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 [Perez-Cabre], 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.

http://diposit.ub.edu/dspace/bitstream/2445/118388/1/664334.pdf

Roadmap on optical security

Organic materials with long-lived, color-tunable phosphorescence are potentially useful for optical recording, anti-counterfeiting, and bioimaging. Herein, we develop a series of novel host-guest organic phosphors allowing dynamic color tuning from the cyan (502 nm) to orange red (608 nm). Guest materials are employed to tune the phosphorescent color, while the host materials interact with the guest to activate the phosphorescence emission. These organic phosphors have an ultra-long lifetime of 0.7 s and a maximum phosphorescence efficiency of 18.2 %. Although color-tunable inks have already been developed using visible dyes, solution-processed security inks that are temperature dependent and display time-resolved printed images are unprecedented. This strategy can provide a crucial step towards the next-generation of security technologies for information handling.

Wide-Range Color-Tunable Organic Phosphorescence Materials for Printable and Writable Security Inks

Information security is a critical issue in modern society and image watermarking can effectively prevent unauthorized information access. Optical image watermarking techniques generally have advantages of parallel high-speed processing and multi-dimensional capabilities compared to digital approaches. This paper provides a comprehensive review of the research works related to optical image hiding and watermarking techniques conducted in the past decade. The past research works have focused on two major aspects: various optical systems for image hiding, and the methods for embedding the optical system output into a host image. A summary of the state-of-the-art works is made from these two perspectives.

Review on optical image hiding and watermarking techniques

A discussion and a cryptanalysis of the optical phase-truncated Fourier-transform-based cryptosystem are presented in this paper. The concept of an optical asymmetric cryptosystem, which was introduced into the optical image encryption scheme based on phase-truncated Fourier transforms in 2010, is suggested to be retained in optical encryption. A new method of attack is also proposed to simultaneously obtain the main information of the original image, the two decryption keys from its cyphertext, and the public keys based on the modified amplitude-phase retrieval algorithm. The numerical results illustrate that the computing efficiency of the algorithm is improved and the number of iterations is much less than that by the specific attack, which has two iteration loops.

Discussion and a new attack of the optical asymmetric cryptosystem based on phase-truncated Fourier transform

High performance optical encryption based on computational ghost imaging with QR code and compressive sensing technique

We introduce for the first time the concept of an information “container” before a standard optical encrypting procedure. The “container” selected is a QR code which offers the main advantage of being tolerant to pollutant speckle noise. Besides, the QR code can be read by smartphones, a massively used device. Additionally, QR code includes another secure step to the encrypting benefits the optical methods provide. The QR is generated by means of worldwide free available software. The concept development probes that speckle noise polluting the outcomes of normal optical encrypting procedures can be avoided, then making more attractive the adoption of these techniques. Actual smartphone collected results are shown to validate our proposal.

/pdf/optical-encryption-and-qr-codes-secure-and-noise-free-11pvppex7s.pdf

Optical encryption and QR codes: Secure and noise-free information retrieval

Molecular tests for viral diagnostics are essential to confront the COVID-19 pandemic, but their production and distribution cannot satisfy the current high demand. Early identification of infected people and their contacts is the key to being able to isolate them and prevent the dissemination of the pathogen; unfortunately, most countries are unable to do this due to the lack of diagnostic tools. Dogs can identify, with a high rate of precision, unique odors of volatile organic compounds generated during an infection; as a result, dogs can diagnose infectious agents by smelling specimens and, sometimes, the body of an infected individual. We trained six dogs of three different breeds to detect SARS-CoV-2 in respiratory secretions of infected patients and evaluated their performance experimentally, comparing it against the gold standard (rRT-PCR). Here we show that viral detection takes one second per specimen. After scent-interrogating 9,200 samples, our six dogs achieved independently and as a group very high sensitivity, specificity, predictive values, accuracy, and likelihood ratio, with very narrow confidence intervals. The highest metric was the negative predictive value, indicating that with a disease prevalence of 7.6%, 99.9% of the specimens indicated as negative by the dogs did not carry the virus. These findings demonstrate that dogs could be useful to track viral infection in humans, allowing COVID-19 free people to return to work safely.

https://biorxiv.org/content/10.1101/2020.06.17.158105v1.full.pdf

Dog Savior: Immediate Scent-Detection of SARS-COV-2 by Trained Dogs

We present equilateral hyperbolic zone plates with variable focal length, which are formed as moire patterns by a mutual rotation of two identical basic grids. Among others, all principal zone plates, except of the spherical one, can be used as these basic transmittances. Three most important advantages of the proposed moire zone plates are: a constant aperture of the created element during the mutual movement of basic grids, lack of aberrations due to their undesired mutual lateral displacements and high diffraction efficiency of the binary phase version. To obtain clearer moire fringe pattern, a radial carrier frequency can be added additionally to the transmittances of basic grids. The destructive interference between both arms of the focal cross of the equilateral hyperbolic moire zone plate can be obtained by a constant phase shift introduced in the transmittances of the basic grids. Potential applications of discussed elements are indicated, including the most promising one in the three-point alignment technique.

