Double Random Phase Encoding Technique Research Articles

Security analysis and modified attack algorithms for a nonlinear optical cryptosystem based on DRPE

In this paper, security of a nonlinear optical cryptosystem based on double random phase encoding (DRPE) is analyzed. In the cryptosystem, a time-varying nonlinear term is combined with the classical DRPE technique to enhance security. The advantages of the nonlinear term are its easy distribution and no effect on the decrypted image. Also, it is confirmed that the method is resistant to conventional plaintext attacks such as known-plaintext attack, chosen-plaintext attack, and ciphertext only attack. However, our security analysis shows that the method is vulnerable to the modified chosen-plaintext, and known-plaintext attacks. The original image can be recovered successfully using the proposed attack algorithms. Numerical simulation results are presented to validate the proposed attack methods and test effectiveness of our analysis.

Block-Based Optical Color Image Encryption Based on Double Random Phase Encoding

This paper investigates and presents a block-based opto-color cipher using double random phase encoding (DRPE) with different block sizes. The color plainimage is divided into equal-sized blocks and then converted to an optical signal by an optical emitter. The obtained optical signal is encrypted by employing the DRPE technique, which applies two types of phase modulation, time, and Fourier domains. Finally, the optical color cipherimage is, upon detection, converted to digital format by a charge-coupled device digital camera. Experiments and security analysis show that the proposed block-based optical color image cipher using DRPE with increased block size is secure, effective, and including a good immunity to channel noise.

Optical image transformation and encryption by phase-retrieval-based double random-phase encoding and compressive ghost imaging

An optical image transformation and encryption scheme is proposed based on double random-phase encoding (DRPE) and compressive ghost imaging (CGI) techniques. In this scheme, a secret image is first transformed into a binary image with the phase-retrieval-based DRPE technique, and then encoded by a series of random amplitude patterns according to the ghost imaging (GI) principle. Compressive sensing, corrosion and expansion operations are implemented to retrieve the secret image in the decryption process. This encryption scheme takes the advantage of complementary capabilities offered by the phase-retrieval-based DRPE and GI-based encryption techniques. That is the phase-retrieval-based DRPE is used to overcome the blurring defect of the decrypted image in the GI-based encryption, and the CGI not only reduces the data amount of the ciphertext, but also enhances the security of DRPE. Computer simulation results are presented to verify the performance of the proposed encryption scheme.

Image encryption using the Gyrator transform and random phase masks generated by using chaos

The Gyrator transform (GT), chaotic random phase masks (CRPMs) and a random permutation of the Jigsaw transform (JT) are utilized to design an images encryption-decryption system. The encryption-decryption system is based on the double random phase encoding (DRPE) in the Gyrator domain (GD), this technique uses two random phase masks (RPMs) to encode the image to encrypt (original image) into a random noise. The RPMs are generated by using chaos, these masks are CRPMs. The parameters of the chaotic function have the control of the generation of the CRPMs. We apply a random permutation to the resulting image of the DRPE technique, with the purpose of obtaining an encrypted image with a higher randomness. In order to successfully retrieve the original image (without errors or noise-free) at the output of the decryption system is necessary to have all the proper keys, which are: the rotation angles of the GTs, the parameters of the chaotic function utilized to generate the two CRPMs and the random permutation of the JT. We check and analyze the validity of the image encryption and decryption systems by means of computing simulations.

Security enhancement for double-random phase encryption using orthogonally encoded image and electronically synthesized key data

We propose a security-enhanced double-random phase encryption (DRPE) scheme using orthogonally encoded image and electronically synthesized key data to cope with the security problem of DRPE technique caused by fixed double-random phase masks for encryption. In the proposed scheme, we adopt the electronically synthesized key to frequently update the phase mask using a spatial light modulator, and also employ the orthogonal encoding technique to encode the image and electronically synthesized key data, which can enhance the security of both data. We provide detailed procedures for encryption and decryption of the proposed scheme, and provide the simulation results to show the encryption effects of the proposed scheme.

Multiple-image encryption by space multiplexing based on compressive sensing and the double-random phase-encoding technique.

In this paper, a new multiple-image encryption and decryption technique that utilizes the compressive sensing (CS) concept along with a double-random phase encryption (DRPE) has been proposed. The space multiplexing method is employed for integrating multiple-image data. The method, which results in a nonlinear encryption system, is able to overcome the vulnerability of classical DRPE. The CS technique and space multiplexing are able to provide additional key space in the proposed method. A numerical experiment of the proposed method is implemented and the results show that the proposed method has good accuracy and is more robust than classical DRPE. The proposed system is also employed against chosen-plaintext attacks and it is found that the inclusion of compressive sensing enhances robustness against the attacks.

