1,075 research outputs found
Hidden in the Cloud : Advanced Cryptographic Techniques for Untrusted Cloud Environments
In the contemporary digital age, the ability to search and perform operations on encrypted data has become increasingly important. This significance is primarily due to the exponential growth of data, often referred to as the "new oil," and the corresponding rise in data privacy concerns. As more and more data is stored in the cloud, the need for robust security measures to protect this data from unauthorized access and misuse has become paramount.
One of the key challenges in this context is the ability to perform meaningful operations on the data while it remains encrypted. Traditional encryption techniques, while providing a high level of security, render the data unusable for any practical purpose other than storage. This is where advanced cryptographic protocols like Symmetric Searchable Encryption (SSE), Functional Encryption (FE), Homomorphic Encryption (HE), and Hybrid Homomorphic Encryption (HHE) come into play. These protocols not only ensure the confidentiality of data but also allow computations on encrypted data, thereby offering a higher level of security and privacy.
The ability to search and perform operations on encrypted data has several practical implications. For instance, it enables efficient Boolean queries on encrypted databases, which is crucial for many "big data" applications. It also allows for the execution of phrase searches, which are important for many machine learning applications, such as intelligent medical data analytics. Moreover, these capabilities are particularly relevant in the context of sensitive data, such as health records or financial information, where the privacy and security of user data are of utmost importance.
Furthermore, these capabilities can help build trust in digital systems. Trust is a critical factor in the adoption and use of digital services. By ensuring the confidentiality, integrity, and availability of data, these protocols can help build user trust in cloud services. This trust, in turn, can drive the wider adoption of digital services, leading to a more inclusive digital society.
However, it is important to note that while these capabilities offer significant advantages, they also present certain challenges. For instance, the computational overhead of these protocols can be substantial, making them less suitable for scenarios where efficiency is a critical requirement. Moreover, these protocols often require sophisticated key management mechanisms, which can be challenging to implement in practice. Therefore, there is a need for ongoing research to address these challenges and make these protocols more efficient and practical for real-world applications.
The research publications included in this thesis offer a deep dive into the intricacies and advancements in the realm of cryptographic protocols, particularly in the context of the challenges and needs highlighted above.
Publication I presents a novel approach to hybrid encryption, combining the strengths of ABE and SSE. This fusion aims to overcome the inherent limitations of both techniques, offering a more secure and efficient solution for key sharing and access control in cloud-based systems. Publication II further expands on SSE, showcasing a dynamic scheme that emphasizes forward and backward privacy, crucial for ensuring data integrity and confidentiality. Publication III and Publication IV delve into the potential of MIFE, demonstrating its applicability in real-world scenarios, such as designing encrypted private databases and additive reputation systems. These publications highlight the transformative potential of MIFE in bridging the gap between theoretical cryptographic concepts and practical applications. Lastly, Publication V underscores the significance of HE and HHE as a foundational element for secure protocols, emphasizing its potential in devices with limited computational capabilities.
In essence, these publications not only validate the importance of searching and performing operations on encrypted data but also provide innovative solutions to the challenges mentioned. They collectively underscore the transformative potential of advanced cryptographic protocols in enhancing data security and privacy, paving the way for a more secure digital future
A Trust Management Framework for Vehicular Ad Hoc Networks
The inception of Vehicular Ad Hoc Networks (VANETs) provides an opportunity for road users and public infrastructure to share information that improves the operation of roads and the driver experience. However, such systems can be vulnerable to malicious external entities and legitimate users. Trust management is used to address attacks from legitimate users in accordance with a user’s trust score. Trust models evaluate messages to assign rewards or punishments. This can be used to influence a driver’s future behaviour or, in extremis, block the driver. With receiver-side schemes, various methods are used to evaluate trust including, reputation computation, neighbour recommendations, and storing historical information. However, they incur overhead and add a delay when deciding whether to accept or reject messages. In this thesis, we propose a novel Tamper-Proof Device (TPD) based trust framework for managing trust of multiple drivers at the sender side vehicle that updates trust, stores, and protects information from malicious tampering. The TPD also regulates, rewards, and punishes each specific driver, as required. Furthermore, the