Le 10ème problème de Hilbert, consistant à trouver les solutions entières d'équations polynomiales est un problème crucial en cryptanalyse. Si ce dernier a été prouvé indécidable, Coppersmith publia en 1996 une méthode basée sur la réduction de réseaux permettant de trouver efficacement l'ensemble des petites solutions de certaines équations polynomiales. De nombreuses applications de cette méthode ont vu le jour dans le domaine de la cryptanalyse à clé publique, notamment lorsque le cryptosystème est exécuté sur un système embarqué et qu'une partie de la clé secrète est dévoilée par la réalisation d'attaques physiques sur le dispositif. Dans ce contexte, nous proposons une attaque physique sur le schéma de signature RSA en mode CRT où une application de la méthode de Coppersmith permet de compléter l'information obtenue par l'attaque physique. Nous proposons également un nouvel algorithme déterministe basé sur la méthode de Coppersmith pour factoriser les entiers de la forme $N=p^rq^s$ en temps polynomial lorsque $r$ ou $s$ sont suffisamment grands. Enfin, si les applications de la méthode de Coppersmith sont nombreuses, en pratique, du fait que les réseaux à réduire soient gigantesques, les petites solutions ne peuvent être retrouvées que jusqu'à une borne qui est plus petite que la borne théorique annoncée. Aussi, une autre contribution de cette thèse consiste en la proposition de deux méthodes permettant une accélération du temps d'exécution de l'algorithme de Coppersmith. Lorsque les deux méthodes sont combinées, le nouvel algorithme s'effectue des centaines de fois plus rapidement pour des paramètres typiques, permettant ainsi dans de nombreux cas d'atteindre la borne théorique. / The 10th Hilbert problem, which consists in finding integer solutions to polynomial equations is a crucial problem in cryptanalysis, which has been proven to be undecidable. However, Coppersmith published in 1996 a method based on lattice reduction, which allows to efficiently find all small solutions to some polynomial equations. Many applications of this method have risen in public key cryptanalysis, especially when the cryptosystem is executed on embedded systems and part of the secret key is revealed through physical attacks performed on the device. In this context, we propose in this thesis a physical attack on the RSA signature scheme when the CRT mode is used, where an application of Coppersmith's method allows to complete the information previously obtained by the physical attack. We also propose a new deterministic algorithm based on Coppersmith's method for factoring integers of the form $N=p^rq^s$ in polynomial time, under the condition that $r$ and/or $s$ are sufficiently large.Finally, if the applications of Coppersmith's method are numerous, in practice, since the lattices to be reduced are huge, the small solutions can only be recovered until a bound which is smaller than the enounced theoretical bound. Thus, another contribution of this thesis lies in the proposition of two methods which allow to speed up the execution time of Coppersmith's algorithm. When both speedups are combined, the new algorithm performs hundreds of times faster for typical parameters, which allows to reach the theoretical bound in many cases.

No description available.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This paper will investigate the areas which must be addressed to implement a truly integrated Range instrumentation system on a GPS-based Range, using a patented L-Band commanding scheme. Hardware issues will be highlighted as well the issues to be addressed in changing from an audio tone-frequency modulated command system to a digital system incorporating encryption and spread spectrum. Some thoughts addressing costs and schedule to incorporate this approach into the architecture of the U. S. Air Force Range Standardization and Automation (RSA) architecture, as a candidate GPS-based Range are also presented, as well as a discussion of the benefits to be accrued over the existing system, if this approach were adopted.

