Optical Image Encryption Scheme Research Articles

Optical image authentication and encryption scheme with computational ghost imaging

Most of the previous image encryption schemes overlook certifying the source of the encrypted images, thus the receiver may be misled by messages coming from unauthorized users or wrong sources. To simultaneously accomplish image encryption and source authentication of the encrypted images, an optical image authentication and encryption scheme is proposed by integrating computational ghost imaging (CGI) with quick response (QR) code. Firstly, the plaintext image is converted into a QR code and encrypted by a scrambling-diffusion structure. Then, the authentication image is enciphered by a CGI system and a diffusion structure. The intermediate resulting images are marked and embedded into the random matrices to withstand the differential attack. Moreover, the source of the encrypted images can be identified by the reconstructed authentication image and the nonlinear correlation coefficient (NCC) result. The authentication is considered successful if a sharp peak appears in the center of the NCC result. Numerical simulations show that the proposed scheme can not only withstand different attacks, but also avoid being misled by misinformation during the decryption process.

Secure Optical Image Communication Using Double Random Transformation and Memristive Chaos

The issue of information security in photonics environment has attracted more and more attention, especially when the secure communication of optical digital images has become a research hotspot. In this paper, we propose a hybrid encryption scheme for color images in the frequency and spatial domains based on double random transform and memristor hyperchaotic system. Firstly, we decompose the color image into RGB channels and then perform fast fourier transform (FFT) to transform the digital image from the spatial domain to the frequency domain. Secondly, two-phase masks are generated using the memristor hyperchaotic system, and the Fresnel diffraction optical transformation method is performed twice for encryption. Thirdly, the transformation from the frequency domain to the spatial domain is completed using inverse fast fourier transform (IFFT). Finally, the image is permuted and diffused using the chaotic sequences to obtain the final cipher image. Double random phase encryption expands the key space, while the combination of spatial and frequency domains improves the resistance to attacks. Based on cryptanalysis theory, we introduce a dynamic key associated with plain image, which can effectively resist plain attack. The experimental results show that the optical digital image encryption scheme has a large key space, excellent comprehensive performance, and can resist common attacks. In addition, we verify the hardware feasibility and ease of implementation of the proposed algorithm in an embedded optical communication network experimental platform. Therefore, our proposed scheme in this paper is a preferred optical digital image secure communication technology scheme with good application prospects.

Optical single-channel color image encryption based on chaotic fingerprint phase mask anddiffractive imaging.

An optical single-channel color image encryption scheme based on chaotic fingerprint phase mask and diffractive imaging is proposed. In this proposed encryption scheme, the fingerprint used to generate therandom phase masks is served as a secret key directly. Additionally, the random phase masks generated by the fingerprint, chaotic Lozi map, and secure hash algorithm (SHA-256) are used only as interim variables. With the help of the chaotic fingerprint phase masks placed at different diffraction distances, the color image that is encoded into a grayscale pattern by the phase-truncation technique is encrypted into a noise-like diffraction pattern. For decryption, the color image can be retrieved from the noise-like diffraction pattern by using an iterative phase retrieval algorithm, fingerprint, and phase keys generated from the encryption process. Since the fingerprint key shared by the sender and authorized receiver is strongly linked with the user and does not need to be transmitted over the open network, the security of this proposed encryption scheme can be greatly improved. Additionally, the parameters of the chaotic Lozi map and Fresnel diffraction distances can also provide additional security to the proposed encryption scheme. Furthermore, compared with the encryption schemes based on digital holography, the implementation of this proposed encryption scheme is relatively simple. The numerical simulations and analysis verify the feasibility, security, and robustness of this proposed encryption scheme.

Optical image encryption based on two-channel detection and deep learning

Aside from its application to the vulnerability analysis of optical cryptosystems, deep learning (DL) technique can also be used as a potential basis for optical cryptography itself. Here, we report a new optical image encryption scheme based on two-channel detection and DL. The encryption process consists of two-channel signal detection within the optical encryption system where three random binary masks are involved, and the training of a neural network to derive an approximate model. The two optically encoded patterns collected with a pair of CCD cameras are recombined into a single speckle image by using two independent sparse matrices. In the training section, the neural network is trained to find the mapping relationship between the speckle images and their corresponding original objects. Besides the model parameters, the decryption requires the use of the matrix keys, which avoids a situation where the DL-based cryptosystem is designed such that security relies entirely on the trained network itself. To the best of our knowledge, this is the first report using a single-wavelength, dual-channel system for diffuse optical encryption. Experimental results demonstrate the feasibility and good performance of the proposed scheme.