trust score determines the classes of message that a driver can access. Dissemination of feedback is only required when there is an attack (conflicting information). A Road-Side Unit (RSU) rules on a dispute, using either the sum of products of trust and feedback or official vehicle data if available. These “untrue attacks” are resolved by an RSU using collaboration, and then providing a fixed amount of reward and punishment, as appropriate. Repeated attacks are addressed by incremental punishments and potentially driver access-blocking when conditions are met. The lack of sophistication in this fixed RSU assessment scheme is then addressed by a novel fuzzy logic-based RSU approach. This determines a fairer level of reward and punishment based on the severity of incident, driver past behaviour, and RSU confidence. The fuzzy RSU controller assesses judgements in such a way as to encourage drivers to improve their behaviour. Although any driver can lie in any situation, we believe that trustworthy drivers are more likely to remain so, and vice versa. We capture this behaviour in a Markov chain model for the sender and reporter driver behaviours where a driver’s truthfulness is influenced by their trust score and trust state. For each trust state, the driver’s likelihood of lying or honesty is set by a probability distribution which is different for each state. This framework is analysed in Veins using various classes of vehicles under different traffic conditions. Results confirm that the framework operates effectively in the presence of untrue and inconsistent attacks. The correct functioning is confirmed with the system appropriately classifying incidents when clarifier vehicles send truthful feedback. The framework is also evaluated against a centralized reputation scheme and the results demonstrate that it outperforms the reputation approach in terms of reduced communication overhead and shorter response time. Next, we perform a set of experiments to evaluate the performance of the fuzzy assessment in Veins. The fuzzy and fixed RSU assessment schemes are compared, and the results show that the fuzzy scheme provides better overall driver behaviour. The Markov chain driver behaviour model is also examined when changing the initial trust score of all drivers
Climate Change and Critical Agrarian Studies
Climate change is perhaps the greatest threat to humanity today and plays out as a cruel engine of myriad forms of injustice, violence and destruction. The effects of climate change from human-made emissions of greenhouse gases are devastating and accelerating; yet are uncertain and uneven both in terms of geography and socio-economic impacts. Emerging from the dynamics of capitalism since the industrial revolution — as well as industrialisation under state-led socialism — the consequences of climate change are especially profound for the countryside and its inhabitants. The book interrogates the narratives and strategies that frame climate change and examines the institutionalised responses in agrarian settings, highlighting what exclusions and inclusions result. It explores how different people — in relation to class and other co-constituted axes of social difference such as gender, race, ethnicity, age and occupation — are affected by climate change, as well as the climate adaptation and mitigation responses being implemented in rural areas. The book in turn explores how climate change – and the responses to it - affect processes of social differentiation, trajectories of accumulation and in turn agrarian politics. Finally, the book examines what strategies are required to confront climate change, and the underlying political-economic dynamics that cause it, reflecting on what this means for agrarian struggles across the world. The 26 chapters in this volume explore how the relationship between capitalism and climate change plays out in the rural world and, in particular, the way agrarian struggles connect with the huge challenge of climate change. Through a huge variety of case studies alongside more conceptual chapters, the book makes the often-missing connection between climate change and critical agrarian studies. The book argues that making the connection between climate and agrarian justice is crucial
Trusted Provenance with Blockchain - A Blockchain-based Provenance Tracking System for Virtual Aircraft Component Manufacturing
The importance of provenance in the digital age has led to significant interest in utilizing blockchain technology for tamper-proof storage of provenance data. This thesis proposes a blockchain-based provenance tracking system for the certification of aircraft components. The aim is to design and implement a system that can ensure the trustworthy, tamper-resistant storage of provenance documents originating from an aircraft manufacturing process. To achieve this, the thesis presents a systematic literature review, which provides a comprehensive overview of existing works in the field of provenance and blockchain technology. After obtaining strategies to utilize blockchain for the storage of provenance data on the blockchain, a system was designed to meet the requirements of stakeholders in the aviation industry. The thesis utilized a systematic approach to gather requirements by conducting interviews with stakeholders. The system was implemented using a combination of smart contracts and a graphical user interface to provide tamper-resistant, traceable storage of relevant data on a transparent blockchain. An evaluation based on the requirements identified during the requirement engineering process found that the proposed system meets all identified requirements. Overall, this thesis offers insight into a potential application of blockchain technology in the aviation industry and provides a valuable resource for researchers and industry professionals seeking to leverage blockchain technology for provenance tracking and certification purpose
