This thesis investigates the modelling of fade countermeasures (FCMs) for the design of geostationary Ka band digital satellite communication systems. The analysis focuses on a typical low-power low-rate very small aperture terminal application using adaptive forward error correction as a way of counteracting the high level of detected dynamic atmospheric fading. The management and performance of such systems is conditioned greatly by the ability of practical controllers at detecting the actual level of total signal attenuation. At 20 or 30 GHz, rain attenuation and tropospheric scintillation are the two major propagation effects of interest. Part of the solution relies on the consideration and integration of their random and dynamic nature in the design process. The finite response time of practical countermeasure systems is a source of performance degradation which can be minimised by the implementation of predictive control strategies. This is the focal point of this thesis. A novel on-line short-term predictor matched to the Ka band fading process is proposed. While the rain attenuation component is efficiently predicted, tropospheric scintillation is the source of the estimation error. To take this into account, a statistical model, based on an extension of the global fading model for rain and scintillation, is then developed so that long term performance of predictive countermeasures can be drawn. Two possible ways to compensate for scintillation-induced prediction errors, namely the fixed and variable detection margin approaches, are proposed, analysed and then compared. This is achieved by calculating the FCM utilisation factor, as well as the throughput and bit error rate performance of a typical Ka band system in the presence of dynamic fading within the context of predictive fade countermeasure control operations. In the last part of this thesis, the inclusion of instantaneous frequency scaling in the design of efficient FCM control schemes is investigated. This is applicable to systems using fade detection at a base frequency. In particular, a new statistical model, accounting for the impact of the stochastic temporal variations of rain drop size distribution on rain attenuation, is presented. This thesis further confirms that countermeasure systems are technologically viable. The consideration of more specific design problems does not change the overall validity of this statement. In this thesis, it is shown that a predictive FCM technique, based on readily available punctured convolutional codes, with their relatively modest coding gain, is sufficient to provide high link availability and user data throughput on a low-power low-rate in-bound VSAT link.

Supercavitating torpedoes pose new threats to submarines, surface ships, and shore targets whose current countermeasures are inadequate against this technology. These torpedoes have the advantage over their predecessors and companion weapons of dramatically increased speed, which reduces the reaction time available for deploying a countermeasure heightening the threat to their intended target. Proliferation of supercavitating torpedoes has motivated research on countermeasures against them as well as on the fluid phenomenon which makes them possible. The goal of this research was to investigate an envisaged countermeasure; an acoustic field capable of slowing or diverting the weapon by disrupting the cavitation envelope. The research focused on the interactions between high-level sound signals and a supercavity produced by a small free-flying projectile. In order to conduct this study it was necessary to achieve three preliminary accomplishments involving the design of: 1) experimental apparatus that allowed for the study of a small-scale supercavitating projectile in the laboratory environment; 2) apparatus and software for measuring and recording information about projectile dynamics and supercavity geometry; and 3) an acoustic array and power source capable of focusing the desired sound signal in the path of the supercavitating object. Positive results have been found which show that the accuracy of a supercavitating projectile can indeed be adversely affected by the sound signal. This research concludes with results that indicate that it is acoustic cavitation in the medium surrounding the supercavity that is responsible for the reduced accuracy. A hypothesis has been presented addressing the means by which the acoustic cavitation could cause this effect. Additionally, corrugations on the cavity/water interface imposed by the pressure signal have been observed and characterized.

La sécurité de l'information repose étroitement sur les circuits intégrés (CI). Malheureusement, les CIs sont soumis à de nombreuses menaces telles que les attaques par canaux auxiliaires ou par injection de fautes. Ce travail se concentre sur les petites vulnérabilités et les contremesures liées à l’algorithme ECDSA. La motivation est qu’une source de vulnérabilité peut être utilisée dans différent scénario d’attaque. En corrigeant la vulnérabilité, les attaques existantes sont évitées mais également les attaques non découvertes ou non publiées utilisant la vulnérabilité en question. De plus, bien que le scalaire sur courbe elliptique soit au cœur de la sécurité de tous les schémas cryptographiques à base de courbe elliptique, l’ensemble du système a besoin d’être sécurisé. Une vulnérabilité concernant simplement quelques bits de secret peut suffire à récupérer la clef privée et donc doit être évité.L’ECDSA peut être implémenté de différentes façons, en logiciel ou via du matériel dédié ou un mix des deux. De nombreuses architectures différentes sont donc possibles pour implémenter un système à base d’ECDSA. Pour cette raison, ces travaux se concentrent principalement sur les contremesures algorithmiques. / Information security heavily relies on integrated circuits (ICs). Unfortunately, ICs face a lot of threats such as side channel or fault attacks. This work focuses on small vulnerabilities and countermeasures for the Elliptic Curve Digital Signature Algorithm (ECDSA). The motivation is that leakage sources may be used in different attack scenarios. By fixing the leakage, existing attacks are prevented but also undiscovered or non-disclosed attacks based on the leakage. Moreover, while the elliptic curve scalar algorithm is at the heart of the security of all elliptic curve related cryptographic schemes, all the ECDSA system needs security. A small leakage of few secret bits may conduct to fully disclose the private key and thus should be avoided.The ECDSA can be implemented in different flavors such as in a software that runs on a microcontroller or as a hardware self-contained block or also as a mix between software and hardware accelerator. Thus, a wide range of architectures is possible to implement an ECDSA system. For this reason, this work mainly focuses on algorithmic countermeasures as they allow being compliant with different kinds of implementations.

