Multiple-image Encryption Research Articles

Optical asymmetric cryptosystem for multiple image encryption through vector field encoding

Optical asymmetric cryptosystem for multiple image encryption through vector field encoding

Multiple image encryption based on multiplexing holography with Kramers–Kronig relations

Multiplexing techniques can store multiple wavefront information of object beams in one hologram, which is a way to realize multi-image encryption. In this paper, an optical multi-image encryption method based on Kramers-Kronig multiplexing digital holography is proposed. In the encryption process, multiple images are subjected to Fresnel diffraction at a certain distance and modulated by a random phase mask. The modulated images then interfere with the reference beam and form a noise-like compound ciphertext. In the decryption process, the information of the original images can be extracted directly from the positive frequency part of the spectrum. Compared to the traditional image encryption based on off-axis digital holography, this method enables the decryption of images in the case of spectrum overlap. The feasibility of our proposed method is demonstrated through numerical simulations, which provide a novel approach for the field of multi-image encryption based on digital holography.

Novel multiple color images encryption and decryption scheme based on a bit-level extension algorithm

Digital images play a crucial role in modern communication, but the accompanying privacy concerns have become increasingly prominent. In this context, image encryption technology has emerged as a vital means to safeguard the security of digital image information. Over the past few years, a number of effective image encryption schemes have been developed. However, the amalgamation of bit-level encryption techniques with compression algorithms remains underexplored. To leverage the advantages of these two technologies in terms of security and practicality, a novel multiple color images encryption and decryption scheme is devised based on a bit-level extension algorithm. Firstly, four color images are compressed by the discrete wavelet transform (DWT) to reduce transmission and storage consumption. Secondly, to carry out the bit-level scrambling and diffusion operations on pixels with fractional parts in the DWT domain and maintain the decryption image quality as much as possible, a bit-level extension algorithm is developed. Finally, three rounds of scrambling and diffusion operations based on the bit-level extension algorithm are conducted to enhance the randomness of the ciphertext image and conceal the plaintext information. To reinforce the resistance of the presented image encryption and decryption scheme towards the chosen-plaintext and the differential attacks, secret keys are produced with the hash function SHA-512. The presented scheme undergoes a comprehensive analysis including decryption quality, key security, and resistance to the statistical and the differential attacks. The results are: average PSNR = 31.2631 dB, key space reaches 2472, correlation coefficients are almost 0, average entropy = 7.9985 bits, average NPCR = 99.6089%, and average UACI = 33.4658%. Moreover, experimental simulations demonstrate that our solution exhibits a degree of resilience to noise interference and data loss. In summary, our presented multiple color images encryption and decryption scheme based on a bit-level extension algorithm is effective and reliable.

Multiple face images encryption based on a new non-adjacent dynamic coupled mapping lattice

There have been limited research studies on encryption algorithms specifically designed for certain encryption scenarios. Aiming at different types of face images, this paper presents a multiple face images encryption algorithm based on a new non-adjacent coupled mapping lattice with dynamic parameter (NCMLP). NCMLP has a more comprehensive parameter range, better chaos, and more complex dynamic behavior Compared to classical non-adjacent coupled lattice mapping, which is suitable for encryption. The encryption algorithm firstly uses face detection technology to extract multiple face information and to generate a double-layer key, then scrambles the face information by three-dimensional bit-level cyclic shift, and finally encrypts the global information using 3D pixel level scrambling and 3D double index diffusion. It is worth mentioning that the algorithm has high security and can be applied to ordinary images. The experimental results and safety analysis show that the information entropy can exceed 7.9992, the histogram variance can be less than 1072, the pixel number change rate can reach 99.6323%, and the unified average change intensity can reach 33.5495%, all of which are very close to the ideal values.

