Blockchain Papers

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.

Suthee Ruangwises, Mitsugu Iwamoto

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.

Weiliang Ma, Qian Xiong, Xuanhua Shi, Xiaosong Ma · 10 authors

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.

Xavier Salleras

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.

Hiroyuki Kido

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.

Joanna Clarke, John R. Littlewood, George Karani

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.

Stefanía Paladini, Krishnendu Saha

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. 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(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; 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Adrian Kuenzler

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.

Wenqian Xue, Bosen Lian, Jialu Fan, Tianyou Chai · 5 authors

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.

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.

Damiano Di Francesco Maesa, Andrea Lisi, Paolo Mori, Laura Ricci · 5 authors

Recent years have witnessed, especially in Europe, a shift aimed at bringing users back at the center of digital systems. This has driven innovation towards the affirmation of decentralized systems, in line with the Self Sovereign Identity paradigm. User control over the consumption and disclosure of their data is a key topic of such drive. In this paper we show how it is possible to apply this increasingly popular concept to a traditionally centralized and opaque digital process: Access Control systems. To this aim we expand the XACML standard for Attribute Based Access Control systems with the novel concept of private attributes, i.e. attributes whose values should not be disclosed while still contributing to a policy evaluation result after user consent. Basing our proposal on blockchain systems, we show how to leverage smart contracts and zero knowledge proofs to allow for transparent policies evaluation without disclosing the value of such sensible attributes. Beside formalizing our goals, presenting the system architecture, and discussing its advantages and drawbacks with respect to the traditional model, we provide a reference example to show our proposal innovative capabilities and provide a prototype experimental evaluation to prove its feasibility.

Xin Liu, Xiaofen Tu, Dan Luo, Gang Xu · 6 authors

In recent years, with the development of information security, secure multi-party computation has gradually become a research hotspot in the field of privacy protection. The intersection and union computation of graphs is an important branch of secure computing geometry. At present, the intersection and union of graphs are almost designed under the semi-honest model, and few solutions are proposed under the malicious model. However, the solution under the malicious model is more secure and has important theoretical and practical significance. In this paper, the possible malicious behaviors of computing the intersection and union of graphs are analyzed. Using the Lifted-ElGamal threshold cryptosystem and zero-knowledge proof method, the secure multi-party computation algorithm of graphs’ intersection and union under the malicious model is designed. The real/ideal model paradigm is used to prove the security of the algorithm, the efficiency of the algorithm is analyzed in detail, and the feasibility is verified through experiment.

Junqin Huang, Linghe Kong, Jingwei Wang, Guihai Chen · 7 authors

Internet of Vehicles (IoV) has become an indispensable technology to bridge vehicles, persons, and infrastructures and is promising to make our cities smarter and more connected. It enables vehicles to exchange vehicular data (e.g., GPS, sensors, and brakes) with different entities nearby. However, sharing these vehicular data over the air raises concerns about identity privacy leakage. Besides, the centralized architecture adopted in existing IoV systems is fragile to single point-of-failure and malicious attacks. With the emergence of blockchain technology, there is the chance to solve these problems due to its features of being tamper-proof, traceability, and decentralization. In this article, we propose a privacy-preserving vehicular data sharing framework based on blockchain. In particular, we design an anonymous and auditable data sharing scheme using Zero-Knowledge Proof (ZKP) technology so as to protect the identity privacy of vehicles while preserving the vehicular data auditability for Trusted Authorities (TAs). In response to high mobility of vehicles, we design an efficient multi-sharding protocol to decrease blockchain communication costs without compromising the blockchain security. We implement a prototype of our framework and conduct extensive experiments and simulations on it. Evaluation and analysis results indicate that our framework can not only strengthen system security and data privacy but also reduce communication complexity by \(O(\frac{n\sqrt {m}}{m^2})\) times compared to existing sharding protocols.

