaotic System and Variable-Step Josephus Problem

In this paper, an image encryption algorithm based on a hyperchaotic system and variable-step Josephus problem is proposed. Based on an in-depth analysis of the classic Josephus problem, a new variable-step Josephus problem that combines the pseudorandom sequence with the Josephus problem is proposed. Firstly, the hash value of the plaintext image is calculated, which is converted to the initial value of the chaotic system. Secondly, the chaotic system is iterated to generate four pseudorandom sequences X, Y, Z, and W. The sequences X, Y, and Z are input as parameters into the variable-step Josephus function to scramble the positions of the rows, pixel bits, and columns of the image, respectively. Finally, the elements of the sequence W and the image pixels are used to perform the addition operation. According to the experiments, the information entropy of the encrypted image with size 256 ∗ 256 reaches 7.997 and the adjacent correlations in three directions are within ±0.01. The experimental results show that image encryption algorithm proposed in this paper has plaintext sensitivity and can resist the common attacks.

Chaotic image encryption algorithm based on hybrid multi-objective particle swarm optimization and DNA sequence

This paper studies an image encryption algorithm based on multi-objective particle swarm optimization (MOPSO), DNA encoding sequence and one-dimensional Logistic map. First, the key of this paper consists of the sub-key sequence selected by particle swarm optimization (PSO), a hash value of the plaintext image, and a shuffle mark bit. Create random DNA mask images using Logistic map and DNA encoding. Then use it and the block-shuffled plaintext DNA encoding sequence to operate to form an encryption system. In PSO, the position value of a particle represents a position of the plaintext image, the iterative PSO algorithm is based on the information entropy and correlation coefficient. Finally, obtains the best ciphertext, and returns the value of the best particle at this time. Simulation experiment and security analysis show that the correlation coefficient and entropy of ciphertext are excellent, and it can resist all kinds of typical attacks and has better encryption effect.

A Novel Selective Encryption Method Based on Skin Lesion Detection

Due to the semitrusted cloud, privacy protection of medical images in medical imaging clouds has become a precondition. For the privacy of patients and the security of medical images in the cloud, this paper proposes a selective encryption based on DNA sequence and chaotic maps for skin lesion image. Initially, we design a transition region-based level set evolution functional which is merged into a variational level set expression with two extra energy functionals, to segment skin lesion image. Once skin lesion detection has been performed, the detected skin lesion pixels are encrypted by employing chaotic systems and DNA sequences. We apply 2D-LASM and 1D-LSS to produce the pseudorandom sequences and use the hash function of the plaintext image to calculate the secret keys of the encryption system. Results demonstrate that the proposed segmentation method is particularly suitable for the detection of skin lesion images with strong noise and complex background. Meanwhile, security analysis also reveals that this selective encryption has a large security key space and high sensitivity to the plaintext image and the secret key.

Visual Quality Assessment for Perceptually Encrypted Light Field Images

Perceptual encryption has received widespread attention as a technology for protecting multimedia visual information. In multimedia applications, perceptual encryption only protects a portion of the content without previewing all the information. At present, perceptual encryption is mostly oriented to conventional plain images while few methods aim at visual security measures for perceptually encrypted images. Existing solutions usually adopt well-known quality assessment metrics to measure the visual quality of encrypted images. However, they often exhibit undesired behavior on perceptually encrypted images with low quality. As a typical representation of three-dimensional scenes, light field images record the intensity and direction of light during propagation which is distinct from 2-D images. In this paper, we construct a perceptually encrypted light field image database (PE-LFID) for quality assessment based on 14 reference light field plaintext images. For each scene, we employ four encryption methods, each of which has six levels. Additionally, a novel visual security evaluation method based on PE-LFID is proposed by taking into account the local and global features of the light field images. First, we use a multi-threshold edge detection method to obtain the edge similarity in the spatial domain of the light field image. Afterwards, the epipolar plane image (EPI) generated from the angular domain of the light field image is used to calculate the gradient magnitude similarity, which is expressed as a global feature. Furthermore, the final quality prediction score is calculated by adaptively weighting between local and global features. We conduct extensive experiments on the proposed PE-LFID to assess the performance of classical and state-of-the-art IQA models. The experimental results demonstrate the effectiveness of the proposed method for visual security evaluation of perceptually encrypted light field images, as well as the scalability of PE-LFID.

