A central tenet in mechanism design is the ability to irrevocably commit to a mechanism. Commitment is achieved by public declaration, letting players verify incentive properties in advance and the outcome in retrospect. However, public declaration can reveal superfluous information that is private to the mechanism designer, such as her target function or costs. We propose a new approach to commitment, and show how to commit to, and run, any given mechanism without disclosing it, while enabling the verification of incentive properties and the outcome -- all without any mediators. Our framework leverages zero-knowledge proofs -- a cornerstone of modern cryptographic theory.
Giampaolo Bella, Pietro Biondi, Stefano Bognanni, Sergio Esposito
Attackers may attempt exploiting Internet of Things (IoT) devices to operate them unduly as well as to gather personal data of the legitimate device owners’. Vulnerability Assessment and Penetration Testing (VAPT) sessions help to verify the effectiveness of the adopted security measures. However, VAPT over IoT devices, namely VAPT targeted at IoT devices, is an open research challenge due to the variety of target technologies and to the creativity it may require. Therefore, this article aims at guiding penetration testers to conduct VAPT sessions over IoT devices by means of a new cyber Kill Chain (KC) termed PETIoT. Several practical applications of PETIoT confirm that it is general, while its main novelty lies in the combination of attack and defence steps. PETIoT is demonstrated on a relevant example, the best-selling IP camera on Amazon Italy, the TAPO C200 by TP-Link, assuming an attacker who sits on the same network as the device’s in order to assess all the network interfaces of the device. Additional knowledge is generated in terms of three zero-day vulnerabilities found and practically exploited on the camera, one of these with High severity and the other two with Medium severity by the CVSS standard. These are camera Denial of Service (DoS), motion detection breach and video stream breach. The application of PETIoT culminates with the proof-of-concept of a home-made fix, based on an inexpensive Raspberry Pi 4 Model B device, for the last vulnerability. Ultimately, our responsible disclosure with the camera vendor led to the release of a firmware update that fixes all found vulnerabilities, confirming that PetIoT has valid impact in real-world scenarios.
In crowdsourcing systems, requesters publish tasks, and interested workers provide answers to get rewards. Worker anonymity motivates participation since it protects their privacy. Anonymity with unlinkability is an enhanced version of anonymity because it makes it impossible to ``link'' workers across the tasks they participate in. Another core feature of crowdsourcing systems is worker quality which expresses a worker's trustworthiness and quantifies their historical performance. Notably, worker quality depends on the participation history, revealing information about it, while unlinkability aims to disassociate the workers' identities from their past activity. In this work, we present AVeCQ, the first crowdsourcing system that reconciles these properties, achieving enhanced anonymity and verifiable worker quality updates. AVeCQ relies on a suite of cryptographic tools, such as zero-knowledge proofs, to (i) guarantee workers' privacy, (ii) prove the correctness of worker quality scores and task answers, and (iii) commensurate payments. AVeCQ is developed modularly, where the requesters and workers communicate over a platform that supports pseudonymity, information logging, and payments. In order to compare AVeCQ with the state-of-the-art, we prototype it over Ethereum. AVeCQ outperforms the state-of-the-art in three popular crowdsourcing tasks (image annotation, average review, and Gallup polls). For instance, for an Average Review task with $5$ choices and $128$ participating workers AVeCQ is 40\% faster (including overhead to compute and verify the necessary proofs and blockchain transaction processing time) with the task's requester consuming 87\% fewer gas units.
Lennart Linden, Dominik K. Klein, Karl A. Kalina, Jörg Brummund · 6 authors
In the present work, a hyperelastic constitutive model based on neural networks is proposed which fulfills all common constitutive conditions by construction, and in particular, is applicable to compressible material behavior. Using different sets of invariants as inputs, a hyperelastic potential is formulated as a convex neural network, thus fulfilling symmetry of the stress tensor, objectivity, material symmetry, polyconvexity, and thermodynamic consistency. In addition, a physically sensible stress behavior of the model is ensured by using analytical growth terms, as well as normalization terms which ensure the undeformed state to be stress free and with zero energy. In particular, polyconvex, invariant-based stress normalization terms are formulated for both isotropic and transversely isotropic material behavior. By fulfilling all of these conditions in an exact way, the proposed physics-augmented model combines a sound mechanical basis with the extraordinary flexibility that neural networks offer. Thus, it harmonizes the theory of hyperelasticity developed in the last decades with the up-to-date techniques of machine learning. Furthermore, the non-negativity of the hyperelastic neural network-based potentials is numerically examined by sampling the space of admissible deformations states, which, to the best of the authors' knowledge, is the only possibility for the considered nonlinear compressible models. For the isotropic neural network model, the sampling space required for that is reduced by analytical considerations. In addition, a proof for the non-negativity of the compressible Neo-Hooke potential is presented. The applicability of the model is demonstrated by calibrating it on data generated with analytical potentials, which is followed by an application of the model to finite element simulations. In addition, an adaption of the model to noisy data is shown and its [...]
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Elasticity and Material Modeling
Model Reduction and Neural Networks
Advanced Numerical Methods in Computational Mathematics
The purpose of blockchain technology is to solve the trust problem between people or institutions and make the communication data and network communication of the Internet. In the past, cryptography lost money. Passwords are used to protect data, and the cost is relatively high. But with blockchain, cryptography becomes valuable. The formation of blockchain has made new contributions to cryptography and done something we could not do in the past. With blockchain, cryptography is "valuable". In fact, there are many cryptographic primitives used in blockchain, such as hash, digital signature, and etc. Moreover, digital signature not only uses standard digital signature, but also uses ring signature, connectable ring signature, one-time signature, borromer ring signature, multi signature, homomorphic encryption, homomorphic commitment, accumulator, zero knowledge proof, etc. As well as the recently popular password signature toss. As mentioned above, the popularity of blockchain technology will completely break the centralized pattern, indicating the advent of a new era in the future - Web3.0. This paper focuses on the application of encryption technology in blockchain and expounds in detail the applications of such as hash function and ring signature in blockchain. This study analyzes the application of cryptography in blockchain and discusses to the development of encryption technology in the future.
Open access
Blockchain Technology Applications and Security
Cryptography and Data Security
Advanced Steganography and Watermarking Techniques
Xinyu Liu, Shan Ji, Xiaowan Wang, Liang Liu · 5 authors
Blockchain, with its characteristics of non-tamperability and decentralization, has had a profound impact on various fields of society and has set off a boom in the research and application of blockchain technology. However, blockchain technology faces the problem of data availability attacks during its application, which greatly limits the scope and domain of blockchain applications. One of the most advantageous researches to address this problem is the scalable data availability solution that integrates coding theory design into the Merkle tree promise. Based on this scheme, this paper combines a zero-knowledge accumulator with higher efficiency and security with local repair coding, and proposes a data availability scheme with strong dataset privacy protection. The scheme first encodes the data block information on the blockchain to ensure tamper-proof data, and then uses a zero-knowledge accumulator to store the encoded data block information. Its main purpose is to use zero-knowledge property to protect the accumulation set information stored in the accumulator from being leaked and to ensure that no other information about the accumulation set is revealed during the data transmission. It fundamentally reduces the possibility of attackers generating fraudulent information by imitating block data and further resists data availability attacks.
