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Chaos-based image encryption has become a prominent area of research in recent years. In comparison to ordinary chaotic systems, fractional-order chaotic systems tend to have a greater number of control parameters and more complex dynamical characteristics. Thus, an increasing number of researchers are introducing fractional-order chaotic systems to enhance the security of chaos-based image encryption. However, their suggested algorithms still suffer from some security, practicality, and efficiency problems. To address these problems, we first constructed a new fractional-order 3D Lorenz chaotic system and a 2D sinusoidally constrained polynomial hyper-chaotic map (2D-SCPM). Then, we elaborately developed a multi-image encryption algorithm based on the new fractional-order 3D Lorenz chaotic system and 2D-SCPM (MIEA-FCSM). The introduction of the fractional-order 3D Lorenz chaotic system with the fourth parameter not only enables MIEA-FCSM to have a significantly large key space but also enhances its overall security. Compared with recent alternatives, the structure of 2D-SCPM is simpler and more conducive to application implementation. In our proposed MIEA-FCSM, multi-channel fusion initially reduces the number of pixels to one-sixth of the original. Next, after two rounds of plaintext-related chaotic random substitution, dynamic diffusion, and fast scrambling, the fused 2D pixel matrix is eventually encrypted into the ciphertext one. According to numerous experiments and analyses, MIEA-FCSM obtained excellent scores for key space (2541), correlation coefficients (<0.004), information entropy (7.9994), NPCR (99.6098%), and UACI (33.4659%). Significantly, MIEA-FCSM also attained an average encryption rate as high as 168.5608 Mbps. Due to the superiority of the new fractional-order chaotic system, 2D-SCPM, and targeted designs, MIEA-FCSM outperforms many recently reported leading image encryption algorithms.

Nowadays, the utilization of memristors to enhance the dynamical properties of chaotic systems has become a popular research topic. In this paper, we present the design of a novel 2D memristor-enhanced polynomial hyper-chaotic map (2D-MPHM) by utilizing the cross-coupling of two TiO2 memristors. The dynamical properties of the 2D-MPHM were investigated using Lyapunov exponents, bifurcation diagrams, and trajectory diagrams. Additionally, Kolmogorov entropy and sample entropy were also employed to evaluate the complexity of the 2D-MPHM. Numerical analysis has demonstrated the superiority of the 2D-MPHM. Subsequently, the proposed 2D-MPHM was applied to a multi-channel image encryption algorithm (MIEA-MPHM) whose excellent security was demonstrated by key space, key sensitivity, plaintext sensitivity, information entropy, pixel distribution, correlation analysis, and robustness analysis. Finally, the encryption efficiency of the MIEA-MPHM was evaluated via numerous encryption efficiency tests. These tests demonstrate that the MIEA-MPHM not only possesses excellent security but also offers significant efficiency advantages, boasting an average encryption rate of up to 87.2798 Mbps.

Medical image encryption is important for maintaining the confidentiality of sensitive medical data and protecting patient privacy. Contemporary healthcare systems store significant patient data in text and graphic form. This research proposes a New 5D hyperchaotic system combined with a customised U-Net architecture. Chaotic maps have become an increasingly popular method for encryption because of their remarkable characteristics, including statistical randomness and sensitivity to initial conditions. The significant region is segmented from the medical images using the U-Net network, and its statistics are utilised as initial conditions to generate the new random sequence. Initially, zig-zag scrambling confuses the pixel position of a medical image and applies further permutation with a new 5D hyperchaotic sequence. Two stages of diffusion are used, such as dynamic DNA flip and dynamic DNA XOR, to enhance the encryption algorithm’s security against various attacks. The randomness of the New 5D hyperchaotic system is verified using the NIST SP800-22 statistical test, calculating the Lyapunov exponent and plotting the attractor diagram of the chaotic sequence. The algorithm validates with statistical measures such as PSNR, MSE, NPCR, UACI, entropy, and Chi-square values. Evaluation is performed for test images yields average horizontal, vertical, and diagonal correlation coefficients of –0.0018, –0.0002, and 0.0007, respectively, Shannon entropy of 7.9971, Kolmogorov Entropy value of 2.9469, NPCR of 99.61%, UACI of 33.49%, Chi-square “PASS” at both the 5% (293.2478) and 1% (310.4574) significance levels, key space is 2 500 and an average encryption time of approximately 2.93 s per 256 × 256 image on a standard desktop CPU. The performance comparisons use various encryption methods and demonstrate that the proposed method ensures secure reliability against various challenges.

The advancement in digital communication poses a risk to the confidentiality of every individual. To protect information, chaos-based encryption is being exploited in recent research. The complexity of the algorithm is yielded by introducing a hyperchaotic map. This paper proposes a novel Two-Dimensional Henon Ikeda Map (2D-HIM) by combining the Henon map and the Ikeda map. The pseudo-random sequence is generated by the novel 2D-HIM applied to the DNA-based image encryption algorithm. This algorithm ensures the scrambling of pixels into an encrypted form that is unrecognisable. The cryptosystem has been analysed on various colour images, obtaining nearly an NPCR of 99.75%, a UACI of 33.84%, and an entropy of 7.99. Thus, the proposed algorithm ensures resistance against various statistical attacks and differential attacks, implying a robust solution to confidentiality in open communication and suitability for use in cryptographic applications.