Security analysis on an interference-based optical image encryption scheme.

In this paper, the security strength of the improved optical cryptosystem based on interference has been evaluated. Compared to the previous interference-based cryptosystems in which the plaintext is encoded into two phase-only masks (POMs), here the plaintext is encoded into a POM and an amplitude mask (AM). Since the information of the plaintext cannot be recovered directly when one of the masks is released in the decryption process of the improved cryptosystem, it seems that it is free from the silhouette problem. However, we found that the random phase mask (RPM) serving as the encryption key is not related to the plaintext. Thus, it is possible to recover the RPM first by using the known-plaintext attack (KPA). Moreover, the POM and the AM generated in the encryption path only contains the phase and amplitude information, respectively. Thus, these can be utilized as additional constraints in the proposed iterative process. Based on these findings, two kinds of hybrid attacks, including a KPA and the iterative processes with different constraints, are proposed to crack the improved cryptosystem. In the designed KPA with a pair of the known plaintext and its corresponding masks, the RPM is recovered first. With the aid of the recovered RPM, two iterative processes with different released masks are proposed to recover the information of the plaintext without any knowledge of another mask. To the best of our knowledge, this is the first time that the existence of the silhouette problem in the cryptosystem under study has been reported. Numerical simulation has been carried out to validate the feasibility and effectiveness of the proposed hybrid attacks.

Optical image encryption scheme based on quantum s-box and meaningful ciphertext generation algorithm

With the development of quantum computers, difficult computational problems of classical cryptosystems could potentially become solvable. Hence, due to the powerful computing power of quantum computers, all current cryptographic algorithms based on computational complexity may become ineffective. Furthermore, most of the ciphertexts generated by traditional encryption schemes are noise-like, and such ciphertexts are easily suspected by cryptanalysts during transmission. To solve these problems, a novel image encryption scheme is proposed by visually meaningful ciphertext generation and quantum walks (QWs). The proposed scheme is composed of three phases: (I) Permutation, (II) Diffusion, and (III) Visually meaningful ciphertext generation. In phase I, the quantum substitution box (s-box) is firstly constructed by QWs, and the original image is permutated by the quantum s-box to reduce the correlation between adjacent pixels. In phase II, the permutated quantum image is diffused by a key image, which is constructed by the probability matrix generated by the same QWs. In phase III, the diffused image is disguised as a meaningful image to avoid the suspicions of cryptanalysts. Compared to traditional encryption algorithms, the introduction of quantum technology effectively improves the security of the cryptosystem. Compared to previous quantum encryption methods, our algorithm generates meaningful ciphertexts that can further enhance security by preventing cryptanalysts from suspecting noise-like ciphertexts. Thus, our encryption scheme is secure even in the future quantum computer age. Besides, the decryption time of our proposed scheme can also be effectively reduced since the decryption process can be optically implemented, partially. Therefore, real-time scenarios can be satisfied. Simulation results and numerical analysis show the effectiveness of the proposed scheme.

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.

Cryptoanalysis on the optical image encryption scheme based on full phase encoding and equal modulus decomposition.

In this paper, the security of a security-enhanced optical cryptosystem based on full phase encoding and equal modulus decomposition (EMD) is evaluated. Compared to the original EMD-based image scheme in which plaintext is the amplitude information of the spectrum to generate two complex-valued masks with equal moduli, phase-encoded plaintext is regarded as the input of EMD-based structure to generate masks in the full phase encoding and EMD combined cryptosystem. It seems that the security strength has been improved by decreasing the number of constraints in the iterative attack; however, it is found that this scheme is still under security risk. Thus, we propose two iterative attacks based on normalization operator and phase-retrieval techniques with different constraints to break the security-enhanced scheme. Numerical simulations are carried out to demonstrate the feasibility and effectiveness of the proposed attacks.