Abstract Decomposition puzzles are pencil-and-paper logic puzzles that involve partitioning a rectangular grid into several regions to satisfy certain rules. In this paper, we construct a generic card-based protocol called printing protocol , which can be used to physically verify solutions of decompositon puzzles. We apply the printing protocol to develop card-based zero-knowledge proof protocols for two such puzzles: Five Cells and Meadows. These protocols allow a prover to physically show that he/she knows solutions of the puzzles without revealing them.
Zero-knowledge proof (ZKP) is a cryptographic protocol that allows one party to prove the correctness of a statement to another party without revealing any information beyond the correctness of the statement itself. It guarantees computation integrity and confidentiality, and is therefore increasingly adopted in industry for a variety of privacy-preserving applications, such as verifiable outsource computing and digital currency.
Mohammed Balfaqih, Zain Balfagih, Akram A. Almohammedi, Khaled Mofawiz Alfawaz
The smart city concept serves the well-being of the urban population in order to improve quality of life in different life aspects including logistic services. However, the continuous growth of logistics volume combined with information opaqueness and process complexity led to challenging issues related to managing the services and information of logistics. Hence, efficient management of logistics activities with traceability and condition monitoring capabilities is required to ensure quality and safe delivery. It is necessary also to ensure the accuracy and dependability of distribution data. In this context, this paper proposes a smart and privacy-preserving logistics system for high-price goods distribution. An intelligent parcel (iParcel) containing piezoresistive sensors is developed to pack delivered goods during shipping process for violation detection such as severe fall or theft. Moreover, smart contracts based on blockchain is also developed for automatic approval and payment with the consideration of distributing the shipping information between legitimate logistics parties only. A zero-knowledge proof is used to conceal blockchain address and prove the authentication. iParcels are automatically tracked and traced in which upon violation occurrence, the contract is cancelled, and the payment is refunded. The transaction fee per party is reasonable for high-price products in the pay of guarantee successful shipment.
The amount of sensitive information that service providers handle about their users has become a concerning fact in many use cases, where users have no other option but to trust that those companies will not misuse their personal information. To solve that, Self-Sovereign Identity (SSI) systems have become a hot topic of research in recent years: SSI systems allow users to manage their identities transparently. Recent solutions represent the rights of users to use services as Non-Fungible Tokens (NFTs) stored on Blockchains, and users prove possession of these rights using Zero-Knowledge Proofs (ZKPs). However, even when ZKPs do not leak any information about the rights, the NFTs are stored as public values linked to known accounts, and thus, they can be traced. In this paper, we design a native privacy-preserving NFT model for the Dusk Network Blockchain, and on top of it, we deploy Citadel: our novel full-privacy-preserving SSI system, where the rights of the users are privately stored on the Dusk Network Blockchain, and users can prove their ownership in a fully private manner.
Federated learning (FL) protects training data in clients by collaboratively training local machine learning models of clients for a global model, instead of directly feeding the training data to the server. However, existing studies show that FL is vulnerable to various attacks, resulting in training data leakage or interfering with the model training. Specifically, an adversary can analyze local gradients and the global model to infer clients’ data, and poison local gradients to generate an inaccurate global model. It is extremely challenging to guarantee strong privacy protection of training data while ensuring the robustness of model training. None of the existing studies can achieve the goal. In this paper, we propose a robust privacy-preserving federated learning framework (PILE), which protects the privacy of local gradients and global models, while ensuring their correctness by gradient verification where the server verifies the computation process of local gradients. In PILE, we develop a verifiable perturbation scheme that makes confidential local gradients verifiable for gradient verification. In particular, we build two building blocks of zero-knowledge proofs for the gradient verification without revealing both local gradients and global models. We perform rigorous theoretical analysis that proves the security of PILE and evaluate PILE on both passive and active membership inference attacks. The experiment results show that the attack accuracy under PILE is between$[50.3\%,50.9\%]$, which is close to the random guesses. Particularly, compared to prior defenses that incur the accuracy losses ranging from 2% to 13%, the accuracy loss of PILE is negligible, i.e., only$\pm 0.3\%$accuracy loss.
Standard probabilistic models face fundamental challenges such as data scarcity, a large hypothesis space, and poor data transparency. To address these challenges, we propose a novel probabilistic model of data-driven temporal propositional reasoning. Unlike conventional probabilistic models where data is a product of domain knowledge encoded in the probabilistic model, we explore the reverse direction where domain knowledge is a product of data encoded in the probabilistic model. This more data-driven perspective suggests no distinction between maximum likelihood parameter learning and temporal propositional reasoning. We show that our probabilistic model is equivalent to a highest-order, i.e., full-memory, Markov chain, and it can also be viewed as a hidden Markov model requiring no distinction between hidden and observable variables. We discuss that limits provide a natural and mathematically rigorous way to handle data scarcity, including the zero-frequency problem. We also discuss that a probability distribution over data generated by our probabilistic model helps data transparency by revealing influential data used in predictions. The reproducibility of this theoretical work is fully demonstrated by the included proofs.
The research project discussed in this paper is driven by the United Kingdom’s (UK’s) need to reduce operational energy and carbon by promoting the adoption of the Active Building (AB) concept for UK building projects. The AB concept offers a practical solution to reducing the operational energy use and carbon emissions of buildings by using emerging technologies applied to architectural design; thus, helping the UK meet its decarbonisation targets and, consequently, helping to combat the global problem of climate change. The aim of the project was to design and implement an AB Protocol with an AB Toolkit, to provide a knowledge base and sustainable architectural design guidance to aid the design of ABs. The AB Toolkit was tested, evaluated, and refined by engaging with architectural designers in the UK through focus groups (FGs) that combined data collection with knowledge dissemination—a method which provided a contribution to the continuous professional development (CPD) of architectural designers in the UK, while aiding the research project. The FG data proved the original hypothesis that a whole host of measures are needed to support the adoption of the AB concept (as outlined in the AB Protocol), but that some design guidance was needed initially to enable the development of other supporting measures. Therefore, the main output of this research project was the development of a structured approach to enable architectural designers and other built-environment professionals to adopt the AB concept for the delivery of net zero operational energy buildings, supporting the aims of the SPECIFIC Innovation and Knowledge Centre, Swansea University, and the Active Building Centre (ABC). The method of data collection developed, and the structured approach to enabling the adoption of a new concept outlined, could be beneficial to other researchers.
