Traditional solutions to information security in communication systems act in the application layer and are oblivious to the effects in the physical layer. Physical-layer security methods, of which information-theoretic security is a special case, try to extract security from the random effects in the physical layer. In information-theoretic security, there are two asymptotic notions of secrecy---weak and strong secrecy This dissertation investigates the problem of information-theoretic strong secrecy on the binary erasure wiretap channel (BEWC) with a specific focus on designing practical codes. The codes designed in this work are based on analysis and techniques from error-correcting codes. In particular, the dual codes of certain low-density parity-check (LDPC) codes are shown to achieve strong secrecy in a coset coding scheme. First, we analyze the asymptotic block-error rate of short-cycle-free LDPC codes when they are transmitted over a binary erasure channel (BEC) and decoded using the belief propagation (BP) decoder. Under certain conditions, we show that the asymptotic block-error rate falls according to an inverse square law in block length, which is shown to be a sufficient condition for the dual codes to achieve strong secrecy. Next, we construct large-girth LDPC codes using algorithms from graph theory and show that the asymptotic bit-error rate of these codes follow a sub-exponential decay as the block length increases, which is a sufficient condition for strong secrecy. The secrecy rates achieved by the duals of large-girth LDPC codes are shown to be an improvement over that of the duals of short-cycle-free LDPC codes.

No description available.

This thesis presents a computationally efficient cryptosystem based on chaotic continuous-interval cellular automata (CCA). This cryptosystem increases data protection as demonstrated by its flexibility to encrypt/decrypt information from distinct sources (e.g., text, sound, and images). This cryptosystem has the following enhancements over the previous chaos-based cryptosystems: (i) a mathematical model based on a new chaotic CCA strange attractor, (ii) integration of modules containing dynamical systems to generate complex sequences, (iii) generation of an unlimited number of keys due to the features of chaotic phenomena obtained through CCA, which is an improvement over previous symmetric cryptosystems, and (iv) a high-quality concealment of the cryptosystem strange attractor. Instead of using differential equations, a process of mixing chaotic sequences obtained from CCA is also introduced. As compared to other recent approaches, this mixing process provides a basis to achieve higher security by using a higher degree of complexity for the encryption/decryption processes. This cryptosystem is tested through the following three methods: (i) a stationarity test based on the invariance of the first ten statistical moments, (ii) a polyscale test based on the variance fractal dimension trajectory (VFDT) and the spectral fractal dimension (SFD), and (iii) a surrogate data test. This cryptosystem secures data from distinct sources, while leaving no patterns in the ciphertexts. This cryptosystem is robust in terms of resisting attacks that: (i) identify a chaotic system in the time domain, (ii) reconstruct the chaotic attractor by monitoring the system state variables, (iii) search the system synchronization parameters, (iv) statistical cryptanalysis, and (v) polyscale cryptanalysis.

This thesis presents a computationally efficient cryptosystem based on chaotic continuous-interval cellular automata (CCA). This cryptosystem increases data protection as demonstrated by its flexibility to encrypt/decrypt information from distinct sources (e.g., text, sound, and images). This cryptosystem has the following enhancements over the previous chaos-based cryptosystems: (i) a mathematical model based on a new chaotic CCA strange attractor, (ii) integration of modules containing dynamical systems to generate complex sequences, (iii) generation of an unlimited number of keys due to the features of chaotic phenomena obtained through CCA, which is an improvement over previous symmetric cryptosystems, and (iv) a high-quality concealment of the cryptosystem strange attractor. Instead of using differential equations, a process of mixing chaotic sequences obtained from CCA is also introduced. As compared to other recent approaches, this mixing process provides a basis to achieve higher security by using a higher degree of complexity for the encryption/decryption processes. This cryptosystem is tested through the following three methods: (i) a stationarity test based on the invariance of the first ten statistical moments, (ii) a polyscale test based on the variance fractal dimension trajectory (VFDT) and the spectral fractal dimension (SFD), and (iii) a surrogate data test. This cryptosystem secures data from distinct sources, while leaving no patterns in the ciphertexts. This cryptosystem is robust in terms of resisting attacks that: (i) identify a chaotic system in the time domain, (ii) reconstruct the chaotic attractor by monitoring the system state variables, (iii) search the system synchronization parameters, (iv) statistical cryptanalysis, and (v) polyscale cryptanalysis.

