Due to their massive user base and request load, large-scale Internet applications have mainly focused on goals such as performance and scalability. As a result, many of these applications rely on weaker but more efficient and simpler authentication mechanisms. However, as recent incidents have demonstrated, powerful adversaries are exploiting the weaknesses in such mechanisms. While more robust authentication mechanisms exist, most of them fail to address the scale and security needs of these large-scale systems. In this dissertation we demonstrate that by taking into account the specific requirements and threat model of large-scale Internet applications, we can design authentication protocols for such applications that are not only more robust but also have low impact on performance, scalability and existing infrastructure. In particular, we show that there is no inherent conflict between stronger authentication and other system goals. For this purpose, we have designed, implemented and experimentally evaluated three robust authentication protocols: Proxychain, for SIP-based VoIP authentication; One-Time Cookies (OTC), for Web session authentication; and Direct Validation of SSL/TLS Certificates (DVCert), for server-side SSL/TLS authentication. These protocols not only offer better security guarantees, but they also have low performance overheads and do not require additional infrastructure. In so doing, we provide robust and practical authentication mechanisms that can improve the overall security of large-scale VoIP and Web applications.

E-crimes continue to generate grave challenges to the ICT regulatory agenda. Because e-crimes involve a wrongful appropriation of information online, it is enquired whether information is property which is capable of being stolen. This then requires an investigation to be made of the law of property. The basis for this scrutiny is to establish if information is property for purposes of the law. Following a study of the Roman-Dutch law approach to property, it is argued that the emergence of an information society makes real rights in information possible. This is the position because information is one of the indispensable assets of an information society. Given the fact that information can be the object of property, its position in the law of theft is investigated. This study is followed by an examination of the conventional risks that ICTs generate. For example, a risk exists that ICTs may be used as the object of e-crimes. Furthermore, there is a risk that ICTs may become a tool in order to appropriate information unlawfully. Accordingly, the scale and impact of e-crimes is more than those of the offline crimes, for example theft or fraud. The severe challenges that ICTs pose to an information society are likely to continue if clarity is not sought regarding: whether ICTs can be regulated or not, if ICTs can be regulated, how should an ICT regulatory framework be structured? A study of the law and regulation for regulatory purposes reveals that ICTs are spheres where regulations apply or should apply. However, better regulations are appropriate in dealing with the dynamics of these technologies. Smart-regulations, meta-regulations or reflexive regulations, self-regulations and co-regulations are concepts that support better regulations. Better regulations enjoin the regulatory industries, for example the state, businesses and computer users to be involved in establishing ICT regulations. These ICT regulations should specifically be in keeping with the existing e-authentication measures. Furthermore, the codes-based theory, the Danger or Artificial Immune Systems (the AIS) theory, the Systems theory and the Good Regulator Theorem ought to inform ICT regulations. The basis for all this should be to establish a holistic approach to e-authentication. This approach must conform to the Precautionary Approach to E-Authentication or PAEA. PAEA accepts the importance of legal rules in the ICT regulatory agenda. However, it argues that flexible regulations could provide a suitable framework within which ICTs and the ICT risks are controlled. In addition, PAEA submit that a state should not be the single role-player in ICT regulations. Social norms, the market and nature or architecture of the technology to be regulated are also fundamental to the ICT regulatory agenda. / Jurisprudence / LL. D.

Avec l’arrivée des dernières générations de téléphones chiffrés (BlackBerry PGP, iPhone), l’extraction des données par les experts est une tâche de plus en plus complexe et devient un véritable défi notamment après une catastrophe aérienne ou une attaque terroriste. Dans cette thèse, nous avons développé des attaques physiques sur systèmes cryptographiques à des fins d’expertises judiciaires. Une nouvelle technique de re-brasage à basse température des composants électroniques endommagés, utilisant un mélange eutectique 42Sn/58Bi, a été développée. Nous avons exploité les propriétés physico-chimiques de colles polymères et les avons utilisées dans l’extraction de données chiffrées. Une nouvelle technique a été développée pour faciliter l’injection et la modification à haute-fréquence des données. Le prototype permet des analyses en temps réel des échanges processeur-mémoire en attaque par le milieu. Ces deux techniques sont maintenant utilisées dans des dispositifs d’attaques plus complexes de systèmes cryptographiques. Nos travaux nous ont mené à sensibiliser les colles polymères aux attaques laser par pigmentation. Ce processus permet des réparations complexes avec une précision laser de l’ordre de 15 micromètres. Cette technique est utilisable en réparations judiciaires avancées des crypto-processeurs et des mémoires. Ainsi, les techniques développées, mises bout à bout et couplées avec des dispositifs physiques (tomographie 3D aux rayons X, MEB, laser, acide fumant) ont permis de réussir des transplantations judiciaires de systèmes chiffrés en conditions dégradées et appliquées pour la première fois avec succès sur les téléphones BlackBerry chiffrés à l’aide de PGP. / When considering the latest generation of encrypted mobile devices (BlackBerry’s PGP, Apple’s iPhone), data extraction by experts is an increasingly complex task. Forensic analyses even become a real challenge following an air crash or a terrorist attack. In this thesis, we have developed physical attacks on encrypted systems for the purpose of forensic analysis. A new low-temperature re-soldering technique of damaged electronic components, using a 42Sn/58Bi eutectic mixture, has been developed. Then we have exploited the physico-chemical properties of polymer adhesives and have used them for the extraction of encrypted data. A new technique has been developed to facilitate injection and high-frequency data modification. By a man-in-the-middle attack, the prototype allows analysing, in real-time, the data exchanges between the processor and the memory. Both techniques are now used in more complex attacks of cryptographic systems. Our research has led us to successfully sensitise polymer adhesives to laser attacks by pigmentation. This process allowed complex repairs with a laser with 15 micrometres precision and has been used in advanced forensic repair of crypto-processors and memory chips. Finally, the techniques developed in this thesis, put end-to-end and coupled with physical devices (X-ray 3D tomography, laser, SEM, fuming acids), have made it possible to have successful forensic transplants of encrypted systems in degraded conditions. We have successfully applied them, for the first time, on PGP-encrypted BlackBerry mobile phone.