Muhammad Muneem Shabir, Syed Muhammad Danish, Kaiwen Zhang
Video conferencing has become an essential tool for working from home. However, poor audio/video quality resulting from unstable Internet connections undermines the productivity of important tasks. Additionally, the static monetization model for ISP networks, which employs third parties, cannot support on-demand and dynamic Quality-of-Service sessions that are necessary to maximize the Quality-of-Experience (QoE) of video conferencing. To address this, we introduce BlockQoS: Fair Monetization of On-Demand Quality-of-Service using Blockchains. BlockQoS allows clients to request and manage their Quality-of-Service requirements through a blockchain-based platform operating using a smart contract. It implements a decentralized monetization model to eliminate third parties, enforce transparency in service-level agreements (SLAs), and reduce blockchain operating costs by utilizing off-chain billing validated using zero-knowledge proofs (zk-SNARK). Additionally, we propose a Quality-of-Service delivery verification mechanism that enforces service level agreements on the hardware external to the blockchain, and a dynamic evaluation method based on the concept of Nash equilibrium in game theory that prevents malicious behavior by ISPs and users. We implemented BlockQoS over Ethereum with a Ryu controller, zk-SNARK, and SGX. Our experiments show that BlockQoS offers transaction cost reduction of up to 88% (gas cost) and latency reduction of up to 87% compared to the state-of-the-art on-chain solutions.
Zhe Zhang, Min Zhou, Chao Wang, Yingying Wang · 7 authors
A new approach to conquer the thermal phase drift of an optical fiber Fabry-Perot interferometer (FPI) sensor is proposed and experimentally demonstrated. By employing a hollow-core anti-resonant fiber (HC-ARF) and optimizing the fusion splicing (includes mode field adaptation) between the lead-in single-mode fiber (SMF) and the HC-ARF, a high spectral resolution ( λ /Δ λ ≈ 3.8 × 10 4 ) optical fiber air-cavity FPI sensor with a fringe visibility higher than 7 dB is constructed. To eliminate the thermal phase drift (i.e. temperature crosstalk) of the sensor that originates from the intrinsic thermal expansion effect of the silica material of the HC-ARF, the FPI air cavity is connected to the external environments, by which the effect of air expelling from the cavity with temperature increasing can well compensate the temperature-induced cavity elongation. As a result, the thermal phase drift of the FPI is reduced to zero at a temperature range of ∼ 80–110 °C and within the temperature range of 40–80 °C, the thermal phase drift is still halved compared with the sealed FPI cavity. The nearly zero thermal phase drift of a FPI at such a temperature range has never been achieved before, to our best knowledge. As a proof of concept, a temperature-immune fiber-optic strain sensor is demonstrated. This work offers a new and efficient approach to eliminate the thermal phase drift (i.e. temperature crosstalk) of a fiber-optic device, which may significantly improve the measurement accuracy and detection limit of fiber-optic FPI sensors. Furthermore, the principle and schema can be generalized to a wide variety of fiber-optic devices.
From the day Dennis Tito became the first private citizen to travel to space for no other reason but the sake of the experience itself, space tourism stops being a chimaera and became a reality, albeit an elitist one. And if only seven passengers flew to the International Space Station (ISS) on board of Russian Soyuz rockets during the new millennium's first decade, other modalities of space tourism—such as sub-orbital travel—are increasingly getting commercialised due to its growing technological and financial accessibility (Chang, 2020). After years of hiatus, the sub-orbital commercial flights resumed in 2019, propelled by the combined contribution of the public (e.g., NASA) and private companies (such as Virgin Galactic and Blue Origin) in the main spacefaring countries. New entrants in the launching segment, even countries with no previous spacefaring history, such as New Zealand, have enhanced the potential for further development (Zhang & Wang, 2020). 2021 saw the record number of 14 civilians who experienced space travel (Space Foundation, 2022), almost doubling the number of all previous years combined. The vision of SpaceX (2020) to commercialise space flights to Mars by 2050 is regarded a distant but increasingly possible with the recent technological development and economic interest in space. Other endeavours, such as the building of orbiting space hotels (the Voyager Station due to open as early as 2027; CNN, 2021) are other, visionary on-going efforts to expand the remit of extreme tourism. And if until recently the market dimensions were limited, they are rapidly peaking up pace. A report from Northern Sky Research (2021) estimates at US $ 385 million revenues from orbital tourism, projected to grow as high as US$ 605 million by 2029. The suborbital segment looks even more dynamic, with an estimated compound annual growth rate (CAGR) of 24.5% in the decade 2021–2031. All this raises important questions about its sustainability and even the case for space tourism in the first place. Some consider it environmentally costly when not ethically unsavoury (Cohen, 2017; Guerster et al., 2019), and requiring overcoming formidable regulatory challenges (Padhy & Padhy, 2021). Especially for what concerns the costing side of space tourism, there is no breakthrough in sight, even though reusable rockets have done considerable progress in lowering the budget requirements for space missions (CSIS, 2020). Until the entire space adventure is dominated by the so-called ‘tyranny of the rocket equation’ (Petitt, as cited by Young, 2015, p.45), which translates in 90% of the weight of a rocket being just the fuel to lift it off the planet's surface, the economic burden will remain, and so will the associated environmental costs. Hence, the need to critically evaluate whether space tourism can indeed be made sustainable and ethical and, if so, what are the preconditions for making this happen. Interestingly, while any sustainability discourse for space is derived from the sustainable tourism frameworks, the applicability of sustainability indicators to space tourism remains unclear and never clearly defined before, a clear gap in the knowledge we have identified in this study. Although most authors are optimistic about the economic sustainability of space tourism, the predictions for social and environmental sustainability are not as promising. The moral dilemma of the equal distribution of space tourism generated wealth and its environmental impact are sensitive areas that require robust conceptualisation and empirical analysis. Moreover, the growing interest in space tourism research makes the absence of a theoretically grounded and robust analytical framework to enhance sustainability even more remarkable. This is the second, evident knowledge gap this article intends to address: devise a conceptual model that, building on the sustainable tourism framework and Dubin's (1970) theory building two-stage approach, is adapted to space tourism as an example of ‘frontier’ tourism with unique peculiar characters. Section 2 offers a working definition of space tourism, discusses how it fits in the overall debates about ethical tourism and sustainability, and is instrumental for what comes next: a systematic review of the literature of sustainable tourism from Dennis Tito's travel in 2001 up to 2021, aiming at identifying relevant indicators for sustainable tourism and evaluate their applicability to space tourism. Section 3 briefly covers the methodological aspects of both systematic reviews and conceptual models and identifies the above-mentioned indicators. Building on the critical analysis of 101 indicators, Section 4 designs a brand-new conceptual model for sustainable space tourism. As it stands, there is a fourth field (technology) altogether missing in the traditional model by White et al. (2006) and derived studies. Adopting Industry 4.0 (I4.0 afterwards; Sun et al., 2012; Baldwin, 2019; Schwab, 2015; Kagermann et al., 2011; Lasi et al., 2014) framework in relation to the space sector (Cristians & Methven, 2017; Forcina & Falcone, 2021; Vaidya et al., 2018), the analysis demonstrates why technology represents the cornerstone of the conceptual model presented in this article. Section 5 concludes that sustainability can be fully achieved in space tourism only when technology takes the front seat, with Industry 4.0 and its nine pillars unleashing their revolutionary capabilities. Due to the nature and scope of this study, we have focused mainly on sub-orbital tourism, although its conclusions can be opportunely expanded to include outer space activities. The final section also explores the potential of the conceptual model herein developed for empirical research, paving the way for next steps, future research, and proof of concept. There is still ambiguity about what qualifies as space tourism (Johnson & Martin, 2016). The European Space Agency (ESA 2008, p. 19) defines it as an “activity that will encompass the execution of sub-orbital flights by privately-funded and/or privately-operated vehicles and the associated technology development driven by the space tourism market”. Chang (2017) and Cohen and Spector (2019a) define commercial space travel as leisure and recreation, allowing tourists to experience zero-gravity and celestial observation. Spector (2020b) categorises space tourism into three broad subcategories, i.e. sub-orbital, orbital, and beyond-orbital (ie, outer