Research on multiple-image encryption method using modified Gerchberg–Saxton algorithm and chaotic systems

Research on multiple-image encryption method using modified Gerchberg–Saxton algorithm and chaotic systems

Multiple-image encryption algorithm based on the stereo Zigzag transformation

Multiple-image encryption algorithm based on the stereo Zigzag transformation

Multiple-Image Encryption Scheme Based on an N-Dimensional Chaotic Modular Model and Overlapping Block Permutation–Diffusion Using Newly Defined Operation

Some existing chaotic maps have the drawbacks of a narrow range of chaotic parameters and discontinuities, which may be inherited by new chaotic systems generated from them as seed maps. We propose a chaotic model that can generate N-dimensional chaotic systems to overcome the problem. By fixing the original parameters of the seed map in the chaotic range, we then introduce new parameters and use modular operations to widen the range of the parameters and increase the complexity. Simulation results show that the generated chaotic system has good chaotic dynamics. Based on this chaotic model, we propose a multiple-image encryption algorithm that is not limited by image type, number, and size. The resistance to plaintext attacks is enhanced by a permutation–diffusion algorithm based on overlapping blocks. We design a newly defined lookup table operation based on Latin squares with enhanced nonlinearity and randomness. By adjusting the overlapping block parameters and the number of Latin squares, users can design different encryption levels to balance encryption efficiency and encryption effectiveness. The experimental results show that the proposed image encryption algorithm can effectively encrypt multiple images, and all the evaluation indexes reach the expected value.

Multi-layer permutation-substitution operations based novel lossless multiple color image encryption

Multi-layer permutation-substitution operations based novel lossless multiple color image encryption

A novel structure of fast and efficient multiple image encryption

A novel structure of fast and efficient multiple image encryption

Novel multiple-image encryption algorithm based on a two-dimensional hyperchaotic modular model

Current multiple-image encryption schemes usually require a fixed number or the same size of images. Therefore, this paper proposes a multiple-image encryption algorithm that can encrypt any number, size, and type of image. Firstly, we propose a two-dimensional chaotic model, which can generate multiple types of chaotic systems to solve the defects of some existing chaotic systems and reduce the design difficulty of chaotic systems. The generated chaotic systems are proven to have better performance through bifurcation diagrams, phase diagrams, Lyapunov exponent, and sample entropy analysis. Secondly, we fuse multiple images and then use SHA-512 to generate a secret key to increase resistance to plaintext attacks. We embed the size message of the original image into the fused image pixels, eliminating the need to transmit the size message separately from the secret key. Finally, we propose a simultaneous permutation and diffusion algorithm to improve security and efficiency. Experimental simulations and security analysis show that the proposed algorithm can encrypt multiple images of different sizes and types with good attack resistance and encryption efficiency.

Multi-key optical encryption based on two-channel incoherent scattering imaging.

Optical encryption has been extensively researched in the field of information security due to its characteristics of being parallel and multi-dimensionsal. However, most of the proposed multiple-image encryption systems suffer from a cross-talk problem. Here, we propose a multi-key optical encryption method based on a two-channel incoherent scattering imaging. In the encryption process, plaintexts are coded by the random phase mask (RPM) in each channel and then coupled by an incoherent superposition to form the output ciphertexts. In the decryption process, the plaintexts, keys, and ciphertexts, are treated as a system of two linear equations with two unknowns. By utilizing the principles of linear equations, the issue of cross-talk can be mathematically resolved. The proposed method enhances the security of the cryptosystem through the quantity and order of the keys. Specifically, the key space is significantly expanded by removing the requirement of uncorrected keys. This approach provides a superior method that can be easily implemented in various application scenarios.

A Multiple-Medical-Image Encryption Method Based on SHA-256 and DNA Encoding.

Ensuring the privacy and secrecy of digital medical images has become a pressing issue as a result of the quick development of smart medical technology and the exponential growth in the quantity of medical images transmitted and stored in networks. The lightweight multiple-image encryption approach for medical images that is suggested in this research can encrypt/decrypt any number of medical photos of varied sizes with just one encryption operation and has a computational cost that is similar to encrypting a single image. The plaintext images with different sizes are filled at the right and bottom of the image to ensure that the size of all plaintext images is uniform; then, all the filled images are stacked to obtain a superimposed image. The initial key, which is generated using the SHA-256 technique, is then used as the starting value of the linear congruence algorithm to create the encryption key sequence. The cipher picture is then created by encrypting the superimposed image with the encryption key and DNA encoding. The algorithm can be made even more secure by implementing a decryption mechanism that decrypts the image independently in order to reduce the possibility of information leaking during the decryption process. The outcomes of the simulation experiment demonstrate the algorithm's strong security and resistance to interference such as noise pollution and lost image content.