Equilateral hyperbolic moiré zone plates with variable focus obtained by rotations

Background: Abnormal and stereotypic behaviors in horses have been widely studied around the world and different epidemiological situations have been described for behavioral disturbances. Objective: To determine the frequency of abnormal and stereotypic behaviors in a population of police patrolling horses. Additionally, to establish chronic stress levels in the population of interest. Methods: Twenty police horses were evaluated. The animals went through 48 hours of continuous observation to record the frequency of normal, abnormal, and stereotypic behaviors. Cortisol index (CI) was calculated for all the subjects. Results: A 65% of the horses expressed behavioral disturbances, with 55% corresponding to stereotypies. The abnormal behaviors consisted on wood chewing, pawing, and bed eating. Stereotypic behaviors were weaving, stall walking, and aerophagia (crib-biting or wind sucking). According to the CI, 13 horses were under chronic stress (CI < 0.30). Conclusion: High level of chronic stress, expressed as abnormal and stereotypic behaviors, was observed in the horses. Keywords: cortisol, equine, ethogram, stress, welfare. Resumen Antecedentes: Los comportamientos anormales y estereotipados en caballos han sido ampliamente estudiados en el mundo, asi como tambien diversas situaciones epidemiologicas relacionadas con estos disturbios. Objetivo: Determinar la frecuencia de los comportamientos anormales y estereotipados en una poblacion de caballos de patrullaje de la policia y establecer su nivel de estres cronico. Metodos: Se evaluaron 20 caballos. Los animales fueron observados durante 48 horas continuas para recopilar los comportamientos anormales y estereotipados. El indice del cortisol (CI) fue calculado para todos los animales. Resultados: El 65% de la poblacion estudiada expreso disturbios del comportamiento, y el 55% de dichos disturbios se clasifico como estereotipias. Los comportamientos anormales observados consistieron en lignofagia, patear y comer cama. Los comportamientos estereotipados fueron balanceo, caminar en circulos y aerofagia. El CI mostro presencia de estres cronico en 13 caballos (CI < 0.30). Conclusion: Se encontro un alto porcentaje de estres cronico en los caballos de la policia, expresado como comportamientos anormales y estereotipados. Palabras clave: bienestar, cortisol, equino, estres, etograma. Resumo Antecedentes: Comportamentos anormais e estereotipados de cavalos tem sido amplamente estudados no mundo, assim como tambem diversas situacoes epidemiologicas relacionadas com estes disturbios. Objetivo: Determinar a frequencia de comportamentos anormais e estereotipados em uma populacao de cavalos de patrulhamento da policia e estabelecer seu nivel de estresse cronico. Metodos: Foram avaliados 20 equinos. Os animais foram observados durante 48 horas continuas para gravar os comportamentos anormais e estereotipados. O indice do cortisol (CI) foi calculado para todos os equinos. Resultados: O 65% da populacao estudada expressaram disturbios do comportamento, 55% dos disturbios foram estereotipias. Os comportamentos anormais observados foram lignofagia, escoicear a baia e comer cama. Os comportamentos estereotipados foram movimentos laterais repetitivos, movimentos aleatorios na baia e aerofagia. O CI mostrou presenca de estresse cronico em 13 cavalos ao mostrar valores menores a 0.30. Conclusao: Se determinou um alto porcentagem de estresse cronico nos cavalos da policia, expressado na forma de comportamentos anormais e estereotipados. Palavras chave: bem-estar, cortisol, equino, estresse, etograma.

/pdf/frequency-of-abnormal-and-stereotypic-behaviors-in-urban-4gk6ltatf6.pdf

Frequency of abnormal and stereotypic behaviors in urban police patrolling horses: a continuous 48-hour study

Moire patterns in the form of equilateral hyperbolic zone plates have been studied. They are created by a mutual rotation of basic grids which turn out to be zone plates described by conic curves and include as a special case hyperbolic and elliptical zone plates. The obtained moire zone plates change their focal length in function of the rotation's angle between the superposed grids that generated them and therefore they can be of interest in three-point method used for determination of small displacements of great engineering structures. Simulations as well as experimental results are presented.

Alejandro Mira

Papers

Optical encryption and QR codes: Secure and noise-free information retrieval

Dog Savior: Immediate Scent-Detection of SARS-COV-2 by Trained Dogs

Equilateral hyperbolic moiré zone plates with variable focus obtained by rotations

Frequency of abnormal and stereotypic behaviors in urban police patrolling horses: a continuous 48-hour study

Varifocal zone plates obtained by moire