http://hdl.handle.net/10609/4561 Recerca de la UOC i IN3 en Informàtica, tecnologia i multimèdia 2013-06-18T01:46:53Z http://hdl.handle.net/10609/22121 Title: High capacity robust audio watermarking scheme based on FFT and linear regression Authors: Fallahpour, Mehdi; Megías Jiménez, David Abstract: This paper proposes a novel high capacity audio watermarking algorithm to embed data and extract them in a bit-exact manner by changing some of the magnitudes of the FFT spectrum. The key idea is to divide the FFT spectrum into short frames and change the magnitudes of the selected FFT samples using linear regression and the average of the samples of each frame. Using the average of FFT magnitudes leads to improved robustness, since this variable is more invariant against manipulations compared to the magnitudes of single samples. In addition, linear regression helps to minimize the alterations of FFT samples, which results in better transparency. Apart from very remarkable capacity, transparency and robustness, this scheme provides three parameters which facilitate the regulation of these properties. The experimental results show that the method has a high capacity (0.5 to 2.3 kbps), without significant perceptual distortion (ODG is about ¿1) and provides robustness against common audio signal processing such as echo, added noise, filtering and MPEG compression (MP3). Description: Peer-reviewed 2012-03-31T22:00:00Z http://hdl.handle.net/10609/20842 Title: Proceedings of the 6th International Symposium on Frontiers of Information Systems and Network Applications (FINA-2013) Authors: Colomina Torregrosa, Ignacio; Arnedo MorenoMatsuo, Joan; Clarisó Viladrosa, Robert 2013-03-25T23:00:00Z http://hdl.handle.net/10609/17781 Title: Algoritmos genéticos para la anonimización de grafos Authors: Casas-Roma, Jordi; Herrera-Joancomartí, Jordi; Torra Reventós, Vicenç Abstract: En los últimos años se ha producido un incremento importante en el uso de los grafos como herramientas para la representación de información. Es muy importante poder preservar la privacidad de los usuarios cuando se desea publicar parte de esta información, especialmente en el caso de las redes sociales. En este caso es imprescindible aplicar un proceso de anonimización en los datos que permita preservar la privacidad de los usuarios. En este artículo se presenta un nuevo algoritmo para la anonimización de grafos, llamado Genetic Graph Anonymization (GGA), basado en la modificación de aristas para preservar el modelo de k-anonimidad.; En els últims anys s'ha produït un increment important en l'ús dels grafs com a eines per a la representació d'informació. És molt important poder preservar la privacitat dels usuaris quan es vol publicar algunes de les informacions, especialment en el cas de les xarxes socials. En aquest cas és imprescindible aplicar un procés d'anonimització a les dades que permeti preservar la privacitat dels usuaris. En aquest article es presenta un nou algoritme per l'anonimització de grafs, anomenat Genetic Graph Anonymization (GGA), basat en la modificació d'arestes per preservar el model de k-anonimitat.; In recent years there has been a significant increase in the use of graphs as tools for the representation of information. It is very important to preserve the privacy of users when they want to publish some of this information, especially in the case of social networks. In this case it is essential to apply an anonymizing process in the data that allows to preserve the privacy of the users. This paper presents a new algorithm for graph anonymization, called Genetic Graph Anonymization (GGA), based on the modification of edges to preserve the k-anonymity model. Description: Peer-reviewed 2012-08-31T22:00:00Z http://hdl.handle.net/10609/17744 Title: Experimental evaluation of anonymous protocols under the JXTA middleware Authors: Arnedo Moreno, Joan; Domingo Prieto, Marc; Pérez Gilabert, Noemi Abstract: JXTA is a peer-to-peer (P2P) middleware which has undergone successive iterations through its 10 years of history, slowly incorporating a security baseline that may cater to different applications and services. However, in order to appeal to a broader set of secure scenarios, it would be interesting to take into consideration more advanced capabilities, such as anonymity. There are several proposals on anonymous protocols that can be applied in the context of a P2P network, but it is necessary to be able to choose the right one given each application¿s needs. In this paper, we provide an experimental evaluation of two relevant protocols, each one belonging to a different category of approaches to anonymity: unimessage and split message. We base our analysis on two scenarios, with stable and non-stable peers, and three metrics: round trip-time (RTT), node processing time and reliability. 