Energy Harvesting and Sensor Based Hardware Security Primitives for Cyber-Physical Systems

The last few decades have seen a large proliferation in the prevalence of cyber-physical systems. Although cyber-physical systems can offer numerous advantages to society, their large scale adoption does not come without risks. Internet of Things (IoT) devices can be considered a significant component within cyber-physical systems. They can provide network communication in addition to controlling the various sensors and actuators that exist within the larger cyber-physical system. The adoption of IoT features can also provide attackers with new potential avenues to access and exploit a system\u27s vulnerabilities. Previously, existing systems could more or less be considered a closed system with few potential points of access for attackers. Security was thus not typically a core consideration when these systems were originally designed. The cumulative effect is that these systems are now vulnerable to new security risks without having native security countermeasures that can easily address these vulnerabilities. Even just adding standard security features to these systems is itself not a simple task. The devices that make up these systems tend to have strict resource constraints in the form of power consumption and processing power. In this dissertation, we explore how security devices known as Physically Unclonable Functions (PUFs) could be used to address these concerns. PUFs are a class of circuits that are unique and unclonable due to inherent variations caused by the device manufacturing process. We can take advantage of these PUF properties by using the outputs of PUFs to generate secret keys or pseudonyms that are similarly unique and unclonable. Existing PUF designs are commonly based around transistor level variations in a special purpose integrated circuit (IC). Integrating these designs within a system would still require additional hardware along with system modification to interact with the device. We address these concerns by proposing a novel PUF design methodology for the creation of PUFs whose integration within these systems would minimize the cost of redesigning the system by reducing the need to add additional hardware. This goal is achieved by creating PUF designs from components that may already exist within these systems. A PUF designed from existing components creates the possibility of adding a PUF (and thus security features) to the system without actually adding any additional hardware. This could allow PUFs to become a more attractive security option for integration with resource constrained devices. Our proposed approach specifically targets sensors and energy harvesting devices since they can provide core functions within cyber-physical systems such as power generation and sensing capabilities. These components are known to exhibit variations due to the manufacturing process and could thus be utilized to design a PUF. Our first contribution is the proposal of a novel PUF design methodology based on using components which are already commonly found within cyber-physical systems. The proposed methodology uses eight sensors or energy harvesting devices along with a microcontroller. It is unlikely that single type of sensor or energy harvester will exist in all possible cyber-physical systems. Therefore, it is important to create a range of designs in order to reach a greater portion of cyber-physical systems. The second contribution of this work is the design of a PUF based on piezo sensors. Our third contribution is the design of a PUF that utilizes thermistor temperature sensors. The fourth contribution of this work is a proposed solar cell based PUF design. Furthermore, as a fifth contribution of this dissertation we evaluate a selection of common solar cell materials to establish which type of solar cell would be best suited to the creation of a PUF based on the operating conditions. The viability of the proposed designs is evaluated through testing in terms of reliability and uniformity. In addition, Monte Carlo simulations are performed to evaluate the uniqueness property of the designs. For our final contribution we illustrate the security benefits that can be achieved through the adoption of PUFs by cyber-physical systems. For this purpose we chose to highlight vehicles since they are a very popular example of a cyber-physical system and they face unique security challenges which are not readily solvable by standard solutions. Our contribution is the proposal of a novel controller area network (CAN) security framework that is based on PUFs. The framework does not require any changes to the underlying CAN protocol and also minimizes the amount of additional message passing overhead needed for its operation. The proposed framework is a good example of how the cost associated with implementing such a framework could be further reduced through the adoption of our proposed PUF designs. The end result is a method which could introduce security to an inherently insecure system while also making its integration as seamless as possible by attempting to minimize the need for additional hardware

ENABLING IOT AUTHENTICATION, PRIVACY AND SECURITY VIA BLOCKCHAIN

Although low-power and Internet-connected gadgets and sensors are increasingly integrated into our lives, the optimal design of these systems remains an issue. In particular, authentication, privacy, security, and performance are critical success factors. Furthermore, with emerging research areas such as autonomous cars, advanced manufacturing, smart cities, and building, usage of the Internet of Things (IoT) devices is expected to skyrocket. A single compromised node can be turned into a malicious one that brings down whole systems or causes disasters in safety-critical applications. This dissertation addresses the critical problems of (i) device management, (ii) data management, and (iii) service management in IoT systems. In particular, we propose an integrated platform solution for IoT device authentication, data privacy, and service security via blockchain-based smart contracts. We ensure IoT device authentication by blockchain-based IC traceability system, from its fabrication to its end-of-life, allowing both the supplier and a potential customer to verify an IC’s provenance. Results show that our proposed consortium blockchain framework implementation in Hyperledger Fabric for IC traceability achieves a throughput of 35 transactions per second (tps). To corroborate the blockchain information, we authenticate the IC securely and uniquely with an embedded Physically Unclonable Function (PUF). For reliable Weak PUF-based authentication, our proposed accelerated aging technique reduces the cumulative burn-in cost by ∼ 56%. We also propose a blockchain-based solution to integrate the privacy of data generated from the IoT devices by giving users control of their privacy. The smart contract controlled trust-base ensures that the users have private access to their IoT devices and data. We then propose a remote configuration of IC features via smart contracts, where an IC can be programmed repeatedly and securely. This programmability will enable users to upgrade IC features or rent upgraded IC features for a fixed period after users have purchased the IC. We tailor the hardware to meet the blockchain performance. Our on-die hardware module design enforces the hardware configuration’s secure execution and uses only 2,844 slices in the Xilinx Zedboard Zynq Evaluation board. The blockchain framework facilitates decentralized IoT, where interacting devices are empowered to execute digital contracts autonomously

