Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-10-01T16:46:31Z No. of bitstreams: 1 ELLOÁ BARRETO GUEDES DA COSTA - DISSERTAÇÃO PPGCC 2011..pdf: 1433883 bytes, checksum: fb9fa0561b94ab2b495915f5f377c364 (MD5) / Made available in DSpace on 2018-10-01T16:46:31Z (GMT). No. of bitstreams: 1 ELLOÁ BARRETO GUEDES DA COSTA - DISSERTAÇÃO PPGCC 2011..pdf: 1433883 bytes, checksum: fb9fa0561b94ab2b495915f5f377c364 (MD5) Previous issue date: 2011-03-25 / Este trabalho apresenta um ataque quântico de comprometimento permanente ao gerador pseudo-aleatório de Blum-Micali. A segurança deste gerador, classificado como criptograficamente seguro, baseia-se na hipótese de intratabilidade do problema do logaritmo discreto perante a Computação Clássica. O ataque proposto faz uso do algoritmo quântico de busca em conjunto com o algoritmo quântico para o logaritmo discreto para comprometer a imprevisibilidade do gerador, recuperando todas as saídas passadas e futuras do mesmo. O presente trabalho também descreve generalizações deste ataque que o adequam a uma gama mais vasta de geradores, incluindo geradores da Construção de Blum-Micali e geradores com múltiplos predicados difíceis. Tais generalizações também abrangem a realização de ataques em situações adversas, por exemplo, quando o adversário captura bits não consecutivos ou quando há menos bits que o requerido. Comparado à sua contrapartida clássica, o algoritmo quântico proposto nesse trabalho possui um ganho quadrático em relação à recuperação do representante do estado interno do gerador, seguido de um ganho superpolinomial na obtenção dos demais elementos do estado interno. Estes resultados caracterizam ameaças,elaboradas com Computação Quântica, contra a segurança de geradores utilizados em diversas aplicações criptográficas. / This dissertation presents a quantum permanent compromise attack to the Blum-Micali pseudorandom generator. The security of this generator, classified as cryptographically secure, is based on the hypothesis of intractability of the discrete logarithm problem in Classical Computing. The proposed attack is based on the quantum search algorithm jointly with the quantum discrete logarithm procedure and aims to compromise the unpredictability of the referred generator, recovering all of its past and future outputs. This work also describes generalizations that enables attacks to generators from the Blum-Micali construction and also to generators with multiple hard-core predicates. Such generalizations also allow attacks when the adversary intercepts non-consecutive bits or when there are less bits than required. Compared to its classical counterpart, the proposed algorithm has a quadractic speedup regarding the retrieval of the representant of the generator’s internal state followed by a super polynomial speedup regarding the obtention of the entire generator’sinternalstate. These results represent menaces of the Quantum Computing paradigm against the security of pseudorandom generators adopted in many real-world cryptosystems.

The subject of this work deals with the problem of channel estimation for CDMA systems. This method of multiple access when individual users share the same full bandwidth simultaneously and are differentiated with any of pseudorandom sequences, is now the most perspective method. That is proved by its wide implementation in mobile networks of the third generation and higher systems. This work describes basic theory principles of spread spectrum, above all DS-CDMA (Direct Sequence-CDMA) and furthermore some phenomena of radio wireless channel that affect changes in transmitted signal in its way from transmitter to receiver. Terms of fading, multipath propagation, loss, refraction, scattering of the wave and Rice and Rayleigh probability density functions are mentioned. The third chapter deals with yet known and used capabilities of channel estimation. Differences, advantages and disadvantages of so-called blind estimation or training-based estimation are discussed. Two algorithms: LS method and sliding correlator are analyzed in more detail. There is also description of their simulations in Matlab and some results of these simulations are discussed. The last chapter deals with comparison of main characteristics and achievable accuracy of wireless channel impulse response estimation by both methods, and their possible utilization in real live.

This work deals with scheduling problem in particular plastic production service. The solution is based on heuristic algorithms, programming languages C + +, C # and is built on the .NET framework and LINQ to XML. It provides the users with comparisons of the heuristic approach with genetic algorithms applied to production problem. All methods results are compared in relation to hand-arranged plans.