2012-09-25T22:00:00Z http://hdl.handle.net/10609/17743 Title: jxSensor: a sensor network integration layer for JXTA Authors: Domingo Prieto, Marc; Vilajosana Guillén, Xavier; Arnedo MorenoMatsuo, Joan Abstract: Nowadays, Wireless Sensor Networks (WSN) are already a very important data source to obtain data about the environment. Thus, they are key to the creation of Cyber-Physical Systems (CPS). Given the popularity of P2P middlewares as a means to efficiently process information and distribute services, being able to integrate them to WSN¿s is an interesting proposal. JXTA is a widely used P2P middleware that allows peers to easily exchange information, heavily relying on its main architectural highlight, the capability to organize peers with common interests into peer groups. However, right now, approaches to integrate WSNs to a JXTA network seldom take advantage of peer groups. For this reason, in this paper we present jxSensor, an integration layer for sensor motes which facilitates the deployment of CPS¿s under this architecture. This integration has been done taking into account JXTA¿s idiosyncrasies and proposing novel ideas, such as the Virtual Peer, a group of sensors that acts as a single entity within the peer group context. 2012-09-25T22:00:00Z http://hdl.handle.net/10609/17742 Title: Split message-based anonymity for JXTA applications Authors: Arnedo MorenoMatsuo, Joan; Pérez Gilabert, Noemi Abstract: JXTA is an open peer-to-peer (P2P) protocols specification that, in its about 10 years of history, has slowly evolved to appeal to a broad set of applications. As part of this process, some long awaited security improvements have been included in the latest versions. However, under some contexts, even more advanced security requirements should be met, such as anonymity. Several approaches exist to deploy anonymity in P2P networks, but no perfect solution exists. Even though path-based approaches are quite popular, it is considered that, in dynamic groups, using a split message-based one is better. In this work, we propose an anonymity service for JXTA using such approach. The proposal takes advantage JXTA's core services, in a manner so that it can be easily integrated to existing end applications and services. 2012-07-03T22:00:00Z http://hdl.handle.net/10609/17741 Title: Actas de la XII Reunión Española sobre Criptología y Seguridad de la Información (RECSI 2012) Authors: García Domínguez, Àlex; Arnedo Moreno, Joan; Domingo Prieto, Marc Abstract: JXTA is a mature set of open protocols, with more than 10 years of history, that enable the creation and deployment of peer-to-peer (P2P) networks, allowing the execution of services in a distributed manner. Throughout its lifecycle, it has slowly evolved in order to appeal a broad set of different applications. Part of this evolution includes providing basic security capabilities in its protocols in order to achieve some degree of message privacy and authentication. However, under some contexts, more advanced security requirements should be met, such as anonymity. There are several methods to attain anonymity in generic P2P networks. In this paper, we propose how to adapt a replicated message-based approach to JXTA, by taking advantage of its idiosyncracies and capabilities. 2012-09-04T22:00:00Z http://hdl.handle.net/10609/17301 Title: El Contexto Epidemiológico del Melanoma en la Teledermatología Authors: de Dios Romero, Alberto; Alumno Máster telemedicina Abstract: Se realiza una crítica a la implantación de un proyecto Teledermatología como estrategia de prevención del melanoma y las consecuencias negativas cuyos riesgos podrían superar a los beneficios. Description: Peer-reviewed 2011-12-31T23:00:00Z http://hdl.handle.net/10609/17181 Title: A Secure and Anonymous Cooperative Sensing Protocol for Cognitive Radio Networks Authors: Rifà-Pous, Helena; Garrigues Olivella, Carles Abstract: Spectrum is an essential resource for the provision of mobile services. In order to control and delimit its use, governmental agencies set up regulatory policies. Unfortunately, such policies have led to a deficiency of spectrum as only few frequency bands are left unlicensed, and these are used for the majority of new emerging wireless applications. One promising way to alleviate the spectrum shortage problem is adopting a spectrum sharing paradigm in which frequency bands are used opportunistically. Cognitive radio is the key technology to enable this shift of paradigm. Cognitive radio networks are self-organized systems in which devices cooperate to use those spectrum ranges that are not occupied by licensed users. They carry out spectrum sensing in order to detect vacant channels that can be used for communication. Even though spectrum sensing is an active area of research, an important issue remains unsolved: the secure authentication of sensing reports. Not providing security enables the input of false data in the system thus empowering false results. This paper presents a distributed protocol based on wireless physical layer security, symmetric cryptography and one-way functions that allows determining a final sensing decision from multiple sources in a quick and secure way, as well as it preserves users¿ privacy. 