space, such as in a lunar base or a Martian outpost) and so do Friel (2020), Cohen and Spector (2019a), Chang (2015) and Webber (2013). On the other hand, Ma et al. (2020); Soleimani et al. (2019), and earlier Weaver (2011) include spacecraft launching observation as such. Damjanov and Crouch (2018), Frischauf et al. (2018) Weeks and Faiyetole (2014) add digital components (EVR, enhanced virtual reality) to the definition. From a legal point of view, that the definition of an astronaut (there is still no legal counterpart to ESA's industry definition of a space tourist; Failat, 2012) consist of two main aspects: the training required for the task and distance from Earth's surface they reach. Requirements vary a great deal, and if 6 months are generally considered necessary to visit the ISS (UNOOSA, 2022b), Virgin Galactic asks for only 1 week of preparatory training for suborbital flights (Virgin Galactic, 2022). Still, the non-professional personnel in space are considered ‘visiting crewmembers’ by the Inter-Governmental Agreement (‘IGA’) in an agreement reached between the space agency's participating to the ISS project (NASA, 2002). Although without binding legal value beyond the ISS, it constitutes nonetheless a ‘trendsetting, if not an industry standard’ (Von der Dunk, 2013). This matters, because the definition of the phenomenon affects its perception as feasible, ethically sustainable, and economically viable. Tourism is a significant contributor to many national economies, directly contributing on average 4.4% of national GDP and 21.5% of service exports in OECD countries (OECD, 2020). Even as a niche subsector (Friel, 2020), space tourism is rapidly becoming attractive for its high-skill job creation and revenue spillovers (Zhang & Wang, 2020). The economic multiplier of such developments will be higher than other industries (Cole, 2015), whereas the knowledge and skill base will facilitate space infrastructure construction (Komerath et al., 2007; Zhang & Wang, 2020). Friel (2020) and Spector (2020a) predict that space tourism will benefit terrestrial tourism destinations in the launching countries, facilitating all types of space flights and (Webber, 2013) becoming a pivotal sector of the economy due to economy of scale. space as a the of as the by and the during the of astronaut Space tourism can and public have a new from the traditional space research 2012) private is even in the is infrastructure private economic growth with potential for for while such as space Space tourism will still from to and models on the potential of the space tourism market (Chang, Cohen & 2015; et al., 2007; & 2013) are of in of (Zhang & Wang, 2020). (Komerath et al., a for the space tourism et al. identified training of of the as the most critical is et al., and Crouch with such recent & et al., et al., who perception also a and The industry will require a to tourists in an of space et al., and that and as important areas of research in the next The so-called space (the of the from the not to to companies but only to is for commercial tourism as the analysis of between national and their and 2015; and of & The only the commercial or extreme tourism (the and adventure & A legal in its will a and the legal of commercial the for the space tourism & and (2013). outer space and traditional in future studies. 2017; & and the economic sustainability of space tourism with the legal and for and tourists & of the space tourism and 2013) for the sector will also need in about relevant at the tourism sector in that research in sustainable p. Still, years the the industry is not to and systematic literature review have the of sustainable tourism et al., 2018), and their et al., 2015), indicators et al., 2017; & et al., 2020), challenges and to sustainability and et al., et al., 2021). (2018), and et al. (2018) and et al. (2018) have such to the tourism from to the and A is the need for a of sustainable indicators, which have in number and the a et al., for the industry and making it to and their & and et al., 2015, the of and as the for such and (2014) and et al. (2018) empirical that sustainability concerns and and There is the and of what constitutes a for sustainability, from from to for & And when it comes to space tourism, sustainability a The of the space sector 2019; are the of the space missions and their environmental are in the of a interest of the space and progress orbiting have due to 2018), when it comes to such as tourism, A the of private space both in of of and social the ethical dilemma for commercial space the (2018) discusses the moral of for space Other the for the of outer space and of tourists in space and the of an equal distribution of from space tourism 2020). Weeks and Faiyetole (2014) a to space to public and on sensitive social The impact of space tourism on and is of social space as tourism, (2020) and into the and other space the is a of and predict that space tourism and on Spector and and so do Cohen and Spector in outer space. the environmental sustainability of space tourism remains a Tourism such as Cohen (2018), et al. if space tourism can be sustainable at such as and (2018) and (2006) considered the impact of the in the space due to which have the potential to further environmental to the in space is of growing 2021; & to (2018), space tourism the Earth's and more as the of to space tourism will to the Earth's A recent by (2020) the impact of development on and of space tourism such as and (2020) and Spector that the in the which can on with space and the lunar being the to a new framework for sustainable space tourism, tourism the overall et al., 2019; components such as and Space tourism is such a and experience that to skill to et al., 2020), the of tourism & 2020). more than the for to into space tourism et al., 2012; et al., 2020), we to define in which way an experience that most as not can be and to a sustainable this we have the literature on space tourism to the tourism sustainability & et al., et al., 2018), three dimensions of sustainability, and three dimensions were for a they were derived from the theory of and as an framework to a sustainable tourism model et al., from which conceptual model for sustainable space tourism models are a in social more than et al., 2020). by the and model and et al., and have in tourism and et al., 2019; et al., 2019; although they have not to model sustainable space tourism so As as conceptual systematic reviews are The framework in this article is the et al., et al., et al., identifying all the et & 2015), for and and making about A number of have for this review on space tourism, that of and the of The in the by & social environmental & and to indicators for sustainability in and the of the framework is in the et al., also with et al. when they that sustainability is not and that the of indicators is to of and still or about and in et & and in view, it to indicators for sustainable tourism when no definition of the the of the indicators in the important of the p. et al. (2017) and et al. (2018), both identified a of sustainability indicators. and (2020) first of 101 sustainability indicators economic indicators, and indicators, to their and by empirical 1 in a 2 from the first to what as the most relevant in the review that tourism are the most economic indicators. and of of and areas and their impact on the are the more as for environmental of sustainability (the social and components have in this article White et al., conceptual such as and in the tourism development and tourism to and of such and are in studies. Some of (e.g., tourism to and of such of due to the required to for a et al., 2016). The literature that there are between and sustainability as they to have focused more on environmental and sustainability to and is critical et al., 2011; et al., for analytical framework for the space tourism while other indicators and for et al., The of such indicators for sustainable space tourism of a critical and of indicators by are of due to their high of the space which a great from tourism. are in combined in as both for in of framework and possible to a between the indicators in 2 and the developed for the conceptual framework of space tourism. The is in 3 in and in in the next Section to the conceptual model for sustainable space tourism, we have combined Dubin's theory building (1970) as by to and a model which from and And if traditional theory building between the and the empirical research as two although we are clearly on the first the proof of to future about this in Section we have developed the conceptual model at a its framework and it with the relevant also in which way have in The point is the and cited conceptual model of sustainable tourism first presented by White et al., and adapted in the presented in The first conceptual model developed on White et al. (2006) and it to the of space tourism as in 2 and there is the literature on sustainable tourism on and space tourism on the other is that there are three components and there is no agreement in the literature about which is the most the three components are for sustainable tourism as White et al. (2006) as it is not to model space tourism, and it is to a fourth is and, in its it to a sustainable for tourism, no the way sustainability 2 how to technology in the conceptual model of sustainable space tourism. Some have defined space tourism industry as a niche a of to the this will it is not possible to the of space tourism without its technological which is a of to space. we not have space tourism (the of the of there no way for to the of the of outer This is the reason why technology to be in the as the fourth to space tourism not only sustainable but even we can further than that, to sustainability, we need to the way sustainability can be by a of Space technology as of the to the on by (UNOOSA, in from to and 2022). Even of the most the environmental recently efforts to the 2015; et al., et al., 2021) to enhance the Space as it is defined in the public is by a between Industry 4.0 and if not the have in the space sector (the of et al., 2021) in a brand-new of the sector itself, which the of sustainability at its at this and the way technology the space tourism sustainability it is at the other, more traditional and their indicators. the fourth in the it is possible to and a of the indicators for sustainable tourism in 2 to the new model for space tourism and indicators. 