In future human spaceflight missions, with prolonged exposure to microgravity, resistive and aerobic exercises will be countermeasures for bone loss, muscle loss, and decreased aerobic capacity. Two of the exercises of interest are squats and rowing. The cyclic forces produced during these exercises are at relatively low frequencies which are likely to excite structural resonances of space vehicles. Vibration Isolation Systems (VIS) are being designed to be paired with future exploration exercise devices in order to prevent these cyclic exercise forces from impacting the space vehicle. The VIS may be configured such that a platform supports the human and exercise device. There is limited knowledge about the interaction between a human exercising and a dynamic platform. This research sought to fill part of the knowledge gap and study how the force inputs to the platform change as well as how exercise form was affected. For this research, a system which can produce dynamic responses similar to those of a prospective VIS platform was used. This system is the Computer Assisted Rehabilitation Environment (CAREN) (Motekforce Link, Amsterdam, Netherlands). Simplified sinusoidal responses were implemented in a single degree of freedom, vertical (heave) motion, and also in multi-degree of freedom, heave and pitch motion. Human subject testing was conducted using four subjects with exercise experience. The subjects completed squats and rows, while standing, in both static (platform not moving) and dynamic (with platform moving) conditions. Subjects aimed to synchronize with platform motion, at the appropriate phase. Kinetic and kinematic data were collected via force plate measurements and motion capture, respectively. Testing was completed with several predetermined frequencies for platform motion, but also at each subject’s baseline frequency, which was the measured, comfortable exercise rate for the subject. Data were processed and arranged in a presentable format. Results showed attenuation of the vertical component of forces between the comparable frequency static and dynamic platform conditions, as expected, for most subjects in the squat exercise. This was seen only in the heave with pitch condition during rows for most subjects. Results also showed increasing amplitude of forces as frequency increased, which was also expected. Knee angle range of motion was well maintained between static and dynamic conditions. These results suggest that conditions desirable for both VIS and exercise are possible. Further testing and extended analysis at additional amplitudes, frequencies, and degrees of freedom are of interest and warrant further study. This work contributed knowledge and data regarding the forces involved and human kinematics produced while exercising with platform motion. These data can further be used as inputs and requirements for VIS design work, VIS and human biomechanical modeling, and exercise countermeasure development. This work achieved the objectives of establishing an appropriate test environment and developing platform dynamics in which human-VIS interaction could be studied. It also acted as a proof-of-concept for future testing which can be conducted to answer new questions relating to dynamic platform motion effects on human activity.