隨著全球電子商務的蓬勃發展，為在資訊流通與資料保護之間取得平衡，跨境資訊流動議題在國際經貿整合中往往也成為各國談判的焦點之一。其中，TPP中各國更進一步地處理「當地設立伺服器」議題，並提案將以「必要性測試」作為各國施行該措施之前提，本文遂就該測試在相關措施下之運作進行探討，並針對我國未來制度上與國際接軌之方向提出建議。 本文透過文獻分析法，歸納出必要性測試的評估過程中有「替代性措施對政策目標之貢獻程度」、「政策目標或價值之重要性」、「對國際貿易之限制性」幾個重要因素，另外在針對澳洲措施的分析中，有司法管轄權、技術、國際間合作狀況與行政成本，需納入考量之因素。然而，我國法制中尚未有更具體的管制措施，而經貿協議中僅止於承認彼此之資訊流通管制規範。未來或可參考澳洲之做法，同時由前歸納之因素評估該作法之必要性。 / The issue of trans-border data flow has been treated as one of those significant trade liberalization topics while global electronic commerce continues to surge and countries are striving to build common ground on the balance between data flow as well as data protection. Among these efforts of trade integration, “necessity test” was proposed when the members within TPP go further to negotiate whether the regulation of “localization data center” should be banned or not. In this article, we will conduct analysis toward how will the test work with potentially disputing measures and provide suggestions for Taiwan’s legislation to be geared to international treaties and standards. Through documentary analysis, factors evaluated against possible alternative measures when exercising necessity tests are summed up as contribution made by the compliance measure to the enforcement of the law or regulation at issue, the importance of the common interests or values protected by that law or regulation, and the accompanying impact of the law or regulation on imports or exports. Furthermore, as what has been shown by analyzing the Australian measure, we concluded that jurisdiction, techniques, international cooperation and administrative costs should also be taken into account. However, due to the lack of more practical measures and the topic in Taiwan’s concluded trade agreements is still in its infancy, I suggested that related authority can take the Australia’s measure as an example on basis of the above-mentioned factors.

The means of personal data protection in courts, legal acts, regulating that, are analyzed in the final work ,,Legal aspects of personal data protection in the judicial system“. The implementation of information technologies in the work of courts has fasten the judge of cases, though when the automate administration of personal data started, the danger personal data to be detected has increased, breaking the persons` right to privacy. The author also analyses the purpose of a courts` information system LITEKO and the data, which is administrated with this program. It is aiming to find out the measures, which can be used to strengthen the protection of personal data. The author while analyzing the practical situation of personal data protection in courts, gives recommendations, how occurring problems could be solved. The work brings us to the main conclusion, that personal data protection and the right to the privacy should not be made absolute. The ways how to protect personal data and the right to privacy in court processes, to guarantee the quality of court process and the reliability in courts should be found.

Die zunehmende Verfügbarkeit adressbezogener Daten im Zusammenhang mit der Nutzung geometrischer Raster zur Raumuntergliederung haben die Voraussetzungen für kleinräumige Analysen deutlich verbessert. Bei der Verwendung personenbezogener Daten müssen datenschutzrechtliche Vorgaben eingehalten werden, falls die Rasterzellen zu wenig Fallzahlen enthalten. Vielfach werden diese Rasterzellen ausgeblendet, wodurch Informationen in der Karte verloren gehen. Eine datenschutzkonforme Alternative stellt die Aggregation von Rasterzellen dar, bis die Fallzahlen einen vorgegebenen Grenzwert überschreiten. In diesem Beitrag werden Möglichkeiten vorgestellt und bewertet, nach denen sich datenschutzkonforme Mischrasterkarten erzeugen lassen. Besonderes Augenmerk wird auf die Auflösungsverluste der erzeugten Mischrasterkarten gelegt, um geeignete Datengrundlagen für kleinräumige Analysen zu schaffen.

