In recent years, the transmission security of image information has become an important research direction in the internet field. In this work, we propose a quantum image chaos encryption scheme based on quantum long-short term memory (QLSTM) network. We find that because the QLSTM network has a complex structure and more parameters, when the QLSTM network is used to improve the Lorenz chaotic sequence, its largest Lyapunov exponent is 2.5465% higher than that of the original sequence and 0.2844% higher than that the sequence improved by the classical long-short term memory (LSTM) network, while its result is closer to 1 and more stable in the 0–1 test. The improved sequence of QLSTM network has better chaotic performance and is predicted more difficultly, which improves the security of single chaotic system encryption. The original image is stored in the form of quantum states by using the NCQI quantum image representation model, and the improved sequence of QLSTM network is used to control the three-level radial diffusion, quantum generalized Arnold transform and quantum W-transform respectively, so that the gray value and pixel position of the quantum image are changed and the final encrypted image is obtained. The encryption scheme proposed in this work obtains the average information entropy of all three channels of RGB of greater than 7.999, the average value of pixel number change rate of 99.6047%, the average value of uniform average change intensity of 33.4613%, the average correlation of 0.0038, etc. In the test of statistical properties, the encryption scheme has higher security than some other traditional methods and can resist the common attacks.
In recent years, the transmission security of image information has become an important research direction in the internet field. In this work, we propose a quantum image chaos encryption scheme based on quantum long-short term memory (QLSTM) network. We find that because the QLSTM network has a complex structure and more parameters, when the QLSTM network is used to improve the Lorenz chaotic sequence, its largest Lyapunov exponent is 2.5465% higher than that of the original sequence and 0.2844% higher than that the sequence improved by the classical long-short term memory (LSTM) network, while its result is closer to 1 and more stable in the 0–1 test. The improved sequence of QLSTM network has better chaotic performance and is predicted more difficultly, which improves the security of single chaotic system encryption. The original image is stored in the form of quantum states by using the NCQI quantum image representation model, and the improved sequence of QLSTM network is used to control the three-level radial diffusion, quantum generalized Arnold transform and quantum W-transform respectively, so that the gray value and pixel position of the quantum image are changed and the final encrypted image is obtained. The encryption scheme proposed in this work obtains the average information entropy of all three channels of RGB of greater than 7.999, the average value of pixel number change rate of 99.6047%, the average value of uniform average change intensity of 33.4613%, the average correlation of 0.0038, etc. In the test of statistical properties, the encryption scheme has higher security than some other traditional methods and can resist the common attacks.
ABSTRACT Quantum image encryption is crucial for data protection, but current methods lack attack resistance and have complex encryption processes. This paper proposes a quantum long short ‐ term memory (QLSTM)‐based quantum image encryption method to enhance chaotic sequences and achieve chaos synchronisation control. The QLSTM network improves the Lorenz chaotic sequence, increasing its unpredictability. An adaptive synchronisation control algorithm, using the enhanced chaotic sequence from QLSTM, ensures sender‐receiver synchronization. Optimised through deep neural networks, the system maintains stable synchronization under interference. New cryptographic quantum infrastructure (NCQI) was constructed, and images were encrypted using third‐order radial diffusion, quantum generalised Arnold transform, and quantum W transform. The QLSTM‐improved chaotic sequence showed excellent LLE and 0–1 test results. Information entropy was near 8, with R, G and B channels exceeding 7.999. Anti‐attack analysis revealed high information entropy, strong attack resistance, and number of pixels change rate/unified average changing intensity (NPCR/UACI) values of 99.698% and 33.460%, respectively, indicating significant pixel‐level changes. Combining quantum chaotic system prediction with the QLSTM model enhanced quantum communication stability and anti‐interference ability. This QLSTM‐based quantum encryption method, with chaos synchronisation control, significantly improves encryption security and reliability, maintaining high information entropy and complexity under attacks, proving its effectiveness in image encryption.
Background: Quantum image processing is rapidly developing in the field of quantum computing, and it can be successfully implemented on the Noisy Intermediate-Scale Quantum (NISQ) device. Quantum image encryption holds a pivotal position in this domain. However, the encryption process often encounters security vulnerabilities and entails complex computational complexities, thereby consuming substantial quantum resources. To address this, the present study proposes a quantum image encryption algorithm based on four-dimensional chaos. Methods: The classical image is first encoded into quantum information using the Generalized Quantum Image Representation (GQIR) method. Subsequently, the trajectory of the four-dimensional chaotic system is randomized, and multi-dimensional chaotic keys are generated to initially encrypt the pixel values of the image. Then, the Arnold transformation is applied to randomly encrypt the pixel positions, resulting in the encrypted image. During the decryption process, the inverse process of encryption is employed to restore the original image. Results: We simulated this process in the Python environment, and the information entropy analysis experiment showed that the information entropy of the three encrypted images reached above 7.999, so the system has good encryption. At the same time, the correlation of the pixel distribution after the encryption algorithm is weak, which proves that the control parameters of the chaotic system can effectively reduce the correlation between pixels in the image. In the final key space analysis, the key space issued by our encryption can reach $10 140 \gg 2 128 $. Conclusion: Our method is resistant to destructive attacks and can produce scrambled images with higher encryption and usability. This algorithm solves the problems of general encryption algorithms such as periodicity, small key space, and vulnerability to statistical analysis, and proposes a reliable and effective encryption scheme. By making full use of the characteristics of Arnold transformation permutation, ergodicity and the randomness of the four-dimensional chaotic system, the encryption algorithm uses the larger key space provided by the four-dimensional Lorenz system.
