A new simple technique for improving the random properties of chaos-based cryptosystems

A new technique for improving the security of chaos-based stream ciphers has been proposed and tested experimentally. This technique manages to improve the randomness properties of the generated keystream by preventing the system to fall into short period cycles due to digitation. In order to test this technique, a stream cipher based on a Skew Tent Map algorithm has been implemented on a Virtex 7 FPGA. The randomness of the keystream generated by this system has been compared to the randomness of the keystream generated by the same system with the proposed randomness-enhancement technique. By subjecting both keystreams to the National Institute of Standards and Technology (NIST) tests, we have proved that our method can considerably improve the randomness of the generated keystreams. In order to incorporate our randomness-enhancement technique, only 41 extra slices have been needed, proving that, apart from effective, this method is also efficient in terms of area and hardware resources

ANÁLISIS DEL VALOR DE MARCA DE LAS ENTIDADES FINANCIERAS: EL EFECTO HALO Y EL MODELO DE ELECCIÓN DISCRETA

El presente trabajo trata de cuantificar el valor de marca y el posicionamiento de las entidades financieras en dos mercados diferentes: consumidores finales y microempresas. Así mismo, se busca identificar las dimensiones de imagen de mayor peso a la hora de elegir a una entidad como la de mejor valoración global. A través del modelo de elección discreta y del análisis del efecto halo ,se comprueba la importancia del trato personal al cliente como la variable de mayor peso en la elección de marca. Además, se observa la mayor intensidad del efecto halo para las cajas de ahorros en el caso de los consumidores particulares. Sin embargo, en el segmento de microempresas, el valor de marca es superior para los bancos

A 1 Gbps Chaos-Based Stream Cipher Implemented in 0.18 m CMOS Technology

In this work, a novel chaos-based stream cipher based on a skew tent map is proposed and implemented in a 0.18 µm CMOS (Complementary Metal-Oxide-Semiconductor) technology. The proposed ciphering algorithm uses a linear feedback shift register that perturbs the orbits generated by the skew tent map after each iteration. This way, the randomness of the generated sequences is considerably improved. The implemented stream cipher was capable of achieving encryption speeds of 1 Gbps by using an approximate area of ~20,000 2-NAND equivalent gates, with a power consumption of 24.1 mW. To test the security of the proposed cipher, the generated keystreams were subjected to National Institute of Standards and Technology (NIST) randomness tests, proving that they were undistinguishable from truly random sequences. Finally, other security aspects such as the key sensitivity, key space size, and security against reconstruction attacks were studied, proving that the stream cipher is secure

Corporate Social Responsibility: definition and practice in the hospitality sector. Meliá Hotels International case study

RESUMEN: La Responsabilidad Social Corporativa (RSC) es un área de gran interés en la actualidad. Sin embargo, existe cierta ambigüedad en torno a su significado, el papel que juega en el sector hotelero y el modo en que ha de desarrollarse en esta industria. Esta investigación ofrece un estudio exploratorio e ilustrativo basado en el análisis de Meliá Hotels International (MHI) –empresa líder en el sector con presencia en 27 países–. Analizando el caso de MHI se aportará información relevante sobre aspectos relativos a la RSC tales como la definición de este concepto, el nivel de conocimiento por parte de la empresa, sus preocupaciones en materia de RSC, el tipo de iniciativas socialmente responsables desarrolladas y el nivel de participación de la compañía en dichas actividades. Este estudio aporta información relevante para el incremento de la eficiencia en el desarrollo de estas estrategias en el sector hotelero al tiempo que permite la difusión de buenas prácticas.ABSTRACT: Corporate Social Responsibility (CSR) is an area of great interest. However little is known about what CSR means and how it should be practiced in organizations. This research provides an exploratory and illustrative analysis based on Meliá Hotels International (MHI) –leading company with presence in 27 countries–. Analyzing the business case study of MHI this study will provide useful information on aspects of CSR such as MHI´s definition of this concept, its level of knowledge, its CSR concerns, socially responsible initiatives developed and MHI´s level of involvement in CSR. This study provides significant information for increasing efficiency in the development of these strategies in the hotel sector while allowing the dissemination of good practice

Oral Serum-Derived Bovine Immunoglobulin/Protein Isolate Has Immunomodulatory Effects on the Colon of Mice that Spontaneously Develop Colitis

Dietary immunoglobulin concentrates prepared from animal plasma can modulate the immune response of gut-associated lymphoid tissue (GALT). Previous studies have revealed that supplementation with serum-derived bovine immunoglobulin/protein isolate (SBI) ameliorates colonic barrier alterations in the mdr1a-/- genetic mouse model of IBD. Here, we examine the effects of SBI on mucosal inflammation in mdr1a-/- mice that spontaneously develop colitis. Wild type (WT) mice and mice lacking the mdr1a gene (KO) were fed diets supplemented with either SBI (2% w/w) or milk proteins (Control diet), from day 21 (weaning) until day 56. Leucocytes in mesenteric lymph nodes (MLN) and in lamina propria were determined, as was mucosal cytokine production. Neutrophil recruitment and activation in MLN and lamina propria of KO mice were increased, but were significantly reduced in both by SBI supplementation (p < 0.05). The increased neutrophil recruitment and activation observed in KO mice correlated with increased colon oxidative stress (p < 0.05) and SBI supplementation reduced this variable (p < 0.05). The Tact/Treg lymphocyte ratios in MLN and lamina propria were also increased in KO animals, but SBI prevented these changes (both p < 0.05). In the colon of KO mice, there was an increased production of mucosal proinflammatory cytokines such as IL-2 (2-fold), IL-6 (26-fold) and IL-17 (19-fold), and of chemokines MIP-1β (4.5-fold) and MCP-1 (7.2-fold). These effects were significantly prevented by SBI (p < 0.05). SBI also significantly increased TGF-β secretion in the colon mucosa, suggesting a role of this anti-inflammatory cytokine in the modulation of GALT and the reduction of the severity of the inflammatory response during the onset of colitis