As Information Security (IS) standards do not always effectively cater for Social Engineering (SE) attacks, the expected results of an Information Security Management System (ISMS), based on such standards, can be seriously undermined by uncontrolled SE vulnerabilities. ISO/IEC 17799:2005 is the subject of the current analysis as it is the type of standard not restricted to technical controls, while encompassing proposals from other standards and generally-accepted sets of recommendations in the field. Following an analysis of key characteristics of SE and based on the study of Psychological and Social aspects of SE and IS, a detailed examination of ISO/IEC 17799:2005 is presented and an assessment of the efficiency of its controls with respect to SE is provided. Furthermore, enhancements to existing controls and inclusion of new controls aimed at strengthening the defense against Social Engineering are suggested. Measurement and quantification issues of IS with respect to SE are also dealt with. A novel way of assessing the level of Information Assurance in a system is proposed and sets the basis for future work on this subject. / Information Systems / M. Sc. (Information Systems)

La révolution numérique est ambivalente. Si elle constitue un moyen de renforcer la capacité de l'Etat à réaliser ses missions et celle des individus à exercer certains de leurs droits, elle permet simultanément l'enregistrement et la conservation d'une part croissante de l'existence individuelle quotidienne. Face au renforcement des possibilités de contrôle de l'individu, il est régulièrement proposé d'inscrire, dans les textes situés au sommet d, la hiérarchie des normes, un droit fondamental à la protection des données personnelles car l'existence d'un tel droit améliorerait la protection offerte à l'individu. La thèse procède à une analyse descriptive, explicative et évaluative du droit fondamental à la protection des données personnelles. Afin de démontrer la construction d'un tel droit par la jurisprudence constitutionnelle française et les jurisprudences européennes, l'étude s'est d'abord attaché à découvrir les soubassements de celui-ci. Ce droit a ensuite pu être précisé et distingué des autres droits fondamentaux tels que le droit au respect de la vie privée. Afin de mesurer la portée de ce droit, l'étude s'est ensuite attachée à analyser les restrictions dont il peut faire l'objet lorsqu'il entre en conflit avec d'autres intérêts individuels également protégés ou avec des contraintes collectives relevant de l'intérêt général. L'amélioration de la protection offerte à l'individu n'est donc pas aussi évidente qu'il pourrait paraitre. Elle pourrait cependant résulter de la restructuration du processus normatif que ce droit fondamental à la protection des données personnelles implique. / The digital revolution is ambivalent. On the one hand, it empowers the State to strengthen its ability to fulfil its responsibilities and the individuals to exercise some of their rights, yet on the other hand, it enables the capturing and storing of an increasing part of day to day personal life. In order to address the increased surveillance of individuals, proposals are regularly put forward to incorporate, at the very highest judicial level, a human right to personal data protection, as the existence of such a right would improve the protection afforded to individuals. This thesis undertakes a descriptive, explanatory and evaluative analysis of the human right to personal data protection. In order to examine the making of such a right by the French constitutional court, the European Court of Human Rights and the Court of Justice of the European Union, this study sets out first to reveal its foundations. The right to data protection is then clearly identified and distinguished from other human rights such as the right to privacy. In order to measure the extent of such a right, the study then focusses on analysing the restrictions to which it may be subject when in conflict with other equally protected individual rights or with collective constraints of general interest. The enhancement of the protection afforded to the individual is therefore not as straightforward as it may initially seem. Such enhancement could however arise from the restructuring of the normative process which this human right to data protection implies.

No description available.