Optical systems as information processing systems have become quite impressive recently in optical image encryption and watermarking. Benefits of optical systems over the electronic counterparts are that optical processing provides the maximum number of degrees of freedom, and that optical encryption is ideal for information stored in holographic media. Various schemes have been proposed in the last decade. In this article, we review the recent progress and patents in this field, and point out some challenges that might lead to practical optical information security systems Keywords: Double random phase encoding, holography, information security, Optical encryption, phase retrieval, Optical systems, multidimensional information s, spatial coherence, polarization, Optical image encryption, cryptosystem, discrete fractional fourier transform, encoding technique, micro-optics system, decryption method
Optical systems as information processing systems have become quite impressive recently in optical image encryption and watermarking. Benefits of optical systems over the electronic counterparts are that optical processing provides the maximum number of degrees of freedom, and that optical encryption is ideal for information stored in holographic media. Various schemes have been proposed in the last decade. In this article, we review the recent progress and patents in this field, and point out some challenges that might lead to practical optical information security systems Keywords: Double random phase encoding, holography, information security, Optical encryption, phase retrieval, Optical systems, multidimensional information s, spatial coherence, polarization, Optical image encryption, cryptosystem, discrete fractional fourier transform, encoding technique, micro-optics system, decryption method
Abstract Information security and authentication are important challenges facing society. Recent attacks by hackers on the databases of large commercial and financial companies have demonstrated that more research and development of advanced approaches are necessary to deny unauthorized access to critical data. Free space optical technology has been investigated by many researchers in information security, encryption, and authentication. The main motivation for using optics and photonics for information security is that optical waveforms possess many complex degrees of freedom such as amplitude, phase, polarization, large bandwidth, nonlinear transformations, quantum properties of photons, and multiplexing that can be combined in many ways to make information encryption more secure and more difficult to attack. This roadmap article presents an overview of the potential, recent advances, and challenges of optical security and encryption using free space optics. The roadmap on optical security is comprised of six categories that together include 16 short sections written by authors who have made relevant contributions in this field. The first category of this roadmap describes novel encryption approaches, including secure optical sensing which summarizes double random phase encryption applications and flaws [Yamaguchi], the digital holographic encryption in free space optical technique which describes encryption using multidimensional digital holography [Nomura], simultaneous encryption of multiple signals [Pérez-Cabré], asymmetric methods based on information truncation [Nishchal], and dynamic encryption of video sequences [Torroba]. Asymmetric and one-way cryptosystems are analyzed by Peng. The second category is on compression for encryption. In their respective contributions, Alfalou and Stern propose similar goals involving compressed data and compressive sensing encryption. The very important area of cryptanalysis is the topic of the third category with two sections: Sheridan reviews phase retrieval algorithms to perform different attacks, whereas Situ discusses nonlinear optical encryption techniques and the development of a rigorous optical information security theory. The fourth category with two contributions reports how encryption could be implemented at the nano- or micro-scale. Naruse discusses the use of nanostructures in security applications and Carnicer proposes encoding information in a tightly focused beam. In the fifth category, encryption based on ghost imaging using single-pixel detectors is also considered. In particular, the authors [Chen, Tajahuerce] emphasize the need for more specialized hardware and image processing algorithms. Finally, in the sixth category, Mosk and Javidi analyze in their corresponding papers how quantum imaging can benefit optical encryption systems. Sources that use few photons make encryption systems much more difficult to attack, providing a secure method for authentication.
Optical information security is one of the most important research directions in information science and technology, especially in the copyright protection, confidential information transmission/storage and military remote sensing. Since double random phase encoding technology (DRPE) was proposed, optical image encryption technology has become the main topic of optical information security and it has been developed and studied deeply. Much significant research and investigation on optical image encryption have been presented based on DRPE or further optical operation, such as digital holography, and Fresnel transform, gyrator transform. In this paper, the optical encryption system for gray image and color image is reviewed.