Trata-se de tese de doutorado que analisa a possibilidade da adoção de contramedidas por Estados não diretamente lesados por um ato ilícito internacional diante da violação de uma norma protetora de direitos humanos. Partindo do estudo sobre a responsabilidade internacional dos Estados, analisam-se as consequências jurídicas advindas desta responsabilidade, dentre elas, o direito de outros Estados de adotarem contramedidas contra o Estado violador do Direito Internacional. Com base em pesquisa documental, jurisprudencial e bibliográfica, averigua-se a legalidade da adoção de contramedidas por Estados não diretamente lesados, levando-se em conta o trabalho da Comissão de Direito Internacional da ONU, a jurisprudência, a doutrina e a prática dos Estados nesta matéria. Argumenta-se que a existência de uma norma consuetudinária garante o direito dos Estados recorrerem a contramedidas mesmo quando estes não tenham sido diretamente lesados pelo ato internacionalmente ilícito, nos casos em que a obrigação violada é devida à comunidade internacional como um todo. Estuda-se também a necessidade da adoção das contramedidas em resposta a violações graves a normas de proteção de direitos humanos fundamentais, tendo em vista o sistema global de proteção destes direitos. Conclui-se que, diante da eficácia limitada dos mecanismos de proteção global dos direitos humanos do Direito Internacional atual, as contramedidas adotadas por Estados não diretamente lesados são não somente legais, mas necessárias à garantia da mais ampla proteção aos direitos humanos fundamentais. / This work is a doctoral thesis that analyzes the possibility of the resort to countermeasures by non directly injured States in light of the violation of a norm protecting human rights. Starting from a study of the international responsibility, the legal consequences of this responsibility are analyzed, among them, the right of other States to adopt countermeasures against the State violating the International Law. Based on a documental, jurisprudential and bibliographic research, the legality of the adoption of countermeasures by non directly injured States is verified taking in account the work of the International Law Commission of the UN, the jurisprudence, and the State practice in the subject. It is argued that the existence of a customary norm guarantees the right of States to resort to countermeasures even when they are not directly injured by the internationally unlawful act, in the cases where the violated obligation is due to the international community as a whole. The necessity of the resort to countermeasures in light of serious violations of norms protecting fundamental human rights in view of the global system for protection of these rights. It is concluded that in view of the limited efficacy of the global mechanisms for the protection of human rights in the current International Law, the countermeasures adopted by non directly injured States are not only legal, but also necessary to the guarantee of the broadest protection of fundamental human rights.

Les altérations du cycle veille/sommeil sont fréquentes dans le milieu militaire. Elles induisent une dégradation des performances, et peuvent potentiellement causer des conséquences sur l’état de santé à long terme des personnels. Ce travail de thèse a pour objectif d’évaluer deux contre-mesures, l’effet de 6 nuits d’extension de sommeil d’une part et les effets de 8 semaines d’entrainement physique d’autre part sur la performance cognitive (attention soutenue, inhibition, mémoire de travail), la pression de sommeil, les réponses endocriniennes et inflammatoires, et la fonction neuromusculaire au cours d’une privation totale de sommeil et de la récupération subséquente. Les résultats principaux mettent en évidence que six nuits d’extension de sommeil ont pour effet de limiter (i) la dégradation de la performance cognitive (attention soutenue et mémoire de travail) et physique, (ii) l’apparition de micro-sommeils observées au cours d’une période de privation totale de sommeil. L’extension de sommeil a également induit une diminution des concentrations circulantes de prolactine et une augmentation des concentrations circulantes d’IGF-1. Les résultats ont également montré que 8 semaines d’entrainement physique permettent de limiter la dégradation de la performance psychomotrice (i.e. conduite simulée) induite par la privation totale de sommeil sans modifications significatives des réponses endocriniennes. Ainsi, ces types de stratégies préventives permettraient de limiter les dégradations de la performance et pourraient être combinées à des contre-mesures nutritionnelles et/ou pharmacologiques / The alterations of sleep/wake cycle are frequent in military area. They induce performance degradation and can potentially induced some consequences on health status in the long-term among military personnel. The aim of this thesis work is to assess two countermeasures, the effects of six nights of sleep extension and the effects of 8 weeks of physical training on cognitive performance (sustained attention, inhibition, working memory), sleep pressure, hormonal and inflammatory responses and neuromuscular function during total sleep deprivation and the subsequent period. The main results are that 6 nights of sleep extension limit (i) degradation of cognitive performance (sustained attention and working memory) and physical performance, (ii) involuntary micro-sleeps during total sleep deprivation period. Likewise, the sleep extension induces a decrease of circulating prolactin concentration and an increase of circulating IGF-1 concentration. Results have shown that 8 weeks of physical training limit the degradation of psychomotor performance (i.e. simulated driving) induced by total sleep deprivation without changes in hormonal responses. Thus these kinds of preventives strategies would limit the performance degradation and could be combined with nutritional and/or pharmacological countermeasures

With ZigBee being the world’s leading IoT protocol, users are vulnerable to attacks on the wireless communication between ZigBee devices and the information that can be gained from them. For users to protect themselves from potential attacks they need to be aware of what information can be extracted and how it can be countered. Through an eavesdropping experiment, done using three individual sensors from different vendors, various packets with potential for misuse have been identified within the area of building security. With the potential areas of misuse identified, there is also a need for countermeasures against these threats. Countermeasures were identified through a collection of literature that was summarized in order to provide a wide range of alternatives, suitable to different scenarios. The experiment was limited to the functions of the sensors used, as well as traffic using the ZigBee protocol. This study pinpoints a potential for misuse of the ZigBee traffic sent between devices and shows that the ZigBee protocol is fundamentally flawed from a security aspect. Whilst countermeasures exist, they are not applicable to every situation which is why the ZigBee protocol itself needs further development to be considered secure.