Dynamical analysis and image encryption application of a novel memristive hyperchaotic system

In this paper, a new four-dimensional memristive hyperchaotic system is constructed based on Liu chaotic system by introducing a flux-controlled memristor model. Then the dynamic characteristics of the new system such as phase portraits, dissipation, Lyapunov exponent and power spectrum are investigated. Subsequently, a novel image encryption algorithm is designed based on the chaotic sequence generated by the proposed hyperchaotic system combining the hash algorithm and DNA sequence operations. In this image encryption algorithm, the coupling relationship between plaintext and ciphertext is established by using the hash value of plaintext image obtained by hash algorithm, and then the plaintext is decomposed into eight bit-plane, to improve the efficiency of the algorithm, only the higher four bit-plane are selected for scrambling. After scrambling, the data stream is further processed by the DNA encoding/decoding rules and DNA sequence operations to obtain the intermediate ciphertext. Finally, the ultimate encrypted image is obtained by performing order and reverse-order diffusion operations at the pixel level on the intermediate ciphertext. Experimental results and security analysis show that the proposed algorithm has excellent image encryption performance and can resist a variety of common attacks against the image encryption system.

A secure image encryption scheme with compression-confusion-diffusion structure

This paper presents a novel image compression-encryption scheme, which has the compression-confusion-diffusion Structure. Firstly, based on Chebyshev chaotic map, a Gauss measurement matrix is constructed and optimized, which is applied to compressive sensing. Then, an image compression-encryption algorithm is proposed by using a six-dimensional discrete chaotic map. In the proposed scheme, the original image is transformed into a sparse coefficient matrix by discrete wavelet transform, and the sparse coefficients are measured by using the optimized Gauss measurement matrix to get the measured values. Then, the measured values are quantized into integer values and the compressed image is obtained. Furtherly, the compressed image is encrypted by using a six-dimensional chaotic map. In the process of encryption, the plaintext image is divided into two parts, when encrypting the second part, the first part is used as part of the key. While encrypting the first part, the ciphertext of the second part is used as part of the key. Thus, the algorithm has strong confusion and diffusion effect and makes ciphertext sensitive to plaintext. Experimental results such as effects of compression-encryption, key space analysis, key sensitivity analysis, differential analysis, histograms analysis, information entropy analysis, and correlation coefficients analysis show that the proposed scheme is secure and has high application potential.

On a Symmetric Image Encryption Algorithm Based on the Peculiarity of Plaintext DNA Coding

Many plaintext-related or non-plaintext-related image encryption algorithms based on chaotic systems have been found inefficient and insecure under chosen plaintext attacks. In this paper, a novel plaintext-related mechanism based on the peculiarity of plaintext DNA coding (PPDC) is presented and used to developed a symmetric image encryption algorithm. In our scheme, a hyper-chaotic Lorenz system is used to produce four chaotic sequences. Firstly, by using one chaotic sequence to control the DNA rules, the original image is encoded to obtain the image DNA coding and PPDC, and another chaotic sequence is encoded into a DNA sequence, which is used in the DNA XOR operation. Then, the processing of the remaining two chaotic sequences by using the PPDC is performed to obtain two key streams, which are used in the permutation stage. After performing the traditional permutation operation and DNA XOR operation, the cipher image is obtained. Because of the use of the PPDC, the key streams used in the permutation stage are related to the secret keys and plaintext image, which gives the encryption system higher plaintext sensitivity and security. The simulation experimental results and security analysis demonstrate that the proposed encryption system possesses high efficiency and security and can resist various typical attacks like exhaustive attack, statistical attack, and differential attack effectively.