Attack on double-random-phase-encoding-based image hiding method

The double-random phase-encoding (DRPE) technique is a typical optical image encryption technique, which can also be used for image hiding. Usually, the secret image is encrypted with the DRPE technique and the encoded image is hidden into the host image via superimposition to obtain the stego-image. The attack technique on the DRPE-based image hiding method was proposed in this paper. Firstly, a randomly selected superimposition coefficient was used to approximate the original superimposition coefficient to extract the hidden encoded images from the stego-images approximately. Then, the chosen-plaintext attack technique on the DRPE-based optical image encryption technique was applied to recover the random phase masks used in the DRPE technique. The theoretical analysis indicated that, without considering the computational error, the recovered secret image via the proposed attack technique is identical to the original one. Even considering the computational error, it is identical to the secret image recovered with the original DRPE-based image hiding method, which demonstrates that the attack on the DRPE-based image hiding method is successfully achieved. The numerical simulation results demonstrated the correctness of the theoretical analysis.

Optical double image encryption employing a pseudo image technique in the Fourier domain

A novel optical encryption method is proposed involving double image encryption in which one image is introduced as the pseudo image while the other is the original object image. The Double Random Phase Encoding technique is used to encrypt both the pseudo and object images into complex images. A unique binary image is then employed to first generate the random phase key for the object image encryption and then to embed the encrypted object image into the encrypted pseudo image, which acts as host image. Both the second random phase mask used for encoding the pseudo image and the binary image act as encryption keys. If an attacker attempts to crack the random phase key and decrypt the original object image, the pseudo image will be obtained instead. Simulation results and robustness tests are performed which demonstrate the feasibility of the algorithm.

Performance analysis on a watermarking method based on double random phase encoding technique

When digital watermarking is used for piracy tracking, different watermarks are needed to be embedded into different distributions of a digital product. Based on double random phase encoding (DRPE) technique, cascaded-phases iterative algorithm and random-phase-shift algorithm, Chen et al. proposed a method to generate many different embedded watermarks from one reference watermark, while the embedded watermark can be recognized by testing the correlation between the recovered watermark and the original reference watermark. In this way, only the reference watermark instead of the embedded watermarks needs to be stored and managed. However, since the recovered watermark may be different from the embedded watermark, especially under any image processing, the correlation between the recovered watermark and the reference watermark may be different from the correlation between the embedded watermark and the reference watermark, which may result in wrong recognition. In this paper, the performance of Chen's method was analyzed with numerical simulations. The results indicated that, to correctly recognize the embedded watermark, the number of generated embedded watermarks with Chen's method is limited.

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.

Evaluations of phase-only double random phase encoding based on key-space analysis

Although initial research shows that double-random phase encoding (DRPE) is vulnerable to known-plaintext attacks that use phase retrieval algorithms, subsequent research has shown that phase-only DRPE, in which the Fourier amplitude component of an image encrypted with classical DRPE remains constant, is resistant to attacks that apply phase retrieval algorithms. Herein, we numerically analyze the key-space of DRPE and investigate the distribution property of decryption keys for classical and phase-only DRPE. We determine the difference in the distribution property of successful decryption keys for these DRPE techniques from the numerical analysis results and then discuss the security offered by them.

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.

Optical encryption using pseudorandom complex spatial modulation

In this paper we propose a new (to our knowledge) complex spatial modulation method to encode data pages applicable in double random phase encryption (DRPE) to make the system more resistant to brute-force attack. The proposed modulation method uses data page pixels with random phase and amplitude values with the condition that the intensity of the interference of light from two adjacent pixels should correspond to the encoded information. A differential phase contrast technique is applied to recover the data page at the output of the system. We show that the proposed modulation method can enhance the robustness of the DRPE technique using point spread function analysis. Key space expansion is determined by numeric model calculations.

Efficient Text Encryption and Hiding with Double-Random Phase-Encoding

In this paper, a double-random phase-encoding technique-based text encryption and hiding method is proposed. First, the secret text is transformed into a 2-dimensional array and the higher bits of the elements in the transformed array are used to store the bit stream of the secret text, while the lower bits are filled with specific values. Then, the transformed array is encoded with double-random phase-encoding technique. Finally, the encoded array is superimposed on an expanded host image to obtain the image embedded with hidden data. The performance of the proposed technique, including the hiding capacity, the recovery accuracy of the secret text, and the quality of the image embedded with hidden data, is tested via analytical modeling and test data stream. Experimental results show that the secret text can be recovered either accurately or almost accurately, while maintaining the quality of the host image embedded with hidden data by properly selecting the method of transforming the secret text into an array and the superimposition coefficient. By using optical information processing techniques, the proposed method has been found to significantly improve the security of text information transmission, while ensuring hiding capacity at a prescribed level.