Η παρούσα διπλωματική εργασία έγινε στα πλαίσια του Προγράμματος Μεταπτυχιακών Σπουδών Ηλεκτρονικής και Υπολογιστών, στο Τμήμα Φυσικής του Πανεπιστημίου Πατρών. Αντικείμενό της αποτελεί η μελέτη του φυσικού επιπέδου συστημάτων κινητής τηλεφωνίας τρίτης γενιάς και η εξομοίωση χαρακτηριστικού καναλιού του φυσικού επιπέδου σύμφωνα με την παγκόσμια προτυποποίηση 3GPP. Στο πρώτο κεφάλαιο γίνεται ιστορική ανασκόπηση των συστημάτων προηγούμενων γενεών. Αναφέρονται βασικά προβλήματα που πρέπει να αντιμετωπίσει ένα τηλεπικοινωνιακό σύστημα καθώς και η βασική δομή των κυψελοειδών συστημάτων. Γίνεται εισαγωγή στα συστήματα τρίτης γενιάς ως προς τις απαιτήσεις, τις υπηρεσίες που προσφέρουν, την προτυποποίηση και την αρχιτεκτονική τους. Στο δεύτερο κεφάλαιο μελετώνται οι τρόποι πολλαπλής πρόσβασης με ιδιαίτερη έμφαση στην προσπέλαση με διαίρεση κωδικών. Αναλύονται τα συστήματα διάχυσης φάσματος. Γίνεται εκτενής αναφορά και υλοποίηση προγραμμάτων για τις ψευδοτυχαίες ακολουθίες και τις ακολουθίες Gold. Στο τρίτο κεφάλαιο μελετάται η δομή δικτύων επικοινωνίας κατά το μοντέλο OSI. Αναφέρονται τα επίπεδα των τηλεπικοινωνιακών συστημάτων με διεξοδική μελέτη του φυσικού επιπέδου και στις διεπαφές που χρησιμοποιεί για επικοινωνία καθώς και στις υπηρεσίες που προσφέρει. Αναλύεται η δομή όλων των φυσικών καναλιών και εξομοιώνεται η διαδικασία ενθυλάκωσης του καναλιού PRACH. Στο τέταρτο κεφάλαιο αναλύονται οι κώδικες διάχυσης των φυσικών καναλιών ανερχόμενης ζεύξης καθώς και η διαδικασία διάχυσης τους. Δημιουργούνται προγράμματα που παράγουν αυτούς τους κώδικες και γίνεται εξομοίωση της διάχυσης και της αποδιάχυσης του PRACH καναλιού. Στο πέμπτο κεφάλαιο αναφέρεται η διαδικασία κωδικοποίησης πηγής και μελετάται η PSK διαμόρφωση και αποδιαμόρφωση που χρησιμοποιούν τα συστήματα τρίτης γενιάς. Υλοποιούνται προγράμματα που εξομοιώνουν τη συνολική διαδικασία σε ενθόρυβο κανάλι AWGN μελετώντας την επίδραση του θορύβου σε μεταδιδόμενο σήμα. Όλες οι εξομοιώσεις υλοποιήθηκαν με το πρόγραμμα Matlab 7.1. / This master thesis is a part of the post-graduate course of the Physics department of the University of Patras, on Electronics and Computers. Its main objective is the study of the physical layer of 3rd generation telecommunication systems and the simulation of a particular channel, in accordance to 3GPP specifications. In the first chapter we review telecommunication systems of previous generations. We also refer to major problems that need to be dealt with and also the basic structure of cellular networks. 3rd generation telecommunication systems, their requirements, offered services, standardisation and architecture are all introduced. In the second chapter we study multiple access methods, emphasising CDMA methods. Moreover, spread spectrum systems are analysed. Finally we refer to pseudorandom and Gold sequences. Programs are created which generate these sequences. In the third chapter we look into the structure of communication networks according to the OSI model. The layers of telecommunication systems are mentioned, laying emphasis on the physical layer, the interfaces used for communication as well as the offered services. We report all physical channels and we simulate the encapsulation of the PRACH channel. In the fourth chapter we analyse the spreading and scrambling codes referring to the uplink channels. Next we point out the code allocation process. Programs are created which generate these spreading and scrambling codes and we finally simulate the spreading and de-spreading process of the PRACH channel. In the fifth chapter we outline the source coding process using PCM, and we study PSK modulation and demodulation which are used by 3rd generation telecommunication systems. We create programs that simulate the whole procedure in a noisy channel, and we study the effect of AWGN. The programs were created and the simulations were run using Matlab version 7.1.

The race to computing power increases every day in the simulation community. A few years ago, scientists have started to harness the computing power of Graphics Processing Units (GPUs) to parallelize their simulations. As with any parallel architecture, not only the simulation model implementation has to be ported to the new parallel platform, but all the tools must be reimplemented as well. In the particular case of stochastic simulations, one of the major element of the implementation is the pseudorandom numbers source. Employing pseudorandom numbers in parallel applications is not a straightforward task, and it has to be done with caution in order not to introduce biases in the results of the simulation. This problematic has been studied since parallel architectures are available and is called pseudorandom stream distribution. While the literature is full of solutions to handle pseudorandom stream distribution on CPU-based parallel platforms, the young GPU programming community cannot display the same experience yet. In this thesis, we study how to correctly distribute pseudorandom streams on GPU. From the existing solutions, we identified a need for good software engineering solutions, coupled to sound theoretical choices in the implementation. We propose a set of guidelines to follow when a PRNG has to be ported to GPU, and put these advice into practice in a software library called ShoveRand. This library is used in a stochastic Polymer Folding model that we have implemented in C++/CUDA. Pseudorandom streams distribution on manycore architectures is also one of our concerns. It resulted in a contribution named TaskLocalRandom, which targets parallel Java applications using pseudorandom numbers and task frameworks. Eventually, we share a reflection on the methods to choose the right parallel platform for a given application. In this way, we propose to automatically build prototypes of the parallel application running on a wide set of architectures. This approach relies on existing software engineering tools from the Java and Scala community, most of them generating OpenCL source code from a high-level abstraction layer.