Multiple-image encryption algorithm based on Sarrus rule and 3D Fibonacci matrix

Using images to transmit information becomes more common in the new era, but the image information can easily be stolen and tampered with the malicious damage during transmission. In this paper, firstly, inspired by the famous Sarrus rule the theory of linear algebra theory, the Sarrus model is established to scramble images; secondly, the pixel positions of plain images are scrambled with the established Sarrus model to obtain the stereo scrambled matrix; thirdly, two-dimensional Fibonacci matrix is extended to three-dimensional (3D) space; finally, the image matrix is divided into cubes which are diffused by the 3D Fibonacci matrix. Experimental analyses indicate that the new algorithm has the characteristics of large key space, high key sensitivity, high efficiency and can resist to the plaintext attacks, statistical attacks, etc.

Triple Color Image Encryption Using Hybrid Digital/Optical Scheme Supported by High-Order Chaos

Image security has attracted increasing interest, wherein image encryption is an effective and direct method that can be implemented using digital, optical, or hybrid techniques. The challenge is how to design a high-speed, and high-security level multiple color image encryption scheme which makes use of advanced techniques such as chaotic system and deep learning. This issue is addressed in this paper where a nine-dimensional (9D) chaotic-based Hybrid Digital/Optical Encryption (HDOE) scheme is proposed for triple color images. The scheme consists of cascading digital and optical encryption parts controlled separately by the chaotic sequences. The nine chaotic sequences are grouped into three sets, and each set is responsible for the encryption of one of the RGB channels independently. The digital part uses fusion, XOR operation, and scrambling. The optical part uses two independent chaotic phase masks in the optical Fourier transforms domain. A Denoising Convolution Neural Network (DnCNN) is designed to assist the robustness of the decrypted images against Gaussian noise. The simulation results reveal that the proposed triple-image HDOE scheme offers entropy of 7.9991, 7.9987, and 7.9991 bits for R, G, and B channels, respectively,  and infinite Peak Signal-to-Noise Ratio (PSNR) for the decrypted images.

Deep-learning-based cross-talk free and high-security compressive encryption with spatially incoherent illumination.

Incoherent optical cryptosystem is promising for its immunity against coherent noise and insensitivity to misalignment, and compressive encryption is desirable considering the increasingly demand on the exchange of encrypted data via Internet. In this paper, we propose a novel optical compressive encryption approach with spatially incoherent illumination based on deep learning (DL) and space multiplexing. For encryption, the plaintexts are individually sent to the scattering-imaging-based encryption (SIBE) scheme where they are transformed to scattering images with noise appearances. Afterwards, these images are randomly sampled and then integrated into a single package (i.e., ciphertext) by space multiplexing. The decryption is basically the inverse of the encryption, while it involves an ill-posed problem (i.e., recovering the noise-like scattering image from its randomly sampled version). We demonstrated that such a problem can be well resolved by DL. The proposal is radically free from the cross-talk noise existing in many current multiple-image encryption schemes. Also, it gets rid of the linearity bothering the SIBE and is hence robust against the ciphertext-only attack based on phase retrieval algorithm. We present a series of experimental results to confirm the effectiveness and feasibility of the proposal.

A flexible and visually meaningful multi-image compression, encryption and hiding scheme based on 2D compressive sensing

Background: Encrypting plain images into noise-like cipher images is a common method in image encryption. However, when noise-like images appear in public networks, they are more likely to attract attention and suffer more cryptanalysis. To solve this problem, researchers propose the concept of visually meaningful image encryption scheme, which encrypts a plain image into a visually meaningful cipher image. Objective: In order to realize the visual security of cipher image and increase information capacity, this paper proposes a flexible visually secure multi-image compression, encryption and hiding scheme based on two-dimensional compressive sensing (2DCS), which can flexibly complete the compression and encryption of multiple plain images without increasing the amount of ciphertext data. Methods: The scheme is divided into encryption process and embedding process. In the encryption process, the plain image is randomly scrambled and non-linear gray value transformed to obtain a pre-encrypted integer matrix, then 2DCS is used to compress the pre-encrypted integer matrix to get the secret image. Repeat this process for multiple plain images to obtain multiple secret images. In the embedding process, integer wavelet transform and bit-plane decomposition are used to embed multiple secret images into the quantized coefficient matrix of host image to get the modified coefficient matrix, and then the inverse integer wavelet transform is used to transform the modified coefficient matrix into spatial space to get the visually meaningful cipher image. Result: The simulation experiment verifies the feasibility and effectiveness of the visually meaningful multi-image encryption scheme, and users can choose to improve the system's encryption capacity or cipher image's visual security according to their own needs.