Multiple-image encryption based on nonlinear amplitude-truncation and phase-truncation in Fourier domain

The classical double random phase encoding technique (DRPE) is vulnerable to chosen ciphertext attacks, known-plaintext attacks and chosen-plaintext attacks for its linearity. In order to avoid the disadvantages originated from the linearity and symmetric, an improved method for multiple-image encryption based on nonlinear operations in Fourier domain is proposed. The random phase masks (RPMs) for encryption and additive keys which are determined by the original images and generated by the nonlinear operations in encryption process, are necessary for image decoding. As a result of the nonlinear operations, the increase in the number of keys, removal of linearity and high robustness could be achieved in this cryptosystem. Computer simulations are presented to demonstrate its good performance, and the security is analyzed as well.

Hybrid encoding method for hiding information by assembling double-random phase-encoding technique and binary encoding method

A hybrid encoding method is used to assemble the double-random phase-encoding technique and the binary encoding method. Because the double-random phase-encoding technique is robust for noises and the binary encoding method is free of using external keys, the proposed hybrid encoding method has their advantages. The hybrid encoding method first encodes a covert image to form a complex-number matrix by using the double-random phase-encoding technique, where two random real-number matrices are used to increase the security of the encoding work. Then the elements of the two random real-number matrices and the elements of the complex-number matrix are encoded to form a binary-bit string by using the binary encoding method. Finally, the binary data in the binary-bit string are encoded into a host image to form an overt image with hidden information by using a gray-value modulation method. The decoding work is easy for authorized people, but it is very difficult for unauthorized people. Therefore, the proposed hybrid encoding method is a very useful encoding method.

Information-hiding scheme with high capacity based on double-random phase-encoding technique

A double-random phase-encoding technique based information-hiding scheme was improved for high capacity information hiding.The hidden image was encoded with double-random phase-encoding technique and embedded into the enlarged host image to obtain the composed image.The superposition method to embed the encoded image was different from the original method,which could increase the information hiding capacity.In addition,compared with the original method,the quality of the composed image was improved,while the quality of the recovered hidden image was maintained.Also,the security of the method was enhanced markedly.Theoretical analysis and experimental results demonstrate the effectiveness of the improved scheme.

Information-hiding scheme with high capacity based on double-random phase-encoding technique

A double-random phase-encoding technique based information-hiding scheme was improved for high capacity information hiding.The hidden image was encoded with double-random phase-encoding technique and embedded into the enlarged host image to obtain the composed image.The superposition method to embed the encoded image was different from the original method,which could increase the information hiding capacity.In addition,compared with the original method,the quality of the composed image was improved,while the quality of the recovered hidden image was maintained.Also,the security of the method was enhanced markedly.Theoretical analysis and experimental results demonstrate the effectiveness of the improved scheme.

Increasing the data hiding capacity and improving the security of a double-random phase-encoding technique based information hiding scheme

A double-random phase-encoding technique based information hiding scheme was analyzed and improved. By encoding the hidden image with the double-random phase-encoding technique, and embedding the encoded image into the enlarged host image to generate the composed image, the original scheme can recover the hidden image from the composed image directly (i.e., without using the original host image) with satisfying quality. For the proposed improved scheme, 3 values (other than 2 values as in the original scheme) are embedded into each 2 × 2 block within the enlarged host image, resulting in increasing the data hiding capacity around 50%, while not influence the qualities of the composed image and the reconstructed hidden image seriously. In addition, the security of the original scheme is enhanced markedly. Theoretical analysis and experimental results demonstrate the effectiveness of the improved scheme.

Security analysis and improvement on a double-random phase-encoding technique based information hiding method

The security of an information hiding method using the double-random phase-encoding technique is analyzed and improved. The method encodes the hidden image with the double-random phase-encoding technique, and then embeds the real and imaginary parts of the encoded image to an enlarged host image. Recovering the hidden image from the composed image does not need the original host image, while the quality of the reconstructed image is satisfying. However, the original method is insecure in the sense of information hiding, since the composed image can be detected easily with some technical metrics. The security is improved by adding random perturbation on the encoded data. The validity of the improved method is demonstrated by numerical simulation experiments.