Denial of Service Attack over Secure Neighbor Discovery (SeND)

IPv6, the Internet Protocol suite version 6, uses a Neighbor Discovery Protocol (NDP). NDP mainly replaces router discovery and the Address Resolution Protocol (ARP) and thereafter redirects the functions used in IPv4 i.e. the Internet Protocol suite version 4. The NDP system is a stateless protocol since it does not need the dynamic host’s configuration protocol server to enable the various IPv6 nodes for determining the connected hosts along with the IPv6 network routers. To add layers of protection to NDP, the SeND (Secure Neighbor Discovery) extension was developed, which provides router authorization, proof of address ownership, and message protection for the protocol. SeND employs CGAs (Cryptographically Generated Addresses) and X.509 certificates. Despite its many advantages, deploying SeND is not easy, and it is still vulnerable to certain DoS (Denial-of-Service) attacks. The components of SeND and its responses to NDP threats are further elaborated in this paper. In addition, an overview of the implementation of SeND, its limitations, existing vulnerabilities, and current deployment challenges are also presented.  Furthermore, to test the performance of SeND under a DoS attack, a test bed was implemented and the results discussed.

Evaluation of on-demand routing in mobile ad hoc networks and proposal for a secure routing protocol

Secure routing Mobile Ad hoc Networks (MANETs) has emerged as an important MANET research area. Initial work in MANET focused mainly on the problem of providing efficient mechanisms for finding paths in very dynamic networks, without considering the security of the routing process. Because of this, a number of attacks exploit these routing vulnerabilities to manipulate MANETs. In this thesis, we performed an in-depth evaluation and performance analysis of existing MANET Routing protocols, identifying Dynamic Source Routing (DSR) as the most robust (based on throughput, latency and routing overhead) which can be secured with negligible routing efficiency trade-off. We describe security threats, specifically showing their effects on DSR. We proposed a new routing protocol, named Authenticated Source Routing for Ad hoc Networks (ASRAN) which is an out-of-band certification-based, authenticated source routing protocol with modifications to the route acquisition process of DSR to defeat all identified attacks. Simulation studies confirm that ASRAN has a good trade-off balance in reference to the addition of security and routing efficiency

A Distributed Audit Trail for the Internet of Things

Sharing Internet of Things (IoT) data over open-data platforms and digital data marketplaces can reduce infrastructure investments, improve sustainability by reducing the required resources, and foster innovation. However, due to the inability to audit the authenticity, integrity, and quality of IoT data, third-party data consumers cannot assess the trustworthiness of received data. Therefore, it is challenging to use IoT data obtained from third parties for quality-relevant applications. To overcome this limitation, the IoT data must be auditable. Distributed Ledger Technology (DLT) is a promising approach for building auditable systems. However, the existing solutions do not integrate authenticity, integrity, data quality, and location into an all-encompassing auditable model and only focus on specific parts of auditability. This thesis aims to provide a distributed audit trail that makes the IoT auditable and enables sharing of IoT data between multiple organizations for quality relevant applications. Therefore, we designed and evaluated the Veritaa framework. The Veritaa framework comprises the Graph of Trust (GoT) as distributed audit trail and a DLT to immutably store the transactions that build the GoT. The contributions of this thesis are summarized as follows. First, we designed and evaluated the GoT a DLT-based Distributed Public Key Infrastructure (DPKI) with a signature store. Second, we designed a Distributed Calibration Certificate Infrastructure (DCCI) based on the GoT, which makes quality-relevant maintenance information of IoT devices auditable. Third, we designed an Auditable Positioning System (APS) to make positions in the IoT auditable. Finally, we designed an Location Verification System (LVS) to verify location claims and prevent physical layer attacks against the APS. All these components are integrated into the GoT and build the distributed audit trail. We implemented a real-world testbed to evaluate the proposed distributed audit trail. This testbed comprises several custom-built IoT devices connectable over Long Range Wide Area Network (LoRaWAN) or Long-Term Evolution Category M1 (LTE Cat M1), and a Bluetooth Low Energy (BLE)-based Angle of Arrival (AoA) positioning system. All these low-power devices can manage their identity and secure their data on the distributed audit trail using the IoT client of the Veritaa framework. The experiments suggest that a distributed audit trail is feasible and secure, and the low-power IoT devices are capable of performing the required cryptographic functions. Furthermore, the energy overhead introduced by making the IoT auditable is limited and reasonable for quality-relevant applications

