<p>Authenticated Group Key Agreement Protocols are protocols allowing a group of principals to contributively generate a key by the exchange of messages on a network possibly controlled by an attacker. Furthermore, their execution also guarantees all group members that the key they obtained can only be known by the other intended protocol participants. These protocols can be exploited in many applications such as audio or videoconferencing, replicated servers (such as database, web, time servers), chat or network games for instance.</p> <p>AGKAP's present several particularities that make them interesting case studies for research in the theory of security. At first, the consideration of the number of protocol participants as a parameter raises several complexity problems that are not present in the classical two or three-party frameworks. Furthermore, up to now, the security properties of group protocols have roughly been considered as direct extensions of two-party properties, what does not capture several plausible attack scenarios. A second interesting aspect of the analysis of AGKAP's is the consideration of Diffie-Hellman-type primitives, that present properties out of the scope of most classical models.</p> <p>We started our study with the construction of a simple model for the analysis of a classical family of protocols: the Cliques AGKAP's. This allowed us to discover several attacks and define different flavors of group security properties. We then tried to fix these protocols, what led us to extend our model in order to prove that it is in fact impossible to build a secure AGKAP based on the same design assumptions as the Cliques protocols. Finally, we designed a new AGKAP based on different cryptographic primitives (signature and hash functions) for which we proved authentication, freshness and secrecy properties. A comparison with a similar AGKAP developed in parallel to ours is also proposed.</p>

Thesis (M.S.)--Rochester Institute of Technology, 2009. / Typescript. Includes bibliographical references (leaves 62-65).

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 117-122). Also available in electronic version.

The question regarding what makes child trafficking persistent in conflict and post-war settings has been subject to intense debate. The human trafficking literature makes general conclusions that trafficking is a by-product of civil wars, and in the process child traffickers exploit the breakdown of the rule of law. As such it is perceived that the governance of the problem of child trafficking can be effective whenever peace and stability is realised and when legal frameworks for protecting children are in place. Prompted by these assertions, I conducted a field study in South Sudan, a country emerging from one of Africa’s longest running and most brutal civil wars fought between the government in Khartoum and Sudanese Peoples Liberation Movement/Army (SPLM/A). The Sudan’s civil wars ended after the signing of the Comprehensive Peace Agreement in 2005. Whilst the termination of the war raised expectations that the international anti-trafficking conventions, treaties and customary laws protecting children would have enforcement powers and would guarantee the rights and safety of the child, the peace failed to deliver on these expectations. Based on empirical data obtained through an intensive micro-level qualitative research conducted in South Sudan over three months, the research findings reveal that a number of challenges pose serious difficulties in enforcing international counter-trafficking legislations and child protection instruments. These challenges are compounded by the interplay of the emerging socio-economic and political development in the post-independent South Sudan.

The growth and prevalence of the private military industry has led many to conclude that the state has outsourced one of its core functions: public security. As a global non-state actor, PMSCs pose a risk to state sovereignty by undermining the democratic legitimacy of armed forces and challenging the states international monopoly over force. This study, using the tripartite model in English school theory, refutes this commonly held belief by examining the regulatory methods that have brought PMSCs squarely under state control. This study organizes regulatory efforts in a three level concept of national, international and self-regulatory methods, and based on the increased national regulatory methods, mixed with international norms and weak self-regulation, concludes that states maintain their primacy over violence in world politics.