Santiago Cuéllar Gempeler, Bill Harris, James Parker, Stuart Pernsteiner · 6 authors

Currently, when a security analyst discovers a vulnerability in critical software system, they must navigate a fraught dilemma: immediately disclosing the vulnerability to the public could harm the system’s users; whereas disclosing the vulnerability only to the software’s vendor lets the vendor disregard or deprioritize the security risk, to the detriment of unwittingly-affected users. A compelling recent line of work aims to resolve this by using Zero Knowledge (ZK) protocols that let analysts prove that they know a vulnerability in a program, without revealing the details of the vulnerability or the inputs that exploit it. In principle, this could be achieved by generic ZK techniques. In practice, ZK vulnerability proofs to date have been restricted in scope and expressibility, due to challenges related to generating proof statements that model real-world software at scale and to directly formulating violated properties. This article presents Cheesecloth , a novel proof-statement compiler, which proves practical vulnerabilities in ZK by soundly-but-aggressively preprocessing programs on public inputs, selectively revealing information about executed control segments, and formalizing information leakage using a novel storage-labeling scheme. Cheesecloth ’s practicality is demonstrated by generating ZK proofs of well-known vulnerabilities in (previous versions of) critical software, including the Heartbleed information leakage in OpenSSL, a memory vulnerability in the FFmpeg multimedia encoding framework, a cryptographic implementation bug in the Secure Scuttlebutt decentralised social network, and a denial of service vulnerability in OpenSSL.

Rajani Singh, Ashutosh Dhar Dwivedi, Gautam Srivastava, Pushpita Chatterjee · 5 authors

Several emerging areas, such as sensor networks, the Internet of Things (IoT), and distributed networks are gaining traction where resource-constrained devices communicate by sharing privacy-preserving information. Due to heavy cryptographic components, standard cryptographic algorithms do not fit these IoT devices. In this article, we propose an efficient zero-knowledge blockchain-based privacy-preserving decentralized healthcare finance system that is suitable for lightweight computer devices. The proposed design mainly focuses on noninteractive zero-knowledge proof, which substantially reduces the cost of communication between two devices. We explain the system framework and its use case for a healthcare financial system at a micro-level. However, it can also be extended easily to more general financial systems. Our system framework is efficient and lightweight, using more efficient zero-knowledge-based proofs; validation of the transactions is done in milliseconds. As an advancement to our work, the proposed healthcare financial system for lightweight computer devices is also auditable without leaking any extra information than required.

Matthias Babel, Johannes Sedlmeir

Today, digital identity management for individuals is either inconvenient and error-prone or creates undesirable lock-in effects and violates privacy and security expectations. These shortcomings inhibit the digital transformation in general and seem particularly concerning in the context of novel applications such as access control for decentralized autonomous organizations and identification in the Metaverse. Decentralized or self-sovereign identity (SSI) aims to offer a solution to this dilemma by empowering individuals to manage their digital identity through machine-verifiable attestations stored in a "digital wallet" application on their edge devices. However, when presented to a relying party, these attestations typically reveal more attributes than required and allow tracking end users' activities. Several academic works and practical solutions exist to reduce or avoid such excessive information disclosure, from simple selective disclosure to data-minimizing anonymous credentials based on zero-knowledge proofs (ZKPs). We first demonstrate that the SSI solutions that are currently built with anonymous credentials still lack essential features such as scalable revocation, certificate chaining, and integration with secure elements. We then argue that general-purpose ZKPs in the form of zk-SNARKs can appropriately address these pressing challenges. We describe our implementation and conduct performance tests on different edge devices to illustrate that the performance of zk-SNARK-based anonymous credentials is already practical. We also discuss further advantages that general-purpose ZKPs can easily provide for digital wallets, for instance, to create "designated verifier presentations" that facilitate new design options for digital identity infrastructures that previously were not accessible because of the threat of man-in-the-middle attacks.

