Carmen Sánchez Ávila - Academia.edu (original) (raw)

Uploads

Papers by Carmen Sánchez Ávila

Page 13. UNIVERSIDAD POLITÉCNICA DE MADRID UNIVERSIDAD COMPLUTENSE DE MADRID 13 Revista Mentoring... more Page 13. UNIVERSIDAD POLITÉCNICA DE MADRID UNIVERSIDAD COMPLUTENSE DE MADRID 13 Revista Mentoring &amp;amp; Coaching. Número 3 (2010)· 13-29 RED DE MENTORIA EN ENTORNOS UNIVERSITARIOS ESPAÑOLES ...

ABSTRACT In October 2000, after three years of competition between 15 candidate algorithms, the N... more ABSTRACT In October 2000, after three years of competition between 15 candidate algorithms, the National Standards and Technology (NIST) chose the Rijndael algorithm to be adopted as Advanced Encryption Standard (AES) by the U.S. Department of Commerce, replacing to Data Encryption Algorithm (DES), which has been the standard since 1977. The authors analyze the structure and design of new AES, following three criteria: a) resistance against all known attacks; b) speed and code compactness on a wide range of platforms; and c) design simplicity; as well as its similarities and dissimilarities with other symmetric ciphers. On the other side, the principal advantages of new AES with respect to DES and T-DES, as well as its limitations, are investigated. Thus, for example, the fact that the new cipher and its inverse use different components, which practically eliminates the possibility for weak and semi-weak keys, as existing for DES, and the non-linearity of the key expansion, which practically eliminates the possibility of equivalent keys, are two of the principal advantages of new cipher. Finally, the implementation aspects of Rijndael cipher and its inverse are treated. Thus, although Rijndael is well suited to be implemented efficiently on a wide range of processors and in dedicated hardware, we have concentrated our study on 8-bit processors, typical for current smart cards and on 32-bit processors, typical for PCs

Novática: Revista de la Asociación de Técnicos de Informática, 2004

el principal objetivo de este trabajo consiste en exponer las cualidades que hacen de la "Cr... more el principal objetivo de este trabajo consiste en exponer las cualidades que hacen de la "Criptografia de Curva Eliptica" el tipo de criptografia mas adecuado para ser utilizado en plataformas con distintas restricciones relacionadas con la velocidad del procesador, el ancho de banda, seguridad y memoria. Se han comparado distintas caracteristicas de algoritmos de clave publica con algoritmos de curva eliptica, para ver las ventajas que presenta el uso de la criptografia de curva eliptica. Concretamente, se ha llevado a cabo una comparacion entre distintos criptosistemas de clave publica (tales como ElGamal para cifrado y Diffie-Hellman para intercambio de claves) y los correspondientes basados en teoria de curva eliptica; subrayando principalmente las caracteristicas de velocidad de los algoritmos. Ademas, se han analizado distintas funciones llamadas por los algoritmos de curva eliptica para encontrar las mas lentas, las mas criticas.

Estudios Canarios: Anuario del Instituto de Estudios Canarios, 2017

espanolLa talla original de la Virgen de Candelaria del templo tinerfeno del mismo nombre desapar... more espanolLa talla original de la Virgen de Candelaria del templo tinerfeno del mismo nombre desaparecio en el aluvion del ano 1826. A pesar de los intentos de localizarla despues del desastre que arraso la iglesia y convento de los frailes dominicos donde se encontraba nada pudo lograrse, siendo sustituida por la actual, realizada en el siguiente ano. Tras rememorar los hechos acaecidos en la devastacion exponemos todas las opciones posibles en cuanto al destino de la imagen mariana, ya en tierra como en mar. Se analizan los tipos posibles de madera en la que pudiera estar hecha y la capacidad de emerger por flotabilidad en las aguas, asi como los destinos y rumbos si alli hubiera caido. Finalmente, y dentro de las hipotesis probables, se propone la que consideramos la mas adecuada situacion y estado que hoy tendria la imagen de Candelaria. EnglishThe original wood carving of the Virgin of Candelaria of the temple of Tenerife of the same name disappeared in the flood of 1826. Despite attempts to locate it after the disaster that devastated the church and convent of the dominican friars where it was, anything could be achieved, and was replaced by the present carving, carried out in the following year. After compile the events of the devastation we expose all possible options regarding the fate of the marian image, on land and at sea; we analyze the possible types of wood used and the ability to emerge in the water, as well as destinations and directions there. Finally, it is proposed what we consider the most likely location and condition nowadays of the carving of Candelaria.