In order to improve the security of quantum color images, this study proposes a novel algorithm for quantum color image encryption based on three-dimensional chaotic systems. The encrypted quantum color image is represented by the novel quantum image representation for color digital image model. The original image is first perturbed by the Arnold transform and then the RGB channel is perturbed separately from the chaotic sequence generated by the new three-dimensional chaotic system by the xor operation. Evaluation metrics such as histogram, information entropy, and correlation of neighboring pixels of the image are analyzed using MATLAB. The simulation results show that the pixel values of the encrypted image are uniformly distributed and the algorithm enhances the security of quantum color images. The specific quantum circuit diagram of the encryption algorithm is given in the paper. The superposition and entanglement properties of quantum physics greatly improve the efficiency of complex image processing algorithms, and the overall complexity of the circuit is O(n), which is efficient and implementable.
The paper proposes a lossless quantum image encryption scheme based on substitution tables (S-box) scrambling, mutation operation and general Arnold transform with keys. First, the key generator builds upon the foundation of SHA-256 hash with plain-image and a random sequence. Its output value is used to yield initial conditions and parameters of the proposed image encryption scheme. Second, the permutation and gray-level encryption architecture is built by discrete Arnold map and quantum chaotic map. Before the permutation of Arnold transform, the pixel value is modified by quantum chaos sequence. In order to get high scrambling and randomness, S-box and mutation operation are exploited in gray-level encryption stage. The combination of linear transformation and nonlinear transformation ensures the complexity of the proposed scheme and avoids harmful periodicity. The simulation shows the cipher-image has a fairly uniform histogram, low correlation coefficients closed to 0, high information entropy closed to 8. The proposed cryptosystem provides 2256 key space and performs fast computational efficiency (speed = 11.920875 Mbit/s). Theoretical analyses and experimental results prove that the proposed scheme has strong resistance to various existing attacks and high level of security.
Abstract In recent years, extensive research has been conducted on encryption algorithms based on square images. However, relatively few studies have evaluated nonsquare images. In this paper, we propose a novel encryption algorithm for nonequal length images. This algorithm incorporates bitplane chaotic mapping and Arnold transformation. To implement the algorithm effectively, we first transform the plain image into two binary sequences of equal size. Then, we introduce a new diffusion strategy to mutually diffuse these two sequences. Next, we utilize a chaotic map to control the swapping of binary elements between the two sequences. This process allows for the permutation of bits from one bitplane to any other bitplane. Finally, we employ the Arnold transform to scramble the positional information of the image, resulting in the final encrypted image. Using the parameters of nonequal Arnold transformation and the initial value of the Lorenz chaotic map as keys not only simplify the transmission of keys, but also makes the cryptosystem have infinite key space for resisting brute force attacks. Experimental results and security analysis verify that the proposed quantum image encryption algorithm can encrypt nonsquare images, and has good performance in terms of nonstatistical properties, key sensitivity, robustness and so on. Moreover, simulation experiments based on Qiskit successfully verify the correctness and feasibility of the quantum image encryption algorithm.
In the wake of the information security era, ensuring the privacy, accuracy, and reliability of images has become imperative. In this paper, a quantum image encryption method combining quantum Arnold transform and a hyper 5D chaotic system is devised. Furthermore, first, a nonlinear color quantization model (NCQI) is used to convert digital images in standard RGB format into quantum color images. Then, based on the size of the converted quantum color image, the corresponding encryption key is generated using the hyper 5D chaotic system. In the encryption stage, we use the key to encrypt the converted quantum color image. This process entails two principal steps: First, we use quantum Arnold transform to scramble the pixel positions in the image and, subsequently, diffuse the pixel values through a carefully designed cyclic shift strategy to achieve the preliminary encryption of the image. To further strengthen the encryption security, we use a quantum rotation gate to perform quantum rotation transformation on the color channel of each pixel point in the encrypted image separately. These well-designed encryption processes, in succession, significantly enhance the security of the image. This paper provides the corresponding quantum circuit design and validates both the efficacy and security of the quantum image encryption scheme through simulation experimental results.