Chaotic-based image encryption approaches have attracted great attention in the field of information security. The properties of chaotic maps such as randomness and sensitivity have given new ways to develop efficient encryption approaches. But chaotic maps require initial parameters to develop random sequences. The selection of these parameters is a tedious task. To obtain the optimal initial parameters, evolutionary optimization approaches have been utilized in image encryption. Therefore, in this paper, a hyper-chaotic map is optimized using a multiobjective evolutionary optimization approach. A dual local search based multiobjective optimization (DLS-MO) is used to obtain the optimal parameters of a hyper-chaotic map and encryption factors. Then, using optimal parameters, a hyper-chaotic map develops the secret keys. These secret keys are then used to perform permutation and diffusion on a plain image to develop the encrypted image. To perform encryption, permutation–permutation–diffusion–diffusion architecture is adopted for better confusion and diffusion. Experimental results show that the proposed approach provides better performance in comparison to existing competitive approaches.

In this paper, aiming at defects which are low security properties, high costs of storage and transmission for exiting image encryption and compression algorithms. An algorithm which combined image compression and encryption based on hyper-chaotic map is proposed. In this algorithm, the original image is compressed by compression sensing (CS), and then the compressed image is encrypted through improved Arnold matrix transformation algorithm, Modular operation algorithm and combined the 3D hyper-chaotic map. The experimental results and theoretical analyses show that the proposed algorithm has superior safety performance and compression characteristics, which may reduce the costs of data transmission and improve the encryption efficiency. What’s more, it provides the theoretical guidance and experimental basis for digital image encryption in practical application.

This work is an attempt to address some issues related to practical hardware realization of power attack-resistant chaos-based encryption schemes. First, we introduce a new two-dimensional chaotic map based on a modified logistic-tent map. The proposed map has a very wide range of sustained chaotic and hyper-chaotic behavior over its large key parameters space. The presented map is practically realized using a digital field programmable gate array. Experimental validation of the map’s enhanced chaotic behavior is provided. Then the map is employed to efficiently generate chaotic clock signals appropriate for reliable image encryption applications. A proposed image encryption scheme which is driven by the generated chaotic clock signals is designed. The immunity against the powerful correlation power analysis attack is achieved in the proposed image encryption scheme even in the case when some secret key parameters of the encryption process are leaked. The present study paves the way to further explore how to build efficient chaos-based encryption schemes immune to other types of well-known effective attacks.

To ensure the security transmission of audio signals in instant messaging tools, a chaos-based dual-channel one-time one-key audio encryption scheme was proposed. First, a non-degenerate 2D integer domain hyper chaotic map (2D-IDHCM) over GF(2 n ) was constructed, the results of dynamics analysis showed that the 2D-IDHCM has ergodicity and large Lyapunov exponents. Then, based on 2D-IDHCM, two keyed strong S-Boxes were constructed. Further, an audio encryption & decryption algorithm was designed using 2D-IDHCM and keyed strong S-Boxes. The novelty includes: (1) 2D-IDHCM has no dynamic degradation, fast iteration speed and no need for data type conversion, which improves the efficiency of the algorithm. (2) The algorithm includes confusion process and diffusion process, which are resistant to most common attacks. Experimental results and security analysis demonstrated that the algorithm is sensitive to the initial condition, reduces the correlation of the original audio, and the total key space can reach 2 224 . In addition, NPCR and UACI are all close to their ideal values of 99.6094070% and 33.4635070%, and the information entropy is close to the ideal value of 8.

In this paper, we propose a secure image encryption method using compressive sensing (CS) and a two-dimensional linear canonical transform (2D LCT). First, the SHA256 of the source image is used to generate encryption security keys. As a result, the suggested technique is able to resist selected plaintext attacks and is highly sensitive to plain images. CS simultaneously encrypts and compresses a plain image. Using a starting value correlated with the sum of the image pixels, the Mersenne Twister (MT) is used to control a measurement matrix in compressive sensing. Then, the scrambled image is permuted by Lorenz’s hyper-chaotic systems and encoded by chaotic and random phase masks in the 2D LCT domain. In this case, chaotic systems increase the output complexity, and the independent parameters of the 2D LCT expand the key space of the suggested technique. Ultimately, diffusion based on addition and modulus operations yields a cipher-text image. Simulations showed that this cryptosystem was able to withstand common attacks and had adequate cryptographic features.

This paper introduces a new fast image encryption scheme based on a chaotic system and cyclic shift in the integer wavelet domain. In order to increase the effectiveness and security of encryption, we propose a new diffusion scheme by using bidirectional diffusion and cyclic shift and apply it to our encryption scheme. First, a two-level integer wavelet transform is used to split the plaintext picture into four low-frequency components. Second, we use random sequences generated by Chen’s hyper-chaotic system to scramble four low-frequency components. The initial value is determined by Secure Hash Algorithm 256-bit (SHA256) and user-defined parameters, which increases the plaintext sensitivity. Then, the new diffusion scheme is applied to the matrix containing most of the information and matrices are transformed by a one-level inverse integer wavelet. Finally, to create the ciphertext image, the diffused matrices are subjected to the one-level inverse integer wavelet transform. In the simulation part, we examine the suggested algorithm’s encryption impact. The findings demonstrate that the suggested technique has a sufficient key space and can successfully fend off common attacks.