Double Random Phase Encoding System Research Articles

A Novel Virtual Optical Image Encryption Scheme Created by Combining Chaotic S-Box with Double Random Phase Encoding.

The double random phase encoding (DRPE) system plays a significant role in encrypted systems. However, it is a linear system that leads to security holes in encrypted systems. To tackle this issue, this paper proposes a novel optical image encryption scheme that combines a chaotic S-box, DRPE, and an improved Arnold transformation (IAT). In particular, the encryption scheme designs a chaotic S-box to substitute an image. The chaotic S-box has the characteristics of high nonlinearity and low differential uniformity and is then introduced to enhance the security of the DRPE system. Chaotic S-boxes are resistant to algebraic attacks. An IAT is used to scramble an image encoded by the DRPE system. Meanwhile, three chaotic sequences are obtained by a nonlinear chaotic map in the proposed encryption scheme. One of them is used for XOR operation, and the other two chaotic sequences are explored to generate two random masks in the DRPE system. Simulation results and performance analysis show that the proposed encryption scheme is efficient and secure.

Security-enhanced optical cryptosystem using nonergodic scrambling phase mask.

Cryptanalysis revealed a security flaw in the double random phase encoding (DRPE) system, and the original image was recovered via a ciphertext-only attack. In this paper, a nonergodic scrambling phase mask (NESPM) is designed, and a security-enhanced cryptosystem is established by replacing the bonded random phase mask (RPM) in the DRPE system with the designed NESPM. The original image in the security-enhanced cryptosystem is optically scrambled at "macropixel" level by the bonded NESPM, instead of being diffused by the RPM, as in the DRPE system. Due to such a scrambling operation, the ergodic property of the Fourier-plane speckle pattern in the designed cryptosystem is removed, and the original image cannot be recovered via the attack. Experimental results demonstrate that the designed cryptosystem is resistant to the attack. Security enhancement is achieved.

Security-enhanced optical nonlinear cryptosystem based on double random phase encoding

Security is the critical requirement for optical encryption. A security-enhanced nonlinear cryptosystem is designed by introducing a time-varying nonlinear term in the double random phase encoding (DRPE) system. The nonlinear term, which is a randomly generated complex distribution, is introduced in the encryption process and has no influence on the decryption of original image. The nonlinear term is not transmitted to receivers of ciphertexts, therefore, there is no need to manage and distribute it. The designed cryptosystem is demonstrated to be resistant to various attacks including ciphertext-only attacks, known-plaintext attacks and chosen-plaintext attacks. In addition, the nonlinear cryptosystem is simple, and has the same optical implementation as that of conventional DRPE system.

Image encryption and watermarking combined dynamic chaotic hopping pattern with double random phase encoding DRPE

In modern civilization information, security is a crucial problem. Image encryption and watermarking can effectively protect information from unauthorized access. This paper introduces a new vigorous symmetric optical image encryption and watermarking technique. This technique depends on a novel dynamic delay chaotic hopping pattern (DDCHP) combined with double random phase encoding (DRPE). To get a robust watermark image, the plain image is first watermarked with a binary secret message using a new chaotic hopping pattern (CHP) and then encrypted using a DRPE system that is controlled by double random independent keys generated with double DDCHP. In this symmetric cryptosystem, three different chaotic maps are used to enlarge the key space of the proposed cryptosystem against brute-force attack and overcome the linearity and vulnerable of the classical DRPE. The system keys are hypersensitive and their initial parameters are selected carefully. Security scrutiny proves the efficiency of the suggested cryptosystem. Therefore, the obtained simulation results prove that the cryptosystem is robust enough against the known attacks, such as statistical attack (uniform histograms of different encrypted images, correlation coefficients between the plain and the encrypted image is as low as 5.46 × 10−6), differential attack (99.99% NPCR and 38.6% UACI), brute force attack (large enough key space), and entropy attack. Moreover, the robustness of the watermark (secret message) is proved due to the solidity of CHP. The proposed approach can be used in different implementations like secure military communications, e-finance, e-healthcare, authenticated multimedia broadcasting, etc.

