Double optical image encryption using discrete Chirikov standard map and chaos-based fractional random transform

The paper presents an opto-double color image cipher using two dimensional (2D) chaotic Arnold transform (AT) as a preprocessing scrambling stage and 2D chaotic Logistic adjusted Sine map (LASM) phase masks in the Fresnel (Fr)-based Hartley Transform (HT). In the proposed opto-double color image cipher, the 2D chaotic LASM is utilized to create chaotic phase masks. The color plainimage red, green and blue channels are firstly scrambled with 2D chaotic AT. Then, the scrambled color plainimage red, green and blue R-G-B channels are modulated using the 2D chaotic LASM phase mask and transformed with the Fr-based HT. The transformed complex R-G-B channels distributions are secondly scrambled with the 2D chaotic AT, modulated secondly with the 2D chaotic LASM phase mask and transformed with Fr-based HT. The utilization of 2D chaotic LASM phase masks in addition to the 2D chaotic AT provides efficient key administration and communication. Also, optical geometric parameters are considered as extra additional keys that enhances the secrecy of the proposed scheme. A comprehensive security study is employed for the proposed scheme and test results verifies and ensures that the proposed scheme is highly immune and resistant against most potential attacks.

Background: Among optical encryption techniques, Double Random Phase Encoding (DRPE) is one of the most widely used. Individual identities and the process of recognition remain essential to ensuring proper data access security.Aim: The study aims to optimize an approach that ensures the significant performance effectiveness of the cancelable biometric methods for different templates and the associated time taken to transform biometric data.Problem: This study is majorly concerned about the performance effectiveness of cancelable biometric methods that measure the likelihood that an authorized effort may be mistakenly rejected as unauthorized. Also, when compromised, several non-renewability safety challenges arise, and insufficient matching performance templates are required to build a security protection method.Method and material. The study uses supervised learning for the Double Random Phase Encoding Method (DRPE), a 4F optical encryption system, and 20 randomly chosen photos from the ORL database of faces.Results. The result based on the supervised learning for the Double Random Phase Encoding Method revealed false positive rates for both the fingerprint and face templates.Conclusion. The study concluded that the performance effectiveness of the cancelable biometric in this study has a false positive rate likelihood that an authorized effort may not be mistakenly rejected as an unauthorized one.

Full Poincaré beams, which cover all polarization states on the Poincaré sphere, provide a unique and complete degree of freedom for polarization manipulation in optical encryption. This paper introduces a novel optical image encryption method based on double random phase encoding (DRPE) system with multi-dimensional keys of full Poincaré beam. The encryption process begins by preprocessing the full Poincaré beam with a polarizer, followed by loading the image to be encrypted along this polarization direction, and finally performing encryption via the DRPE system. The scheme integrates conventional optical keys, such as wavelength, topological charge, amplitude, and phase, with the complete polarization dimension afforded by the full Poincaré beam, as well as the spatial loading dimension of the image placed behind the lens. By synergistically combining these multi-dimensional keys, the encryption system significantly expands the key space. Additionally, the dual random phase modulation capability of the DRPE system further enhances information security. This work establishes a new paradigm for high-security optical encryption.

In conventional symmetric encryption, it is common for the encryption/decryption key to be reused for multiple plaintexts. This gives rise to the concept of a known-plaintext attack. In optical image encryption systems, such as double random phase encoding (DRPE), this is also the case. With optical encryption, if one knows a plaintext-ciphertext pair, one can carry out a known-plaintext attack more efficiently than a bruteforce attack, using heuristics based on phase retrieval or simulated annealing. However, it is more likely that an attacker will find an imperfect encryption/decryption key using such heuristics. Such an imperfect key will work for the known plaintext-ciphertext pair, but not an arbitrary unseen plaintext-ciphertext pair using the original key. In this paper, we illustrate the problem and attempt to characterise the increase in security it affords optical encryption.