Novel architectures and strategies for security offloading

Internet has become an indispensable and powerful tool in our modern society. Its ubiquitousness, pervasiveness and applicability have fostered paradigm changes around many aspects of our lives. This phenomena has positioned the network and its services as fundamental assets over which we rely and trust. However, Internet is far from being perfect. It has considerable security issues and vulnerabilities that jeopardize its main core functionalities with negative impact over its players. Furthermore, these vulnerabilities¿ complexities have been amplified along with the evolution of Internet user mobility. In general, Internet security includes both security for the correct network operation and security for the network users and endpoint devices. The former involves the challenges around the Internet core control and management vulnerabilities, while the latter encompasses security vulnerabilities over end users and endpoint devices. Similarly, Internet mobility poses major security challenges ranging from routing complications, connectivity disruptions and lack of global authentication and authorization. The purpose of this thesis is to present the design of novel architectures and strategies for improving Internet security in a non-disruptive manner. Our novel security proposals follow a protection offloading approach. The motives behind this paradigm target the further enhancement of the security protection while minimizing the intrusiveness and disturbance over the Internet routing protocols, its players and users. To accomplish such level of transparency, the envisioned solutions leverage on well-known technologies, namely, Software Defined Networks, Network Function Virtualization and Fog Computing. From the Internet core building blocks, we focus on the vulnerabilities of two key routing protocols that play a fundamental role in the present and the future of the Internet, i.e., the Border Gateway Protocol (BGP) and the Locator-Identifier Split Protocol (LISP). To this purpose, we first investigate current BGP vulnerabilities and countermeasures with emphasis in an unresolved security issue defined as Route Leaks. Therein, we discuss the reasons why different BGP security proposals have failed to be adopted, and the necessity to propose innovative solutions that minimize the impact over the already deployed routing solution. To this end, we propose pragmatic security methodologies to offload the protection with the following advantages: no changes to the BGP protocol, neither dependency on third party information nor on third party security infrastructure, and self-beneficial. Similarly, we research the current LISP vulnerabilities with emphasis on its control plane and mobility support. We leverage its by-design separation of control and data planes to propose an enhanced location-identifier registration process of end point identifiers. This proposal improves the mobility of end users with regards on securing a dynamic traffic steering over the Internet. On the other hand, from the end user and devices perspective we research new paradigms and architectures with the aim of enhancing their protection in a more controllable and consolidated manner. To this end, we propose a new paradigm which shifts the device-centric protection paradigm toward a user-centric protection. Our proposal focus on the decoupling or extending of the security protection from the end devices toward the network edge. It seeks the homogenization of the enforced protection per user independently of the device utilized. We further investigate this paradigm in a mobility user scenario. Similarly, we extend this proposed paradigm to the IoT realm and its intrinsic security challenges. Therein, we propose an alternative to protect both the things, and the services that leverage from them by consolidating the security at the network edge. We validate our proposal by providing experimental results from prof-of-concepts implementations.Internet se ha convertido en una poderosa e indispensable herramienta para nuestra sociedad moderna. Su omnipresencia y aplicabilidad han promovido grandes cambios en diferentes aspectos de nuestras vidas. Este fenómeno ha posicionado a la red y sus servicios como activos fundamentales sobre los que contamos y confiamos. Sin embargo, Internet está lejos de ser perfecto. Tiene considerables problemas de seguridad y vulnerabilidades que ponen en peligro sus principales funcionalidades. Además, las complejidades de estas vulnerabilidades se han ampliado junto con la evolución de la movilidad de usuarios de Internet y su limitado soporte. La seguridad de Internet incluye tanto la seguridad para el correcto funcionamiento de la red como la seguridad para los usuarios y sus dispositivos. El primero implica los desafíos relacionados con las vulnerabilidades de control y gestión de la infraestructura central de Internet, mientras que el segundo abarca las vulnerabilidades de seguridad sobre los usuarios finales y sus dispositivos. Del mismo modo, la movilidad en Internet plantea importantes desafíos de seguridad que van desde las complicaciones de enrutamiento, interrupciones de la conectividad y falta de autenticación y autorización globales. El propósito de esta tesis es presentar el diseño de nuevas arquitecturas y estrategias para mejorar la seguridad de Internet de una manera no perturbadora. Nuestras propuestas de seguridad siguen un enfoque de desacople de la protección. Los motivos detrás de este paradigma apuntan a la mejora adicional de la seguridad mientras que minimizan la intrusividad y la perturbación sobre los protocolos de enrutamiento de Internet, sus actores y usuarios. Para lograr este nivel de transparencia, las soluciones previstas aprovechan nuevas tecnologías, como redes definidas por software (SDN), virtualización de funciones de red (VNF) y computación en niebla. Desde la perspectiva central de Internet, nos centramos en las vulnerabilidades de dos protocolos de enrutamiento clave que desempeñan un papel fundamental en el presente y el futuro de Internet, el Protocolo de Puerta de Enlace Fronterizo (BGP) y el Protocolo de Separación Identificador/Localizador (LISP ). Para ello, primero investigamos las vulnerabilidades y medidas para contrarrestar un problema no resuelto en BGP definido como Route Leaks. Proponemos metodologías pragmáticas de seguridad para desacoplar la protección con las siguientes ventajas: no cambios en el protocolo BGP, cero dependencia en la información de terceros, ni de infraestructura de seguridad de terceros, y de beneficio propio. Del mismo modo, investigamos las vulnerabilidades actuales sobre LISP con énfasis en su plano de control y soporte de movilidad. Aprovechamos la separacçón de sus planos de control y de datos para proponer un proceso mejorado de registro de identificadores de ubicación y punto final, validando de forma segura sus respectivas autorizaciones. Esta propuesta mejora la movilidad de los usuarios finales con respecto a segurar un enrutamiento dinámico del tráfico a través de Internet. En paralelo, desde el punto de vista de usuarios finales y dispositivos investigamos nuevos paradigmas y arquitecturas con el objetivo de mejorar su protección de forma controlable y consolidada. Con este fin, proponemos un nuevo paradigma hacia una protección centrada en el usuario. Nuestra propuesta se centra en el desacoplamiento o ampliación de la protección de seguridad de los dispositivos finales hacia el borde de la red. La misma busca la homogeneización de la protección del usuario independientemente del dispositivo utilizado. Además, investigamos este paradigma en un escenario con movilidad. Validamos nuestra propuesta proporcionando resultados experimentales obtenidos de diferentes experimentos y pruebas de concepto implementados