Physical Unclonability Framework for the Internet of Things

Ph. D. ThesisThe rise of the Internet of Things (IoT) creates a tendency to construct unified architectures with a great number of edge nodes and inherent security risks due to centralisation. At the same time, security and privacy defenders advocate for decentralised solutions which divide the control and the responsibility among the entirety of the network nodes. However, spreading secrets among several parties also expands the attack surface. This conflict is in part due to the difficulty in differentiating between instances of the same hardware, which leads to treating physically distinct devices as identical. Harnessing the uniqueness of each connected device and injecting it into security protocols can provide solutions to several common issues of the IoT. Secrets can be generated directly from this uniqueness without the need to manually embed them into devices, reducing both the risk of exposure and the cost of managing great numbers of devices. Uniqueness can then lead to the primitive of unclonability. Unclonability refers to ensuring the difficulty of producing an exact duplicate of an entity via observing and measuring the entity’s features and behaviour. Unclonability has been realised on a physical level via the use of Physical Unclonable Functions (PUFs). PUFs are constructions that extract the inherent unclonable features of objects and compound them into a usable form, often that of binary data. PUFs are also exceptionally useful in IoT applications since they are low-cost, easy to integrate into existing designs, and have the potential to replace expensive cryptographic operations. Thus, a great number of solutions have been developed to integrate PUFs in various security scenarios. However, methods to expand unclonability into a complete security framework have not been thoroughly studied. In this work, the foundations are set for the development of such a framework through the formulation of an unclonability stack, in the paradigm of the OSI reference model. The stack comprises layers propagating the primitive from the unclonable PUF ICs, to devices, network links and eventually unclonable systems. Those layers are introduced, and work towards the design of protocols and methods for several of the layers is presented. A collection of protocols based on one or more unclonable tokens or authority devices is proposed, to enable the secure introduction of network nodes into groups or neighbourhoods. The role of the authority devices is that of a consolidated, observable root of ownership, whose physical state can be verified. After their introduction, nodes are able to identify and interact with their peers, exchange keys and form relationships, without the need of continued interaction with the authority device. Building on this introduction scheme, methods for establishing and maintaining unclonable links between pairs of nodes are introduced. These pairwise links are essential for the construction of relationships among multiple network nodes, in a variety of topologies. Those topologies and the resulting relationships are formulated and discussed. While the framework does not depend on specific PUF hardware, SRAM PUFs are chosen as a case study since they are commonly used and based on components that are already present in the majority of IoT devices. In the context of SRAM PUFs and with a view to the proposed framework, practical issues affecting the adoption of PUFs in security protocols are discussed. Methods of improving the capabilities of SRAM PUFs are also proposed, based on experimental data.School of Engineering Newcastle Universit

Trusted and Privacy-preserving Embedded Systems: Advances in Design, Analysis and Application of Lightweight Privacy-preserving Authentication and Physical Security Primitives