On the Cryptanalysis of a Bit-Level Image Chaotic Encryption Algorithm

In this paper, the security analysis of a bit-level image chaotic encryption algorithm based on the 1D chaotic map is proposed. The original image chaotic encryption algorithm includes bit-level permutation encryption, diffusion encryption, and linear transform. Deciphering of it can be divided into two stages. First, bit-level permutation encryption, diffusion encryption, and linear transform can be simplified into bit-level equivalent permutation encryption and equivalent diffusion encryption, which is a key breakthrough point of cryptanalysis. Second, the chaotic sequence generated by this algorithm is independent of the plaintext image. Therefore, the equivalent diffusion key and the equivalent permutation key can be obtained by chosen-plaintext attack, respectively. Theoretical analysis and numerical simulation experiment results verify the effectiveness of the analytical method. Finally, some suggestions are proposed to promote the security of the original image chaotic encryption algorithm.

On the Security Analysis of a Hopfield Chaotic Neural Network-Based Image Encryption Algorithm

In this paper, the security analysis of a color image encryption algorithm based on Hopfield chaotic neural network is given. The original chaotic image encryption algorithm includes permutation encryption and diffusion encryption. The result of cryptanalysis shows that the chaotic sequences generated by this algorithm are independent of plaintext image, and there exist equivalent permutation key and equivalent diffusion key. Therefore, according to chosen-plaintext attack, the equivalent diffusion key and the equivalent permutation key can be obtained by choosing two special plaintext images and the corresponding ciphertext images, respectively, and the plaintext image is further recovered from the ciphertext image. Theoretical analysis and numerical simulation experiment results verify the effectiveness of the analytical method. Finally, some improved suggestions for the original encryption algorithm are proposed to promote the security.

GSAPSO-MQC:medical image encryption based on genetic simulated annealing particle swarm optimization and modified quantum chaos system

Due to the large amount of image information data, high redundancy and high pixel correlation, the traditional medical image encryption algorithm is easy to be attacked by chosen plaintext. Therefore, a new medical image encryption algorithm combining genetic simulated annealing particle swarm optimization and modified quantum chaos system is proposed to obtain better security performance. Firstly, an improved quantum chaotic system is used to generate the key stream. Then the selection and cross operation of genetic algorithm are used to process the plaintext image. The optimal sequence generated by simulated annealing algorithm is used to scramble the image. Meanwhile, the particle swarm optimization (PSO) algorithm is introduced into the simulated annealing mechanism. The initial temperature is set according to the optimal fitness value of the initial population. Metropolis is used to optimize the generation of individual optimal position and global optimal position, and the inertial weight parameters of PSO algorithm are optimized to avoid particles falling into local optimal in the optimization process and improve the convergence speed of the algorithm. Through these three operations, the histogram of the scrambled image can be equalized to resist statistical attack. Experimental results and performance analysis show that the encryption system proposed in this paper can resist many typical attacks such as histogram analysis, correlation analysis, differential attack and violent attack, and has high security and encryption efficiency. Compared with other encryption methods, the encryption efficiency of our proposed method has improved by approximately 10%.

Chaotic image encryption algorithm based on block theory and reversible mixed cellular automata

In this paper, a new chaotic image encryption algorithm based on block theory and reversible mixed cellular automata model is proposed. Different from traditional confusion-diffusion structure, this paper employs new three-tier architecture, i.e. diffusion-confusion-diffusion. The first diffusion operation adopts the traditional diffusion method, which aims to avoid direct operation on plaintext and further enhance the encryption effect. The next scrambling and diffusion operations are based on image blocks and a new dynamical system, namely reversible mixed cellular automata model. The scrambling operation is divided into two parts, inter block scrambling and intra block scrambling, all the above operations are based on pixel level. Then, diffusion operation is performed and its implementation is based on the evolution of constructed reversible mixed cellular automata with balanced rules. In addition, the initial values and parameters of the adopted chaotic system, two dimensional (2D) Logistic map, are obtained using SHA 256 hash function related to plaintext image. The use of hash function makes the chaotic sequences completely different when encrypt different images, which enhances the ability to resist known-plaintext and chosen-plaintext attacks. Simulation results and performance analysis bear out that the encryption algorithm proposed in this paper has higher security performance and can resist different attacks efficiently.

