Tracking Internet users is one of the most controversial and discussed IT topic nowadays. Except of the publicly known tracking by marketing agencies, there even appeared secret methods of surface monitoring of USA population. Because, as shown in this thesis, majority of existing tools for defence against tracking on the Internet are cooperating with trackers, the goal of this thesis is to develop independent defend tool that would block tracking. After mentioning the motivation for tracking and its history there are analysed all known and widespread tracking methods in detail. The two following sections of the thesis are describing the world biggest companies performing the user tracking and their tools and options to defend against each method of tracking by available defensive tools. The practical part of the thesis contains the description, example of usage and manual for developed defensive tool, that protects users on the Internet against the most widespread tracking methods by restricting communication with suspicious 3-rd party servers.

Les réseaux cellulaires ont connu une croissance phénoménale du trafic alimentée par les nouvelles technologies d'accès cellulaire. Cette croissance est en grande partie tirée par l'émergence du trafic HTTP adaptatif streaming (HAS) comme une nouvelle technologie de diffusion des contenus vidéo. Le principe du HAS est de rendre disponible plusieurs qualités de la même vidéo en ligne et que les clients choisissent la meilleure qualité qui correspond à leur bande passante. Chaque niveau d'encodage est segmenté en des chunks, qui dont la durée varie de 2 à 10 secondes. L'émergence du HAS a introduit des nouvelles contraintes sur les systèmes de livraison des contenus vidéo en particulier sur les systèmes de caches. Dans ce contexte, nous menons une analyse détaillée des données du trafic HAS collecté en France et fournie par le plus grand opérateur de téléphonie mobile du pays. Tout d'abord, nous analysons et modélisons le comportement des clients qui demandent des contenus VoD et live. Ces analyses nous ont permis d'identifier les facteurs qui impactent la performance des systèmes de cache et de proposer un nouveau algorithme de remplacement de contenus qu'on appelle WA-LRU. WA-LRU exploite la localité temporelle des chunks dans le contenu et la connaissance de la charge du trafic dans le réseau afin d'améliorer la performance du cache. Ensuite, nous analysons et modélisons la logique d'adaptation entre les qualités vidéo basés sur des observations empiriques. Nous montrons que le changement fréquent entre les encodages réduit considérablement la performance des systèmes de cache. Dans ce contexte, nous présentons CF-DASH une implémentation libre d'un player DASH qui vise à réduire les changements fréquents entre qualités, assure une bonne QoE des clients et améliore la performance des systèmes de caches. La deuxième partie de la thèse est dédié à la conception, simulation et implémentation d'une solution de préchargement des contenus vidéo sur terminaux mobiles. Nous concevons un système que nous appelons «Central Predictor System (CPsys)" qui prédit le comportement des clients mobiles et leurs consommations des vidéos. Nous évaluons CPSys avec des traces de trafic réel. Enfin, nous développons une preuve de concept de notre solution de préchargement. / Recently, cellular networks have witnessed a phenomenal growth of traffic fueled by new high speed broadband cellular access technologies. This growth is in large part driven by the emergence of the HTTP Adaptive Streaming (HAS) as a new video delivery method. In HAS, several qualities of the same videos are made available in the network so that clients can choose the quality that best fits their bandwidth capacity. This strongly impacts the viewing pattern of the clients, their switching behavior between video qualities, and thus beyond on content delivery systems. In this context, we provide an analysis of a real HAS dataset collected in France and provided by the largest French mobile operator. Firstly, we analyze and model the viewing patterns of VoD and live streaming HAS sessions and we propose a new cache replacement strategy, named WA-LRU. WA-LRU leverages the time locality of video segments within the HAS content. We show that WA-LRU improves the performance of the cache. Second, we analyze and model the adaptation logic between the video qualities based on empirical observations. We show that high switching behaviors lead to sub optimal caching performance, since several versions of the same content compete to be cached. In this context we investigate the benefits of a Cache Friendly HAS system (CF-DASH) which aims at improving the caching efficiency in mobile networks and to sustain the quality of experience of mobile clients. Third, we investigate the mobile video prefetching opportunities. We show that CPSys can achieve high performance as regards prediction correctness and network utilization efficiency. We further show that CPSys outperforms other prefetching schemes from the state of the art. At the end, we provide a proof-of-concept implementation of our prefetching system.