<p>Дисертација истражује утицај примене дитерског сигнала (дискретног аналогног униформног шума) генерисаног новом методом на повећање ефективне резолуције мерних инструмената базираних на стохастичкој дигиталној мерној методи. У дисертацији је дат преглед досадашњих решења базираних на стохастичкој дигиталној мерној методи у циљу сагледавања потребе и оправданости истраживања. Предложено решење представља комбинацију псеудослучајног и истински случајног генератора и као такво задржава најбоље особине из обе области. Дaт je прeдлoг нoве методе гeнeрисaњa шумa унифoрмнe рaспoдeлe aмплитудa. Умeстo уoбичajeнoг нaчинa гeнeрисaњa кoришћeњeм гeнeрaтoрa псeудoслучajних брojeвa и Д/А кoнвeртoрa, oвдe сe прeдлaжe гeнeрисaњe зaснoвaнo нa нeунифoрмнoм одабирању тeстeрaстoг или троугаоног нaпoнa. Oсим уштeдe збoг нeкoришћeњa Д/А кoнвeртoрa, дoбит je и мoгућнoст гeнeрисaњa нaпoнa из кoнтинуалнoг, умeстo дискрeтнoг скупa aмплитудa. Вeћинa дaнaшњих хaрдвeрских гeнeрaтoрa псeудoслучajнoг нaпoнa, сe бaзирa нa употреби микрoкoнтрoлeра и Д/A кoнвeртoра, пa je нa тaj нaчин рeзoлуциja гeнeрисaњa псeудoслучajнoг нaпoнa oгрaничeнa резолуцијом Д/A кoнвeрторa. Одабирањем тестерастог или троугаоног напона предложеном методом се остварује готово неограничена резолуција. Употреба овако генерисаног дитерског сигнала доводи до повећања ефективне резолуције код стохастичких мерних инстурмената. Симулацијом је одређена оптимална структура генератора на основу предложене методе. Експериментална мерења су изведена помоћу развијеног прототипа хардверског генератора.</p> / <p>Disertacija istražuje uticaj primene diterskog signala (diskretnog analognog uniformnog šuma) generisanog novom metodom na povećanje efektivne rezolucije mernih instrumenata baziranih na stohastičkoj digitalnoj mernoj metodi. U disertaciji je dat pregled dosadašnjih rešenja baziranih na stohastičkoj digitalnoj mernoj metodi u cilju sagledavanja potrebe i opravdanosti istraživanja. Predloženo rešenje predstavlja kombinaciju pseudoslučajnog i istinski slučajnog generatora i kao takvo zadržava najbolje osobine iz obe oblasti. Dat je predlog nove metode generisanja šuma uniformne raspodele amplituda. Umesto uobičajenog načina generisanja korišćenjem generatora pseudoslučajnih brojeva i D/A konvertora, ovde se predlaže generisanje zasnovano na neuniformnom odabiranju testerastog ili trougaonog napona. Osim uštede zbog nekorišćenja D/A konvertora, dobit je i mogućnost generisanja napona iz kontinualnog, umesto diskretnog skupa amplituda. Većina današnjih hardverskih generatora pseudoslučajnog napona, se bazira na upotrebi mikrokontrolera i D/A konvertora, pa je na taj način rezolucija generisanja pseudoslučajnog napona ograničena rezolucijom D/A konvertora. Odabiranjem testerastog ili trougaonog napona predloženom metodom se ostvaruje gotovo neograničena rezolucija. Upotreba ovako generisanog diterskog signala dovodi do povećanja efektivne rezolucije kod stohastičkih mernih insturmenata. Simulacijom je određena optimalna struktura generatora na osnovu predložene metode. Eksperimentalna merenja su izvedena pomoću razvijenog prototipa hardverskog generatora.</p> / <p>The dissertation investigates the impact of the application of the dithering signal (discrete analogue uniform noise) generated by the new method for increasing the effective resolution of measurement instruments based on the stochastic digital measurement method. The dissertation provides an overview of the existing solutions based on the stochastic digital measurement method in order to understand the need and justification of the research. The proposed solution represents a combination of a pseudorandom and truly random generator and as such holds the best features in both areas. А suggestion of a new way of generating the noise of the uniform distribution of amplitudes is presented. Instead of the usual way of generating using a pseudorandom number generator and a D/A converter, the generation based on the nonuniform sampling of sawtooth or triangle voltage is proposed. In addition to the savings due to the non-use of a D/A converter, the possibility of generating voltages from a continual instead of a discrete amplitude set is also obtained. Most of today&#39;s hardware pseudorandom voltage generators are based on the use of a microcontroller and D/A converter, so in this way the resolution of the pseudorandom voltage generation is limited by the resolution of the D/A converter. By sampling the sawtooth or triangle voltage using the proposed method, almost unlimited resolution is achieved. The use of this generated dither signal leads to an increase in effective resolution in stochastic measuring instruments. The simulation determined the optimal structure of the generator based on the proposed method. Experimental measurements were made using developed hardware.</p>