Radio Frequency Identification (RFID) enables RFID readers to perform fully automatic wireless identification of objects labeled with RFID tags and is widely deployed to many applications, such as access control, electronic tickets and payment as well as electronic passports. This prevalence of RFID technology introduces various risks, in particular concerning the privacy of its users and holders. Despite the privacy risk, classical threats to authentication and identification systems must be considered to prevent the adversary from impersonating or copying (cloning) a tag. This thesis summarizes the state of the art in secure and privacy-preserving authentication for RFID tags with a particular focus on solutions based on Physically Unclonable Functions (PUFs). It presents advancements in the design, analysis and evaluation of secure and privacy-preserving authentication protocols for RFID systems and PUFs. Formalizing the security and privacy requirements on RFID systems is essential for the design of provably secure and privacy-preserving RFID protocols. However, existing RFID security and privacy models in the literature are often incomparable and in part do not reflect the capabilities of real-world adversaries. We investigate subtle issues such as tag corruption aspects that lead to the impossibility of achieving both mutual authentication and any reasonable notion of privacy in one of the most comprehensive security and privacy models, which is the basis of many subsequent works. Our results led to the refinement of this privacy model and were considered in subsequent works on privacy-preserving RFID systems. A promising approach to enhance the privacy in RFID systems without lifting the computational requirements on the tags are anonymizers. These are special devices that take off the computational workload from the tags. While existing anonymizer-based protocols are subject to impersonation and denial-of-service attacks, existing RFID security and privacy models do not include anonymizers. We present the first security and privacy framework for anonymizer-enabled RFID systems and two privacy-preserving RFID authentication schemes using anonymizers. Both schemes achieve several appealing features that were not simultaneously achieved by any previous proposal. The first protocol is very efficient for all involved entities, achieves privacy under tag corruption. It is secure against impersonation attacks and forgeries even if the adversary can corrupt the anonymizers. The second scheme provides for the first time anonymity and untraceability of tags against readers as well as secure tag authentication against collisions of malicious readers and anonymizers using tags that cannot perform public-key cryptography (i.e., modular exponentiations). The RFID tags commonly used in practice are cost-efficient tokens without expensive hardware protection mechanisms. Physically Unclonable Functions (PUFs) promise to provide an effective security mechanism for RFID tags to protect against basic hardware attacks. However, existing PUF-based RFID authentication schemes are not scalable, allow only for a limited number of authentications and are subject to replay, denial-of-service and emulation attacks. We present two scalable PUF-based authentication schemes that overcome these problems. The first protocol supports tag and reader authentication, is resistant to emulation attacks and highly scalable. The second protocol uses a PUF-based key storage and addresses an open question on the feasibility of destructive privacy, i.e., the privacy of tags that are destroyed during tag corruption. The security of PUFs relies on assumptions on physical properties and is still under investigation. PUF evaluation results in the literature are difficult to compare due to varying test conditions and different analysis methods. We present the first large-scale security analysis of ASIC implementations of the five most popular electronic PUF types, including Arbiter, Ring Oscillator, SRAM, Flip-Flop and Latch PUFs. We present a new PUF evaluation methodology that allows a more precise assessment of the unpredictability properties than previous approaches and we quantify the most important properties of PUFs for their use in cryptographic schemes. PUFs have been proposed for various applications, including anti-counterfeiting and authentication schemes. However, only rudimentary PUF security models exist, limiting the confidence in the security claims of PUF-based security mechanisms. We present a formal security framework for PUF-based primitives, which has been used in subsequent works to capture the properties of image-based PUFs and in the design of anti-counterfeiting mechanisms and physical hash functions

AEGIS : a single-chip secure processor

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (p. 225-240).Trust in remote interaction is a fundamental challenge in distributed computing environments. To obtain a remote party's trust, computing systems must be able to guarantee the privacy of intellectual property and the integrity of program execution. Unfortunately, traditional platforms cannot provide such guarantees under physical threats that exist in distributed environments. The AEGIS secure processor enables a physically secure computing platform to be built with a main processor as the only trusted hardware component. AEGIS empowers a remote party to authenticate the platform and guarantees secure execution even under physical threats. To realize the security features of AEGIS with only a single chip, this thesis presents a secure processor architecture along with its enabling security mechanisms. The architecture suggests a technique called suspended secure processing to allow a secure part of an application to be protected separately from the rest. Physical random functions provide a cheap and secure way of generating a unique secret key on each processor, which enables a remote party to authenticate the processor chip.(cont.) Memory encryption and integrity verification mechanisms guarantee the privacy and the integrity of off-chip memory content, respectively. A fully-functional RTL implementation and simulation studies demonstrate that the overheads associated with this single-chip approach is reasonable. The security components in AEGIS consumes about 230K logic gates. AEGIS, with its off-chip protection mechanisms, is slower than traditional processors by 26% on average for large applications and by a few percent for embedded applications. This thesis also shows that using AEGIS requires only minor modifications to traditional operating systems and compilers.by Gookwon Edward Suh.Ph.D

