Disseny i implementació d'un esquema criptogràfic d'enquesta electrònica remota

Amb aquest projecte es vol proposar un esquema criptogràfic que permeti realitzar una enquesta de forma electrònica. La solució es basa en criptografia de clau pública, que en la actualitat es fa servir de manera habitual tant en el comerç electrònic com en altres aplicacions criptogràfiques.

HELPER. Aplicación de gestión de flota

Helper proporciona la gestió de la flota del sistema d'emergències de Catalunya que utilitza un model sanitari centralitzat pel que fa a la recepció de les trucades ia la logística però amb bases sanitàries distribuïdes per tot el territori català.

Implementación de un esquema criptográfico para gestionar deforma segura las historias médicas de los pacientes a través de una red de comunicaciones

En aquest projecte de final de carrera s'ha dissenyat, implementat i provat un sistema que utilitzant criptografia de clau pública, garanteix la correcta utilització de les dades en un procés de consulta i complimentació d'una història clínica informatitzada consultada a distància.

An anonymous reputation mechanism for cloud computing networks using volunteer resources

One of the major problems when using non-dedicated volunteer resources in adistributed network is the high volatility of these hosts since they can go offlineor become unavailable at any time without control. Furthermore, the use ofvolunteer resources implies some security issues due to the fact that they aregenerally anonymous entities which we know nothing about. So, how to trustin someone we do not know?.Over the last years an important number of reputation-based trust solutionshave been designed to evaluate the participants' behavior in a system.However, most of these solutions are addressed to P2P and ad-hoc mobilenetworks that may not fit well with other kinds of distributed systems thatcould take advantage of volunteer resources as recent cloud computinginfrastructures.In this paper we propose a first approach to design an anonymous reputationmechanism for CoDeS [1], a middleware for building fogs where deployingservices using volunteer resources. The participants are reputation clients(RC), a reputation authority (RA) and a certification authority (CA). Users needa valid public key certificate from the CA to register to the RA and obtain thedata needed to participate into the system, as now an opaque identifier thatwe call here pseudonym and an initial reputation value that users provide toother users when interacting together. The mechanism prevents not only themanipulation of the provided reputation values but also any disclosure of theusers' identities to any other users or authorities so the anonymity isguaranteed.

Disseny i implementació d¿una plataforma per a la recollida i signatura d'iniciatives legislatives populars

Aquest projecte implementa una plataforma web per a la creació i signatura digital d'iniciatives legislatives populars. La solució es basa en la implementació d'un sistema d'autenticació mitjançant SSL i certificats digitals.

