Amalia Orue

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Impacto de comunidades educativas virtuales: el caso de Educar Ecuador

Santiago, 2020

La comunidad educativa virtual "Educar Ecuador" constituye una iniciativa del Ministeri... more La comunidad educativa virtual "Educar Ecuador" constituye una iniciativa del Ministerio de Educación para la integración de las tecnologías en la enseñanza. Sobre su impacto, existen múltiples estudios, pero a nivel macro, lo que ha limitado obtener datos sobre sus efectos por áreas y asignaturas. A partir de ello, se desarrolló un estudio transversal (2017-2018) para analizar la correlación estadística entre la implementación de la comunidad educativa y el rendimiento académico en la asignatura de matemáticas. La muestra fue de 150 alumnos de Contable y Administración de Sistemas. Se aplicó una encuesta y para los análisis se optó por aplicar regresiones lineales. Los análisis de regresión simple entre el rendimiento y los factores asociados al uso de las TIC, en los dos últimos cursos escolares, evidencian que la variable de incidencia de clases presenciales con uso de tecnologías dentro del aula resultó de alto impacto sobre el rendimiento académico final.

Randomness study of the concatenation of generalized sequences

Logic Journal of the IGPL, 2022

Keystream sequences should look as random as possible, i.e. should present no logical pattern to ... more Keystream sequences should look as random as possible, i.e. should present no logical pattern to be exploited in cryptographic attacks. The generalized self-shrinking generator, a sequence generator based on irregular decimation, produces a family of sequences with good cryptographic properties. In this work, we display a detailed analysis on the randomness of the sequences resulting from the concatenation of elements of this family. We apply the most important batteries of statistical and graphical tests providing powerful results and a new method to construct sequences with good cryptographic properties.

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Randomness Analysis for GSS-sequences Concatenated

13th International Conference on Computational Intelligence in Security for Information Systems (CISIS 2020), 2020

The most prolific acacias in southern Europe (Acacia dealbata, A. melanoxylon and A. longifolia) ... more The most prolific acacias in southern Europe (Acacia dealbata, A. melanoxylon and A. longifolia) are rapidly spreading in its westernmost area: Portugal and NW Spain, where congeners with invasion potential are already established. We performed a bibliographic search of acacia invasions in southern Europe and used spatial data on acacia distribution and abiotic parameters in Iberia to check the influence of abiotic factors on acacia invasion. According to our results, in Iberia A. dealbata and A. melanoxylon seem limited by high soil pH (pH CaCl 2 > 5.5), frequent frosts (> 21 to 40 d yr -1 ) and low annual precipitation (< 500 to 1000 mm); data were inconclusive for A. longifolia, while A. saligna prefers neutral soils in the driest and warmest areas. The percentage of area occupied by A. dealbata and A. melanoxylon increases significantly with the percentage of burnt surface. In the literature, acacias' invasiveness is usually attributed to their high resprouting and seeding capacity and to native exclusion through their allelopathic potential; symbiotic promiscuity with rhizobia; high environmental plasticity; and adaptation to burnt, cleared and resource-poor land. However, it is unknown how acacias became so invasive in western Iberia, where native Fabaceae shrubs with similar ecological traits (and invaders outside their natural range) are abundant. Invasive acacias can modify fire and water regimes, aboveground biodiversity, and topsoil characteristics (microbial communities, pH, organic matter and macronutrients levels); nevertheless, sound comparisons with mature stands of Iberian legumes for these and other soil properties (N fluxes, micronutrients) are lacking. As several acacias outcompete Iberian Fabaceae shrubs partly thanks to enemy release, the introduction of biocontrol agents (as for A. longifolia in Portugal) can be useful for invasion control.

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Enhancing the Learning of Cryptography Through Concept Maps

Advances in Intelligent Systems and Computing, 2019

This paper proposes an approach of teaching centered on students which emphasizes the creative an... more This paper proposes an approach of teaching centered on students which emphasizes the creative and effective use of technology. This approach meets students learning objectives using concept maps and shows how they can be used as an instructional tool to enhance the learning of Cryptography. The use of concept maps allows students to acquire a set of key mathematical competencies, such as representing mathematical entities, manipulating symbols and formalisms, and communicate in, with, and about mathematics.