L’obiettivo generale del progetto di ricerca è valutare la percezione della qualità dei servizi offerti in due RSA del Nord Italia e proporre interventi di miglioramento. Nel primo capitolo della tesi sono stati descritti i principali modelli teorici della qualità dei servizi. La letteratura riconosce la mancanza di scale validate che esplorano la percezione della qualità dei servizi nelle RSA Italiane. Per questo motivo, è stato realizzato uno studio di validazione e adattamento della versione italiana della scala SERVQUAL. Nel secondo capitolo della tesi è stato presentato uno studio qualitativo retrospettivo. Partendo dagli eventi critici che si sono verificati nella RSA, sono stati analizzati i principali episodi positivi e negativi ricordati dai famigliari degli anziani. I risultati sono stati utilizzati per ipotizzare nuovi percorsi di intervento e per fornire strategie organizzative per migliorare la gestione degli eventi problematici. La letteratura riconosce l’importanza del coinvolgimento dei famigliari per il benessere degli anziani. Per questo motivo, in questo progetto di ricerca sono state delineate le basi concettuali per l’applicazione di un modello collaborativo di assessment all’interno delle RSA. Nello specifico, il terzo capitolo della tesi ha esplorato l'efficacia dell’Assessment Terapeutico attraverso una meta-analisi multilivello e nell'ultimo capitolo della tesi è stata applicata una componente del modello di Assessment Collaborativo e Terapeutico nelle RSA. / The general aim of the present research project was to broaden the knowledge and understanding of the ways in which elderly’s family members perceive the quality of service and propose interventions to improve services. To lay the ground for discussion about the quality of services offered by nursing homes, Chapter 1 provides a historical overview of the models of the quality of services. Given the lack of validated measures of the quality of services in Italian nursing homes, I presented data regarding the validation and adaptation of the Italian version of the SERVQUAL Scale. Chapter 2 introduced a retrospective qualitative study. Starting from critical events that occurred in nursing homes, I analyzed family members’ observations of the incidents. The results were used to generate new paths for interventions to improve the family members’ evaluation of services and to provide organizational strategies to improve the management of problematic events. Given the effect of family involvement on elder people’s well-being, I presented the conceptual underpinnings and the applicability of a collaborative model of assessment in nursing homes. Chapter 3 explored the effectiveness of the Therapeutic Assessment model through a multilevel meta-analytic study. From these results, a component of the Collaborative and Therapeutic Assessment model was applied in nursing homes, as described in the last chapter.

Made available in DSpace on 2016-08-19T18:16:00Z (GMT). No. of bitstreams: 1 FABIO FRANCA SILVA.pdf: 387985 bytes, checksum: b614ae131f06a658fbdac4196b4d623c (MD5) Previous issue date: 2009-04-06 / FUNDAÇÃO DE AMPARO À PESQUISA E AO DESENVOLVIMENTO CIENTIFICO E TECNOLÓGICO DO MARANHÃO / Recurrent spontaneous abortion (RSA) is defined as two or more consecutive spontaneous pregnancy losses before the 20th week of gestation, a situation that occurs in 1 to 2% of women in reproductive age. Genetic, anatomical, endocrine, infectious and immunologic factors through mechanisms that relate to the Major Histocompatibility Complex (MHC) and the presence of certain HLA (Human Leukocyte Antigens) are associated to RSA. HLA gene is located on the short arm of chromosome 6 between the 6p21.31 and 6p21.33 regions. This gene is inherited in haplotypes and expressed in codominance, having influence on modulation and induction of mother tolerance during the pregnancy. The aim of this study was to compare the allelic frequencies of