Optical information security techniques are developed at a fast pace over the past two decades. In the present scenario, where enormous amount of data is being exchanged, information security plays an important role in protecting the information/data from unauthorized use/access. In this context, securing information using optical means has become relevant, given the suitable features of speed and multiple degrees of freedom that optical cryptosystems offer. Asymmetric cryptosystems have been introduced as an upgrade over the conventional double random phase encoding technique and they show resistance towards the known-plaintext attack. This paper reviews the symmetric and asymmetric cryptosystems and their attack analysis.
With the exponential growth of digital communication channels, the transmission and storage of high-dimensional multimedia data, including images and videos, have become crucial to modern information systems. The areas like defense, healthcare and banking utilize the modern communication channels very often to share information. Thus, ensuring the confidentiality, integrity, and authenticity of sensitive visual information has become a critical challenge. Although there are various conventional data security algorithms that exist, they often encounter limitations in handling large-scale image data due to high computational complexity and slow processing speed. Optical cryptosystems have emerged as a promising alternative owing to their inherent parallelism, multidimensional processing capability, large key space, and high-speed implementation. In this review, recent advancements in optical cryptosystems beyond classical DRPE scheme are summarized. Particularly, we examine the asymmetric optical cryptosystems based on PTFT, QZ decomposition, QZ synthesis, SVD, GSVD, interference, and computer-generated holography. Moreover, this review also discussed the emerging approaches of optical data security using structured light beams such as vector vortex beams. Finally, the review covered various techniques to test the vulnerabilities of optical cryptosystems such as plaintext and modified plaintext attacks, AI based cryptographic attacks, and iterative attacks designed for asymmetric cryptosystems. The objective of this review article is to serve as a reference text for readers from a variety of research backgrounds interested in the domain of optical information security.
There has been considerable attention paid in recent literature to the use of optical signal processing in the field of image encryption and security. In most cases this involves the use of optical transforms based on quadratic phase systems (to implement the optical Fourier Transform (FT), the optical fractional Fourier Transform (FRT), the Fresnel transform (FST) and the most general Linear Canonical Transform (LCT). Random phase screens or random shifting.stages are applied after optically transforming to a new domain. The process may be repeated for deeper encryption. Each stage of the encryption process may change the position and spatial extension of the complex distribution on the plane normal to the propagation axis. Each stage may also change the frequency distribution of the signal. Therefore, the space bandwidth product (SBP), which is equal to the number of discrete samples that are required to fully represent our signal, will also change. In general the encrypted image is complex and recording must be carried out using a holographic material or using digital holographic methods. In each case it is desirable to know the spatial extension of the signal to be recorded, its position, and its spatial frequency extension. In this way we can determine which holographic materials will meet the criteria or which cameras will have a suitable number of pixels, greater than or equal to the space bandwidth product, if digital holography is used. We show how the matrices associated with the effect of a LCT on the Wigner Distribution Function (WDF) provide us with an efficient method for finding the position, spatial extent, spatial frequency extent and space bandwidth product of the encrypted signal. We review a number of methods, which have recently been proposed in the literature for the encryption of two-dimensional information using optical systems based on the FT, FRT, FST and LCT. We apply the new matrix technique to some of them.
In the modern era, the secure transmission and storage of information are among the utmost priorities. Optical security protocols have demonstrated significant advantages over digital counterparts, i.e., a high speed, a complex degree of freedom, physical parameters as keys (i.e., phase, wavelength, polarization, quantum properties of photons, multiplexing, etc.) and multi-dimension processing capabilities. This paper provides a comprehensive overview of optical cryptosystems developed over the years. We have also analyzed the trend in the growth of optical image encryption methods since their inception in 1995 based on the data collected from various literature libraries such as Google Scholar, IEEE Library and Science Direct Database. The security algorithms developed in the literature are focused on two major aspects, i.e., symmetric and asymmetric cryptosystems. A summary of state-of-the-art works is described based on these two aspects. Current challenges and future perspectives of the field are also discussed.