This master's thesis analyses and demonstrates selected IPv6 attacks including two Man-in-the-Middle attacks and one Denial of Service attack - Rogue Router Advertisement, Neighbor Cache Poisoning and Duplicate Address Detection DoS, respectively. In the first part the author presents necessary information related to the issue and provides detailed information on how to realize these attacks in practice using publicly available tools. The second part of the thesis presents various ways of mitigating presented attacks, analyses implementations of some of those countermeasures on Cisco and H3C devices and discussess their applicability.

The objective of the thesis is to design and implement in the VHDL language a simple multiprocessor supporting parallel computing. Furthemore, the author has designed and realized universal transparent generic interconnection layer with the objective to connect any given number of processor cores to shared address space using arbitrated bus. Parametrized cache has been allocated to each core in the layer. MSI protocol was used to deal with the issue of memory coherence of the implemented system. Direct and indirect synchornisation support is available to the user. In order to verify the functionality of the system, simple processor core has been designed and implemented, and its copies were connected to the interconnection layer. Various testing programmes have been used to verify the functionality of the system, which also confirmed that the acceleration of computing has been achieved successfully. Virtex6 chip has been used to test the whole system.

Parallel, adaptive Level-of-Detail in VR simulations. Parameters for efficient reuse of already calculated reductions are investigated. Choosen reduction algorithms are evaluated. Parameters for communication within the distributed application are determined. An implementation is introduced. / Paralleles, adaptives Level-of-Detail komplexer Objekten in VR-Simulationen. Die Parameter für eine effiziente Wiederverwendung bereits berechneter Reduktionen werden untersucht. Ausgewählte Reduktionsalgorithmen werden evaluiert. Die Parameter für die Kommunikation in der verteilten Applikation werden ermittelt. Eine Implementation wird vorgestellt.

L'objectif de cette thèse est de fournir des algorithmes d'optimisation pour l'accès aux services vidéo qu’ils soient non-gérés (Internet TV) ou gérés (IPTV). Nous étudions des statistiques récentes concernant les services vidéo non-gérés comme YouTube et nous proposons des techniques d'optimisation appropriées qui pourraient améliorer l'accès aux fichiers vidéos et réduire le coût de cet accès. En outre, l’analyse des coûts joue un rôle important dans les décisions qui concernent la mise en cache des fichiers vidéos et celles liées au choix des périodes temporelles d'hébergement de ces fichiers sur les serveurs. En ce qui concerne les services vidéo gérés appelés IPTV, nous avons mené des expériences sur une architecture ouverte IPTV-collaboration entre différents opérateurs. Ce modèle est analysé selon un critère de coût d’investissement et d'exploitation à l'intérieur de la sphère domestique. En outre, nous avons introduit une solution d’optimisation dynamique de l'arbre « minimum spanning tree » (MST) pour le service IPTV multicast. Lors d’un accès nomade, les arbres statiques pourraient être incapables de fournir le service de manière efficace vu que l'utilisation de la bande passante augmente aux côté des points de streaming (racines de la topologie). Finalement, nous étudions des mesures de sécurité fiables en streaming vidéo basées sur la méthodologie de la chaîne de hachage et nous proposons un nouvel algorithme hybride. Nous effectuons des comparaisons entre les différentes manières utilisées dans la réalisation de la fiabilité des chaînes de hachage basées sur les classifications génériques / The aim of this thesis is to provide optimization algorithms for accessing video services either in unmanaged or managed ways. We study recent statistics about unmanaged video services like YouTube and propose suitable optimization techniques that could enhance files accessing and reduce their access costs. Moreover, this cost analysis plays an important role in decision making about video files caching and hosting periods on the servers. Under managed video services called IPTV, we conducted experiments for an open-IPTV collaborative architecture between different operators. This model is analyzed in terms of CAPEX and OPEX costs inside the domestic sphere. Moreover, we introduced a dynamic way for optimizing the Minimum Spanning Tree (MST) for multicast IPTV service. In nomadic access, the static trees could be unable to provide the service in an efficient manner as the utilization of bandwidth increases towards the streaming points (roots of topologies). Finally, we study reliable security measures in video streaming based on hash chain methodology and propose a new algorithm. Then, we conduct comparisons between different ways used in achieving reliability of hash chains based on generic classifications