HLA-A*, HLA-B* and HLA-DRB1* loci in women with and without RSA. It was a case-control study in 200 women (100 for each group) between 18 and 35 years of age. All samples were typified by the PCR-SSOP method (Polymerase Chain Reaction-Sequence Specific Oligonucleotide Probes). The most frequent alleles observed in the group of women with and without RSA were: HLAA* 02 (56%) and (49%), HLA-DRB1*13 (31%) and (39%) respectively - there was no statistical significative difference when compared among the groups for this alleles; HLA-A*24 (12%) e (25%), (OR: 0.41; 95% CI: 0.18-0.92; p=0.028); HLA-A*34 (8%) e (1%), (OR: 8.61; 95% CI: 1.06-187.04; p=0.034); HLA-B*35 (16%) e (41%) (OR: 0.27; 95% CI: 0.13 0.56; p=0.0002). The most frequent haplotypes observed in the group of women with and without RSA were: A*02DRB1*16 (12%) e (2%) (OR: 6.68; 95% CI: 1.36 44.52; p=0.012) respectively. In this research, DRB1* locus in women with RSA was in linkage disequilibrium (p=0.01.). The high frequency of HLA-A*02 and HLA-DRB1*13 alleles in this study was due to the wide distribution of this allele in the population of Maranhão. HLA-A*24 e HLA-B*35 alleles were considered as a protection factor and HLA-A*34 allele was considered as a risk factor to RSA. The A*02DRB1*16 haplotype was the most frequent and considered as a risk factor to RSA. In order to confirm the observed results in this research, a study involving a higher sample size is necessary as well as genetic epidemiology researches to shed light on the role of HLA antigens and/or its connection to other genes as a risk factor. / Abortamento Espontâneo Recorrente (AER) caracteriza-se por duas ou mais perdas conceptuais espontâneas e consecutivas antes da 20ª semana de gestação, acometendo entre 1% e 2% das mulheres em idade reprodutiva. Fatores genéticos, anatômicos, endócrinos, infecciosos e imunológicos, por meio de mecanismos que relacionam o Complexo Principal de Histocompatibilidade (CPH) e a frequência de determinados antígenos HLA (Antígeno Leucocitário Humano), estão associados ao AER. O gene HLA localiza-se no braço curto do cromossomo 6 entre as regiões 6p21.31 e 6p21.33, é herdado em bloco e expresso em co-dominância. O mesmo exerce uma grande influência na modulação e indução da tolerância materna durante a gestação. Esta pesquisa teve como objetivo verificar as frequências alélicas dos loci HLA-A*, -B* e - DRB1* em mulheres com e sem AER. Realizou-se um estudo caso-controle em 200 mulheres (100 para cada grupo), entre 18 e 35 anos de idade. Todas as amostras foram tipificadas pelo método PCR-SSOP (Reação em cadeia da Polimerase Sondas de Oligonucleotídios de Sequências Especificas). Os alelos mais frequentes tanto em mulheres com e sem AER foram, respectivamente: HLA-A*02 (56%) e (49%), HLADRB1* 13 (31%) e (39%)-embora sem resultado estatisticamente significante; HLAA* 24 (12%) e (25%), (OR: 0,41; 95% IC: 0,18-0,92; p=0,028); HLA-A*34 (8%) e (1%), (OR: 8,61; 95% IC: 1,06-187,04; p=0,034); HLA-B*35 (16%) e (41%) (OR: 0,27; 95% IC: 0,13 0,56; p=0,0002). Os haplótipos mais frequentes em mulheres com e sem AER foram, respectivamente: A*02DRB1*16 (12%) e (2%) (OR 6,68; 95% IC: 1,36 44,52; p=0,012). No presente estudo, apenas o locus DRB1* apresentou desequilíbrio de ligação significante (p=0,01) em mulheres com AER. A elevada frequência dos alelos HLA-A*02 e HLA-DRB1*13 é justificada pela ampla distribuição desses alelos na população maranhense. Os alelos HLA-A*24 e HLA-B*35 apresentaram-se como um fator de proteção e o alelo HLA-A*34 um fator de risco para AER. Para as associações haplotípicas, o haplótipo A*02DRB1*16 foi mais frequente em mulheres com AER, sendo um fator de risco para este grupo. Para a ratificação dos resultados deste trabalho, faz-se necessário aumentar o número amostral, bem como estudos de epidemiologia genética para o melhor entendimento do papel dos antígenos HLA e/ou sua ligação a outros genes como fator de risco para o AER.