3 of indicators as in with for space tourism indicators from as from the literature considered in Section 2 and 3 and the for their A to 3 will that not all the indicators identified have as in the This is due to the of the Some indicators, such as no in the environmental of tourism, while they are an of growing in space tourism such as as in the components of to between space and in all at all as in Section as so 2 and 3 indicators, in a in the indicators are which to the still of development of space tourism an for of not a of when the number is than and their applicability is more and at this than be in the future space travel more other the between 2 and 3 indicators is tourism indicators & of 2 and the recently to sustainability et al., 2021) are to this analytical and it is not by that economy as of the of et al., are both and A of & will also in the space tourism and of the way this the in on the et al., 2021; et al., This is not without are the need to and and a and sensitive in the case of The orbital of space tourism will it to environmental and et al., et al., is not just the for the space sector as a and of the components of sustainable space tourism. the potential to the three other components of sustainable tourism in a way that is not even if we to all this into the conceptual model be and the pivotal of technology and its potential for The next how the model to for the of technology as the cornerstone of the entire The it both at a conceptual et al., 2012; Baldwin, 2019; Schwab, 2015; Kagermann et al., 2011; Lasi et al., 2014) and the of its (Cristians & Methven, 2017; Vaidya et al., Forcina & Falcone, 2021; et al., are to the sector beyond This is evident when at the way the nine pillars (e.g., and and as a are the space and, space tourism The literature on Industry 4.0 conceptualisation that, while its nine pillars et al., it is only when they are all that Industry 4.0 its potential for & this is for industry in this is even more in such as space industry space that not without which the sector the the most on space industry this The space 5 (OECD, 2019), in to for at a decade, in new space the sector from the traditional and and it a such as space and for a lunar to the of (e.g., new fuel and and have facilitating the of private into space SpaceX rockets to to while there is no to an to rocket that still the industry and all the space missions to the of 1 of for a weight into space (NASA, the by an orbiting in (the is just an example of what is to After the is of the most of space only to All the from to and even the lunar surface, are And if the of the economy is as for the sustainability of space tourism, the between space, and all working and is to even more The between Industry sustainability, and economy is still in its early et al., et al., et al., & the for a way et al., 2021). challenges do in the of models to et al., 2019; et al., as it is the case of the space the and the it have not have the as cornerstone of the 2015; and with the of Space 4.0 both by and by the 2016). have just at the & is to As by OECD (2019), 5 will the modalities space tourism takes and its to it And if the is any the only to have space tourism that environmentally sustainable, economically and is to on a technology that to space. for a more sustainable, as as the the of the Earth's all on the Industry 4.0 and can to Space the of the and on their sustainability as and p. be in as aiming for a sustainable than a sustainable this is even more in a sector in as space tourism. this will is a and more than is even though not all of or to the be and this is contribution to There are a to this study, which we fully of the on space tourism and not the and more about in outer space, be their the or Martian clear of the of in space in of the with the and what be for to & The between the to (the way intends to or the to the (the & 2007; & 2013) is way beyond the scope of this we have not considered the and aspects that to tourism of which space can be considered a (Cohen, There are many on the et al., & which we but not for a in the to for it The model only to it The important of the regulatory framework that can space tourism by legal no for the not Due to the of the which require a article by itself, the legal aspects have into the economic of an space, as for the they for the private and commercial dimensions of the most important space tourism There is important from the so is not in of scope but the conceptual in this we have not presented a case to the model itself, for two main because we that what missing in the first a conceptual model for sustainable space tourism on the of White et al. to the for the of space in such an article. This is to be in future studies. The about of a space tourism that can be both and sustainable, just is to with the itself, although of the they will both a if the even space tourism, its is and a only from the that such tourism can and be made This is with a conceptual model that the indicators of sustainable tourism with the of the space is both and that will and even the if this can the the conceptual model to a case to in which way the components identified in and which of we need for this to are the next will be to the of the model not only in an but to evaluate its value for the if that sustainable and space tourism is we into the way technology can a sustainable of the space tourism. technology the to the space adventure as a it can and also be the main to sustainable space tourism. The way we can it is to as a and, as a is a in & at a from of and two working in on the space and Industry The New of and and space for a sustainable economy from the space of is an research interest on and tourism studies. not to this article as no were generated or during the
This note outlines three key areas of transformation that competition law has gone through in the past few decades and considers the direction it should take from here. The idea is to juxtapose the role of ex ante regulation with ex post competition law interventions in getting to grips with novel types of harms that the digital economy has brought about and that increasingly pertain to consumers, the market, and society as a whole. There are essentially two debates around the role of competition that have influenced the manner in which the law contends with data-driven markets. One relates to the goals of competition law.1 Much legal doctrine has assumed that we need one single theory to make competition policy consistent—we may refer to this as first-generation competition law. Another relates to the means by which competition law achieves its goals.2 Here, legal doctrine has focused predominantly on entitlements and market structure—we may call it second-generation competition law. The issues underlying these debates have recently been catalysed by several high-profile empirical investigations that observed rising concentrations of corporate power3 and the associated claim that competition law should be employed to restructure markets, by breaking big technology companies up or by divesting them into separate units.4 Regardless of whether one leans towards ex ante regulation or ex post competition law interventions in dealing with problems of concentration and their harmful economic and social effects, the result of these debates is a set of shared assumptions which have produced the coding structure that has become the node between theory and practice. Analysts have internalized these assumptions, although different camps put their own normative twists on them. The problem is that competition law’s coding structure has become redundant: it no longer represents the deep-seated realities of data-driven markets. In highly concentrated marketplaces, competition law and regulation inevitably work together, depending on and colliding with one another, but neither entirely holds sway. Against this backdrop, competition theory and doctrine can no longer serve one single goal nor can they continue to rely exclusively on entitlements or market structure. And yet much legal scholarship still turns upon these debates.5 The Digital Markets Act (DMA) is perhaps the most pertinent example of this trend.6 Data-driven markets require a distinct frame for conceptualizing novel types of harms—third-generation competition law. This is especially relevant for stalwarts of ex ante regulation who steadfastly maintain that issues around product quality in digital markets are outside the purview of competition law. By insisting that competition law pursues one single goal—usually in terms of low price (and high output)—this perspective severely prejudices any potential reflection as to how the law contends with issues posed by markets with a zero price and frustrates the ability to arrive at an effective resolution of such issues. Apologists of ex post competition law interventions must also adjust their views. There are good reasons behind their belief that decentralization matters; however, they frequently