Unlinkable Policy-based Sanitizable Signatures
In CT-RSA 2020, P3S was proposed as the first policy-based sanitizable signature scheme which allows the signer to designate future message sanitizers by defining an access policy relative to their attributes rather than their keys. However, since P3S utilizes a policy-based chameleon hash (PCH), it does not achieve unlinkability which is a required notion in privacy-preserving applications. Moreover, P3S requires running a procedure to share the secret trapdoor information for PCH with each new sanitizer before sanitizing a new message. We further observe that in order to maintain the transparency in P3S’s multiple-sanitizers setting, the signature size should grow linearly with the number of sanitizers. In this work, we propose an unlinkable policy-based sanitizable signature scheme (UP3S) where we employ a rerandomizable digital signature scheme and a traceable attribute-based signature scheme as its building blocks. Compared to P3S, UP3S achieves unlinkability, does not require new secrets to be shared with future sanitizers prior to sanitizing each message, and has a fixed signature size for a given sanitization policy. We define and formally prove the security notions of the generic scheme, propose an instantiation of UP3S utilizing the Pointcheval-Sanders rerandomizable signature scheme and DTABS traceable attribute-based signature scheme, and analyze its efficiency. Finally, we compare UP3S with P3S in terms of the features of the procedures, scalability, and security models
Cybersecurity applications of Blockchain technologies
With the increase in connectivity, the popularization of cloud services, and the rise
of the Internet of Things (IoT), decentralized approaches for trust management
are gaining momentum. Since blockchain technologies provide a distributed ledger,
they are receiving massive attention from the research community in different application
fields. However, this technology does not provide cybersecurity by itself.
Thus, this thesis first aims to provide a comprehensive review of techniques and
elements that have been proposed to achieve cybersecurity in blockchain-based systems.
The analysis is intended to target area researchers, cybersecurity specialists
and blockchain developers. We present a series of lessons learned as well. One of
them is the rise of Ethereum as one of the most used technologies.
Furthermore, some intrinsic characteristics of the blockchain, like permanent
availability and immutability made it interesting for other ends, namely as covert
channels and malicious purposes.
On the one hand, the use of blockchains by malwares has not been characterized
yet. Therefore, this thesis also analyzes the current state of the art in this area. One
of the lessons learned is that covert communications have received little attention.
On the other hand, although previous works have analyzed the feasibility of
covert channels in a particular blockchain technology called Bitcoin, no previous
work has explored the use of Ethereum to establish a covert channel considering all
transaction fields and smart contracts.
To foster further defence-oriented research, two novel mechanisms are presented
on this thesis. First, Zephyrus takes advantage of all Ethereum fields and smartcontract
bytecode. Second, Smart-Zephyrus is built to complement Zephyrus by
leveraging smart contracts written in Solidity. We also assess the mechanisms feasibility
and cost. Our experiments show that Zephyrus, in the best case, can embed
40 Kbits in 0.57 s. for US 1.82 per bit), the provided stealthiness might be worth the price for attackers. Furthermore,
these two mechanisms can be combined to increase capacity and reduce
costs.Debido al aumento de la conectividad, la popularización de los servicios en la nube
y el auge del Internet de las cosas (IoT), los enfoques descentralizados para la
gestión de la confianza están cobrando impulso. Dado que las tecnologías de cadena
de bloques (blockchain) proporcionan un archivo distribuido, están recibiendo
una atención masiva por parte de la comunidad investigadora en diferentes campos
de aplicación. Sin embargo, esta tecnología no proporciona ciberseguridad por sí
misma. Por lo tanto, esta tesis tiene como primer objetivo proporcionar una revisión
exhaustiva de las técnicas y elementos que se han propuesto para lograr la ciberseguridad
en los sistemas basados en blockchain. Este análisis está dirigido a investigadores
del área, especialistas en ciberseguridad y desarrolladores de blockchain. A
su vez, se presentan una serie de lecciones aprendidas, siendo una de ellas el auge
de Ethereum como una de las tecnologías más utilizadas.
Asimismo, algunas características intrínsecas de la blockchain, como la disponibilidad
permanente y la inmutabilidad, la hacen interesante para otros fines, concretamente
como canal encubierto y con fines maliciosos.
Por una parte, aún no se ha caracterizado el uso de la blockchain por parte
de malwares. Por ello, esta tesis también analiza el actual estado del arte en este
ámbito. Una de las lecciones aprendidas al analizar los datos es que las comunicaciones
encubiertas han recibido poca atención.
