Cryptographic salting for security enhancement of double random phase encryption schemes

Security in optical encryption techniques is a subject of great importance, especially in light of recent reports of successful attacks. We propose a new procedure to reinforce the ciphertexts generated in double random phase encrypting experimental setups. This ciphertext is protected by multiplexing with a 'salt' ciphertext coded with the same setup. We present an experimental implementation of the 'salting' technique. Thereafter, we analyze the resistance of the 'salted' ciphertext under some of the commonly known attacks reported in the literature, demonstrating the validity of our proposal.Fil: Velez Zea, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; ArgentinaFil: Barrera Ramírez, John Fredy. Universidad de Antioquia; ColombiaFil: Torroba, Roberto Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; Argentina. Universidad Nacional de la Plata. Facultad de Ingeniería. Uidet Grupo de Ensayos Mecanicos Aplicados.; Argentin

Noniterative multiplane holographic projection

In this paper, we introduce a mixed complex and phase-only constraint for noniterative computer generation of phase-only holograms from multiplane intensity distributions. We are able to reproduce three-dimensional intensity distributions with the same number of planes achieved with the Gerchberg–Saxton (GS) algorithm; at the same time, we maintain the fast computation time of a noniterative method. In this way, we enable the possibility of multiplane light field control in dynamic applications. We show numerical results for three- and eight-plane holograms, for different interplane distances—using either the same or different amplitude constraints in each plane. In all of these tests, our method results in a comparable or better reconstruction quality than the GS algorithm, while achieving a significant decrease in computing time. Finally, we experimentally demonstrate the capability of our proposal to achieve multiplane holographic projection.Fil: Velez Zea, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; ArgentinaFil: Torroba, Roberto Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; Argentina. Universidad Nacional de La Plata. Facultad de Ingeniería; Argentin

Digital speckle pattern interferometry applied to a surface roughness study

Surface roughness determination is of great interest for many applications. Several methods can be found in the literature, but most of them rely on indirect evaluation of the information, such a s photographic techniques. We propose a method to measure surface roughness that takes advantage of digital speckle pattern interferometry for obtaining the data, and of digital image processing for evaluating it. After defining the problem, a theoretical description is presented, and finally it is compared with experimental results, showing good agreement

Estudio de las figuras de interferencia generadas por cavidades no convencionales

La Óptica es una rama de la Física que ha recibido un importante impulso en el ultimo trienio, fundamentalmente por la adopción del formalismo de la Teoría de las Comunicaciones, así como por la aparición del láser, que se ha convertido en un instrumento invaluable para la comprensión de los procesos básicos de la interacción de la radiación con la materia, a la vez que brinda una fuente de iluminación de características únicas. Con el objeto de comprender mejor los fines de la presente tesis, haré a continuación, una breve exposición de las experiencias que motivaron y dieron forma a las ideas que voy a desarrollar. Básicamente se pueden dividir en dos clases, una de ellas se enmarca en la "Óptica de Fourier", y la otra en lo que llamare, estudio de las figuras interferenciales producidas por reflexiones múltiples en cavidades resonantes no convencionales.Doctor en Físic

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

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.Fil: Barrera, John Fredy. Universidad de Antioquia; ColombiaFil: Mira, Alejandro. Universidad de Antioquia; ColombiaFil: Torroba, Roberto Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Investigaciones Opticas (i); Argentin

Experimental scrambling and noise reduction applied to the optical encryption of QR codes

In this contribution, we implement two techniques to reinforce optical encryption, which we restrict in particular to the QR codes, but could be applied in a general encoding situation. To our knowledge, we present the first experimental-positional optical scrambling merged with an optical encryption procedure. The inclusion of an experimental scrambling technique in an optical encryption protocol, in particular dealing with a QR code “container”, adds more protection to the encoding proposal. Additionally, a nonlinear normalization technique is applied to reduce the noise over the recovered images besides increasing the security against attacks. The opto-digital techniques employ an interferometric arrangement and a joint transform correlator encrypting architecture. The experimental results demonstrate the capability of the methods to accomplish the task.Fil: Barrera, John Fredy. Universidad de Antioquia; ColombiaFil: Vélez, Alejandro. Universidad de Antioquia; ColombiaFil: Torroba, Roberto Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Investigaciones Opticas (i); Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Universidad Nacional de La Plata. Facultad de Ingenieria; Argentin