Lawful interception and the way it is performed have played a significant role in the effectiveness of this type of communication monitoring. Although the secrecy of interception and the related equipment are supposed to provide correct information to a law enforcement agency, there are some countermeasures that can be taken by the subject that can seriously undermine the collection of correct and accurate data. This thesis project attempts to identify the problems that exist for interception of telephony (be it fixed, mobile, or via the Internet). Moreover, there are some suggestions for improvements how lawful interception should be performed in order to avoid possible attacks that could decrease the credibility of the intercepted data. Numerous publications (in print or distributed on the Internet) have described weaknesses in the current state of the art lawful interception when using equipment that can be purchased in the market. This thesis presents improvements in how LI can be conducted in order to avoid these vulnerabilities. Additionally, there is a description of the key escrow systems and the possibility of avoiding one of their most significant vulnerabilities. The main problem of the lawful interception is the rapid changes in telecommunications and the complicated architecture of the telecommunication networks, as both make monitoring vulnerable to specific countermeasures. An analysis of how lawful interception can take place and current countermeasures for lawful interception of Internet telephony are vital in order to identify the problems in carrying out such intercepts today and to make suggestions for improvements. This topic is especially relevant given the current Swedish “FRA lagen” regarding interception of electronic communication going into, out of, and through Sweden. Not only is it important to understand how lawful interception can be performed or prevented, but it is also important to understand how information obtained from lawful interception could be purposely misleading or falsified.

Micro-architectural analysis (MA) is a fast evolving area of side-channel cryptanalysis. This new area focuses on the effects of common processor components and their functionalities on the security of software cryptosystems. The main characteristic of micro-architectural attacks, which sets them aside from classical side-channel attacks, is the simple fact that they exploit the micro-architectural behavior of modern computer systems. Attackers could get running information through malicious software, then get some sensitive information through off-line analysis. This kind of attack has the following features: 1.) side channel information are acquired through software measurement on target machine with no need to use sophisticated devices. 2.) non-privilege process could get the running information of the privilege process. 3.) people can mount both a remote attack and local attack. This thesis mainly focuses one kinds of these attacks, data cache based timing attacks(CBTA). First, the main principle of CBTA is introduced, and several kinds of CBTA technique are discussed. Moreover, theoretical model is given under some attacks. Second, various countermeasures are described and their advantages and disadvantages are pointed out. Based on these discussions, the author proposes two anti-attack measures using hardware modification. Aiming at access-driven attacks, a XOR address remapping technique is proposed, which could obfuscate the mapping relationship between cache line and memory block. Aiming at timing-driven attacks, the IPMG mechanism is proposed innovatively. This mechanism could generate cache miss dynamically through observing the historic miss rate. These two mechanisms are realized on the MIPS processor and their effectiveness is verified on the FPGA board. At last, performance penalty and hardware cost are evaluated. The result shows that the proposed solution is effective with very low performance penalty and area cost

Cryptocurrencies are gaining prominence among individuals and companies alike, resulting in the growing adoption of so-called cryptocurrency wallet applications, as these simplify carrying out transactions. These wallets are available in a myriad of different forms and specifications. For example, there are hardware and software wallets. The latter can be divided into mobile, web, and desktop wallets. All of them offer attackers various ways to exploit vulnerabilities and steal money from victims. It is hard to keep track of this multitude of options and thus choose the right cryptocurrency wallet. For this reason, in this thesis, we collect the findings from previous literature to provide an overview of the various attack surfaces, possible countermeasures, and further research. Our systematic study has shown that there is still a considerable variety of attack vectors, which we have divided into six subcategories, (i) Memory and Storage, (ii) Operating Systems, (iii) Software Layer, (iv) Network Layer, (v) Blockchain Protocol, and (vi) Others. Some of the identified vulnerabilities have currently no solutions at all or hardly applicable countermeasures. However, some are easy to fix and simple to implement. One of the essential measures is to raise awareness of the identified weaknesses and the associated mitigations, if any, among the involved stakeholders, including users, developers, and exchanges.