Novel architectures and strategies for security offloading

Internet has become an indispensable and powerful tool in our modern society. Its ubiquitousness, pervasiveness and applicability have fostered paradigm changes around many aspects of our lives. This phenomena has positioned the network and its services as fundamental assets over which we rely and trust. However, Internet is far from being perfect. It has considerable security issues and vulnerabilities that jeopardize its main core functionalities with negative impact over its players. Furthermore, these vulnerabilities¿ complexities have been amplified along with the evolution of Internet user mobility. In general, Internet security includes both security for the correct network operation and security for the network users and endpoint devices. The former involves the challenges around the Internet core control and management vulnerabilities, while the latter encompasses security vulnerabilities over end users and endpoint devices. Similarly, Internet mobility poses major security challenges ranging from routing complications, connectivity disruptions and lack of global authentication and authorization. The purpose of this thesis is to present the design of novel architectures and strategies for improving Internet security in a non-disruptive manner. Our novel security proposals follow a protection offloading approach. The motives behind this paradigm target the further enhancement of the security protection while minimizing the intrusiveness and disturbance over the Internet routing protocols, its players and users. To accomplish such level of transparency, the envisioned solutions leverage on well-known technologies, namely, Software Defined Networks, Network Function Virtualization and Fog Computing. From the Internet core building blocks, we focus on the vulnerabilities of two key routing protocols that play a fundamental role in the present and the future of the Internet, i.e., the Border Gateway Protocol (BGP) and the Locator-Identifier Split Protocol (LISP). To this purpose, we first investigate current BGP vulnerabilities and countermeasures with emphasis in an unresolved security issue defined as Route Leaks. Therein, we discuss the reasons why different BGP security proposals have failed to be adopted, and the necessity to propose innovative solutions that minimize the impact over the already deployed routing solution. To this end, we propose pragmatic security methodologies to offload the protection with the following advantages: no changes to the BGP protocol, neither dependency on third party information nor on third party security infrastructure, and self-beneficial. Similarly, we research the current LISP vulnerabilities with emphasis on its control plane and mobility support. We leverage its by-design separation of control and data planes to propose an enhanced location-identifier registration process of end point identifiers. This proposal improves the mobility of end users with regards on securing a dynamic traffic steering over the Internet. On the other hand, from the end user and devices perspective we research new paradigms and architectures with the aim of enhancing their protection in a more controllable and consolidated manner. To this end, we propose a new paradigm which shifts the device-centric protection paradigm toward a user-centric protection. Our proposal focus on the decoupling or extending of the security protection from the end devices toward the network edge. It seeks the homogenization of the enforced protection per user independently of the device utilized. We further investigate this paradigm in a mobility user scenario. Similarly, we extend this proposed paradigm to the IoT realm and its intrinsic security challenges. Therein, we propose an alternative to protect both the things, and the services that leverage from them by consolidating the security at the network edge. We validate our proposal by providing experimental results