Generalized description of double random phase encoding by Collins diffraction transformation

We present a generalized theory for describing encryption and decryption by using the double random phase encoding (DRPE) technique under the framework of the Collins diffraction transform formalism. The theory covers to a variety of diffraction domain which includes the Fourier domain (conventional 4f-optical processor), the Fresnel domain and the fractional Fourier transform (FRFT) domain. From the theoretical basis developed in this work, we present novel optical DRPE systems such as Gaussian imaging DRPE, inverse operation DRPE and Fresnel diffraction DRPE systems, which are plausible to implement. It is shown that the maximum number of degrees of freedom (or independent design parameters) of proposed DRPE system increases four times, when compared with the conventional 4f-optical system, which guarantee much more secure encryption and decryption.

Enhancing Security of Double Random Phase Encoding Based on Random S-Box

In this paper, we propose a novel asymmetric cryptosystem for double random phase encoding (DRPE) using random S-Box. While utilising S-Box separately is not reliable and DRPE does not support non-linearity, so, our system unites the effectiveness of S-Box with an asymmetric system of DRPE (through Fourier transform). The uniqueness of proposed cryptosystem lies on employing high sensitivity dynamic S-Box for our DRPE system. The randomness and scalability achieved due to applied technique is an additional feature of the proposed solution. The firmness of random S-Box is investigated in terms of performance parameters such as non-linearity, strict avalanche criterion, bit independence criterion, linear and differential approximation probabilities etc. S-Boxes convey nonlinearity to cryptosystems which is a significant parameter and very essential for DRPE. The strength of proposed cryptosystem has been analysed using various parameters such as MSE, PSNR, correlation coefficient analysis, noise analysis, SVD analysis, etc. Experimental results are conferred in detail to exhibit proposed cryptosystem is highly secure.

Security enhancement of double random phase encryption with a hidden key against ciphertext only attack

In this paper, we propose a security enhanced double random phase encoding (DRPE) encryption system against common ciphertext only attacks (COA). We point out one common weakness of COA schemes that the cracked plaintext image is usually in wrong circularly shifting positions and flipping status. Regarding to this weakness, an extra security layer (either optical or digital) cascaded with the DRPE system is constructed using a hidden key in our work. Simulation results demonstrate that our proposed system has significantly better security strength against COA than conventional DRPE system.

Automatic multicell identification using a compact lensless single and double random phase encoding system

We investigate the use of compact, lensless, single random phase encoding (SRPE) and double random phase encoding (DRPE) systems for automatic cell identification when multiple cells, either of the same or mixed classes, are in the field of view. A microscope glass slide containing the sample is inputted into the single or double random phase encoding system, which is then illuminated by a coherent or partially coherent light source generating a unique opto-biological signature (OBS) that is captured by an image sensor. Statistical features such as mean, standard deviation, skewness, kurtosis, entropy, and Pearson's correlation coefficient are extracted from the OBSs and used for cell identification with the random forest classifier. With the exception of the correlation coefficient, all features were extracted in both the spatial and frequency domains. Experiments are performed with single random phase encoding and double random phase encoding, and system analysis is presented to show the robustness and classification accuracy of the random phase encoding cell identification systems. The proposed systems are compact, as they are lensless and do not have spatial frequency bandwidth limitations due to the numerical aperture of a microscope objective lens. We demonstrate that cell identification is possible using both the SRPE and DRPE systems. While DRPE systems have been extensively used for image encryption, to the best of our knowledge, this is the first report on using DRPE for automated cell identification.

Special ciphertext-only attack to double random phase encryption by plaintext shifting with speckle correlation.