Digital speckle pattern interferometry applied to a surface roughness study

Surface roughness determination is of great interest for many applications. Several methods can be found in the literature, but most of them rely on indirect evaluation of the information, such a s photographic techniques. We propose a method to measure surface roughness that takes advantage of digital speckle pattern interferometry for obtaining the data, and of digital image processing for evaluating it. After defining the problem, a theoretical description is presented, and finally it is compared with experimental results, showing good agreement.Facultad de Ingenierí

Digital speckle pattern interferometry applied to a surface roughness study

Surface roughness determination is of great interest for many applications. Several methods can be found in the literature, but most of them rely on indirect evaluation of the information, such a s photographic techniques. We propose a method to measure surface roughness that takes advantage of digital speckle pattern interferometry for obtaining the data, and of digital image processing for evaluating it. After defining the problem, a theoretical description is presented, and finally it is compared with experimental results, showing good agreement.Facultad de Ingenierí

Experimental scrambling and noise reduction applied to the optical encryption of QR codes

In this contribution, we implement two techniques to reinforce optical encryption, which we restrict in particular to the QR codes, but could be applied in a general encoding situation. To our knowledge, we present the first experimental-positional optical scrambling merged with an optical encryption procedure. The inclusion of an experimental scrambling technique in an optical encryption protocol, in particular dealing with a QR code “container”, adds more protection to the encoding proposal. Additionally, a nonlinear normalization technique is applied to reduce the noise over the recovered images besides increasing the security against attacks. The opto-digital techniques employ an interferometric arrangement and a joint transform correlator encrypting architecture. The experimental results demonstrate the capability of the methods to accomplish the task.Centro de Investigaciones Óptica

Sistemas de precios y bioenergías

Biofuels are a masterpiece of the bioeconomy. Its development must combine environmental care and private profitability. The current pricing system as an inducer of private decisions and allocator of social resources becomes critical on: i) establish and promote new sources of renewable energy (long term); and ii) guarantee offer and profitability (short term). The energy-intensive paradigm, based on fossil fuels, responds to short-term private price signals but generates long-term distortions (it does not include negative externalities or sustainability demands). A shift towards a sustainable energy matrix demands a two-way response: creating the fundamental rules for a new market (“bio-energies”) and establishing a long-term price set that includes environmental restrictions (adjusting private profitability criteria to social objectives). Given the difficulties of the market in making both objectives compatible, state interventions appear. The different pricing schemes have been a fundamental piece in the design of the regulatory frameworks that generated different bio-fuel markets. Four main mechanisms are distinguished: prices set by the Application Authority, pure bids, conditional tenders, and free competition schemes. These schemes have been complemented, in some cases, by schemes that attempt to correct market imperfections (negative externalities) such as the effect of fossil fuels on climate change. The work begins with a theoretical review of the difficulties of the pricing mechanism to allocate the non-renewable resources. Subsequently, it analyses cases of state interventions in biofuel markets.Los biocombustibles son una pieza central de la bioeconomía. Su desarrollo debe compatibilizar los cuidados ambientales y la rentabilidad de los negocios. El actual sistema de precios como inductor de decisiones privadas y asignador de recursos sociales se torna crítico para: i) establecer e impulsar nuevas fuentes de energías renovables (largo plazo); y ii) garantizar la oferta y rentabilidad (corto plazo). El paradigma energo-intensivo, basado en combustibles fósiles, responde a señales de precios privados de corto plazo, pero genera distorsiones a largo plazo (no contempla externalidades negativas ni incluye demandas de sustentabilidad). Un cambio hacia una matriz energética sustentable demanda respuestas en dos direcciones: crear las reglas fundamentales para un nuevo mercado (“las bioenergías”) y establecer un set de precios de largo plazo que incluya las restricciones ambientales (ajustando criterios de rentabilidad privada a objetivos sociales). Ante las dificultades del mercado de compatibilizar ambos objetivos aparecen las intervenciones estatales. Los diferentes esquemas de fijación de precios han resultado una pieza fundamental en el diseño de los marcos normativos que generaron diferentes mercados de biocombustibles. Se distinguen cuatro mecanismos principales: precios fijados por la Autoridad de Aplicación, licitaciones puras, licitaciones condicionadas y esquemas de libre competencia. Estos esquemas han sido complementados, en algunos casos, por mecanismos que intentan corregir imperfecciones de mercado (externalidades negativas), tales como el efecto de los combustibles fósiles en el cambio climático. El trabajo comienza con una revisión teórica de las dificultades del mecanismo de precios como asignador de recursos no renovables. Posteriormente analiza casos de intervenciones estatales en los mercados de los biocombustibles