from prof-of-concepts implementations.Internet se ha convertido en una poderosa e indispensable herramienta para nuestra sociedad moderna. Su omnipresencia y aplicabilidad han promovido grandes cambios en diferentes aspectos de nuestras vidas. Este fenómeno ha posicionado a la red y sus servicios como activos fundamentales sobre los que contamos y confiamos. Sin embargo, Internet está lejos de ser perfecto. Tiene considerables problemas de seguridad y vulnerabilidades que ponen en peligro sus principales funcionalidades. Además, las complejidades de estas vulnerabilidades se han ampliado junto con la evolución de la movilidad de usuarios de Internet y su limitado soporte. La seguridad de Internet incluye tanto la seguridad para el correcto funcionamiento de la red como la seguridad para los usuarios y sus dispositivos. El primero implica los desafíos relacionados con las vulnerabilidades de control y gestión de la infraestructura central de Internet, mientras que el segundo abarca las vulnerabilidades de seguridad sobre los usuarios finales y sus dispositivos. Del mismo modo, la movilidad en Internet plantea importantes desafíos de seguridad que van desde las complicaciones de enrutamiento, interrupciones de la conectividad y falta de autenticación y autorización globales. El propósito de esta tesis es presentar el diseño de nuevas arquitecturas y estrategias para mejorar la seguridad de Internet de una manera no perturbadora. Nuestras propuestas de seguridad siguen un enfoque de desacople de la protección. Los motivos detrás de este paradigma apuntan a la mejora adicional de la seguridad mientras que minimizan la intrusividad y la perturbación sobre los protocolos de enrutamiento de Internet, sus actores y usuarios. Para lograr este nivel de transparencia, las soluciones previstas aprovechan nuevas tecnologías, como redes definidas por software (SDN), virtualización de funciones de red (VNF) y computación en niebla. Desde la perspectiva central de Internet, nos centramos en las vulnerabilidades de dos protocolos de enrutamiento clave que desempeñan un papel fundamental en el presente y el futuro de Internet, el Protocolo de Puerta de Enlace Fronterizo (BGP) y el Protocolo de Separación Identificador/Localizador (LISP ). Para ello, primero investigamos las vulnerabilidades y medidas para contrarrestar un problema no resuelto en BGP definido como Route Leaks. Proponemos metodologías pragmáticas de seguridad para desacoplar la protección con las siguientes ventajas: no cambios en el protocolo BGP, cero dependencia en la información de terceros, ni de infraestructura de seguridad de terceros, y de beneficio propio. Del mismo modo, investigamos las vulnerabilidades actuales sobre LISP con énfasis en su plano de control y soporte de movilidad. Aprovechamos la separacçón de sus planos de control y de datos para proponer un proceso mejorado de registro de identificadores de ubicación y punto final, validando de forma segura sus respectivas autorizaciones. Esta propuesta mejora la movilidad de los usuarios finales con respecto a segurar un enrutamiento dinámico del tráfico a través de Internet. En paralelo, desde el punto de vista de usuarios finales y dispositivos investigamos nuevos paradigmas y arquitecturas con el objetivo de mejorar su protección de forma controlable y consolidada. Con este fin, proponemos un nuevo paradigma hacia una protección centrada en el usuario. Nuestra propuesta se centra en el desacoplamiento o ampliación de la protección de seguridad de los dispositivos finales hacia el borde de la red. La misma busca la homogeneización de la protección del usuario independientemente del dispositivo utilizado. Además, investigamos este paradigma en un escenario con movilidad. Validamos nuestra propuesta proporcionando resultados experimentales obtenidos de diferentes experimentos y pruebas de concepto implementados.Postprint (published version

A security protocol for authentication of binding updates in Mobile IPv6.