The present work is devoted to research the peculiarities of an authentication system of the technical devices with the use of an optical asymmetric holographic encryption on the basis of the Double Random Phase Encoding (DRPE). The series of the numerical experiments was performed to implement the encryption and the decryption of the initial image. The angular spectrum approach was used as a tool for the simulation of the propagation of the light in the free space forward and backward along the whole optical scheme of the DRPE. In the present work the particularities of the authentication system based on an asymmetric approach of the holographic encryption method DRPE were studied.

Intensive studies have been done to get robust encryption algorithms. Due to the importance of image information, optical encryption has played a vital role in information security. Many optical encryption schemes have been proposed but most of them suffer from poor robustness. In this paper six proposed algorithms will be presented for optical encryption to be robust to severe attacks: composite attack. Three of these approaches are based on one level Discrete Wavelet Transform (DWT) and the others are based on Wavelet Packet (WP). Not only will new techniques be presented but also a new proposed chaotic map has been developed as random keys for all algorithms. After extensive comparative study with some traditional techniques, it has been found that the novel algorithms have achieved better performance versus conventional ones. Also it has been found that WP based algorithms have achieved better performance than DWT based ones against severe composite attacks.

The principle of ptychography is applied in known plain text attack on the double random phase encoding (DRPE) system. We find that with several pairs of plain texts and cipher texts, the model of attack on DRPE can be converted to the model of ptychographical imaging. Owing to the inherent merits of the ptychographical imaging, the DRPE system can be breached totally in a fast and nearly perfect way, which is unavailable for currently existing attack methods. Further, since the decryption keys can be seen as an object to be imaged from the perspective of imaging, the ptychographical technique may be a kind of new direction to further analysis of the security of other encryption systems based on double random keys.

Devil׳s vortex Fresnel lens phase masks on an asymmetric cryptosystem based on phase-truncation in gyrator wavelet transform domain

To realize the secure transmission of double images, this paper proposes a double image encryption algorithm based on convolutional neural network (CNN) and dynamic adaptive diffusion. This scheme is different from the existing double image encryption technology. According to the characteristics of digital image, we design a dual-channel (digital channel / optical channel) encryption method, which not only ensures the security of double image, but also improves the encryption efficiency and reduces the possibility of being attacked. First, a chaotic map is used to control the initial values of the 5D conservative chaotic system to enhance the security of the key. Secondary, in order to effectively resist known-plaintext attack and chosen-plaintext attack, we employ a chaotic sequence as convolution kernel of convolution neural network to generate plaintext related chaotic pointer to control the scrambling operation of two images. On this basis, a novel image fusion method is designed, which splits and fuses two images into two different parts according to the amount of information contained. In addition, a dual-channel image encryption scheme, optical encryption channel and digital encryption channel, is designed for the two parts after fusion. The former has better parallelism and higher encryption efficiency, while the latter has higher computational complexity and better encryption reliability. Especially in the digital encryption channel, a new dynamic adaptive diffusion method is designed, which is more flexible and secure than the existing encryption algorithm. Finally, numerical simulation and experimental analysis verify the feasibility and effectiveness of the scheme.

Most of existing optical color image encryption schemes have born security risks due to the adoption of linear transform, and data redundancy for the generation of complex image. To settle these problems effectively, a self-adaptive scheme for double color-image encryption is proposed in this paper. In this scheme, each RGB color component of two secret color images is first compressed and encrypted by 2D compressive sensing (CS) in which measurement matrices are generated by compound chaotic systems. Then, the two measured images are regarded as the real part and imaginary part, constituting a complex image to reduce data redundancy caused by following optical encryption. In the end, the complex image is reencrypted by self-adaptive random phase encoding and discrete fractional random transform (DFrRT) to obtain the final encrypted data. In the process of DFrRT and random phase encoding, the correlations between R, G, B components are adequately utilized. The production of key streams not only depends on the initial value but also on plain-text, and the three color components affect each other to enhance the ability against the known plaintext attack. The projection neural network algorithm is adopted to obtain the decryption images. Simulation results also verify the validity and security of the proposed method.