A Review of Cryptographically Secure PRNGs in Constrained Devices for the IoT

International Joint Conference SOCO’17-CISIS’17-ICEUTE’17 León, Spain, September 6–8, 2017, Proceeding, 2017

In this work we show a deep review of lightweight random and pseudorandom number generators desig... more

Randomness Analysis for the Generalized Self-Shrinking Sequences

Symmetry, 2019

In cryptography, the property of randomness in pseudo-random generators is very important to avoi... more In cryptography, the property of randomness in pseudo-random generators is very important to avoid any pattern in output sequences, to provide security against attacks, privacy and anonymity. In this article, the randomness of the family of sequences obtained from the generalized self-shrinking generator is analyzed. Moreover, the characteristics, generalities and relationship between the t-modified self-shrinking generator and the generalized self-shrinking generator are presented. We find that the t-modified self-shrunken sequences can be generated from a generalized self-shrinking generator. Then, an in-depth analysis of randomness focused on the generalized sequences by means of complete and powerful batteries of statistical tests and graphical tools is done, providing a useful vision of the behaviour of these sequences and proving that they are suitable to be used in cryptography.

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An Intra-Slice Security Solution for Emerging 5G Networks Based on Pseudo-Random Number Generators

IEEE Access, 2018

Future 5G networks must provide communication services to a great and heterogeneous collection of... more Future 5G networks must provide communication services to a great and heterogeneous collection of scenarios: from traditional mobile communications to emerging applications such as Industry 4.0 or the Internet of Things (IoT). In this context, the network slicing technique is defined, where network resources are packaged and assigned in an isolated manner to the sets of users according to their specific requirements. Two different domains are, thus, defined: the intra-slice domain (where dedicated and specific solutions have to be deployed) and the inter-slice domain (including transversal solutions). One of the key topics which should be redefined following this approach is security. Traditionally, some solutions (such as stream ciphers) were not considered in mobile networks. However, 5G systems will be extensively employed in other new and very distinct scenarios, where requirements are different. For example, the use of resource constrained devices with little mobility and real-time data streaming in certain IoT applications suggests the use of stream ciphers (and other similar techniques) as the main security solutions. Therefore, in this paper, we investigate and propose a new security solution for emerging 5G networks, to be applied in the intra-slice domain. The proposed solutions employ lightweight pseudo-random number generators in order to provide the keystream used in stream ciphers which protect the private information and hide the communication signals in the frequency spectrum using spread spectrum techniques. We also describe and evaluate a first implementation of the proposed solution, using both, a simulation scenario and a real deployment.

Contribución de los sistemas dinámicos caóticos al diseño de criptosistemas de clave simétrica

La teoría del caos estudia el comportamiento errático de los sistemas dinámicos no lineales, alta... more La teoría del caos estudia el comportamiento errático de los sistemas dinámicos no lineales, altamente sensibles a las condiciones iniciales (efecto mariposa). Su estudio se remonta a los 1950s, en que el meteorólogo Edward N. Lorenz intentó hacer un modelo de los fenómenos atmosféricos . Generador recursivo múltiple: x n = x n-1 + 12 x n-2 + 0.5 mód 1. Generador congruencial lineal. Como remediar los problemas de los sistemas dinámicos discretos: con pseudocáos Perturbación de los bits menos significativos de los números generados. Rotación de los bits de los números generados. Realización dinámica de los anteriores. Variación dinámica del valor de los parámetros.

Trifork, a New Pseudorandom Number Generator Based on Lagged Fibonacci Maps

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On the security of the Quantum Key Distribution protocols

The advent of quantum computers may compromise the security of today's conventional cryptosystems... more The advent of quantum computers may compromise the security of today's conventional cryptosystems. Quantum key distribution protocols are proposed to ward off such threat; but, for the moment, the proposed quantum protocols are an hybrid of classical and quantum mechanisms and, as a consequence, they will result compromised as easily as conventional cryptography by quantum cryptanalysis.

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Algunas propiedades geometricas del sistema de Lorenz y su aplicación al Criptoanálisis de Criptosistemas Caóticos de Dos Canales

Medallones de espiral múltiple del conjunto de Mandelbrot

Breaking Points in Quartic Maps

International Journal of Bifurcation and Chaos, 2015

Dynamical systems, whether continuous or discrete, are used by physicists in order to study nonli... more Dynamical systems, whether continuous or discrete, are used by physicists in order to study nonlinear phenomena. In the case of discrete dynamical systems, one of the most used is the quadratic map depending on a parameter. However, some phenomena can depend alternatively on two values of the same parameter. We use the quadratic map [Formula: see text] when the parameter alternates between two values during the iteration process. In this case, the orbit of the alternate system is the sum of the orbits of two quartic maps. The bifurcation diagrams of these maps present breaking points at which there is an abrupt change in their evolution.