Nowadays, with the rapid expansion of increasing utilization of renewable energy sources, power grid is evolving into a much complex man-made system in the technological age. Under the new circumstances, traditional methodologies for power system security analysis are facing a serious challenge. For the past decade, many countries have experienced large blackouts, which expose potential problems of current models and methodologies in power industry. On the other hand, since the 9.11 event and frequent suicide bombing attacks in some countries, terrorism has become a major threat for national security. With the extensive growth of terrorism activities, power system, the significant critical infrastructure, probably becomes the target of terrorists. If this happens, the impact is dramatically severe and may yield more frequent blackouts. This Ph.D. thesis aims at developing some advanced models and methodologies for exploring the vulnerability of power system and protecting it against potential terrorism threat. The dissertation mainly consists of the following four parts. (1)Complex network theory based power system security and vulnerability analysis methodologies are introduced. Mathematically, an interconnected complex power grid can be described as a complex network of nodes connected by edges. Generally speaking, topology parameters of network structure include important information of the structure. That is to say, some critical nodes and lines can have significant impact on large-scale blackouts. The thesis will present a new methodology to recognize those critical nodes and lines in power grids. (2)Complex system theory based power grid security and vulnerability analysis methodologies are presented. Power grid is a complex dynamic evolutionary system over years with continuous expansion so as to underpin the ongoing increase of power demand. Some properties of complex systems may have important relationship with large-scale blackouts. In other words, there may be some stages of evolutionary power systems that would be more likely to cause large blackouts. The thesis will investigate the relationship to identify those critical stages of power grids. (3)Game theory is applied to methodologies for power system security and vulnerability analysis. Terrorists are often considered as fully intelligent and strategic actors who can even hire scientists and power engineers to seek the vulnerability of power systems and then launch a vital attack. Game theory does treat actors as fully strategic players and has been successfully applied to many disciplines including economics, political science and military. The thesis will present new models and analysis methods for protecting power systems under terrorism attacks. (4)Cyber security technology is considered in power system security and vulnerability analysis. It is known that information technology plays an import role in today and next generation grid. In this situation, cyber security should be an important issue. If it is vulnerable to malicious threats such as hackers and cyber-terrorists, power grid will not reach its full capabilities. The thesis will present an initial framework to reduce the vulnerability of power grid against potential cyber attack.

Nowadays, with the rapid expansion of increasing utilization of renewable energy sources, power grid is evolving into a much complex man-made system in the technological age. Under the new circumstances, traditional methodologies for power system security analysis are facing a serious challenge. For the past decade, many countries have experienced large blackouts, which expose potential problems of current models and methodologies in power industry. On the other hand, since the 9.11 event and frequent suicide bombing attacks in some countries, terrorism has become a major threat for national security. With the extensive growth of terrorism activities, power system, the significant critical infrastructure, probably becomes the target of terrorists. If this happens, the impact is dramatically severe and may yield more frequent blackouts. This Ph.D. thesis aims at developing some advanced models and methodologies for exploring the vulnerability of power system and protecting it against potential terrorism threat. The dissertation mainly consists of the following four parts. (1)Complex network theory based power system security and vulnerability analysis methodologies are introduced. Mathematically, an interconnected complex power grid can be described as a complex network of nodes connected by edges. Generally speaking, topology parameters of network structure include important information of the structure. That is to say, some critical nodes and lines can have significant impact on large-scale blackouts. The thesis will present a new methodology to recognize those critical nodes and lines in power grids. (2)Complex system theory based power grid security and vulnerability analysis methodologies are presented. Power grid is a complex dynamic evolutionary system over years with continuous expansion so as to underpin the ongoing increase of power demand. Some properties of complex systems may have important relationship with large-scale blackouts. In other words, there may be some stages of evolutionary power systems that would be more likely to cause large blackouts. The thesis will investigate the relationship to identify those critical stages of power grids. (3)Game theory is applied to methodologies for power system security and vulnerability analysis. Terrorists are often considered as fully intelligent and strategic actors who can even hire scientists and power engineers to seek the vulnerability of power systems and then launch a vital attack. Game theory does treat actors as fully strategic players and has been successfully applied to many disciplines including economics, political science and military. The thesis will present new models and analysis methods for protecting power systems under terrorism attacks. (4)Cyber security technology is considered in power system security and vulnerability analysis. It is known that information technology plays an import role in today and next generation grid. In this situation, cyber security should be an important issue. If it is vulnerable to malicious threats such as hackers and cyber-terrorists, power grid will not reach its full capabilities. The thesis will present an initial framework to reduce the vulnerability of power grid against potential cyber attack.