2011-10-31T23:00:00Z http://hdl.handle.net/10609/17161 Title: Generación de Agentes Móviles Seguros a partir de Itinerarios y Arquitecturas Criptográficas Authors: Garrigues Olivella, Carles; Borrell Viader, Joan; Moratalla, Álvaro; Robles Martínez, Sergi Abstract: En este trabajo presentamos un esquema para la creación de agentes móviles seguros a partir de una representación del itinerario que deben seguir, el código a ejecutar, y una especificación de la arquitectura criptográfica con la que estarán protegidos. Este tipo de agentes es muy útil en aplicaciones seguras, pero su programación resulta muy complicada. El esquema propuesto facilita enormemente esta tarea, automatizando el proceso a partir de especificaciones concretas. En la práctica hemos conseguido un sistema de generación de código de fácil utilización que permite, no sólo la programación de agentes móviles seguros, sino también la creación sencilla de nuevos esquemas criptográficos para la protección del código y los datos de los agentes. El sistema puede usarse para desarrollar aplicaciones de propósito general basadas en el framework de ejecución de agentes Jade.; En aquest treball presentem un esquema per a la creació d'agents mòbils segurs a partir d'una representació de l'itinerari que han de seguir, el codi a executar, i una especificació de l'arquitectura criptogràfica amb què estaran protegits. Aquest tipus d'agents és molt útil en aplicacions segures, però la seva programació és molt complicada. L'esquema proposat facilita enormement aquesta tasca, automatitzant el procés a partir d'especificacions concretes. A la pràctica hem aconseguit un sistema de generació de codi de fàcil utilització que permet, no només la programació d'agents mòbils segurs, sinó també la creació senzilla de nous esquemes criptogràfics per a la protecció del codi i les dades dels agents. El sistema es pot utilitzar per construir aplicacions de finalitat general basades en el framework d'execució d'agents Jade. 2004-09-14T22:00:00Z http://hdl.handle.net/10609/17141 Title: Fully Distributed Cooperative Spectrum Sensing for Cognitive Radio Networks Authors: Navarro-Arribas, Guillermo; Rifà Pous, Helena; Garrigues Olivella, Carles Abstract: Cognitive radio networks (CRN) sense spectrum occupancy and manage themselves to operate in unused bands without disturbing licensed users. The detection capability of a radio system can be enhanced if the sensing process is performed jointly by a group of nodes so that the effects of wireless fading and shadowing can be minimized. However, taking a collaborative approach poses new security threats to the system as nodes can report false sensing data to force a wrong decision. Providing security to the sensing process is also complex, as it usually involves introducing limitations to the CRN applications. The most common limitation is the need for a static trusted node that is able to authenticate and merge the reports of all CRN nodes. This paper overcomes this limitation by presenting a protocol that is suitable for fully distributed scenarios, where there is no static trusted node. 2012-09-03T22:00:00Z http://hdl.handle.net/10609/17121 Title: Metodología para el Desarrollo Automatizado de Aplicaciones Seguras Basadas en Agentes Móviles Authors: Garrigues Olivella, Carles; Moratalla, Álvaro; Robles Martínez, Sergi Abstract: En este trabajo presentamos una metodología para el diseño de aplicaciones basadas en agentes móviles seguros, y unas herramientas para aplicar esta metodología. Los recientes avances en el campo de la seguridad de los agentes móviles pueden desbloquear el uso de esta tecnología, pero falta aún superar la complejidad que suponen al programador de las aplicaciones. La metodología propuesta, y el uso de nuestras herramientas, permiten agilizar el proceso de diseño de arquitecturas criptográficas, y de los agentes que las utilizan. La implementación presentada es muy flexible, y permite utilizarse con cualquier plataforma de agentes que siga los estándares de IEEE-FIPA y que permita los esquemas de protección conducidos por agente.; En aquest treball presentem una metodologia per al disseny d'aplicacions basades en agents mòbils segurs, i unes eines per aplicar aquesta metodologia. Els recents avenços en el camp de la seguretat dels agents mòbils poden desbloquejar l'ús d'aquesta tecnologia, però falta encara superar la complexitat que suposen el programador de les aplicacions. la metodologia proposada i l'ús de les nostres eines, permeten agilitzar el procés de disseny d'arquitectures criptogràfiques, i dels agents que les utilitzen. la implementació presentada és molt flexible, i permet la seva utilització amb qualsevol plataforma d'agents que segueixi els estàndards de IEEE-FIPA i que permeti els esquemes de protecció conduïts per agent. 2006-09-06T22:00:00Z