Analysis of singular phase based on double random phase encoding using phase retrieval algorithm

We analyze the properties of the singular phase based on phase retrieval. The phase can be estimated from the result of the known-plaintext attack on a typical optical encryption technique, namely double random phase encoding. The key generated by the singular phase for decryption can be used to decrypt only the known ciphertext image used for the attack. However, it is not obvious whether any unknown ciphertext image can be decrypted using the singular key (a phase key image that has the singular property). Therefore, we prepared various ciphertext images by changing two parameters, namely the plaintext image and a random phase mask in the spatial plane, and analyzed the properties of the singular key by decrypting these unknown ciphertext images. The results show that when the unknown ciphertext images generated by changing only the plaintext image are decrypted, the known plaintext pattern is obtained. In contrast, when the unknown ciphertext images generated by changing only the random phase mask are decrypted, no pattern is obtained. These cases both indicate that cryptanalysis failed. Nevertheless, when the known plaintext pattern is obtained, it indicates that the correlation between the known and unknown random phase masks is high, giving the attacker an important clue.

Secure Image Encryption Algorithm Based on Hyperchaos and Dynamic DNA Coding.

In this paper, we construct a five dimensional continuous hyperchaotic system and propose an image encryption scheme based on the hyperchaotic system, which adopts DNA dynamic coding mechanism and classical scrambling diffusion encryption structure. In the diffusion stage, two rounds of diffusion are adopted and the rules of DNA encoding (DNA decoding) are dynamically changed according to the pixel value of the plaintext image, that is, the rules of DNA encoding (DNA decoding) used to encrypt different images are different, which makes the algorithm can resist chosen-plaintext attack. The encryption (decryption) key is only the initial value of the chaotic system, which overcomes the difficulty of key management in the “one time pad” encryption system. The experimental results and security analysis show that the algorithm has some advantages of large key space, no obvious statistical characteristics of ciphertext, sensitivity to plaintext and key and able to resist differential attacks and chosen plaintext attack. It has good application prospects.

Hyperchaotic image encryption algorithm based on bit-level permutation and DNA encoding

Many chaos-based image encryption algorithms using low-dimensional chaotic mapping and permutation diffusion structures have been proposed recently. However, low-dimensional chaotic maps are less secure than high-dimensional chaotic systems. Furthermore, the permutation process is independent of the plaintext and diffusion process. As a result, they are not very resistant to chosen plaintext attacks and chosen ciphertext attacks. In this paper, we propose a hyper-chaos-based image encryption algorithm that uses a 6-dimensional hyperchaotic system; the key stream generated by hyperchaotic system is related to the plaintext image. Then, bit-level permutation is employed to strengthen the security of the cryptosystem. Finally, DNA coding and operations are employed to change pixels. Theoretical analysis and numerical simulations demonstrate that the proposed algorithm is safe and reliable for image encryption.

Watermarking-Based Secure Plaintext Image Protocols for Storage, Show, Deletion and Retrieval in the Cloud

In this article, we propose secure plaintext image storage protocols in the cloud environment for image owners managing and controlling their outsourced images. To solve control and privacy issues, conventional schemes suggest outsourcing images in the encrypted form. However, encrypted images lose their usability and visibility. For example, image owners cannot quickly find their stored images in the cloud. The proposed protocols encourage plaintext image storage in the cloud with copyright protection of images, visible display, lossless retrieval and controlled deletion via techniques of homomorphic encryption and digital watermarking. We allow the image owner to embed and remove the watermark in a privacy-preserving way without compromising the security of the original data and the computed results. Moreover, the image owner can securely detect the cloud's dishonest act of not completely deleting an image as required or leaking an image without permission. Compared with existing works, our work achieves more functions. We prove that the proposed work achieves the controllable management of the outsourced plaintext images without privacy leakage to unauthorized parties and demonstrate the utility and the efficiency of our protocols through experimental evaluation.

Image encryption algorithm based on the matrix semi-tensor product with a compound secret key produced by a Boolean network

In this paper, a chaotic image encryption algorithm based on the matrix semi-tensor product (STP) with a compound secret key is designed. First, a new scrambling method is designed. The pixels of the initial plaintext image are randomly divided into four blocks. The pixels in each block are then subjected to different numbers of rounds of Arnold transformation, and the four blocks are combined to generate a scrambled image. Then, a compound secret key is designed. A set of pseudosecret keys is given and filtered through a synchronously updating Boolean network to generate the real secret key. This secret key is used as the initial value of the mixed linear-nonlinear coupled map lattice (MLNCML) system to generate a chaotic sequence. Finally, the STP operation is applied to the chaotic sequences and the scrambled image to generate an encrypted image. Compared with other encryption algorithms, the algorithm proposed in this paper is more secure and effective, and it is also suitable for color image encryption.

