The secure transmission of image information is an essential issue in communication, but it is also important in situations where the transmission channel resources are limited, such as quantum transmission. We propose a multi-layer single-pixel imaging end-to-end optical encryption framework with the characteristic advantage of a small key storage space requirement. Compared with previous single-layer encryption methods, the proposed approach greatly expands the key space and enhances the difficulty of brute-force cracking. The framework encrypts the image when the imaging signal is measured, which avoids the risk of leaking the plaintext information in processing. Numerical simulations and experiments verify the feasibility and robustness of this method. The proposed method can encrypt images end-to-end in both spatial and frequency domains, offering a new framework for robust, affordable, and secure optical image encryption.
The secure transmission of image information is an essential issue in communication, but it is also important in situations where the transmission channel resources are limited, such as quantum transmission. We propose a multi-layer single-pixel imaging end-to-end optical encryption framework with the characteristic advantage of a small key storage space requirement. Compared with previous single-layer encryption methods, the proposed approach greatly expands the key space and enhances the difficulty of brute-force cracking. The framework encrypts the image when the imaging signal is measured, which avoids the risk of leaking the plaintext information in processing. Numerical simulations and experiments verify the feasibility and robustness of this method. The proposed method can encrypt images end-to-end in both spatial and frequency domains, offering a new framework for robust, affordable, and secure optical image encryption.
Single-pixel imaging (SPI) enables an invisible target to be imaged onto a photosensitive surface without a lens, emerging as a promising way for indirect optical encryption. However, due to its linear and broadcast imaging principles, SPI encryption has been confined to a single-user framework for the long term. We propose a multi-image SPI encryption method and combine it with orthogonal frequency division multiplexing-assisted key management, to achieve a multiuser SPI encryption and authentication framework. Multiple images are first encrypted as a composite intensity sequence containing the plaintexts and authentication information, simultaneously generating different sets of keys for users. Then, the SPI keys for encryption and authentication are asymmetrically isolated into independent frequency carriers and encapsulated into a Malus metasurface, so as to establish an individually private and content-independent channel for each user. Users can receive different plaintexts privately and verify the authenticity, eliminating the broadcast transparency of SPI encryption. The improved linear security is also verified by simulating attacks. By the combination of direct key management and indirect image encryption, our work achieves the encryption and authentication functionality under a multiuser computational imaging framework, facilitating its application in optical communication, imaging, and security.
Providing secure and efficient transmission for multiple optical images has been an important issue in the field of information security. Here we present a hybrid image compression, encryption and reconstruction scheme based on deep learning-assisted single-pixel imaging (SPI) and orthogonal coding. In the optical SPI-based encryption, two-dimensional images are encrypted into one-dimensional bucket signals, which will be further compressed by a binarization operation. By overlaying orthogonal coding on the compressed signals, we obtain the ciphertext that allows multiple users to access with the same privileges. The ciphertext can be decoded back to the binarized bucket signals with the help of orthogonal keys. To enhance reconstruction efficiency and quality, a deep learning framework based on DenseNet is employed to retrieve the original optical images. Numerical and experimental results have been presented to verify the feasibility and effectiveness of the proposed scheme.
An optical image encryption method is proposed based on Fourier single-pixel imaging and iterated phase retrieval algorithm. First, a binary barcode image containing two groups of horizontal strips is randomly generated and used as the target image in the single-pixel imaging process. Second, considering the barcode image as the amplitude constraint, the original plaintext image is encoded to two phase-only masks using a designed phase retrieval algorithm in Fresnel domain, and these masks are applied as secret keys. Finally, the barcode image is encrypted to a series of measurements using two-step phase shift Fourier single-pixel imaging as the ciphertext. Differing other methods, the original image is not directly imaged and encoded into the ciphertext. Even the ciphertext is obtained by a cracker, only the barcode image may be further discovered. Due to two phase-only masks as secret keys, the security level of the cryptosystem can be enhanced greatly. The simulated results verify the feasibility of the proposed method, and this work provides an effective alternative for the related research.
In the rapidly evolving field of optical information security, single-pixel imaging (SPI) has emerged as a promising technique for hidden information transmission. However, traditional SPI methods face significant challenges, including the need for excessive modulation patterns and the vulnerability of encrypted information during transmission. Furthermore, the field lacks efficient methods to reconstruct both plaintext and ciphertext images from the same set of single-pixel measurements. Here, we propose a novel and efficient encryption strategy for Fourier single-pixel imaging (FSPI) that addresses these critical challenges. Our approach integrates two key innovations: a two-step Fourier-total variation conjugate gradient descent (F-TVCGD) method and a dual-key decryption mechanism. The F-TVCGD method significantly reduces the number of modulation patterns required for image reconstruction, enhancing efficiency and minimizing data redundancy. Our dual-key mechanism enables the reconstruction of both plaintext and ciphertext images from a single set of single-pixel measurements using different decryption keys, significantly enhancing security without compromising efficiency. The incorporation of Fourier symmetric patterns improves the convergence robustness of the symmetric gradient descent (SGD) algorithm, leading to superior performance under challenging conditions such as sparse sampling and noise attacks. Numerical simulations and optical experiments validate our method's improvements in both accuracy and security compared to traditional approaches. Our findings demonstrate that the proposed F-TVCGD and SGD strategies effectively address the challenges of excessive modulation patterns and information vulnerability in FSPI.
Abstract Optical encryption techniques in over the last 10 years have become more important in the area of optical information processing. Several applications, including online payments, medical or biometric image storage or transmission, private military applications, police identification techniques, online banking platforms, governmental services, identity (ID) cards, etc., are only a few examples. Require special and reliable security in the transmission and storage of images. Since digital picture information may be readily accessed by hackers via transmission over the Internet or other communication channels, the issue of photos with unlawful usage is becoming more and more severe. A more effective and secure means of communicating images may be offered via optical encryption. The encryption mechanism and keys are needed at the receiver side in order to decrypt the original optical data. Picture security becomes a highly important subject in communication science as a result of network growth and rising need for image transmission. There are several security issues with picture data, including forgery detection and illegal access. The most straightforward method of picture protection is to encrypt it as text. The traditional text encryption algorithms are inappropriate for picture encryption because of the high correlation present in image data. Over the last two decades, a number of optical approaches have been proposed for photo encryption, with the specific advantage of processing two-dimensional (2D) image data in parallel conduction mode. Therefore, we are doing an extensive investigation on optical image encryption in this work.
A multiple-image encryption (MIE) scheme with a single-pixel detector has been proposed according to the principle of ghost imaging. In this scheme, each of the spatially coherent laser beams is modified by a set of phase-mask keys and illuminates on a secret image. All of the transmitted lights are recorded together by a single-pixel (bucket) detector to obtain a ciphertext, but anyone of the secret images can be decrypted from the ciphertext independently without any mutually overlapped despite some noise in them. The MIE scheme will bring convenience for data storage and transmission, especially in the case that different secret images need to be distributed to different authorized users, because the ciphertext is a real-valued function and this scheme can effectively avoid the secret images being extracted mutually. The basic principle of the MIE scheme is described theoretically and verified by computer simulations. Finally, the feasibility, robustness and encryption capacity are also tested numerically.