An Optical Image Encryption Algorithm Based on a Fractional-Order Laser Hyperchaotic System

In recent years, image encryption schemes based on optical methods have been extensively studied. However, possible optical encryption methods in combination with fractional-order laser hyperchaotic systems have not been reported. Therefore, an optical image encryption scheme based on fractional Fourier transform and five-dimensional host-induced nonlinearity fractional-order laser hyperchaotic system is studied in this paper. Firstly, the dynamical characteristics of the proposed fractional-order laser hyperchaotic system are analyzed, and the DSP platform is used to realize the system. Then, a novel image encryption scheme is proposed combining BP neural network, GF(17) domain diffusion and hyperchaotic, random point scrambling algorithm. Finally, the performance of the encryption scheme is analyzed in detail. This work provides an experimental basis and theoretical guidance for image secure communication combining fractional-order laser hyperchaotic systems and optical methods and offers a new research perspective for optical image encryption.

Optical image encryption scheme with extended visual cryptography and non-mechanical ptychographic encoding

Non-mechanical ptychographic encoding (NPE) transforms the secret information into series of diffractive patterns through a spatial light modulator (SLM), saving the need to fabricate the secret objects. Conventionally, the shares in extended visual cryptography (EVC) are printed on transparent sheets or fabricated with diffractive optical elements and metasurface, but these methods are expensive and disposable. To solve these problems, we proposed an optical image encryption scheme that combines EVC and NPE. In the encryption process, the secret image is decomposed into multiple shares that are digitally loaded on the SLM, and the ciphertexts are generated according to the ptychographic encoding scheme. The decryption is performed by superimposing the shares reconstructed from the ciphertexts. We present optical experiments to demonstrate the feasibility and effectiveness of the proposed method.

Optical color image encryption scheme with a novel DNA encoding algorithm based on a chaotic circuit

An optical setup with a unique color image cryptography technique employing a chaotic system is suggested in this study. For this purpose, deoxyribonucleic acid (DNA) encoding is used as an encryption method. Rössler attractor is employed as a chaotic system and it consists of three differential equations. In order to implement the chaotic system by analog electronic components, a circuit design including operational transconductance amplifier (OTA) is also suggested. Circuit simulations have been performed utilizing LT spice program. In the proposed study, the number of DNA encoding rules has excessively been increased compared to previous studies on DNA encoding technique. Thus, the security of the encryption scheme is enhanced. Numerous security tests such as correlation coefficient, histogram, Shannon entropy, secret key and initial condition sensitivities, plaintext and ciphertext attacks and differential attack have been carried out to evaluate functioning of the introduced cryptography algorithm. The numerical test results prove that the suggested encryption algorithm can resist statistical and differential attacks. Moreover, the cryptology scheme indicates the behavior of sensitivity to initial condition and secret key. The presented algorithm has great performance from the point of encoding rules number and being robust against differential attack. Moreover, enhanced double random phase encoding (DRPE) technique is used in optical stage of the study. By modifying the conventional DRPE method, correlation value between R, G, B components for same pixel have extremely reduced. All numerical analyses regarding chaotic system and encryption scheme have been performed in MATLAB program.

Optical color image encryption based on fingerprint key and phase-shifting digital holography

In this paper, an optical color image encryption scheme based on fingerprint key and three-step phase-shifting digital holography is proposed. In the proposed encryption scheme, the fingerprint is served as secret key directly, and the random phase masks generated from the fingerprint using secure hash algorithm and chaotic map are just used as interim variables. With the help of the fingerprint-based random phase masks located in the linear canonical transform domain and the three-step phase-shifting digital holography, the primary color image that is hidden into a greyscale carrier image can be encrypted into three noise-like holograms. Since the fingerprint key shared by the sender and authorized receiver is strongly linked with the user and need not be transmitted via the networks, the security of the proposed encryption scheme will be enhanced greatly. In addition, the parameters of chaotic map and linear canonical transform can also provide additional security to the proposed encryption scheme. Numerical simulations and analysis have been carried out to verify the feasibility, security and robustness of the proposed encryption scheme.