Nonlinear Encryption for Multiple Images Based on a Joint Transform Correlator and the Gyrator Transform.

A novel nonlinear encryption-decryption system based on a joint transform correlator (JTC) and the Gyrator transform (GT) for the simultaneous encryption and decryption of multiple images in grayscale is proposed. This security system features a high level of security for the single real-valued encrypted image and a high image quality for the multiple decrypted images. The multispectral or color images are considered as a special case, taking each color component as a grayscale image. All multiple grayscale images (original images) to encrypt are encoded in phase and placed in the input plane of the JTC at the same time without overlapping. We introduce two random-phase masks (RPMs) keys for each image to encrypt at the input plane of the JTC-based encryption system. The total number of the RPM keys is given by the double of the total number of the grayscale images to be encrypted. The use of several RPMs as keys improves the security of the encrypted image. The joint Gyrator power distribution (JGPD) is the intensity of the GT of the input plane of the JTC. We obtain only a single real-valued encrypted image with a high level of security for all the multiple grayscale images to encrypt by introducing two new suitable nonlinear modifications on the JGPD. The security keys are given by the RPMs and the rotation angle of the GT. The decryption system is implemented by two successive GTs applied to the encrypted image and the security keys given by the RPMs and considering the rotation angle of the GT. We can simultaneously retrieve the various information of the original images at the output plane of the decryption system when all the security keys are correct. Another result due to the appropriate definition of the two nonlinear operations applied on the JGPD is the retrieval of the multiple decrypted images with a high image quality. The numerical simulations are computed with the purpose of demonstrating the validity and performance of the novel encryption-decryption system.

Multi-layer security based multiple image encryption technique

This paper designs a novel multiple image encryption technique utilizing affine Hill cipher (AHC), reality-preserving two-dimensional discrete fractional Hartley transform (RP2DFrHT) and generalized two-dimensional (2D) Arnold map (AM). In our technique, three indexed images are obtained from three color images. Afterwards, AHC performs a strong degree of confusion and diffusion operations and RP2DFrHT provides real domain output image. Lastly, 2D AM dislocates the image pixel position. After the encryption process, single-channel real-valued encrypted image is obtained which gives convenience in the display, storage and transmission of an image over an unsecured network. The proposed technique is multi-layer secured in the time, frequency and co-ordinate domains. Moreover, the secret keys, arrangements and positions of used parameters all are imperative for the correct decryption process of our technique. Simulation results, security analysis, statistical analysis and comparison analysis ensure that the proposed technique has an excellent encryption effect, sufficient security and robustness.

An exquisite multiple image encryption harnessing multi-scroll Lu–Chen and Chua chaotic systems employing domino strategy

The enormous growth of information in the digital era has urged the researchers to secure the digital content. Guaranteeing security to these aspects remain to be the demanding challenge for the researchers in everyday life. The security needed for the confidential images has grown enormous of ages and in-order to offer exquisite protection for the collection of images in a distinct period of time, Multiple Gray Image Encryption (MGIE) model is proposed here to ensure the prevailing need. This encryption scheme incorporates two chaotic systems namely Chua system and Lu–Chen system due to their complex behavior. The proposed model endeavours the following: (1) source image can be of any type, (2) multiple images can be taken for processing, (3) cris-cross scrambling procedure is followed to absolutely alter the pixel locations, (4) diffusion is accelerated to strengthen the proposed MGIE system. The encryption procedures are interconnected and also provide cascading effect and so termed to be domino encryption strategy. The various experimental measures and performance analyses such as key space, key sensitivity, histogram, correlation, NPCR, UACI, entropy, noise, dataloss, computational complexity, time complexity analysis etc., prove that the MGIE model has inbuilt capacity to blow-away the prevailing attacks. Hence the proposed algorithm is suitable for secure transmission of multiple images.

Multiple-image encryption algorithm based on the bit plane and superpixel

Multiple-image encryption algorithm based on the bit plane and superpixel