Biometrics is an active research field that is increasingly being integrated into current technol... more Biometrics is an active research field that is increasingly being integrated into current technology. As a result, more and more people are becoming familiar with biometric technics such as fingerprint or facial recognition. Nevertheless, there are innovative techniques such as ear-based biometrics which are not very well known yet because they are at initial stages of research. In this work, an ear geometry-based biometric verification system oriented to recognition through mobile phones is presented and evaluated. Feature extraction is carried out by means of Principal Component Analysis and feature matching is performed by a distance-based classifier including Euclidean and Eigen distances. The evaluation has been made according to the specifications included in the ISO/IDE 19795 norm following a zero-effort falsification scenario. To this end, a database including ear images of different users has been captured using the camera of a smartphone. The obtained Equal Error Rate matches 1.11% when Euclidean distance is applied for feature comparison and 5.56% in the case of Eigendistance.

Abstract When an access control system is going to be developed or installed, the security needed... more Abstract When an access control system is going to be developed or installed, the security needed in the application where that system will be applied should be studied deeply. This security environment can deny the use of passwords or PINs, due to their low level of user ...

Pattern Recognition, Feb 1, 2005

Applied sciences, Dec 13, 2019

Interest on palmprint biometrics has experimented a strong growth in the last decades due to its ... more Interest on palmprint biometrics has experimented a strong growth in the last decades due to its useful characteristics as uniqueness, permanence, reliability, user-friendliness, acceptability, non-intrusiveness, and low cost of the acquisition devices, which make it attractive for civil and commercial applications. Accordingly, a wide research has been developed in this field. Nevertheless, there is a lack of evaluation of the results under a common framework which permits to obtain a fair comparison between different methods. In this work an evaluation methodology based on the definitions suggested by the ISO/IDE 19795 norm is provided and applied to evaluate different palmprint feature extraction methods and matching approaches in terms of accuracy and computation time, offering a basis against which to compare future research. Given the growing trend towards touch-less biometrics promoted by the increase in the use of mobile devices, the evaluation has been carried out using two different contact-less hand databases. First database was recorded under totally controlled environmental conditions and providing the user some feedback about the recorded images during the acquisition process, while second database introduces lighting variations as well as no-pose restrictions during the capture.

During the last decades, several different techniques have been proposed for computer recognition... more During the last decades, several different techniques have been proposed for computer recognition of human faces. A further step in the development of these biometrics is to implement them in portable devices, such as mobile phones. Due to this devices' features and limitations it is necessary to select, among the currently available algorithms, the one with the best performance in terms of algorithm overall elapsed time and correct identification rates. The aim of this paper is to offer a complementary study to previous works, focusing on the performance of different supervised classifiers, such as the Normal Bayesian Classifier, Neural Architectures or distance-based algorithms. In addition, we analyse all the proposed algorithms' efficiency over public face databases (ORL, FERET, NIST and the Face Recognition Data from the Essex University). Each one of these databases contains a different number of individuals and particular samples and they present variations among images from the same user (scale, pose, expression, illumination, ...). We expect to simulate many different situations which take place when dealing with face recognition on mobile phones. In order to get a complete comparison, all the proposed algorithms have been implemented and run over all the databases, using the same computer. Different parametrizations for each algorithm have also been tested. Bayesian classifiers and distance-based algorithms turn out to be the most suitable, as their parametrization is simple, the training stage is not as time consuming as others' and classification results are satisfying.

Mathematics and Computers in Simulation, 2003

... AbstractA method for analyzing the quality of iris images is presented in this paper. Iris B... more ... AbstractA method for analyzing the quality of iris images is presented in this paper. Iris Biometrics for personal identification is based on capturing an eye photograph and obtaining a feature vector that allows to identify a human being. ...