insist on an increasingly antiquated notion of how competition operates, in that the only disciplining mechanism in terms of leading actors’ behaviour consists in affording consumers an ‘exit’ option, that is, an opportunity to switch between different alternative offers. The image of the perfectly competitive market, for instance, is exit-centred to the extent that sellers are unable to displease their customers because consumers will swiftly shift from one supplier to another if they are dissatisfied with the products and services they receive. And if switching turns out to be impossible or unworkable, second-best alternatives such as separations or divestitures are thought to reinstate the ability of consumers to switch, pushing concentrated power out to the ends of the Internet and defying any consolidated arrangement involving small groups of dominant undertakings, as though no alternatives prevailed. This note will briefly survey these debates, but the emphasis is on what lies ahead—what ought competition theory and doctrine to resemble in the digital economy? Without a doubt, any answer to this question is unlikely to assume the sophistication and precision that have marked previous debates; however, this is precisely the point of this note. Disputes around data-driven markets regularly turn upon the major Internet platforms’ illegal acquisition of small competitors, their character as monopolies, and their preference for their own related products through network algorithms, resulting in harm to competing producers. Moreover, there are concerns around the platforms’ size and reach, which highlight the risk of suffocating progress, intensifying inequality, and exacerbating social and political polarization.7 To address these harms, policymakers regularly maintain that competition law should be employed to break the companies up or to divest them into previously acquired entities. Proposals such as these, however, contain a complex tension: because the dominant platforms’ activities present risks in economic and non-economic terms, competition law either needs to be repurposed, to deal with a broader set of values, or is required to refrain from contending with non-economic issues altogether—issues that are better dealt with by laws designed specifically to target privacy, data security, fake news, and so forth. The problem with this view is that distrust in the sheer size of big technology platforms, and the reach of their activities, obscures the network benefits that these platforms generate and that they may augment by expansion in the future.8 The tension is in large part a consequence of the debate around the goals of competition law: whether competition law needs to be focused exclusively on consumers, competitors, or both, or whether it should also attend to the social and political harms of market power. First-generation competition law cannot adequately capture the realities of digital markets that implicate seemingly non-economic values such as privacy, diversity, or editorial integrity. It presupposes claims that are based upon price and output when in fact these claims relate mostly to (various types of) product quality.9 Bringing competition theory and doctrine up to date would require theorists to acknowledge that competition law cannot be understood as an avenue to promote one single set of values. Instead, it should be seen as a practical device to underpin consumers’ calls and to align the economic goals of leading actors with the views of their own customers. To be sure, it is perfectly reasonable to argue that competition authorities and courts should focus on one single goal because they lack the required knowledge to make rules that can govern unknown future circumstances in dynamic settings. In the digital economy, however, decisions taken by authorities and courts inevitably affect the policies adopted by dominant incumbent actors, thereby shaping the broader legal and economic landscape. For this very reason, authorities and courts with limited knowledge may adopt instead a blend of different enforcement strategies available—because they are sometimes ignorant. Although this may at first seem counterintuitive, adopting a blend of different enforcement strategies enables authorities and courts to confront incentives to rule broadly while at the same time working towards greater convergence of different pertinent values such as privacy, diversity, editorial integrity, and competition.10 First-generation competition law inexorably collides with this point. That is precisely why stalwarts of regulation and apologists of decentralization regularly pit the values of competition against those associated with special purpose regulation. The camps’ common supposition is that we need regulation or competition, and the mere issue that persists is to assess which realm a particular problem is best associated with. And while debates around the goals of competition law may have shifted our perception as to whether a particular issue belongs to regulation or competition, these debates have barely influenced the manner in which we contemplate the workings of concentrated markets. These quarrels notwithstanding, with the newly enacted DMA, ex ante regulation and ex post competition law interventions now govern together in a space that has relentlessly been negotiated and contested. Contrary to what stalwarts of regulation would suppose, the DMA does not mean that regulation will prejudice competition, that it will impinge upon the continued application of Articles 101 and 102 of the Treaty on the Functioning of the European Union (TFEU) to the behaviour of big technology platforms or that competition law will gradually become redundant. Nor does it mean, as apologists of decentralization would maintain, that we should no longer be required to reconsider the assumptions of first-generation competition law. The DMA creates a regulatory regime that is aimed at ensuring fairness and contestability and when it regulates it does not hold unfettered sway any more than competition law wields unencumbered control when it is engaged.11 To be sure, as an ex ante regulatory instrument governing core platform services offered by entities that qualify as ‘gatekeepers’, the DMA reigns supreme, but in effect, it creates a space of regulatory overlap in which the actual choice is not between ex ante regulation or ex post competition law interventions; rather the choice is both as well as and, and this assumes some significant degree of common ground that accompanies that interdependence.12 Digital markets arguably distort the classic distinction between production, distribution, and consumption. Decisions taken by consumers in the digital economy are increasingly made passively, through implicit or explicit product matching and personalized recommendations rather than through active search. Take artificial intelligence-based algorithms as an example. Such algorithms recommend and purchase products based on spoken, written, or inferred requests obtained from users of digital platforms or devices such as mobile phones, speakers, and smart assistants.13 These algorithms benefit consumers in that they facilitate swifter and more complex transactions, and diminish consumers’ search and transaction costs. But they also work to entrust the ability of consumers to actively search—including their capacity to pick and choose—to big technology firms themselves and place consumers’ decision-making power into the hands of producers. This creates opportunities for misaligning the preferences of consumers with the goods and services actually sold, causing harm to customers, competitors, and the market (including society) as a whole.14 To remedy such harms, competition law usually ensures that consumers have an opportunity to choose between different alternative options. This is the equivalent of the conventional idea in which efficient markets afford consumers an ability to switch between distinct providers so that they can pursue their own commercial transactions at their individual discretion. But in concentrated markets, consumers typically are no longer able (or indeed willing) to choose effectively between alternatives. This is why, in theory at least, competition law is supposed to break big technology companies up—to reinstate the ability of consumers to choose between different alternative offers. Second-generation competition law grew out of its fixation on consumer switching as the only disciplining mechanism in terms of market actors’ behaviour. Even in highly concentrated markets, most of the time, there are thought to be alternatives, particularly where competition by other actors is just one click away. If switching nonetheless ends up being impracticable or turns out to be ineffective, competition law requires structural separation, to reinstate consumers’ choices, and to lessen the adverse effects of dominant incumbent actors on competitors. The main cognates of this account are regulatory arrangements that seek to preserve consumer switching through data portability or interoperability measures.15 Such measures seek to make it easier for participants to compete and to restore the autonomy of consumers, including their ability to choose. As to the predominant role that switching plays in promoting competition, second-generation competition law has not attained a middle ground in the debate around ex ante regulation and ex post competition law interventions; instead, most policy proposals fit into two groups. One is about entitlements: regulation should afford consumers a right to switch—an ability to choose between different options, put in place by mandated interoperability or established rights