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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.

Modern healthcare systems contain a large amount of sensitive information related to a patient in textual and visual form. Surgical videos and diagnosis data such as ultrasound, Computed Tomography (CT) scan, and Magnetic Resonance Imaging (MRI) are examples of healthcare video data. The secure storage and transmission of medical data have become an important issue in medical applications. To handle this challenge, chaos based cryptosystems are widely used these days. The work in this paper proposes a novel 2D Cosine-Sine map that exploits the existing Sine map and cosine transformation in its mathematical computation. The performance assessment of the suggested map indicates that it possesses a broader chaotic range, more dynamic and hyperchaotic nature when compared to existing chaotic maps. The proposed work, also, combines this novel 2D Cosine-Sine map with dynamic DNA encoding to propose a new scheme to encrypt medical videos. The approach consists primarily of four distinct phases. In the initial stage, the video is divided into frames, and for each frame, a chaotic sequence is generated using a 2D Cosine-sine map. During the second stage, we proceed to pixel permutation for each frame by utilizing the chaotic sequence. The third step is diffusion, in this, we integrate the 2D Cosine-Sine map with dynamic DNA encoding and apply double DNA operations to substitute the pixel values. The last step is DNA decoding to get the frames back in binary format. DNA encoding/decoding rules and operands of DNA operations are not fixed. They are selected dynamically using a random key for each frame. The dynamic selection of encoding/decoding rules and operands is a unique feature that enhances the scheme’s security. Simulation results and security analysis proves that the proposed medical video encryption scheme can resist different types of attacks. Graphical abstract

With the aim of tackling insufficient security in the chaotic encryption algorithm for digital images in the Optical Access Network, a color image encryption scheme combining non-degenerate discrete hyperchaotic system and deoxyribonucleic acid (DNA) dynamic encoding is proposed. First, a new non-degenerate hyperchaotic system is constructed with all positive Lyapunov and more complex dynamic characteristics. Furthermore, the key sequence based on non-degenerate hyperchaotic system is generated using plaintext correlation to achieve the effect of a dynamic secret key. Next, a binary bit-planes permutation is performed on the image using one of the key sequences. Then, the chaotic key sequence is used to sequentially perform DNA encoding, obfuscation, and decoding. Finally, a binary bit-planes obfuscation is performed to obtain the final ciphertext. The research results show that the non-degenerate chaotic sequence can pass the NIST 800-22 test, and the corresponding encryption algorithm can resist various common attacks and has a strong anti-interference ability. In addition, the algorithm is verified on ARM-Embedded, which proves that the encryption system proposed in this paper is a feasible secure communication technology scheme. Therefore, the scheme proposed in this paper is helpful to provide new ideas for the design and application of high-security cryptosystem in optical access network.

In order to improve the key space of color image encryption algorithm, the sensitivity to the contents of plain images, the robustness against various types of known attacks, and to achieve the tamper location analysis, a novel color image encryption algorithm based on image hashing, six-dimensional (6D) hyperchaotic and dynamic DNA coding is proposed. Firstly, the color image is pre-processed and the hash sequence is extracted by image hashing algorithm which is used as the initial value and control parameter of chaotic system. Secondly, three color channels of the color image RGB are synthesized into a two-dimensional matrix and the pixels replacement are performed by using the improved two-dimensional chaotic map. Finally, a 6D hyperchaotic system is used to generate random sequences for DNA dynamic coding and arithmetic operations of color images, the encrypted image is obtained. The experimental results show that, compared with the existing methods, the proposed algorithm has a large enough key space, better plain-image sensitivity, better statistical and differential characteristics, as well as can resistant various forms of attacks such as noise and cropping, and the tampering image can be tamper-located analyzed, which has good security and strong robustness.

A new multistage encryption algorithm is proposed by integrating the deep neural network with a new 4D multi-scroll chaotic map to enhance the efficiency and improve the security of image transmission in the open channel. This combined network expands the key space and maintains the secrecy of the key with the multistage encryption algorithm. Initially, the image adaptive key generation process is implemented by the EfficientNet-B3 network to extract the features from the source image, which are then converted into hash values using SHA 256. The hash values are partitioned into four sections, and each section is normalized to give one distinct initial value for the generation of a multi-scroll chaotic sequence. The pseudo-parallel process routes the split source sub-image blocks (128⨯128) of plain text to branch 1 or branch 2, decided by the seed value of the chaotic sequence, increasing the high robustness against the differential and statistical attacks. Each branch contains row and column-wise permutations, bidirectional selective shuffling, and chaotic intra/inter-pixel diffusion in varying orders. The key image diffusion and dynamic DNA diffusion to the intermediate cypher image exhibit a strong avalanche effect. The simulation evaluation on the natural data set images demonstrates the large key space of 2 to the power of 674, high key sensitivity, uniform histogram with entropy value attains the critical values of 7.9, high NPCR value of 99.9%, UACI values with 33.46%, almost zero-pixel correlation and strong robustness to the cropping and noise attacks.