Por otro lado, aunque trabajos anteriores han analizado la viabilidad de los
canales encubiertos en una tecnología blockchain concreta llamada Bitcoin, ningún
trabajo anterior ha explorado el uso de Ethereum para establecer un canal encubierto
considerando todos los campos de transacción y contratos inteligentes.
Con el objetivo de fomentar una mayor investigación orientada a la defensa,
en esta tesis se presentan dos mecanismos novedosos. En primer lugar, Zephyrus
aprovecha todos los campos de Ethereum y el bytecode de los contratos inteligentes.
En segundo lugar, Smart-Zephyrus complementa Zephyrus aprovechando los contratos inteligentes escritos en Solidity. Se evalúa, también, la viabilidad y el coste
de ambos mecanismos. Los resultados muestran que Zephyrus, en el mejor de los
casos, puede ocultar 40 Kbits en 0,57 s. por 1,64 US$, y recuperarlos en 2,8 s.
Smart-Zephyrus, por su parte, es capaz de ocultar un secreto de 4 Kb en 41 s. Si
bien es cierto que es caro (alrededor de 1,82 dólares por bit), el sigilo proporcionado
podría valer la pena para los atacantes. Además, estos dos mecanismos pueden
combinarse para aumentar la capacidad y reducir los costesPrograma de Doctorado en Ciencia y Tecnología Informática por la Universidad Carlos III de MadridPresidente: José Manuel Estévez Tapiador.- Secretario: Jorge Blasco Alís.- Vocal: Luis Hernández Encina
ArchCloudChain Dapp: the efficient workflow for interior designers
The interior design and construction industry involves various stakeholders who must collaborate
and coordinate effectively to ensure the successful realization of projects. However, the existing
workflow often suffers from fragmentation and inefficiency, leading to delays, errors, and
increased costs. To address these challenges, this paper introduces the Arch Cloud Chain Dapp
project, a decentralized software application that leverages blockchain technology and Building
Information Modeling (BIM) to establish a transparent, secure, and efficient platform for
stakeholder collaboration in interior design projects. The primary objective of this project is to
reduce interior design costs while upholding high standards of quality and transparency.
By integrating BIM and blockchain technology, the Arch Cloud Chain Dapp enables stakeholders
to collaborate in real-time, significantly mitigating the risk of errors and miscommunication. Smart
contracts play a crucial role in ensuring the enforceability and transparency of agreements, while
the blockchain serves as an immutable ledger, providing an auditable record of all project
transactions. These innovative features present a novel solution to the challenges faced by the
interior design and construction industry.
The Arch Cloud Chain Dapp project holds significant potential to revolutionize the industry by
streamlining processes, enhancing collaboration, and reducing costs. Through its adoption,
stakeholders can benefit from improved project outcomes, streamlined communication, and
enhanced efficiency, ultimately leading to a more sustainable and prosperous interior design and
construction sector
Next Generation Business Ecosystems: Engineering Decentralized Markets, Self-Sovereign Identities and Tokenization
Digital transformation research increasingly shifts from studying information systems within organizations towards adopting an ecosystem perspective, where multiple actors co-create value. While digital platforms have become a ubiquitous phenomenon in consumer-facing industries, organizations remain cautious about fully embracing the ecosystem concept and sharing data with external partners. Concerns about the market power of platform orchestrators and ongoing discussions on privacy, individual empowerment, and digital sovereignty further complicate the widespread adoption of business ecosystems, particularly in the European Union.
In this context, technological innovations in Web3, including blockchain and other distributed ledger technologies, have emerged as potential catalysts for disrupting centralized gatekeepers and enabling a strategic shift towards user-centric, privacy-oriented next-generation business ecosystems. However, existing research efforts focus on decentralizing interactions through distributed network topologies and open protocols lack theoretical convergence, resulting in a fragmented and complex landscape that inadequately addresses the challenges organizations face when transitioning to an ecosystem strategy that harnesses the potential of disintermediation.
To address these gaps and successfully engineer next-generation business ecosystems, a comprehensive approach is needed that encompasses the technical design, economic models, and socio-technical dynamics. This dissertation aims to contribute to this endeavor by exploring the implications of Web3 technologies on digital innovation and transformation paths. Drawing on a combination of qualitative and quantitative research, it makes three overarching contributions:
First, a conceptual perspective on \u27tokenization\u27 in markets clarifies its ambiguity and provides a unified understanding of the role in ecosystems.