Optical color image encryption based on a voice key under the framework of speckle-illuminated Fourier ptychography

In this paper, an optical color image encryption scheme based on a voice key under the framework of speckle-illuminated Fourier ptychography is proposed. The human voice serves as the secret key directly, and the random phase masks generated from the human voice using the chaotic map and secure hash algorithm are just used as interim variables. With the help of voice-based random phase masks located at different diffraction distances, the primary color image can be encrypted into a series of noise-like intensity cipher images under different speckle patterns’ illumination. During the decryption process, the primary color image can be recovered from the noise-like intensity cipher images with a Fourier ptychographic recovery algorithm, voice-based random phase masks, and their conjugate. Since the voice key is strongly linked with the user, it does not need need to be transmitted from the sender to the authorized receiver via the networks. The security of the proposed encryption scheme will be enhanced greatly. Additionally, the speckle patterns for illumination and diffraction distances can also provide additional security to the proposed encryption scheme. Simulation results and analysis show that the proposed encryption scheme has high security and can resist some common attacks.

Optical image encryption and authentication scheme based on partial joint power spectrum and phase-retrieval technique

In this paper, a novel optical image encryption and authentication scheme based on partial joint power spectrum (JPS) and phase-retrieval technique has been proposed. In the proposed encryption process, a pure amplitude spatial light modulator (SLM) is utilized to modulate and display the entire input plane comprised with the real-valued plaintext and the amplitude key while the random phase mask (RPM) merged with the plaintext could be provided by the ground glass in the practical setup. The entire input plane is regarded as the input of a joint transform correlator (JTC)-based encryption structure while the sub-block (partial JPS) recorded by the charged-couple device (CCD) is the output (ciphertext). Since only the sub-block is recorded in the encryption process, the size of the plaintext could be larger than that of the CCD in a certain degree, which is a major advantage comparing to the conventional JTC-based cryptosystem. In addition, since the size of the ciphertext is irrelative to the size of the plaintext, the security of location key in the entire plane has been enhanced. In addition, the location keys of the chosen sub-block used as the ciphertext are regarded as additional private keys, which enlarges the key spaces of the conventional JTC-based cryptosystem. In the proposed authentication process, the sub-block (ciphertext) is used as the partial amplitude constraint in the iterative process based on phase-retrieval technique and then the decoded image is authenticated by the nonlinear optical verification operator. It is the first time that the optical image encryption and authentication using partial JPS as the ciphertext has been proposed. Numerical simulation is carried out to validate the feasibility and effectiveness of the proposed scheme.

A new color image encryption scheme based on 2DNLCML system and genetic operations

Based on the spatiotemporal chaos of the two Dimensional Nonlinear Coupled Map Lattices (2DNLCML) and genetic operations, a new optical color image encryption scheme is proposed. Because of the spatial nonlinear coupling which replaces traditional adjacent coupling, the 2DNLCML system contains good features such as ergodic pseudo-random sequence, less periodic windows in bifurcations and larger range of parameters in chaotic dynamics, which is more suitable for image encryption. The scheme also performs genetic operations including mutation and crossover for binary coding, thus reducing the computational complexity. Simulations have been carried out and the results demonstrate that the proposed algorithm has properties of large key space, high sensitivity to key, strong resisting attack. So, it is more secure and effective algorithm for encryption of digital images.

Cancelable face and fingerprint recognition based on the 3D jigsaw transform and optical encryption

Biometric systems are widely used now for security applications. Two major problems are encountered in biometric systems: the security problem and the dependence on a single biometric for verification. The security problem arises from the utilization of the original biometrics in databases. So, if these databases are attacked, the biometrics are lost forever. Hence, there is a need to secure original biometrics by keeping them away from utilization in biometric databases. Cancelable biometrics is an emerging security trend in the field of biometric authentication. Cancelable biometric systems depend on the transformation of biometric features into new formats so that users can replace their biometric templates in the same or different systems. In this paper, we present a proposed cancelable face and fingerprint recognition algorithm based on the 3D jigsaw transform and optical encryption. The algorithm adopts the Fractional Fourier Transform (FRFT) in the optical encryption scheme with a single random phase mask. This structure can be implemented all optically with a single lens. The proposed cancelable biometric recognition algorithm employs an optical image encryption scheme that depends on two cascaded stages of 2D-FRFT with separable kernels in both dimensions. The two stages are separated with a random phase mask. A preceding bit plane permutation process is performed on the obtained biometrics prior to the FRFT operation to achieve a high level of security. To validate the proposed algorithm for cancelable biometric recognition, different sets of face and fingerprint images are used. A comparative study is presented between the proposed algorithm and the optical Double Random Phase Encoding (DRPE) algorithm. The simulations results obtained for performance evaluation show that the proposed algorithm is safe, reliable, and feasible. It has good encryption and cancelability that reveal good performance.