A User Centric Security Model for Tamper-Resistant Devices

In this thesis we propose a design for a ubiquitous and interoperable device based on the smart card architecture to meet the challenges of privacy, trust, and security for traditional and emerging technologies like personal computers, smart phones and tablets. Such a de- vice is referred a User Centric Tamper-Resistant Device (UCTD). To support the smart card architecture for the UCTD initiative, we propose the delegation of smart card owner- ship from a centralised authority (i.e. the card issuer) to users. This delegation mandated a review of existing smart card mechanisms and their proposals for modifications/improve- ments to their operation. Since the inception of smart card technology, the dominant ownership model in the smart card industry has been refer to as the Issuer Centric Smart Card Ownership Model (ICOM). The ICOM has no doubt played a pivotal role in the proliferation of the technology into various segments of modern life. However, it has been a barrier to the convergence of different services on a smart card. In addition, it might be considered as a hurdle to the adaption of smart card technology into a general-purpose security device. To avoid these issues, we propose citizen ownership of smart cards, referred as the User Centric Smart Card Ownership Model (UCOM). Contrary to the ICOM, it gives the power of decision to install or delete an application on a smart card to its user. The ownership of corresponding applications remains with their respective application providers along with the choice to lease their application to a card or not. In addition, based on the UCOM framework, we also proposed the Coopetitive Architecture for Smart Cards (CASC) that merges the centralised control of card issuers with the provision of application choice to the card user. In the core of the thesis, we analyse the suitability of the existing smart card architectures for the UCOM. This leads to the proposal of three major contributions spanning the smart card architecture, the application management framework, and the execution environment. Furthermore, we propose protocols for the application installation mechanism and the application sharing mechanism (i.e. smart card firewall). In addition to this, we propose a framework for backing-up, migrating, and restoring the smart card contents. Finally, we provide the test implementation results of the proposed protocols along with their performance measures. The protocols are then compared in terms of features and performance with existing smart cards and internet protocols. In order to provide a more detailed analysis of proposed protocols and for the sake of completeness, we performed mechanical formal analysis using the CasperFDR.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Secure and safe virtualization-based framework for embedded systems development

Tese de Doutoramento - Programa Doutoral em Engenharia Electrónica e de Computadores (PDEEC)The Internet of Things (IoT) is here. Billions of smart, connected devices are proliferating at rapid pace in our key infrastructures, generating, processing and exchanging vast amounts of security-critical and privacy-sensitive data. This strong connectivity of IoT environments demands for a holistic, end-to-end security approach, addressing security and privacy risks across different abstraction levels: device, communications, cloud, and lifecycle managment. Security at the device level is being misconstrued as the addition of features in a late stage of the system development. Several software-based approaches such as microkernels, and virtualization have been used, but it is proven, per se, they fail in providing the desired security level. As a step towards the correct operation of these devices, it is imperative to extend them with new security-oriented technologies which guarantee security from the outset. This thesis aims to conceive and design a novel security and safety architecture for virtualized systems by 1) evaluating which technologies are key enablers for scalable and secure virtualization, 2) designing and implementing a fully-featured virtualization environment providing hardware isolation 3) investigating which "hard entities" can extend virtualization to guarantee the security requirements dictated by confidentiality, integrity, and availability, and 4) simplifying system configurability and integration through a design ecosystem supported by a domain-specific language. The developed artefacts demonstrate: 1) why ARM TrustZone is nowadays a reference technology for security, 2) how TrustZone can be adequately exploited for virtualization in different use-cases, 3) why the secure boot process, trusted execution environment and other hardware trust anchors are essential to establish and guarantee a complete root and chain of trust, and 4) how a domain-specific language enables easy design, integration and customization of a secure virtualized system assisted by the above mentioned building blocks.Vivemos na era da Internet das Coisas (IoT). Biliões de dispositivos inteligentes começam a proliferar nas nossas infraestruturas chave, levando ao processamento de avolumadas quantidades de dados privados e sensíveis. Esta forte conectividade inerente ao conceito IoT necessita de uma abordagem holística, em que os riscos de privacidade e segurança são abordados nas diferentes camadas de abstração: dispositivo, comunicações, nuvem e ciclo de vida. A segurança ao nível dos dispositivos tem sido erradamente assegurada pela inclusão de funcionalidades numa fase tardia do desenvolvimento. Têm sido utilizadas diversas abordagens de software, incluindo a virtualização, mas está provado que estas não conseguem garantir o nível de segurança desejado. De forma a garantir a correta operação dos dispositivos, é fundamental complementar os mesmos com novas tecnologias que promovem a segurança desde os primeiros estágios de desenvolvimento. Esta tese propõe, assim, o desenvolvimento de uma solução arquitetural inovadora para sistemas virtualizados seguros, contemplando 1) a avaliação de tecnologias chave que promovam tal realização, 2) a implementação de uma solução de virtualização garantindo isolamento por hardware, 3) a identificação de componentes que integrados permitirão complementar a virtualização para garantir os requisitos de segurança, e 4) a simplificação do processo de configuração e integração da solução através de um ecossistema suportado por uma linguagem de domínio específico. Os artefactos desenvolvidos demonstram: 1) o porquê da tecnologia ARM TrustZone ser uma tecnologia de referência para a segurança, 2) a efetividade desta tecnologia quando utilizada em diferentes domínios, 3) o porquê do processo seguro de inicialização, juntamente com um ambiente de execução seguro e outros componentes de hardware, serem essenciais para estabelecer uma cadeia de confiança, e 4) a viabilidade em utilizar uma linguagem de um domínio específico para configurar e integrar um ambiente virtualizado suportado pelos artefactos supramencionados

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