Ce travail de thèse s’est tout d’abord attaché à comprendre comment la prise en compte du temps de téléchargement, autrement dit, de la latence, lors de la mise en cache ou de la transmission de données pouvait contribuer aux performances du téléchargement dans les réseaux de caches dont ICN. Nous y introduisons un mécanisme distribué novateur qui décide de l’opportunité de conserver un objet en considérant que plus il a été long à télécharger plus intéressant il semble de le soumettre au cache sous-jacent. Nous montrons que ce nouveau mécanisme surpasse en de nombreux points l’état de l’art, que ce soit du point de vue de la réduction du temps moyen de téléchargement à partir de caches LRU, et de son écart-type (jusqu’à −60% ), que de celui de la vitesse de convergence vers ceux-ci. Dans une seconde phase, nous avons optimisé conjointement les fonctions de mises en cache et de distribution multi-chemin de requêtes de contenus. Troisièmement, nous avons étudié l’équité vis-à-vis des contenus au sein des réseaux de caches et plus particulièrement, d’ICN. Il en ressort que seule suffit une allocation équitable de la bande passante entre les contenus pour que l’équité d’ICN soit complète. Notre dernière contribution vise à aider au passage à l’échelle d’ICN dans contexte où deviennent réalités l’Internet des Objets et son espace de nommage illimité. Nous avons proposé une approche nouvelle au routage dans les réseaux centrés sur l’information, nommée AFFORD, qui combine apprentissage automatique et diffusion aléatoire. / This thesis investigates how making content caching and forwarding latency-aware can improve data delivery performance in Information-Centric Networks (ICN). We introduce a new mechanism that leverages retrieval time observations to decide whether to store an object in a network cache, based on the expected delivery time improvement. We demonstrate that our distributed latency-aware caching mechanism, LAC+, outperforms state of the art proposals and results in a reduction of the content mean delivery time and standard deviation of LRU caches by up to 60%, along with a fast convergence to these figures. In a second phase, we conjointly optimize the caching function and the multipath request forwarding strategies. To this purpose, we introduce the mixed forwarding strategy LB-Perf, directing the most popular content towards the same next hops to foster egress caches convergence, while load-balancing the others. Third, we address ICN fairness to contents. We show that traditional ICN caching, which favors the most popular objects, does not prevent the network from being globally fair, content-wise. The incidence of our findings comforts the ICN community momentum to improve LFU cache management policy and its approximations. We demonstrate that in-network caching leads to content-wise fair network capacity sharing as long as bandwidth sharing is content-wise fair. Finally, we contribute to the research effort aiming to help ICN Forwarding Information Base scale when confronted to the huge IoT era’s namespace.We propose AFFORD, a novel view on routing in named-data networking that combines machine learning and stochastic forwarding.