Optical image encryption based on chaotic fingerprint phase mask and pattern-illuminated Fourier ptychography

An optical image encryption scheme based on chaotic fingerprint phase masks (CFPMs) and pattern-illuminated Fourier ptychography (FP) is proposed. During the encryption process, the primary image that is under the non-uniform intensity patterns’ illumination can be encrypted into multiple low-resolution intensity images with the CFPMs placed respectively at the input plane and the Fourier plane. And during the decryption process, the primary image can be recovered from these encrypted images with a Fourier ptychographic recovery algorithm and CFPMs. In this proposed image encryption scheme, the fingerprint image and the chaotic parameters are served as secret keys directly, and the CFPMs are just used as interim variables and functions. If the fingerprint image is shared by the sender and the authorized receiver, the security of the proposed image encryption scheme will be enhanced greatly, and the management and transmission of the secret keys will also become convenient to some extent. Additionally, the illumination pattern can also act as an additional secret key. Numerical simulations have been performed to verify the feasibility, security and robustness of the proposed image encryption scheme.

Asymmetric Optical Image Encryption With Silhouette Removal Using Interference and Equal Modulus Decomposition

We propose an asymmetric optical image encryption scheme with silhouette removal by using interference and equal modulus decomposition (EMD). Plaintext is first separated into two complex value masks with the same modulus using EMD in the Fresnel transform domain. The two masks are encoded into four phase-only masks (POMs), two of which are treated as ciphertexts and other two as plaintext-dependent private keys by using the inverse Fresnel transform with different diffraction distances and interference-based encryption. Any information about the plaintext, including its silhouette, cannot be retrieved using one, two, or even three of the four POMs. Our scheme also avoids the constraint of the same modulus in EMD and eliminates the vulnerability against the iterative amplitude-phase attack and advanced iterative amplitude-phase attack. Numerical simulations were used to verify the validity and security of our proposed method.

Optical image encryption scheme based on apertured fractional Mellin transform

An optical image encryption scheme is proposed by utilizing an apertured nonlinear fractional Mellin transform (FrMT). Due to its nonlinear property, FrMT is utilized for eliminating potential insecurity in an image encryption system caused by known-plaintext and chosen-plaintext attacks. The aperture in the optical system makes it harder for attackers to collect optical signals in the transmission process. The apertured FrMT can be implemented by log-polar transform and Collins diffraction and the key space of the proposed image encryption algorithm is very large. The orders of the FrMT, the radii of the FrMT domains, the order of the FrFT, the phases generated in the further encryption process, wavelength, side-lengths of hard aperture, and the parameters of logistic map are used as cipher keys. Extensive simulation results demonstrate that the proposed algorithm is feasible, sensitive to the keys, and capable of resisting common classical attacks. The encryption effect changes with the size of apertures.

Secure image encryption scheme using double random-phase encoding and compressed sensing

A secure optical digital image encryption scheme with authentication capability is proposed using double random-phase encoding (DRPE) and compressed sensing (CS). Phase information of the plaintext image is obtained using DRPE and quantized to generate authentication information. Simultaneously, the plaintext image is compressed by CS and its measurements are quantized using the sigmoid map. Then the ciphertext image is obtained by permutation and diffusion after authentication information is embedded in quantified measurements. At receiving end, the authentication information is first extracted by inverse permutation and diffusion, and then the authentication image is obtained by inverse DRPE. Finally, the ciphertext image can be blindly authenticated using a nonlinear cross-correlation method with authentication image and reconstructed image. Experimental results demonstrate the effectiveness of our proposed scheme.