In this paper, a special ciphertext-only attack (COA) scenario to the traditional double random phase encoding (DRPE) technique is proposed based on plaintext shifting. We assume the attacker can illegally manipulate the DRPE system to gain multiple ciphertexts from randomly shifted versions of the same plaintext. The plaintext image can be recovered when our proposed scenario is combined with a speckle correlation attacking method proposed in previous work. Simulation results demonstrate that our proposed scheme can successfully crack the DRPE system even when the speckle correlation method alone fails to work in the conventional single ciphertext scenario due to the small size of the plaintext image. The work in this paper reveals a severe security flaw of DRPE systems when minor position shifting of the plaintext occurs.

Hybrid Color and Grayscale Images Encryption Scheme Based on Quaternion Hartley Transform and Logistic Map in Gyrator Domain

A hybrid color and grayscale images encryption scheme based on the quaternion Hartley transform (QHT), the two-dimensional (2D) logistic map, the double random phase encoding (DRPE) in gyrator transform (GT) domain and the three-step phase-shifting interferometry (PSI) is presented. First, we propose a new color image processing tool termed as the quaternion Hartley transform, and we develop an efficient method to calculate the QHT of a quaternion matrix. In the presented encryption scheme, the original color and grayscale images are represented by quaternion algebra and processed holistically in a vector manner using QHT. To enhance the security level, a 2D logistic map-based scrambling technique is designed to permute the complex amplitude, which is formed by the components of the QHT-transformed original images. Subsequently, the scrambled data is encoded by the GT-based DRPE system. For the convenience of storage and transmission, the resulting encrypted signal is recorded as the real-valued interferograms using three-step PSI. The parameters of the scrambling method, the GT orders and the two random phase masks form the keys for decryption of the secret images. Simulation results demonstrate that the proposed scheme has high security level and certain robustness against data loss, noise disturbance and some attacks such as chosen plaintext attack.

Single-Shot Imaging Without Reference Wave Using Binary Intensity Pattern for Optically-Secured-Based Correlation

In this paper, a novel method is proposed to optically verify the decoded images via single-shot imaging without reference wave using a binary intensity pattern. Optical imaging without reference wave is applied based on double random phase encoding (DRPE), and the recorded intensity pattern is further compressed, which contains only two quantization levels (i.e., 0 and 1). During the decoding, an iterative phase retrieval algorithm is developed and applied. It is demonstrated that decoded images do not visually render the input information due to the designed optical encoding strategy using only one binary intensity pattern, and optical verification is further conducted to effectively verify the decoded images. An additional security layer is established for the developed optical system, since optical verification is conducted based on optical encoding systems without direct observation of input information from the decoded images. It is the first to report the use of only one 1-bit intensity pattern in the DRPE system based on single-shot imaging without reference wave for secured verification via optical correlation.

Attack on Optical Double Random Phase Encryption Based on the Principle of Ptychographical Imaging**Supported by the National Natural Science Foundation of China under Grant Nos 61575197 and 61307018, the K. C. Wong Education Foundation, the President Fund of University of Chinese Academy of Sciences, and the Fusion Funds of Research and Education of Chinese Academy of Sciences.

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.

Double random phase encoding using phase reservation and compression

In recent years, various studies have been conducted to illustrate the vulnerability of double random phase encoding (DRPE). In this paper, we propose a novel method via phase reservation and compression to enhance DRPE security. Only a compressed phase distribution is available in the CCD plane, and the amplitude component is not available or requested for optical decryption. Since only noise-like distributions can be obtained by using the correct security keys during optical decryption, a nonlinear correlation algorithm is further applied for authenticating the decrypted image. It is demonstrated that valid conditions for attack algorithms are broken and high security can be achieved for the DRPE system.