to data portability, which are geared towards both animating rivalry/lowering barriers to entry, and allowing new firms to compete. The other is about market structure: policymakers are concerned that the marketplace itself does not provide consumers with adequate opportunities to switch. The solutions they present almost inevitably involve forcing big technology companies to separate from (some of) their essential services to reinstate consumers’ choices and to lessen the adverse effects of dominant incumbent actors on other players. Both approaches seek to re-establish competition, by rendering users’ data portable and competing firms’ services interoperable. Portability provides consumers with an entitlement to switch; structural separation and/or interoperability afford consumers the ability to choose between different alternative offers by dint of adjustment to market structure. As with the shared assumptions underpinning first-generation competition law, second-generation competition law is difficult to square with the realities of data-driven markets. It rests on the notion of outright regulation or sheer and an perception of how data-driven markets As concerns the and structural are not the only at not the most for consumers to In concentrated marketplaces, consumers are most to have their by some in leading actors’ decision-making as to the on which those actors or their Here, consumers’ preferences can best be put into if users and their in this a to leading actors’ product The of such typically through an avenue of it ensures that in concentrated consumers can a of market to a significant second-generation competition law has the notion that entitlements and market structure are what most for data-driven markets, law in fact that competition authorities and courts work to consumers to leading actors’ product For in the into the that the most effective to competition and consumers’ not to break the up but to require to into the users to out of the data In a the European in upon the to that competing services no than its own its search of consumer preferences into leading actors’ has also been to be adequate in to claims against the to or and are with to dominant As the fact that second-generation competition law does not account for the manner in which data-driven markets it is to that in data-driven markets, and to consumers to from to Take the in In this the understood that been and that has in a of digital companies on consumers’ from platforms to As a separation of the would only have opportunities for entities to compete in and to confront the underlying incentives that the an alternative avenue of it consumers to of terms and of forcing the platform to control of the and of data to consumers, consumers in a to control the of data Second-generation competition law has the that of consumer of its focus on entitlements and market it has not any space for consumers to some control product and sellers by to them. If we the coding structure of second-generation competition law, competition theory and doctrine would be required to what may be the of an extent of manner in which authorities and courts and effectively the policies of leading actors on of consumers, and thereby work to consumers’ views into the market when other of are or In the DMA itself a of to the behaviour of that not only to promote consumer switching but that also to this regulatory overlap and are thought to be the rule rather than the law, for its will have to put emphasis on entitlements and market structure and more on of consumer the role consumers in shaping leading actors’ policies from their rather than to the part they in them from does the DMA for competition theory and The DMA an emphasis on the regulatory but the is more In effect, the DMA that the time is to the that has arguably the of competition theory and competition law. This is an issue that legal scholarship has yet to for both and normative In terms, stalwarts of regulation and apologists of decentralization have been in a the and benefits of but they have on one single between means and Both camps have supposed that competition goals and that the most problems are best exclusively by of regulation. That turns out to be The DMA has what most theorists thought to be the part of the debate around regulation and This is because competition law also a regulatory this holds for and As concerns the competition law a significant structural role in that a of in Articles and DMA from behaviour that competition authorities and courts previously and that relate to that is best understood in terms of Here, competition law regulates in that it is in the is competition law ensures that the DMA DMA that the may a market for the purpose of whether one or more services the digital should be to the of core platform services in DMA or for the purpose of that the contestability of core platform services or that are and which are not effectively by the in its the any relevant of Articles 101 and 102 digital markets well as any other relevant market investigations DMA may some in new in with the the DMA that competition law will a role in its and new rules are and are the result of Here, the in which an issue relates either to ex ante regulation or to ex post competition law interventions ends up being than previously been the DMA (and new will continue to in part on that around of market that is, around how to a significant role in governing markets is for consumers as a Moreover, competition law assumes a role in of the new The in for made it that a extent of market concentration inexorably incentives for services to be towards the and from the preferences of consumers, the market, and society at these leading search social and may through their algorithms and the of other actors, with in terms of product production, and In to be the not only to adjust the and but it also the manner in which policymakers and theorists the underlying It this on of consumers and decision-making on the of the to the for the on in and related and and and/or adopted by in different The DMA several in which by consumers, put in place through has been to ex post competition law interventions with ex ante regulation to contestability and fairness in digital markets. and in concentrated are difficult to they need to be and from through authorities and courts on of consumers as the of the of new laws those and The DMA that taken by authorities and courts can break ground for novel policies that leading actors to consumers’ views into their when and have gradually become more taken on of consumers does not require a debate of issues on an but a in a and in are out through a mechanism of in which and reasonable is such a opportunities for by the law, are in terms, and the main actors are and that their views ex The between and their is distinct from that which authorities and courts on of consumers ex that in is based on the of a rather than on mere assumptions or And it is for consumers to a more perception of how the policies of leading actors work in especially in of the and of data-driven markets. who to with a view to a through are to have a better of the circumstances of a and they may hold of a broader of Moreover, consumer may in in to behaviour and in to new so that authorities and courts can consumer more than the in a competition law also more ends in of the on its the of regulation groups of actors with different of knowledge and from those in competition law including of of and the focus of regulation is typically on that are from the effects of based on actual the are for the most part they are on from past investigations and are up by the shared and of authorities and courts that seek to in a manner that is for incumbent actors to In this the DMA to a of good in markets, that core platform services offered by are to of the arrangement that the DMA is based upon by and large from law that has been put in competition law. It the of consumers in the of leading actors’ to incentives and to underpin consumers’ calls rather than to promote one single set of values. One that the why there are different camps is that different camps hold distinct of how markets That to the point as to why competition law calls for a need to the camps competition law is different from what either but it is also different from what either significant The DMA offers to a middle ground between the camps in to As the DMA, investigations by competition authorities and courts will a Although the DMA in to on competition law is also to the regulatory This is where competition law and the DMA are to in and to different law may not be but it will also be for shaping the new is where the digital economy and competition law will Such may the of entirely new or a towards different market And where it is that market investigations DMA will to the of new core services and of competition are the competition investigations the for new most significant that need to be understood they are taken into the regulatory law is not or by instead, competition law To be sure, there are concerns the application and of the in the DMA But for of the such from competition law and thereby its stalwarts of regulation nor apologists of decentralization are to view this arrangement as But nor will either be to the DMA represents a to debates around data-driven markets. these to the competition theory and doctrine need to be in them are a of assumptions that no longer the realities of data-driven markets. In such markets, regulation and decentralization are neither the DMA nor competition law instead, they govern for about a of this has entirely been by competition theory and It is time to them up to date with the of competition law.