In this work, we investigate the general structure and the concepts behind the contemporary electronic voting schemes, with special emphasis on voter verifiable preferential voting, homomorphic tallying and voter privacy. We firstly propose a modification in the Single Transferable Voting (STV) method to be applied to large scale elections with electoral barriers. Our proposal prevents the loss of votes and distributes them securely to the second or higher choices of their voters. This method is most suitably used in e-voting with the voter verifiable &ldquo / Pr&ecirc / t &agrave / Voter: All-In-One&rdquo / scheme that utilizes mix-networks for anonymity. We present a case study considering 2007 Turkish Parliamentary Elections to demonstrate the effect of preferential voting on the election systems that have electoral barriers. After the mathematical formulation of the election procedure, we calculate the wasted votes in 2007 elections and present simulation results for 69 election regions (that have no independent parliament members) by using a combination of &ldquo / modified STV and d&rsquo / Hondt&rdquo / methods, according to four different, politically unbiased scenarios on the distribution of secondary vote choices. Additionally, we modify the &ldquo / Pr&ecirc / t &agrave / Voter: All-In-One&rdquo / scheme by proposing three security enhancing modifications in its ballot construction phase: 1) ballot serial number, 2) digital signature of the first clerk in the mix-net, 3) different random numbers for each row of the ballot. Finally, we demonstrate the potential of multiplicative homomorphic algorithms like RSA for homomorphic tallying. The idea is based on the association of each candidate on the electronic ballot with a prime number, and unique prime factorization of the general vote product. We propose novel randomization methods for homomorphic RSA tallying, and discuss the performance and complexity of the scheme with such randomizations. Our suggestion for an auditable and verifiable e-voting scheme that employs homomorphic RSA tallying with proper randomization has advantages over El Gamal and Paillier tallying, such as having the least encryption complexity and strong anonymity resistant to unlimited computational power.

Η Ορθογώνια Πολυπλεξία Διαίρεσης Συχνότητας (OFDM) έχει προταθεί ως τεχνική διαμόρφωσης σε οπτικά δίκτυα, λόγω της καλής φασματικής απόδοσής της, της ευελιξίας και της ανοχής της σε βλάβες. Η διαμόρφωση OFDM επιτρέπει την ελαστική ανάθεση φάσματος, χρησιμοποιώντας μεταβλητό πλήθος υποφερουσών, καθώς και την επιλογή του κατάλληλου επιπέδου διαμόρφωσης με βάση την απόσταση της μετάδοσης. Το «Πρόβλημα Δρομολόγης και Ανάθεσης Φάσματος» (RSA) έχει αποδειχθεί ότι είναι ένα NP-πλήρες πρόβλημα, γεγονός που υποδηλώνει τη χρήση γραμμικού προγραμματισμού για τη λύση του. Στόχος της διπλωματικής εργασίας είναι η βελτίωση της απόδοσης του υπάρχοντος αλγορίθμου ακέραιου γραμμικού προγραμματισμού, με χρήση μεταευριστικών, έτσι ώστε στο ίδιο χρονικό διάστημα να υπολογίζεται αποδοτικότερη χρησιμοποίηση του συνολικού απαιτούμενου φάσματος, για το σύνολο των μεταδόσεων στο δίκτυο. / Orthogonal Frequency Division Multiplexing (OFDM) has been proposed as a modulation technique for optical networks, because of its good spectral efficiency, flexibility, and tolerance to impairments. OFDM modulation allows elastic spectrum allocation, using a variable number of subcarriers and choosing an appropriate modulation level, taking into account the transmission distance. The “Routing and Spectrum Allocation” (RSA) problem has been proved to be a NP-complete problem, which suggests the usage of linear programming in order to be solved. This diploma thesis aims to improve the efficiency of the existing integer linear programming algorithm, by using metaheuristics, so that at the same time period a more efficient utilization of the required spectrum is computed, for all network transmissions.