An image watermarking technique based on cascaded iterative Fourier transform

As an optical image encryption technique, the double random phase encoding (DRPE) technique can be used to encrypt the watermark image. However, since the DRPE system may be attacked with cryptanlysis, the security of the DRPE technique is somewhat weak. To improve the security, an image watermark generation algorithm based on cascaded iterative Fourier transform algorithm (CIFT) was proposed. In the proposed algorithm, two phase masks were obtained by applying the CIFT algorithm on the original reference watermark image and the final embedded watermark image was obtained with them. One of the phase masks was kept as the secret key. When detecting the watermark, the embedded watermark was extracted from the watermarked host image. Then, the recovered watermarked was obtained with the extracted watermark and the secret key. By comparing the recovered watermark and the original reference watermark, whether the tested image containing the watermark or not can be judged. With the CIFT algorithm, it is more secure to generate the embedded watermark. In addition, it is practical because only one of the phase masks is needed for watermark recovery. The simulation results show that the proposed method has good imperceptibility and robustness.

Steganographic optical image encryption system based on reversible data hiding and double random phase encoding

This study presents a steganographic optical image encryption system based on reversible data hiding and double random phase encoding (DRPE) techniques. Conventional optical image encryption systems can securely transmit valuable images using an encryption method for possible application in optical transmission systems. The steganographic optical image encryption system based on the DRPE technique has been investigated to hide secret data in encrypted images. However, the DRPE techniques vulnerable to attacks and many of the data hiding methods in the DRPE system can distort the decrypted images. The proposed system, based on reversible data hiding, uses a JBIG2 compression scheme to achieve lossless decrypted image quality and perform a prior encryption process. Thus, the DRPE technique enables a more secured optical encryption process. The proposed method extracts and compresses the bit planes of the original image using the lossless JBIG2 technique. The secret data are embedded in the remaining storage space. The RSA algorithm can cipher the compressed binary bits and secret data for advanced security. Experimental results show that the proposed system achieves a high data embedding capacity and lossless reconstruction of the original images.

Numerical simulation of double random phase encoding

In this paper, we propose a method for the numerical simulation of optical double random phase encoding (DRPE). This method is based on a discrete model of the DRPE system that retains the properties of its optical counterpart and takes into account the capacity of DRPE to spread a signal’s energy in both the space and the spatial frequency domains. Discrete versions of two narrowband lossless diffusers are created to simulate their analogue optical counterparts and their bandwidths control how much the energy of the input signal is spread in both the space and spatial frequency domains as it passes through the system. The limiting case, when complete aliasing (maximum overlap) takes place, is also discussed in relation to our method. In this case, we show our method reduces to a purely numerical encryption procedure which can, nonetheless, be decrypted perfectly. Simulation results are presented to demonstrate the feasibility of the proposed technique.

Encryption by using matrix-added, or matrix-multiplied input images placed in the input plane of a double random phase encoding geometry

In this paper, we describe image encryption by combining the images with several matrices made with letters/numerals and placed in the input plane of a double random phase encoding (DRPE) system. Addition or multiplication of several such matrices with an input image provides a modified image pattern which is encrypted in a DRPE system utilizing the 4-f geometry. For gray scale images, the results of encryption in case of addition of matrices are found more reliable and secure as compared to the results of multiplication. Simulation results are presented in support of the idea. Reliability of the technique has been established by evaluating the mean square-error (MSE) between the decrypted and the original image.

Optical security system using jigsaw transforms of the second random phase mask and the encrypted image in a double random phase encoding system

In this paper, we have described a simple and secure double random phase encoding and decoding system to encrypt and decrypt a two-dimensional gray scale image. We have used jigsaw transforms of the second random phase mask and the encrypted image. The random phase mask placed in the Fourier plane is broken into independent non-overlapping segments by applying the jigsaw transform. To make the system more secure, a jigsaw transform on the encrypted image is also carried out. The encrypted image is also broken into independent non-overlapping segments. The jigsaw transform indices of random phase code and the encrypted image form the keys for the successful retrieval of the data. Encrypting with this technique makes it almost impossible to retrieve the image without using both the right keys. Results of computer simulation have been presented in support of the proposed idea. Mean square error (MSE) between the decrypted and the original image has also been calculated in support of the technique.