A novel cancellable biometric recognition system based on Rubik’s cube technique for cyber-security applications

Double random phase encoding (DRPE) is a typical optical encryption technique, in which the cipher key is allowed to include redundancy between encryption and decryption. It has been shown that phase-only DRPE has the robust to known-plaintext attacks using a phase retrieval algorithm. In addition, it has been also shown that phase only DRPE can decrypt the encrypted image successfully with the singular key that is completely different from the encryption key. In this study, we analyzed the distribution of the key-space in the phase-only DRPE by means of calculating the Euclidean distance between the decryption key and the encryption key and counting the number of the correct decryption keys. As a result of the experiments, we confirmed that the distribution property of the correct keys in the phase-only DRPE is significantly different from the one in the conventional DRPE.

Most of the existing selective encryption schemes are based on image processing and cannot be realized by optical structures, so their practicality is limited. Combining the optical design, a local hybrid optical encryption system based on double random phase encoding is proposed. The system proposed in this paper possesses a common aperture and dual optical path structure, which is widely used in optical design and can effectively improve the practicality of optical encryption system. First, important information and non-important information in the original image are separated by a selective beam splitter. Then light waves carrying important information enter into the 4<i>f</i> system for encryption, and light waves carrying non-important information enter into the diffraction system for encryption. Finally, part of the diffraction system ciphertext is replaced with 4<i>f</i> system ciphertext to obtain the final encrypted image. Decryption is the reverse process of encryption. First, the 4<i>f</i> system ciphertext is cut out from the final ciphertext. Then the 4<i>f</i> system ciphertext is used to restore the information replaced in the diffraction system ciphertext, thereby obtaining the complete diffraction system ciphertext. Finally, the two ciphertexts go through the reverse process of their respective systems to complete the decryption. By comparing the statistical characteristics and mean square error of the original image and the encrypted image, the effectiveness of the proposed system's encryption process is proved. By analyzing the peak signal-to-noise ratio of the original image and the decrypted image, the effectiveness of the proposed system's decryption process is proved. The sensitivity of each key of the system is analyzed to prove the security of the system. Especially the system is highly sensitive to selective encryption key, which proves the effectiveness and security of the proposed system for selective encryption. Through simulation, it is verified that the proposed system is very resistant to diffraction attacks. Even if he can obtain all the diffraction keys, the attacker still cannot obtain the selectively encrypted information. Finally, through simulation, it is verified that the proposed system has good noise resistance and crop resistance, and high robustness as well. The proposed system can realize the selective encryption through optical structure, which is safe, effective and highly robust, and thus improving the practicality of selective optical encryption system.

Secure transmission of sensitive data over open networks is a challenge in the present scenario of digital signal transmissions. Especially in 2D image signals, the adjacent pixel correlation is high which makes it a challenge to encrypt or hide the information from being fraudulently interpreted. Optical signal processing is preferred for image encryption owing to its high speed parallel processing. Fractional transforms are used for the digital implementation of the optical processing due to the fact that fractional orders enable to analyze a time variant signal where each fractional order correspond to an arbitrary angle of rotation. In this work, we apply a fractional Fourier transform for double image encryption, as fractional orders provide randomness and serve as secret key. The complex outcome of transform becomes a limitation due to requirement of double memory for storage and transmission besides computational complexity. To overcome this issue, a reality preserving scheme is applied to obtain real output from transform. A piecewise nonlinear chaotic map is used to introduce chaotic blending in the double image data. The larger key space of PWNCA based blending offers yet another security layer to the optical transform based encryption. The simulation results give testimony to the acquired randomness in the encrypted data. The proposed scheme is quite sensitive to keys and is robust against potential attacks.

Compared with digital methods, image hiding methods by optical ways have many advantages such as high processing speed, high parallel, high encryption dimension etc al. A novel efficient image encryption and hiding method applied by double random phase encoding technique is discussed in this paper. First, the performance of existing optical image hiding systems is analyzed; then specific statistical detection methods to the optical image hiding system are discussed; then extracting attacks to the optical image hiding system are analyzed; finally novel optical image hiding methods by technique of double random phase encoding and digital holography are given out.