Due to the advantages of low latency, small propagation loss, and global coverage, LEO satellite network becomes a cost-effective long-distance communication solution for loT devices in remote areas. Nevertheless, the LEO satellite loT devices deployed for specific tasks are idle most of the time, raising the obvious question for future research: how to effectively share these idle sensing resources. Fortunately, data trusts emerge as a promising strategy to leverage the idle sensing resources. How-ever, the data trust model faces privacy and security challenges in LEO satellite loT scenarios to achieve trusted data trading. Therefore, this article proposes a blockchain-enabled data trust model and a trusted data trading scheme for device providers, data trustees, and general users. Furthermore, exploiting the homomorphic encryption technology, we realize the fine-grained data query and device match in the premise of privacy protection for device providers and general users. Lastly, considering the openness of satellite-terrestrial communication links and the limited computing power of LEO satellite loT devices, we design a non-interactive lightweight authentication protocol based on zero-knowledge proof. The simulation results verify the feasibility, effectiveness, and security performance of the proposed data sharing for LEO satellite loT.
Privacy and security of sensitive health information represents a significant issue within electronic health (e-Health). With breakthroughs in security and privacy in recent decades, the application of cloud technologies on health services have progressed forward. The aim of this research paper is to introduce an appropriate access control model for use in e-Health. To determine the requirements of a modern access control method, research was carried out on numerous scholarly articles sourced from the Google Scholar search engine. A survey which utilized sampling techniques will also be done to affirm the validity of the research. The target audience of the survey are large to medium scale healthcare providers. Qualitative data will be gathered as it better describes the different types of data obtained. As a result, the paper proposed a combination of Role-based Access Control and Attribute-based Access Control which utilizes zero-knowledge SNARK to ensure privacy of patients. Recommendations for future research include experimentation with other encryption algorithms in the proposed system, assessment on the use of different zero-knowledge proof methods for better efficiency and scalability, as well as modern access control methods that embrace expansions and simple authorization.
In this paper, we formulate inverse reinforcement learning (IRL) as an expert-learner interaction whereby the optimal performance intent of an expert or target agent is unknown to a learner agent. The learner observes the states and controls of the expert and hence seeks to reconstruct the expert's cost function intent and thus mimics the expert's optimal response. Next, we add non-cooperative disturbances that seek to disrupt the learning and stability of the learner agent. This leads to the formulation of a new interaction we call zero-sum game IRL. We develop a framework to solve the zero-sum game IRL problem that is a modified extension of RL policy iteration (PI) to allow unknown expert performance intentions to be computed and non-cooperative disturbances to be rejected. The framework has two parts: a value function and control action update based on an extension of PI, and a cost function update based on standard inverse optimal control. Then, we eventually develop an off-policy IRL algorithm that does not require knowledge of the expert and learner agent dynamics and performs single-loop learning. Rigorous proofs and analyses are given. Finally, simulation experiments are presented to show the effectiveness of the new approach.
Taotao Wang, Zibin Lin, Shengli Zhang, Long Shi · 6 authors
A decentralized identity system that can provide users with self-sovereign digital identities to facilitate complete control over their own data is paramount to Web 3.0. The account system on blockchain is an ideal archetype for realizing Web 3.0 decentralized identity. However, a disadvantage of such completely anonymous identity system is that users can create multiple accounts without authentication to obfuscate their activities on the blockchain. In particular, the current anonymous blockchain account system cannot accurately register the social relationships and interactions between real human users, given the amorphous mappings between users and blockchain identities. This work proposes zkBID, a zero-knowledge blockchain-account-based Web 3.0 decentralized identity scheme, to overcome endemic mistrust in blockchain account systems. zkBID links souls (blockchain accounts) to humans (users' personhood credentials) in a one-to-one manner to truly reflect the social relationships and interactions between humans on the blockchain. zkBID conceals the one-to-one relationships between blockchain accounts and users' personhood credentials for privacy protection using zero-knowledge proofs and linkable ring signatures. Thus, with zkBID, the users' blockchain accounts are credibly anonymous. Importantly, zkBID is fully decentralized: all user-related data are generated by users and verified by smart contracts on the blockchain. We implemented zkBID and built a blockchain test network for evaluation purposes. Our tests demonstrate the effectiveness of zkBID and suggest proper ways to configure zkBID system parameters.
Open access
3 source records
cs.CR
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
Graham Cormode, Marcel Dall’Agnol, Tom Gur, Christopher W. Hickey
Streaming interactive proofs (SIPs) enable a space-bounded algorithm with one-pass access to a massive stream of data to verify a computation that requires large space, by communicating with a powerful but untrusted prover. This work initiates the study of zero-knowledge proofs for data streams. We define the notion of zero-knowledge in the streaming setting and construct zero-knowledge SIPs for the two main algorithmic building blocks in the streaming interactive proofs literature: the sumcheck and polynomial evaluation protocols. To the best of our knowledge all known streaming interactive proofs are based on either of these tools, and indeed, this allows us to obtain zero-knowledge SIPs for central streaming problems such as index, point and range queries, median, frequency moments, and inner product. Our protocols are efficient in terms of time and space, as well as communication: the verifier algorithm's space complexity is $\mathrm{polylog}(n)$ and, after a non-interactive setup that uses a random string of near-linear length, the remaining parameters are $n^{o(1)}$. En route, we develop an algorithmic toolkit for designing zero-knowledge data stream protocols, consisting of an algebraic streaming commitment protocol and a temporal commitment protocol.Our analyses rely on delicate algebraic and information-theoretic arguments and reductions from average-case communication complexity.