Sibling rivalry and vocal negotiation in the barn owl Tyto alba

Chez les animaux, les jeunes dépendant des parents durant leur développement sont en compétition pour obtenir la nourriture, qu'ils quémandent par des cris et postures ostentatoires et se disputent physiquement. Les frères et soeurs n'ont pas la même compétitivité, en particulier s'ils diffèrent en âge, et leur niveau de faim fluctue dans le temps. Comme dans tout type de compétition, chacun doit ajuster son investissement aux rivaux, c'est à dire aux besoins et comportements de ses frères et soeurs. Dans le contexte de la famille, selon la théorie de sélection de parentèle, les jeunes bénéficient de leur survie mutuelle et donc de la propagation de la part de gènes qu'ils ont en commun. L'hypothèse de la « négociation frères-soeurs » prédit que, sous certaines conditions, les jeunes négocient entre eux la nourriture, ce qui réduit les coûts de compétition et permet de favoriser les frères et soeurs les plus affamés. La littérature actuelle se focalise sur les signaux de quémande entre enfants et parents et les interactions compétitives frères-soeurs sont étudiées principalement au sein de paires, alors que les nichées ou portées en comprennent souvent de nombreux. Cette thèse vise à mieux comprendre comment et jusqu'à quel point plusieurs jeunes ajustent mutuellement leurs signaux de besoin. C'est une question importante, étant donné que cela influence la répartition de nourriture entre eux, donc la résolution du conflit qui les oppose et à terme leur valeur évolutive. Le modèle d'étude est la chouette effraie (Tyto alba), chez laquelle jusqu'à neufs poussins émettent des milliers de cris chacun par nuit. Ils négocieraient entre eux la prochaine proie indivisible rapportée au nid avant que les parents ne reviennent : un poussin affamé crie plus qu'un autre moins affamé, ce qui dissuade ce dernier de crier en retour et par la suite de quémander la nourriture aux parents. L'investissement optimal correspondrait donc à écarter son frère en permanence vu que l'arrivée des parents est imprévisible, mais à moindre coût. Dans un premier axe, nous avons exploré au sein de dyades les mécanismes acoustiques permettant aux poussins de doser leur effort vocal durant les heures de compétition où ils sont laissés seuls au nid. Nous avons trouvé que les poussins évitent de crier simultanément, ce qui optimiserait la discrimination du nombre et de la durée de leurs cris, lesquels reflètent de façon honnête leur niveau de faim et donc leur motivation. L'alternance des cris paraît particulièrement adaptée au fait que les poussins se fient à des variations temporelles subtiles dans le rythme et la durée de leurs vocalisations pour prendre la parole. En particulier, allonger ses cris tout en criant moins dissuade efficacement le rival de répondre, ce qui permet de monopoliser la parole dans de longs « monologues ». Ces règles seraient universelles puisqu'elles ne dépendent pas de la séniorité, de la faim, ni de la parenté et les poussins répondent à un playback de façon similaire à un vrai frère. Tous ces résultats apportent la première preuve expérimentale que les juvéniles communiquent de façon honnête sur leurs besoins, ajustent activement le rythme de leurs cris et utilisent des composantes multiples de leurs vocalisations d'une façon qui réduit le coût de la compétition. De plus, il s'agit de la première démonstration que des règles de conversation régissent de longs échanges vocaux chez les animaux de façon comparable aux règles basiques observées chez l'Homme. Dans un second axe, nous avons exploré les stratégies comportementales que les poussins adoptent pour rivaliser avec plusieurs frères et soeurs, par le biais d'expériences de playback. Nous avons trouvé que les poussins mémorisent des asymétries de compétitivité entre deux individus qui dialoguent et répondent plus agressivement au moins compétitif une fois qu'ils sont confrontés à chacun isolément. Dans la même ligne, quand ils entendent un nombre variable d'individus criant à un taux variable, les poussins investissent le plus contre des rivaux moins nombreux et moins motivés. En accord avec les prédictions des modèles théoriques, les poussins de chouette effraie escaladent donc les conflits pour lesquels leur chance de gagner contrebalance le plus l'énergie dépensée. Nous révélons ainsi que 1) les jeunes frères et soeurs 'espionnent' les interactions de leurs rivaux pour évaluer leur compétitivité relative, ce qui est sans doute moins coûteux qu'une confrontation directe avec chacun, et 2) dosent leur investissement vocal en fonction du nombre de rivaux actuellement en compétition et de leur motivation de façon concomitante. Ces résultats montrent que les interactions entre frères et soeurs au nid reposent sur des mécanismes similaires à ceux observés, mais encore de façon anecdotique, chez les adultes non apparentés qui se disputent les territoires et partenaires sexuels. Cette thèse souligne donc combien il est crucial de considérer dorénavant la famille comme un réseau de communication à part entière pour mieux comprendre comment les jeunes résolvent les conflits autour du partage des ressources parentales. Plus généralement, elle révèle l'importance de la dynamique temporelle des vocalisations dans les conflits et la communication des animaux. A la lumière de nos résultats, la chouette effraie apparaît comme un modèle clé pour de futures recherches sur la résolution des conflits et la communication acoustique. - In species with parental care, offspring contest priority access to food by begging through conspicuous postures and vocalisations and by physically jockeying. Siblings differ in their competitiveness, especially in the case of age and size hierarchies, and their hunger level fluctuates in time. As in competition in general, each individual should adjust its investment to opponents that is to say to its siblings' needs and behaviours. In the particular context of family, according to kin selection theory, siblings derive extra fitness benefits from their mutual survival and hence the spreading of the genes they share. The "sibling negotiation" predicts that, under certain conditions, young would negotiate among them priority access to food, which reduces competition costs and enables promoting the most hungry siblings. To date, the literature focuses on signals of need between parents and offspring and competitive interactions (in particular among siblings) are mostly studied within pairwise interactions, yet they commonly involve more numerous rivals. This PhD aims at better understanding how and the extent to which several young siblings compete through signalling. This is important since this influences how food is allocated among them, thus the outcome of sibling rivalry and ultimately their fitness. I use the barn owl (Tyto alba) as a model, in which the one to nine nestlings emit a simple noisy call thousands of times per night. Thereby, they would negotiate among them priority access to the indivisible food next delivered prior to parents' feeding visits. A hungry nestling emits more calls than a less hungry sibling, which deters it to call in return and ultimately beg food at parents. The optimal investment thus corresponds to constantly deterring the rival to compete, given that parents' arrival is unpredictable, but at the lowest costs. In the first axis of my thesis, we explored within dyads the acoustic mechanisms by which owlets dose vocal effort when competing during the hours they are left alone. We found that owlets avoid overlapping each other's calls. This would enhance the discrimination of both call number and duration, which honestly reflect individuals' hunger level and hence motivation to compete. Such antiphony seems best adapted to the fact that siblings actually use subtle temporal variations in the rhythm and duration of their calls to take or give their turn. Owlets alternate monologs, in which lengthening calls efficiently deters the rival to respond while reducing call number. Such rules depend neither on seniority, hunger level nor kinship since nestlings responded similarly to a live sibling and an unrelated playback individual. Taken together, these findings provide the first experimental proof that dependent young honestly communicate about their need, actively adjust the timing of their calls and use multicomponent signals in a way that reduces vocal costs. Moreover, this is the first demonstration of conversational rules underlying animal long-lasting vocal exchanges comparable to the basic turn-taking signals observed in humans. In the second axis, we focused on the behavioural strategies owlets adopt to compete with more than one sibling, using playback experiments. We found that singleton bystanders memorised competitive asymmetries between two playback individuals dialoguing and responded more aggressively to the submissive one once they later faced each of both alone. Moreover, when hearing a varying number of nestlings calling at varying rates, owlets vocally invested the most towards fewer and less motivated rivals. In line with predictions from models on conflict settlement, barn owls thus escalate contests in which their chance of winning best counterbalances the energy spent. These results reveal that young socially eavesdrop on their siblings' interactions to assess their relative competitiveness at likely lower costs than direct confrontation, and dose vocal effort relative to both their number and motivation. This shows that young siblings' interactions imply mechanisms similar to those observed, yet still anecdotally, in unrelated adults that contest mates and territories. This PhD therefore highlights how crucial it is to further consider family as a communication network to better understand how siblings resolve conflicts over the share of parental resources. More generally, it provides important insights into the role of the temporal dynamics of signalling during animal contests and communication. In the light of our findings, the barn owl emerges as a key model for future research on conflict resolution and acoustic communication in animals.