To protect the images and provide a more secure cipher image, DNA encoding is crucial in image encryption. Applying a single, easily detectable coding rule to the image during DNA encoding has no impact on the encryption model's security level. Therefore, using various coding rules while applying encryption to the image, dynamic DNA-coding techniques have emerged to strengthen and improve the encryption of the image and its security. This study integrates a dynamic DNA-coding method with an encryption model. The model is applied to gray-scale images, where using a predetermined coding rule, every two bits are DNA-encoded in the image. The proposed model generates the key by sending the image and its metadata to hash functions. Following that, the hyperchaotic system constructs three chaotic sequences using the key, and the Lorenz–Liu chaotic system generates a sequence of coding rules. Then, the image is passed to Arnold Transform, where the resulted image is diffused by applying five chaotic maps. Last, using the coding rules, it is DNA-encoded, provided with the chaotic sequences to DNA, and DNA-decoded. Twelve metrics were used to assess the proposed model on ten widely used images. Results show a promising improvement in performance, since it enhanced the security of the model.

The principle of DNA strand displacement is that DNA molecules always tend to the most stable state, and the most stable DNA structure can be selected for image encryption. In this paper, DNA strand displacement and four-dimensional multi-stable hyper chaotic system are introduced. SHA-256 algorithm is used to generate summary information as the initial value of the four-dimensional multi-stable hyper chaotic system. The system iteratively generates chaotic sequences, and the key is dynamically selected and processed by using the principle of DNA strand displacement. Use the chaotic matrix generated by the Cubic chaotic map to perform dynamic DNA coding with the chaotic matrix of the original image, and perform a series of DNA operations. In this paper, DNA strand displacement is mainly responsible for the processing work before the key is used. The chaotic sequence and the key image are further processed, and two chaotic sequences or one chaotic sequence and the key stream of the small image tend to be stable are selected to generate the final key stream. At the same time, the connection between original image and key is increased. The experimental results and security analysis show that the encryption algorithm not only has good encryption effect on RGB color image, but also has high anti exhaustive attack, anti statistical attack and anti known original image attack.

In this paper, a novel asymmetrical double-wing third order hyperchaotic system is humbly proposed. The dynamic behavior of the system is greatly abundant after properly analyzing the phase diagram, bifurcation diagram, Lyapunov exponents spectrum, Poincare section diagram, and complexity. In addition, chaotic attractors under different parameters of the system are analyzed. In the dynamic analysis of the new system, it is found that the new system has some characteristics, like multi-stability, multi-state transition phenomenon, multiple attractors coexist. These features possess the value of in-depth analysis compared to previous systems and can make it promising for more applications. It is extraordinary attention for this new chaotic system, due to exist on multi-state transition phenomenon. The circuit diagram of the system is designed and implemented. Simultaneously, the circuit of the system is engineered and accomplished by using Multisim circuit simulation software. Furthermore, the limited time synchronization for the system is studied and carried out by an appropriate controller. Ultimately, algorithm of image encryption, novel and efficient, is designed by combining DNA dynamic encryption. The chaotic sequence of the current system is used to encrypt the image, and the key space, encrypted histogram, adjacent pixel correlation, robustness and information entropy are analyzed. The excellent performance analysis results further indicate that this hyperchaotic system has important reference value in the chosen field of chaotic image encryption and synchronization.

A 3D unified chaotic system and dynamic deoxyribonucleic acid i.e. DNA coding-based colour medical image encryption describe in this article. First, the pixels of the original image are circularly rotated horizontally, vertically, and diagonally at bit level. Next every associated two pixels are encoded into DNA bases using dynamic DNA coding. After that, positions of the DNA bases are altered in different directions, which makes extreme shuffling of DNA bases. Finally, the resultant DNA matrix is decoded using the dynamic DNA base decoding technique. Input values of every phase combine to form the decryption key. The runtime formation of decryption key makes the proposed algorithm more secure. The proposed algorithm is simulated, analysed, and tested with some standard evaluation parameters. The results of various tests are exceptionally encouraging and show powerful encryption execution on different types of images it also exhibits the strength of the proposed method against various kinds of cryptographic attacks.

Epigenetic modifications in DNA bases and histone proteins play important roles in the regulation of gene expression and genome stability. Chemical modification of DNA base (e.g., addition of a methyl group at the fifth carbon of cytosine residue) switches on/off the gene expression during developmental process and environmental stresses. The dynamics of DNA base methylation depends mainly on the activities of the writer/eraser guided by non-coding RNA (ncRNA) and regulated by the developmental/environmental cues. De novo DNA methylation and active demethylation activities control the methylation level and regulate the gene expression. Identification of ncRNA involved in de novo DNA methylation, increased DNA methylation proteins guiding DNA demethylase, and methylation monitoring sequence that helps maintaining a balance between DNA methylation and demethylation is the recent developments that may resolve some of the enigmas. Such discoveries provide a better understanding of the dynamics/functions of DNA base methylation and epigenetic regulation of growth, development, and stress tolerance in crop plants. Identification of epigenetic pathways in animals, their existence/orthologs in plants, and functional validation might improve future strategies for epigenome editing toward climate-resilient, sustainable agriculture in this era of global climate change. The present review discusses the dynamics of DNA methylation (cytosine/adenine) in plants, its functions in regulating gene expression under abiotic/biotic stresses, developmental processes, and genome stability.