Cache memories have been usually implemented with Static Random-Access Memory (SRAM) technology since it is the fastest electronic memory technology. However, this technology consumes a high amount of leakage currents, which is a major design concern because leakage energy consumption increases as the transistor size shrinks. Alternative technologies are being considered to reduce this consumption. Among them, embedded Dynamic RAM (eDRAM) technology provides minimal area and leakage by design but reads are destructive and it is not as fast as SRAM. In this thesis, both SRAM and eDRAM technologies are mingled to take the advantatges that each of them o¿ers. First, they are combined at cell level to implement an n-bit macrocell consisting of one SRAM cell and n-1 eDRAM cells. The macrocell is used to build n-way set-associative hybrid ¿rst-level (L1) data caches having one SRAM way and n-1 eDRAM ways. A single SRAM way is enough to achieve good performance given the high data locality of L1 caches. Architectural mechanisms such as way-prediction, swaps, and scrub operations are considered to avoid unnecessary eDRAM reads, to maintain the Most Recently Used (MRU) data in the fast SRAM way, and to completely avoid refresh logic. Experimental results show that, compared to a conventional SRAM cache, leakage and area are largely reduced with a scarce impact on performance. The study of the bene¿ts of hybrid caches has been also carried out in second-level (L2) caches acting as Last-Level Caches (LLCs). In this case, the technologies are combined at bank level and the optimal ratio of SRAM and eDRAM banks that achieves the best trade-o¿ among performance, energy, and area is identi¿ed. Like in L1 caches, the MRU blocks are kept in the SRAM banks and they are accessed ¿rst to avoid unnecessary destructive reads. Nevertheless, refresh logic is not removed since data locality widely di¿ers in this cache level. Experimental results show that a hybrid LLC with an eighth of its banks built with SRAM technology is enough to achieve the best target trade-o¿. This dissertation also deals with performance of replacement policies in heterogeneous LLCs mainly focusing on the energy overhead incurred by refresh operations. In this thesis it is de¿ned a new concept, namely MRU-Tour (MRUT), that helps estimate reuse information of cache blocks. Based on this concept, it is proposed a family of MRUTbased replacement algorithms that randomly select the victim block among those having a single MRUT. These policies are enhanced to leverage recency of information for a few blocks and to adapt to changes in the working set of the benchmarks. Results show that the proposed MRUT policies, with simpler hardware complexity, outperform the Least Recently Used (LRU) policy and a set of the most representative state-of-the-art replacement policies for LLCs. Refresh operations represent an important fraction of the overall dynamic energy consumption of eDRAM LLCs. This fraction increases with the cache capacity, since more blocks have to be refreshed for a given period of time. Prior works have attacked the refresh energy taking into account inter-cell feature variations. Unlike these works, this thesis proposes a selective refresh policy based on the MRUT concept. The devised policy takes into account the number of MRUTs of a block to select whether the block is refreshed. In this way, many refreshes done in a typical distributed refresh policy are skipped (i.e., in those blocks having a single MRUT). This refresh mechanism is applied in the hybrid LLC memory. Results show that refresh energy consumption is largely reduced with respect to a conventional eDRAM cache, while the performance degradation is minimal with respect to a conventional SRAM cache. / Valero Bresó, A. (2013). Hybrid caches: design and data management [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/32663 / TESIS / Premios Extraordinarios de tesis doctorales

This thesis deals with timing analysis of the AES (Advanced Encryption Standard). The design of {\em Rijndael\/}, which is the AES algorithm, is described here. For the side channel attacks is necessary to know the principles of the cache memory in CPU and its architecture. In this thesis are involved major security problems of AES which can be used for successful attacks. Several different implementations of AES are discussed too. Several types of timing attaks are also described. According to the experimentations these attacks should be efficient to the most presently used AES implementations. Finally, the results of this work are described, possible countermeasures against this attack and motions for the next research.

Energy consumption and speed of execution have long been recognized as conflicting requirements for processor design. In this work, we have developed a low-cost dynamic architecture adaptation scheme to save leakage power in caches. This design uses voltage scaling to implement drowsy caches. The importance of a dynamic scheme for managing drowsy caches, arises from the fact that not only does cache behavior change from one application to the next, but also during different phases of execution within the same application. We discuss various implementations of our scheme that provide a tradeoff between granularity of control and design complexity. We investigate a combination of policies where the cache lines can be turned off completely if they are not accessed, when in the drowsy mode. We also develop a simple dynamic cache-way shutdown mechanism, and propose a combination of our dynamic scheme for drowsy lines, with the cache-way shutdown scheme. Switching off cache ways has the potential of greater energy benefits but provides a very coarse grained control. Combining this with the fine grained scheme of drowsy cache lines allows us to exploit more possibilities for energy benefits without incurring a significant degradation in performance. Keywords: Drowsy Cache, Architecture Adaptation, Low Power, Leakage Reduction, Dynamic Scheme