Generalized switched synchronization and dependent image encryption using dynamically rotating fractional-order chaotic systems

This paper presents a generalization, attractor control and multi-scroll generation method for fractional-order chaotic systems through rotation transformation. A novel synchronization-dependent colored image encryption and secure communication scheme is also proposed. The systems with dynamic rotation angle fit successfully in a generalized dynamic switched synchronization scheme. Dynamic control switches specify whether the system acts as a master or slave. Dynamic scaling factors determine whether the master is a single system or a combination of two or more systems. Simulation results validate successful synchronization when rotating fractional-order systems act as slave or master or both. The proposed synchronization is suitable for one-to-one, one-to-many, mutual interconnection and role switching communication applications. The proposed synchronization-dependent image encryption scheme performs rotation angle modulation using the plaintext and XOR logic operation for plaintext image substitution. The performance of the chaotic systems as Pseudo-Random Number Generators (PRNGs) is validated using National Institute of Standards & Technology (NIST). Three synchronization scenarios are tested using Lena image. The performance of the scheme is evaluated through the encrypted image, histogram and its uniformity through chi square test, pixel correlation, Mean Squared Error (MSE), entropy, Peak Signal-to-Noise Ratio (PSNR), key sensitivity, resistance to brute force, differential and other security attacks.

Privacy-Preserving Krawtchouk Moment feature extraction over encrypted image data

Resource-constrained users outsource the massive image data to the cloud to reduce storage and computation overhead locally, but security and privacy concerns seriously hinder the applications of outsourced image processing services. Besides, existing image processing solutions in the encrypted domain still bring high computation overhead, and even lead to characteristic loss. To this end, we propose a Privacy-Preserving Krawtchouk Moment (PPKM) feature extraction framework over encrypted image data by utilizing the Paillier cryptosystem. First, a mathematical framework for PPKM implementation and image reconstruction is presented in the encrypted domain. Then, the detailed expanding factor and upper bound analysis shows that plaintext Krawtchouk moment and plaintext image reconstruction can be realized over encrypted image with PPKM. Furthermore, the computation complexity of PPKM can be significantly reduced with the block-based parallel algorithm. Experimental results verify that the PPKM is feasible and acceptable in practice in terms of image reconstruction capability and image recognition accuracy.

Cryptanalysis and Improvement of a Chaotic Map-Based Image Encryption System Using Both Plaintext Related Permutation and Diffusion.

In theory, high key and high plaintext sensitivities are a must for a cryptosystem to resist the chosen/known plaintext and the differential attacks. High plaintext sensitivity can be achieved by ensuring that each encrypted result is plaintext-dependent. In this work, we make detailed cryptanalysis on a published chaotic map-based image encryption system, where the encryption process is plaintext Image dependent. We show that some designing flaws make the published cryptosystem vulnerable to chosen-plaintext attack, and we then proposed an enhanced algorithm to overcome those flaws.

A new chaotic encrypted image based on the trigonometric circle

ABSTRACT In this paper, we propose a new idea to encrypt images using the piecewise linear chaotic map (PWLCM). We converted the plaintext image abstractly and geometrically in the form of a cylinder so as to form a series of superimposed circles see Figure 2. This imagination allows us to process and encrypt the image using trigonometric operations in a different way. PWLCM used as a pseudo-random generator to perturb the angles generated by our transformation. Our algorithm has high sensitivity in plaintext image and the secret key. Moreover, the results show that the characteristics of our approach have excellent performance, with high scores (NPCR = 99.614%, UACI = 33.422%, entropy (Ciphertext Image) ≈ 8, PSNR = 8,4008 and Correlation Coefficient ≈ 0). The experimental results of the security analysis confirm a high level of security of the proposed cipher text.