Preventing violence by intimate partners in adolescence: an integrative review

Abstract OBJECTIVE To analyze the scientific literature on preventing intimate partner violence among adolescents in the field of health based on gender and generational categories. METHOD This was an integrative review. We searched for articles using LILACS, PubMed/MEDLINE, and SciELO databases. RESULTS Thirty articles were selected. The results indicate that most studies assessed interventions conducted by programs for intimate partner violence prevention. These studies adopted quantitative methods, and most were in the area of nursing, psychology, and medicine. Furthermore, most research contexts involved schools, followed by households, a hospital, a health center, and an indigenous tribe. CONCLUSION The analyses were not conducted from a gender- and generation-based perspective. Instead, the scientific literature was based on positivist research models, intimately connected to the classic public healthcare model and centered on a singular dimension.

Molecular and isotopic characterization of organic samples from the wreck of the Saint-Etienne merchant ship (XVIIIth century): Identification of pitch, fat, hair and sulfur

The wreck U Pezzo, excavated within the Saint Florent Gulf in northern Corsica was identified as the pink, Saint Etienne, a merchant ship which sank on January 31, 1769. In order to determine the composition of organic materials used to coat the hull or to waterproof different parts of the pink, a study of several samples, using molecular biomarker and carbon isotopic analysis, was initiated. The results revealed that the remarkable yellow coat, covering the outside planks of the ship's bottom under the water line, is composed of sulfur, tallow (of ox and not of cetacean origin) and black pitch which corresponds to a mixture called ``couroi'' or ``stuff'. Onboard ropes had been submitted to a tarring treatment with pitch. Hairs mixed with pitch were identified in samples collected between the two layers of the hull or under the sheathing planking. The study also provides a key model for weathering of pitch, as different degrees of degradation were found between the surface and the heart of several samples. Accordingly, molecular parameters for alteration were proposed. Furthermore novel mixed esters between terpenic and diterpenic alcohols and the free major fatty acids (C(14:0), C(16:0), C(18:0)) were detected in the yellow coat. (C) 2009 Elsevier Ltd. All rights reserved.

Esquemes de xifrat homomòrfics per a votació electrònica

This bachelor's degree thesis deals with homomorphic public-key cryptography, or in other words cryptosystems with special addition properties. Such cryptosystems are widely used in real life situations, for instance to make electronic voting secure. In Chapter 1 a few basic algebra results and other key concepts are introduced. Chapters 2 and 3 contain the algorithms and properties of the two cryptosystems which are considered to be the best for e-voting: Paillier and Joye-Libert. The thesis is concluded in Chapter 4, by comparing running times of the two above-mentioned cryptosystems, in simulations of real-life e-voting systems, with up to tens of thousands of voters, and different levels of security. Through these simulations, we discern the situations where each of the two cryptosystems is preferable.

