Secure routing and trust computation in multihop infrastructureless networks

Today's wireless networks rely mostly on infrastructural support for their operation. With the concept of ubiquitous computing growing more popular, research on infrastructureless networks have been rapidly growing. However, such types of networks face serious security challenges when deployed. This dissertation focuses on designing a secure routing solution and trust modeling for these infrastructureless networks. ^ The dissertation presents a trusted routing protocol that is capable of finding a secure end-to-end route in the presence of malicious nodes acting either independently or in collusion, The solution protects the network from active internal attacks, known to be the most severe types of attacks in an ad hoc application. Route discovery is based on trust levels of the nodes, which need to be dynamically computed to reflect the malicious behavior in the network. As such, we have developed a trust computational model in conjunction with the secure routing protocol that analyzes the different malicious behavior and quantifies them in the model itself. Our work is the first step towards protecting an ad hoc network from colluding internal attack. To demonstrate the feasibility of the approach, extensive simulation has been carried out to evaluate the protocol efficiency and scalability with both network size and mobility. ^ This research has laid the foundation for developing a variety of techniques that will permit people to justifiably trust the use of ad hoc networks to perform critical functions, as well as to process sensitive information without depending on any infrastructural support and hence will enhance the use of ad hoc applications in both military and civilian domains. ^

Islamist Cyber Networks in Spanish-Speaking Latin America

Despite significant concern among policy, law enforcement and intelligence communities in the United States (U.S.) over the possible spread of radical Islamist thought throughout the world as part of a global jihad movement, there has been little investigation into the growing cyber networks in Latin America that promote strong anti-Semitic and anti-U.S. messages. This paper offers an overview of that network, focusing on the structure of Shi’ite websites that promote not only religious conversion but are also supportive of Iran -- a designated State-sponsor of terrorism – its nuclear program. Hezbollah, and the “Bolivarian revolution” led by Venezuelan President Hugo Chávez and his allies in Bolivia, Ecuador and Nicaragua. There is also a smaller group of Sunni Muslim websites, mostly tied to the legacy organizations of the Muslim Brotherhood. Many of the Shi’ite websites are linked to each other consistently portray Israel as a Nazi State, and the United States as an imperialist war monger. The Palestinian issue is frequently juxtaposed with the anti-imperialist struggle that those states supporting Chávez’ Bolivarian revolution claim to wage against the United States. Some of the Islamist websites claim thousands of new convert, but such claims are difficult to verify. Most of the websites visited touted the conversion of one or two individuals as significant victories and signs of progress, implying that there are few, if any, mass conversions. While conducting this research, no websites directly claiming to be linked to Hezbollah were found, although there numerous sites hosted by that group that were active until around 2006. Several of the inactive links are supportive of Hezbollah as a political party. No websites linked to al Qaeda were found. Yet a substantial Internet network remains operational. Much of the outreach for Shi’ite Muslims, closely tied to Iran, is sponsored on numerous websites across the region, including El Salvador, Chile, Ecuador, Colombia, Mexico and Bolivia. Numerous Facebook forums for discussion are also hosted around Latin America. These links must be viewed in the context of the rapidly expanding diplomatic, intelligence, political and economic ties of Iran in recent years with the self-proclaimed Bolivarian states. Given the sparse literature available and the rich vein of un-mined information on the sites cited as well as others that one could find with additional research, the cyber network of Islamist groups remains one of the least understood or studied facets of their presence in Latin America and the Caribbean. It merits significantly more investigation.

A study of branching fluid networks for enhancing the performance of thermal -fluid devices

Compact thermal-fluid systems are found in many industries from aerospace to microelectronics where a combination of small size, light weight, and high surface area to volume ratio fluid networks are necessary. These devices are typically designed with fluid networks consisting of many small parallel channels that effectively pack a large amount of heat transfer surface area in a very small volume but do so at the cost of increased pumping power requirements. ^ To offset this cost the use of a branching fluid network for the distribution of coolant within a heat sink is investigated. The goal of the branch design technique is to minimize the entropy generation associated with the combination of viscous dissipation and convection heat transfer experienced by the coolant in the heat sink while maintaining compact high heat transfer surface area to volume ratios. ^ The derivation of Murray's Law, originally developed to predict the geometry of physiological transport systems, is extended to heat sink designs which minimze entropy generation. Two heat sink designs at different scales are built, and tested experimentally and analytically. The first uses this new derivation of Murray's Law. The second uses a combination of Murray's Law and Constructal Theory. The results of the experiments were used to verify the analytical and numerical models. These models were then used to compare the performance of the heat sink with other compact high performance heat sink designs. The results showed that the techniques used to design branching fluid networks significantly improves the performance of active heat sinks. The design experience gained was then used to develop a set of geometric relations which optimize the heat transfer to pumping power ratio of a single cooling channel element. Each element can be connected together using a set of derived geometric guidelines which govern branch diameters and angles. The methodology can be used to design branching fluid networks which can fit any geometry. ^