Cryptography plays a crucial role in today’s society. Given the influence, cryptographic algorithms need to be trustworthy. Cryptographic algorithms such as RSA relies on the problem of prime number factorization to provide its confidentiality. Hence finding a way to make it computationally feasible to find the prime factors of any integer would break RSA’s confidentiality. The approach presented in this thesis explores the possibility of trying to construct φ(n) from n. This enables factorization of n into its two prime numbers p and q through the method presented in the original RSA paper. The construction of φ(n) from n is achieved by analyzing bitwise relations between the two. While there are some limitations on p and q this thesis can in favorable circumstances construct about half of the bits in φ(n) from n. Moreover, based on the research a conjecture has been proposed which outlines further characteristics between n and φ(n).

Ce manuscrit est consacré à l'amélioration des deux méthodes numériques : MMDF et Méthode des Moments avec la technique de la RSA. Dans un premier temps, on présente les outils théoriques sur l'étude du problème de la diffraction par des réseaux lamellaires, éclairée sous incidence classique et les outils de simulation pour résoudre les équations de Maxwell. On choisit comme fonctions de base et de test, les fonctions triangles. On introduit par la suite, la technique de la RSA afin d'améliorer la vitesse de convergence de calcul. Les résultats obtenus sont comparés à ceux de la méthode MMFE et la méthode MMDF de "Lalanne et al". Une étude numérique de la stabilité et de la convergence de la méthode est effectuée. Enfin, on présente une extension de la Méthode des Moments basée sur l'hypothèse de Galerkin au cas de l'incidence conique. Le détail de la résolution des équations Maxwell est décrit. L'application numérique est traitée dans le cas du réseau diélectrique pour mettre au point les influences de l'état de la polarisation et les paramètres physiques. / This manuscript is devoted to improvement of the two numerical methods : MMDF and Method of the Moments with the technique of the RSA. In the first part, we present the theoretical tools on study of the problem of diffraction by binary grating,illuminated of classical incidence and the tools for simulation to solve the Maxwell's equations. We choose like basic functions and test, the functions triangles. In the second part, we introduce the technique of the RSA so to improve the speed of convergence of calculation. The results obtained are compared with those of method MMFE and method MMDF of"Lalanne and al". A numerical study of the stability and convergence of the method are carried. The last part, we present the Method of the Moments with triangle functions as expansion and triangle as test functions to the case of conical incidence. We describe the detail of the resolution of the Maxwell equations. Numerical application is treated in the case of the dielectric grating to develop the influences of state of polarization and the physical parameters.

High data rates and interoperability of vender devices have made WiMAX a prime desire for use worldwide. WiMAX is based on the IEEE 802.16 standard. IEEE 802.16a, b, c & d versions were updated within three years of the first launch of WiMAX. However, during those early years reports were published that highlighted the security weaknesses of the standard. These weaknesses prompted the IEEE to issue a new version, 802.16e to tackle the security issues. Despite this security enhancement, WiMAX remains vulnerable. This research project looks at the vulnerability of WiMAX 802.16e Subscriber Station/Mobile Station authentication at the initial entry and proposes approaches to the prevention of Denial of Service (DoS) attacks at this point in order to secure the Media Access Control (MAC) layer from such threats. A new protocol has been designed and developed to provide confidentiality, authentication and integrity to WiMAX users. This new protocol is integrated with Z algorithm (an algorithm described later in this paper) to provide: • Confidentiality of management messages • Message Authentication code • ID to provide for message integrity and user authentication. A simulation package was also required, to prove that a linear load of DoS attack would disable or exhaust the capacity of the base station of a WiMAX network, as well as providing other simulation functions. The freely available simulation tool NIST (NIST IPSec (Internet Protocol Security) and IKE (Internet Key Exchange) Simulation) is oriented towards fixed network communications (NIIST, 2003). There are no other relevant simulation tools; hence the purpose of this research project is to develop a new tool to simulate WiMAX security vulnerabilities and test the new protocol.