Gestión de confianza en redes ad hoc

El despliegue de un esquema de confianza es fundamental para poder desarrollar servicios de seguridad que permitan administrar y operar una red. Sin embargo, las soluciones empleadas en las redes tradicionales no se adaptan a un entorno ad hoc debido a la naturaleza dinámica y sin infraestructura de estas redes. En el presente trabajo se propone un esquema de confianza práctico y eficiente basado en una infraestructura de clave pública distribuida, umbral y jerárquica, que no requiere sincronización temporal entre todos los nodos de la red. La autorización de usuarios en el sistema se hace a través de certificados de corta duración que eliminan la necesidad de mantener la publicación y diseminación de unas listas de revocación. Por otro lado, una entidad externa de confianza permite alargar la reputación de un usuario de la red más allá de la existencia de la propia red.

Vahva todennus julkisen avaimen järjestelmässä

Arvokasta tai luottamuksellista tietoa käsittelevien palveluiden, kuten pankki- ja kauppa-palveluiden, tarjoaminen julkisessa Internet-verkossa on synnyttänyt tarpeen vahvalle todennukselle, eli käyttäjien tunnistuksen varmistamiselle. Vahvassa todennuksessa käytetään salaus-menetelmien tarjoamia keinoja todennus-tapahtuman tieto-turvan parantamiseen heikkoihin todennusmenetelmiin nähden. Todennusta käyttäjätunnus-salasana-yhdistelmällä voidaan pitää heikkona menetelmänä. Julkisen avaimen järjestelmän varmenteita voidaan käyttää WWW-ympäristössä toimivissa palveluissa yhteyden osapuolten todentamiseen. Tässä työssä suunniteltiin vahva käyttäjän todennus julkisen avaimen järjestelmällä WWW-ympäristössä tarjottavalle palvelulle ja toteutettiin palvelun tarjoavan sovelluksen komponentiksi soveltuva yksinkertainen varmentaja OpenSSL-salaustyökalupaketin avulla. Työssä käydään läpi myös salauksen perusteet, julkisen avaimen järjestelmä ja esitellään olemassaolevia varmentajatoteutuksia ja mahdollisia tieto-turva-uhkia Vahva todennus tulee suunnitella siten, että palvelun käyttäjä ymmärtää, mikä tarkoitus hänen toimillaan on ja miten ne edistävät tietoturvaa. Internet-palveluissa käyttäjän vahva todennus ei ole yleistynyt huonon käytettävyyden vuoksi.

Wireless Authentication and Authorization, case Wireless Access Control System

Lyhyen kantaman radiotekniikoiden hyödyntäminen mahdollistaa uudenlaisten paikallisten palveluiden käytön ja vanhojen palveluiden kehittämisen. Kulunvalvonta on päivittäisenä palveluna valittu työn esimerkkisovellukseksi. Useita tunnistus- ja valtuutustapoja tutkitaan, ja julkisen avaimen infrastruktuuri on esitellään tarkemmin. Langattomat tekniikat Bluetooth, Zigbee, RFID ja IrDA esitellän yleisellä tasolla langattomat tekniikat –luvussa. Bluetooth-tekniikan rakennetta, mukaan lukien sen tietoturva-arkkitehtuuria, tutkitaan tarkemmin. Bluetooth-tekniikkaa käytetään työssä suunnitellun langattoman kulunvalvontajärjestelmän tietojen siirtoon. Kannettava päätelaite toimii käyttäjän henkilökohtaisena luotettuna laitteena, jota voi käyttää avaimena. Käyttäjän tunnistaminen ja valtuuttaminen perustuu julkisen avaimen infrastruktuuriin. Ylläpidon allekirjoittamat varmenteet sisältävät käyttäjän julkisen avaimen lisäksi tietoa hänestä ja hänen oikeuksistaan. Käyttäjän tunnistaminen kulunvalvontapisteissä tehdään julkisen ja salaisen avaimen käyttöön perustuvalla haaste-vastaus-menetelmällä. Lyhyesti, järjestelmässä käytetään Bluetooth-päätelaitteita langattomina avaimina.