Wireless communication technologies have come along way, improving with every generational leap. As communications evolve so do the system architectures, models and paradigms. Improvements have been seen in the jump from 2G to 3G networks in terms of security. Yet these issues persist and will continue to plague mobile communications into the leap towards 4G networks if not addressed. 4G will be based on the transmission of Internet packets only, using an architecture known as mobile IP. This will feature many advantages, however security is still a fundamental issue to be resolved. One particular security issue involves the route optimisation technique, which deals with binding updates. This allows the corresponding node to by-pass the home agent router to communicate directly with the mobile node. There are a variety of security vulnerabilities with binding updates, which include the interception of data packets, which would allow an attacker to eavesdrop on its contents, breaching the users confidentiality, or to modify transmitted packets for the attackers own malicious purposes. Other possible vulnerabilities with mobile IP include address spoofing, redirection and denial of service attacks. For many of these attacks, all the attacker needs to know is the IPv6 addresses of the mobile’s home agent and the corresponding node. There are a variety of security solutions to prevent these attacks from occurring. Two of the main solutions are cryptography and authentication. Cryptography allows the transmitted data to be scrambled in an undecipherable way resulting in any intercepted packets being illegible to the attacker. Only the party possessing the relevant key will be able to decrypt the message. Authentication is the process of verifying the identity of the user or device one is in communication with. Different authentication architectures exist however many of them rely on a central server to verify the users, resulting in a possible single point of attack. Decentralised authentication mechanisms would be more appropriate for the nature of mobile IP and several protocols are discussed. However they all posses’ flaws, whether they be overly resource intensive or give away vital address data, which can be used to mount an attack. As a result location privacy is investigated in a possible attempt at hiding this sensitive data. Finally, a security solution is proposed to address the security vulnerabilities found in binding updates and attempts to overcome the weaknesses of the examined security solutions. The security protocol proposed in this research involves three new security techniques. The first is a combined solution using Cryptographically Generated Addresses and Return Routability, which are already established solutions, and then introduces a new authentication procedure, to create the Distributed Authentication Protocol to aid with privacy, integrity and authentication. The second is an enhancement to Return Routability called Dual Identity Return Routability, which provides location verification authentication for multiple identities on the same device. The third security technique is called Mobile Home Agents, which provides device and user authentication while introducing location privacy and optimised communication routing. All three security techniques can be used together or individually and each needs to be passed before the binding update is accepted. Cryptographically Generated Addresses asserts the users ownership of the IPv6 address by generating the interface identifier by computing a cryptographic one-way hash function from the users’ public key and auxiliary parameters. The binding between the public key and the address can be verified by recomputing the hash value and by comparing the hash with the interface identifier. This method proves ownership of the address, however it does not prove the address is reachable. After establishing address ownership, Return Routability would then send two security tokens to the mobile node, one directly and one via the home agent. The mobile node would then combine them together to create an encryption key called the binding key allowing the binding update to be sent securely to the correspondent node. This technique provides a validation to the mobile nodes’ location and proves its ownership of the home agent. Return Routability provides a test to verify that the node is reachable. It does not verify that the IPv6 address is owned by the user. This method is combined with Cryptographically Generated Addresses to provide best of both worlds. The third aspect of the first security solution introduces a decentralised authentication mechanism. The correspondent requests the authentication data from both the mobile node and home agent. The mobile sends the data in plain text, which could be encrypted with the binding key and the home agent sends a hash of the data. The correspondent then converts the data so both are hashes and compares them. If they are the same, authentication is successful. This provides device and user authentication which when combined with Cryptographically Generated Addresses and Return Routability create a robust security solution called the Distributed Authentication Protocol. The second new technique was designed to provide an enhancement to a current security solution. Dual Identity Return Routability builds on the concept of Return Routability by providing two Mobile IPv6 addresses on a mobile device, giving the user two separate identities. After establishing address ownership with Cryptographically Generated Addresses, Dual Identity Return Routability would then send security data to both identities, each on a separate network and each having heir own home agents, and the mobile node would then combine them together to create the binding key allowing the binding update to be sent securely to the correspondent node. This technique provides protection against address spoofing as an attacker needs two separate ip addresses, which are linked together. Spoofing only a single address will not pass this security solution. One drawback of the security techniques described, however, is that none of them provide location privacy to hide the users IP address from attackers. An attacker cannot mount a direct attack if the user is invisible. The third new security solution designed is Mobile Home Agents. These are software agents, which provide location privacy to the mobile node by acting as a proxy between it and the network. The Mobile Home Agent resides on the point of attachment and migrates to a new point of attachment at the same time as the mobile node. This provides reduced latency communication and a secure environment for the mobile node. These solutions can be used separately or combined together to form a super security solution, which is demonstrated in this thesis and attempts to provide proof of address ownership, reachability, user and device authentication, location privacy and reduction in communication latency. All these security features are design to protect against one the most devastating attacks in Mobile IPv6, the false binding update, which can allow an attacker to impersonate and deny service to the mobile node by redirecting all data packets to itself. The solutions are all simulated with different scenarios and network configurations and with a variety of attacks, which attempt to send a false binding update to the correspondent node. The results were then collected and analysed to provide conclusive proof that the proposed solutions are effective and robust in protecting against the false binding updates creating a safe and secure network for all