This perspective includes frameworks on: (a) technological; (b) economic; and (c) governance aspects of tokenization.
Second, a design perspective on \u27decentralized marketplaces\u27 highlights the need for an integrated understanding of micro-structures, business structures, and IT infrastructures in blockchain-enabled marketplaces. This perspective includes: (a) an explorative literature review on design factors; (b) case studies and insights from practitioners to develop requirements and design principles; and (c) a design science project with an interface design prototype of blockchain-enabled marketplaces.
Third, an economic perspective on \u27self-sovereign identities\u27 (SSI) as micro-structural elements of decentralized markets. This perspective includes: (a) value creation mechanisms and business aspects of strategic alliances governing SSI ecosystems; (b) business model characteristics adopted by organizations leveraging SSI; and (c) business model archetypes and a framework for SSI ecosystem engineering efforts.
The dissertation concludes by discussing limitations as well as outlining potential avenues for future research. These include, amongst others, exploring the challenges of ecosystem bootstrapping in the absence of intermediaries, examining the make-or-join decision in ecosystem emergence, addressing the multidimensional complexity of Web3-enabled ecosystems, investigating incentive mechanisms for inter-organizational collaboration, understanding the role of trust in decentralized environments, and exploring varying degrees of decentralization with potential transition pathways
Trustworthy Decentralized Last Mile Delivery Framework Using Blockchain
The fierce competition and rapidly growing eCommerce market are painful headaches for logistics companies. In 2021, Canada Post’s parcel volume peaked at 361 million units with a minimum charge of $10 per each. The Last-Mile Delivery (LMD) is the final leg of the supply chain that ends with the package at the customer’s doorstep. LMD involves moving small shipments to geographically dispersed locations with high expectations on service levels and precise time windows. Therefore, it is the most complex and costly logistics process, accounting for more than 50% of the overall supply chain cost. Innovations like Crowdshipping, such as Uber and Amazon Flex, help overcome this inefficiency and provide an outstanding delivery experience by enabling freelancers willing to deliver packages if they are around. However, apartfrom the centralized nature of the Crowdshipping platforms, retailers pay a fee for outsourcing the delivery process, which is rising. Besides, they lack transparency, and most of them, if not all, are platform monopolies in the making.
New technologies such as blockchain recently introduced an opportunity to improve logistics and LMD operations. Several papers in the literature suggested employing blockchain and other cryptographic techniques for parcel delivery. Hence,this thesis presents a blockchain-based free-intermediaries crowd-logistics model and investigates the challenges that could harbor adopting this solution, such as user trust, data safety, security of transactions, and tracking service quality. Our framework combines a security assessment that examines the possible vulnerabilities of the proposed design and suggestions for mitigation and protection. Besides, it encourages couriers to act honestly by using a decentralized reputation model for couriers’ ratings based on their past behavior. A security analysis of our proposed system hasbeen provided, and the complete code of the smart contract has been publicly made available on GitHub
Unleashing the power of internet of things and blockchain: A comprehensive analysis and future directions.
As the fusion of the Internet of Things (IoT) and blockchain technology advances, it is increasingly shaping diverse fields. The potential of this convergence to fortify security, enhance privacy, and streamline operations has ignited considerable academic interest, resulting in an impressive body of literature. However, there is a noticeable scarcity of studies employing Latent Dirichlet Allocation (LDA) to dissect and categorize this field. This review paper endeavours to bridge this gap by meticulously analysing a dataset of 4455 journal articles drawn solely from the Scopus database, cantered around IoT and blockchain applications. Utilizing LDA, we have extracted 14 distinct topics from the collection, offering a broad view of the research themes in this interdisciplinary domain. Our exploration underscores an upswing in research pertaining to IoT and blockchain, emphasizing the rising prominence of this technological amalgamation. Among the most recurrent themes are IoT and blockchain integration in supply chain management and blockchain in healthcare data management and security, indicating the significant potential of this convergence to transform supply chains and secure healthcare data. Meanwhile, the less frequently discussed topics include access control and management in blockchain-based IoT systems and energy efficiency in wireless sensor networks using blockchain and IoT. To the best of our knowledge, this paper is the first to apply LDA in the context of IoT and blockchain research, providing unique perspectives on the existing literature. Moreover, our findings pave the way for proposed future research directions, stimulating further investigation into the less explored aspects and sustaining the growth of this dynamic field
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