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Harmonic Analysis in Discrete Dynamical Systems

International Journal of Modern Nonlinear Theory and Application, 2012

In this paper we review several contributions made in the field of discrete dynamical systems, in... more In this paper we review several contributions made in the field of discrete dynamical systems, inspired by harmonic analysis. Within discrete dynamical systems, we focus exclusively on quadratic maps, both one-dimensional (1D) and two-dimensional (2D), since these maps are the most widely used by experimental scientists. We first review the applications in 1D quadratic maps, in particular the harmonics and antiharmonics introduced by Metropolis, Stein and Stein (MSS). The MSS harmonics of a periodic orbit calculate the symbolic sequences of the period doubling cascade of the orbit. Based on MSS harmonics, Pastor, Romera and Montoya (PRM) introduced the PRM harmonics, which allow to calculate the structure of a 1D quadratic map. Likewise, we review the applications in 2D quadratic maps. In this case both MSS harmonics and PRM harmonics deal with external arguments instead of with symbolic sequences. Finally, we review pseudoharmonics and pseudoantiharmonics, which enable new interesting applications.

Dendritas de Misiurewicz en el conjunto de Mandelbrot

Medallones de espiral múltiple en el conjunto de Mandelbrot

A Method to Solve the Limitations in Drawing External Rays of the Mandelbrot Set

Mathematical Problems in Engineering, 2013

The external rays of the Mandelbrot set are a valuable graphic tool in order to study this set. T... more The external rays of the Mandelbrot set are a valuable graphic tool in order to study this set. They are drawn using computer programs starting from the Böttcher coordinate. However, the drawing of an external ray cannot be completed because it reaches a point from which the drawing tool cannot continue drawing. This point is influenced by the resolution of the standard for floating-point computation used by the drawing program. The IEEE 754 Standard for Floating-Point Arithmetic is the most widely used standard for floating-point computation, and we analyze the possibilities of the quadruple 128 bits format of the current IEEE 754-2008 Standard in order to draw external rays. When the drawing is not possible, due to a lack of resolution of this standard, we introduce a method to draw external rays based on the escape lines and Bézier curves.

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Calculation of the Structure of a Shrub in the Mandelbrot Set

Discrete Dynamics in Nature and Society, 2011

We calculate the external arguments of the structure of any shrub in the Mandelbrot set. Before c... more We calculate the external arguments of the structure of any shrub in the Mandelbrot set. Before calculating, we revise, expand, and clarify some tools useful for this paper: harmonics, pseudoharmonics, the concept of structure, the structure of a shrub, and the ancestral route. Finally we present the main contribution of this paper, a three-step algorithm which allows us to calculate the structure of the shrub. In the first step, we use pseudoharmonics that were previously introduced by us, in order to calculate the first and last external arguments of a structural node. In the second step, starting from two general properties of the Misiurewicz points external arguments introduced here by us, we present a new method to calculate the intermediate external arguments. In the last step we introduce a third property that allows us to calculate the external arguments of the representatives of the branches emerging from the structural nodes.

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Drawing and computing external rays in the multiple-spiral medallions of the Mandelbrot set

Computers & Graphics, 2008

The multiple-spiral medallions are beautiful decorations of the Mandelbrot set. Computer graphics... more The multiple-spiral medallions are beautiful decorations of the Mandelbrot set. Computer graphics provide an invaluable tool to study the structure of these decorations with central symmetry, formed by an infinity of baby Mandelbrot sets that have high periods. Up to now, the external arguments of the external rays landing at the cusps of the cardioids of these baby Mandelbrot sets could not be calculated. Recently, a new algorithm has been proposed in order to calculate the external arguments in the Mandelbrot set. In this paper we use an extension of this algorithm for the calculation of the binary expansions of the external arguments of the baby Mandelbrot sets in the multiple-spiral medallions.

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A New Lorenz System Parameter Determination Method and Applications

Arxiv preprint nlin/ …, 2006

This paper describes how to determine the parameter values of the chaotic Lorenz system from one ... more This paper describes how to determine the parameter values of the chaotic Lorenz system from one of its variables waveform. The geometrical properties of the system are used firstly to reduce the parameter search space. Then, a synchronization-based approach, with the help of the same geometrical properties as coincidence criteria, is implemented to determine the parameter values with the wanted accuracy. The method is not affected by a moderate amount of noise in the waveform. As way of example of its effectiveness, the method is applied to figure out directly from the ciphertext the secret keys of two-channel chaotic cryptosystems using the variable z as a synchronization signal, based on the ultimate state projective chaos synchronization.

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