The Internet of Everything

In the era before IoT, the world wide web, internet, web 2.0 and social media made people’s lives comfortable by providing web services and enabling access personal data irrespective of their location. Further, to save time and improve efficiency, there is a need for machine to machine communication, automation, smart computing and ubiquitous access to personal devices. This need gave birth to the phenomenon of Internet of Things (IoT) and further to the concept of Internet of Everything (IoE)

Smart Wireless Sensor Networks

The recent development of communication and sensor technology results in the growth of a new attractive and challenging area - wireless sensor networks (WSNs). A wireless sensor network which consists of a large number of sensor nodes is deployed in environmental fields to serve various applications. Facilitated with the ability of wireless communication and intelligent computation, these nodes become smart sensors which do not only perceive ambient physical parameters but also be able to process information, cooperate with each other and self-organize into the network. These new features assist the sensor nodes as well as the network to operate more efficiently in terms of both data acquisition and energy consumption. Special purposes of the applications require design and operation of WSNs different from conventional networks such as the internet. The network design must take into account of the objectives of specific applications. The nature of deployed environment must be considered. The limited of sensor nodes� resources such as memory, computational ability, communication bandwidth and energy source are the challenges in network design. A smart wireless sensor network must be able to deal with these constraints as well as to guarantee the connectivity, coverage, reliability and security of network's operation for a maximized lifetime. This book discusses various aspects of designing such smart wireless sensor networks. Main topics includes: design methodologies, network protocols and algorithms, quality of service management, coverage optimization, time synchronization and security techniques for sensor networks

Collaborative, Trust-Based Security Mechanisms for a National Utility Intranet

This thesis investigates security mechanisms for utility control and protection networks using IP-based protocol interaction. It proposes flexible, cost-effective solutions in strategic locations to protect transitioning legacy and full IP-standards architectures. It also demonstrates how operational signatures can be defined to enact organizationally-unique standard operating procedures for zero failure in environments with varying levels of uncertainty and trust. The research evaluates layering encryption, authentication, traffic filtering, content checks, and event correlation mechanisms over time-critical primary and backup control/protection signaling to prevent disruption by internal and external malicious activity or errors. Finally, it shows how a regional/national implementation can protect private communities of interest and foster a mix of both centralized and distributed emergency prediction, mitigation, detection, and response with secure, automatic peer-to-peer notifications that share situational awareness across control, transmission, and reliability boundaries and prevent wide-spread, catastrophic power outages

Ordered Merkle Tree a Versatile Data-Structure for Security Kernels

Hidden undesired functionality is an unavoidable reality in any complex hardware or software component. Undesired functionality — deliberately introduced Trojan horses or accidentally introduced bugs — in any component of a system can be exploited by attackers to exert control over the system. This poses a serious security risk to systems — especially in the ever growing number of systems based on networks of computers. The approach adopted in this dissertation to secure systems seeks immunity from hidden functionality. Specifcally, if a minimal trusted computing base (TCB) for any system can be identifed, and if we can eliminate hidden functionality in the TCB, all desired assurances regarding the operation of the system can be guaranteed. More specifcally, the desired assurances are guaranteed even if undesired functionality may exist in every component of the system outside the TCB. A broad goal of this dissertation is to characterize the TCB for various systems as a set of functions executed by a trusted security kernel. Some constraints are deliberately imposed on the security kernel functionality to reduce the risk of hidden functionality inside the security kernel. In the security model adopted in this dissertation, any system is seen as an interconnection of subsystems, where each subsystem is associated with a security kernel. The security kernel for a subsystem performs only the bare minimal tasks required to assure the integrity of the tasks performed by the subsystem. Even while the security kernel functionality may be different for each system/subsystem, it is essential to identify reusable components of the functionality that are suitable for a wide range of systems. The contribution of the research is a versatile data-structure — Ordered Merkle Tree (OMT), which can act as the reusable component of various security kernels. The utility of OMT is illustrated by designing security kernels for subsystems participating in, 1) a remote fle storage system, 2) a generic content distribution system, 3) generic look-up servers, 4) mobile ad-hoc networks and 5) the Internet’s routing infrastructure based on the border gateway protocol (BGP)