Knapsack sets for cryptography

The basic goal of this study is to extend old and propose new ways to generate knapsack sets suitable for use in public key cryptography. The knapsack problem and its cryptographic use are reviewed in the introductory chapter. Terminology is based on common cryptographic vocabulary. For example, solving the knapsack problem (which is here a subset sum problem) is termed decipherment. Chapter 1 also reviews the most famous knapsack cryptosystem, the Merkle Hellman system. It is based on a superincreasing knapsack and uses modular multiplication as a trapdoor transformation. The insecurity caused by these two properties exemplifies the two general categories of attacks against knapsack systems. These categories provide the motivation for Chapters 2 and 4. Chapter 2 discusses the density of a knapsack and the dangers of having a low density. Chapter 3 interrupts for a while the more abstract treatment by showing examples of small injective knapsacks and extrapolating conjectures on some characteristics of knapsacks of larger size, especially their density and number. The most common trapdoor technique, modular multiplication, is likely to cause insecurity, but as argued in Chapter 4, it is difficult to find any other simple trapdoor techniques. This discussion also provides a basis for the introduction of various categories of non injectivity in Chapter 5. Besides general ideas of non injectivity of knapsack systems, Chapter 5 introduces and evaluates several ways to construct such systems, most notably the "exceptional blocks" in superincreasing knapsacks and the usage of "too small" a modulus in the modular multiplication as a trapdoor technique. The author believes that non injectivity is the most promising direction for development of knapsack cryptosystema. Chapter 6 modifies two well known knapsack schemes, the Merkle Hellman multiplicative trapdoor knapsack and the Graham Shamir knapsack. The main interest is in aspects other than non injectivity, although that is also exploited. In the end of the chapter, constructions proposed by Desmedt et. al. are presented to serve as a comparison for the developments of the subsequent three chapters. Chapter 7 provides a general framework for the iterative construction of injective knapsacks from smaller knapsacks, together with a simple example, the "three elements" system. In Chapters 8 and 9 the general framework is put into practice in two different ways. Modularly injective small knapsacks are used in Chapter 9 to construct a large knapsack, which is called the congruential knapsack. The addends of a subset sum can be found by decrementing the sum iteratively by using each of the small knapsacks and their moduli in turn. The construction is also generalized to the non injective case, which can lead to especially good results in the density, without complicating the deciphering process too much. Chapter 9 presents three related ways to realize the general framework of Chapter 7. The main idea is to join iteratively small knapsacks, each element of which would satisfy the superincreasing condition. As a whole, none of these systems need become superincreasing, though the development of density is not better than that. The new knapsack systems are injective but they can be deciphered with the same searching method as the non injective knapsacks with the "exceptional blocks" in Chapter 5. The final Chapter 10 first reviews the Chor Rivest knapsack system, which has withstood all cryptanalytic attacks. A couple of modifications to the use of this system are presented in order to further increase the security or make the construction easier. The latter goal is attempted by reducing the size of the Chor Rivest knapsack embedded in the modified system. '

Um paradigma da química medicinal: a flexibilidade dos ligantes e receptores

In general, molecular modeling techniques applied in medicinal chemistry have been static and drug based. However the active site geometry and the intrinsic flexibility of both receptor and ligand are fundamental properties for molecular recognition and drug action. As a consequence, the use of dynamic models to describe the ligand-receptor complex is becoming a more common procedure. In this work we discuss the relevance of considering the receptor structure in medicinal chemistry studies as well as the flexibility of the ligand-receptor complex.

Algebraic Geometric Codes and their relation to Cryptography using Elliptic Curves

Communication is the process of transmitting data across channel. Whenever data is transmitted across a channel, errors are likely to occur. Coding theory is a stream of science that deals with finding efficient ways to encode and decode data, so that any likely errors can be detected and corrected. There are many methods to achieve coding and decoding. One among them is Algebraic Geometric Codes that can be constructed from curves. Cryptography is the science ol‘ security of transmitting messages from a sender to a receiver. The objective is to encrypt message in such a way that an eavesdropper would not be able to read it. A eryptosystem is a set of algorithms for encrypting and decrypting for the purpose of the process of encryption and decryption. Public key eryptosystem such as RSA and DSS are traditionally being prel‘en‘ec| for the purpose of secure communication through the channel. llowever Elliptic Curve eryptosystem have become a viable altemative since they provide greater security and also because of their usage of key of smaller length compared to other existing crypto systems. Elliptic curve cryptography is based on group of points on an elliptic curve over a finite field. This thesis deals with Algebraic Geometric codes and their relation to Cryptography using elliptic curves. Here Goppa codes are used and the curves used are elliptic curve over a finite field. We are relating Algebraic Geometric code to Cryptography by developing a cryptographic algorithm, which includes the process of encryption and decryption of messages. We are making use of fundamental properties of Elliptic curve cryptography for generating the algorithm and is used here to relate both.