Nowadays, with the rapid expansion of increasing utilization of renewable energy sources, power grid is evolving into a much complex man-made system in the technological age. Under the new circumstances, traditional methodologies for power system security analysis are facing a serious challenge. For the past decade, many countries have experienced large blackouts, which expose potential problems of current models and methodologies in power industry. On the other hand, since the 9.11 event and frequent suicide bombing attacks in some countries, terrorism has become a major threat for national security. With the extensive growth of terrorism activities, power system, the significant critical infrastructure, probably becomes the target of terrorists. If this happens, the impact is dramatically severe and may yield more frequent blackouts. This Ph.D. thesis aims at developing some advanced models and methodologies for exploring the vulnerability of power system and protecting it against potential terrorism threat. The dissertation mainly consists of the following four parts. (1)Complex network theory based power system security and vulnerability analysis methodologies are introduced. Mathematically, an interconnected complex power grid can be described as a complex network of nodes connected by edges. Generally speaking, topology parameters of network structure include important information of the structure. That is to say, some critical nodes and lines can have significant impact on large-scale blackouts. The thesis will present a new methodology to recognize those critical nodes and lines in power grids. (2)Complex system theory based power grid security and vulnerability analysis methodologies are presented. Power grid is a complex dynamic evolutionary system over years with continuous expansion so as to underpin the ongoing increase of power demand. Some properties of complex systems may have important relationship with large-scale blackouts. In other words, there may be some stages of evolutionary power systems that would be more likely to cause large blackouts. The thesis will investigate the relationship to identify those critical stages of power grids. (3)Game theory is applied to methodologies for power system security and vulnerability analysis. Terrorists are often considered as fully intelligent and strategic actors who can even hire scientists and power engineers to seek the vulnerability of power systems and then launch a vital attack. Game theory does treat actors as fully strategic players and has been successfully applied to many disciplines including economics, political science and military. The thesis will present new models and analysis methods for protecting power systems under terrorism attacks. (4)Cyber security technology is considered in power system security and vulnerability analysis. It is known that information technology plays an import role in today and next generation grid. In this situation, cyber security should be an important issue. If it is vulnerable to malicious threats such as hackers and cyber-terrorists, power grid will not reach its full capabilities. The thesis will present an initial framework to reduce the vulnerability of power grid against potential cyber attack.

Food regime theory emerged in the 1980s as a tool to delineate the history of the modern food system. Scholars insist that we have arrived at the third and putative corporate food regime that is dominated by a select group of agribusiness corporations. The corporate food regime"s ascent to dominance will be presented here as a product of the realization of neoliberal trade policies at the urging of the World Trade Organization. Initially promising development to fledgling countries, the WTO"s forays into agriculture have amounted to nothing less than a catastrophe for the Global South. The hope that developing countries would be able to trade their way out of debt has long been abandoned, and the gap between the developed and developing world has only been further exacerbated as a result of trade liberalization. Worse yet, the WTO"s Agreement on Agriculture was intentionally littered with loopholes that allow Northern countries to egregiously subsidize crops that are then exported off to Southern markets at artificially low prices, crippling local producers in the process. Through examining import and export flows in the Global South since the trade agreement, this cruel feature of the modern food system will become evident as will the subsequent jump in agribusiness" profits amid the direst of...

The question regarding what makes child trafficking persistent in conflict and post-war settings has been subject to intense debate. The human trafficking literature makes general conclusions that trafficking is a by-product of civil wars, and in the process child traffickers exploit the breakdown of the rule of law. As such it is perceived that the governance of the problem of child trafficking can be effective whenever peace and stability is realised and when legal frameworks for protecting children are in place. Prompted by these assertions, I conducted a field study in South Sudan, a country emerging from one of Africa’s longest running and most brutal civil wars fought between the government in Khartoum and Sudanese Peoples Liberation Movement/Army (SPLM/A). The Sudan’s civil wars ended after the signing of the Comprehensive Peace Agreement in 2005. Whilst the termination of the war raised expectations that the international anti-trafficking conventions, treaties and customary laws protecting children would have enforcement powers and would guarantee the rights and safety of the child, the peace failed to deliver on these expectations. Based on empirical data obtained through an intensive micro-level qualitative research conducted in South Sudan over three months, the research findings reveal that a number of challenges pose serious difficulties in enforcing international counter-trafficking legislations and child protection instruments. These challenges are compounded by the interplay of the emerging socio-economic and political development in the post-independent South Sudan.