Ebenezer Daniel, Gigi J. Ebenezer

We have come a long way in our fight against leprosy. The skeletal evidence of leprosy from 2000 B.C. in Rajasthan, India, predates similar evidence from the other parts of the world1. From these ancient times to the beginning of 2023, the fight against leprosy has been hard and relentless, the pace accelerating rapidly at the turn of the 21st century. However, India still holds the undesirable distinction of being the leading nation harbouring human leprosy2. Reflections on the future of leprosy must hence consider the enormous work done in the past, often unrecognized through scientific publications. It would be impossible to generate a comprehensive list of all those who served in the field of leprosy, but it will not be amiss to cite a few – Mohandas Karamchand Gandhi, Manohar Dewan, Baba Raghav Das, Abdul Kalam, Robert Cochrane, Dharmendra, H. Srinivasan and Charles K. Job. Although there is a worldwide decline in the various statistics of leprosy, increasing new cases, childhood cases and grade 2 deformity (G2D) in 2021 compared to 2020, in the time of the COVID-19 pandemic when much of leprosy surveillance was reduced, is a cause for concern2. In India, new cases of leprosy increased from 65,147 in 2020 to 75,394 in 2021 and G2D increased from 1572 to 18632. In southeast Asia, new child cases were 5664 in 2020 as compared to 5380 in 20212. Leprosy misdiagnosis All aspects of leprosy, including epidemiological data, depend on the accurate diagnosis of the disease. Leprosy symptoms are often ambiguous, and apart from diseases that closely mimic leprosy, replacing the Ridley-Jopling classification with the WHO Paucibacillary (PB) - Multibacillary (MB) classification, necessary for employing large-scale treatment with multidrug therapy (MDT), has resulted in the unintended consequence of an increase in misdiagnosis3. In Brazil, among 574,181 new leprosy cases, 7477 (1.3%) were misdiagnosed, more common among females, children, PB and indeterminate forms, and in neural leprosy without skin lesions4. The consequences of misdiagnosis are serious and can impact treatment, physical and mental circumstances and ruin the economic productivity of individuals and families. Therefore, finding solutions to reduce the level of misdiagnosis should be a top priority. To end this, experienced leprologists should be retained in tertiary institutions where laboratory facilities exist to evaluate uncertain cases. Their comprehensive knowledge in diagnosing and treating leprosy should be passed on to the next generation. Educational material should be freely and easily accessible. Translating these into local languages is important. Furthermore, adding interactive blogs that relate to these leprosy digital textbooks will be helpful. Tele-leprology The doctrine of early diagnosis, effective treatment and monitoring has not changed over the years and rapidly evolving technologies hold possibilities of preventing damage from the disease. Over the past several decades, telemedicine has gained popularity in several disciplines and the COVID-19 pandemic has solidified its use further5. With widespread internet coverage and smartphones, tele-dermatology is an effective tool even in remote rural areas with inadequate health care. Establishing remote reading centres for diagnosing and monitoring leprosy should be a top priority. These centres could be a part of tertiary leprosy hospitals staffed with experienced leprologists or act as conduits between the field and the leprologists wherever and whenever available. Ideally, image evaluation would require stations with similar computers and calibrated monitors under regulated ambient lighting. A crucial aspect of this system is training workers to take good, gradable images of leprosy lesions. An imaging protocol giving guidelines for standardizing the imaging (magnification, distance from the smartphone and lighting parameters (natural daylight outside the dwellings) should be made available to all workers. Training should include methods of safely and securely transferring uniquely labelled images and patient data to the central reading centre. Certifying the imagers by requesting sample images and giving feedback on the quality of images would make the system more robust. These images would be a permanent record over time and can be evaluated retrospectively as well as be a repository amenable to artificial intelligence investigations6,7. Biomarkers for early diagnosis Predicting the development of the disease or its reactions can mitigate its subsequent deleterious consequences. Some intriguing reports on biomarkers have been published recently including. One on the transcriptional risk signature for predicting the development of leprosy using blood 4-61 months before the actual clinical diagnosis8. Other biomarkers for detecting leprosy include the repetitive element RLEP which is a highly specific target for detecting Mycobacterium leprae, a recombinant multi-epitope antigen and a multiplex real-time quantitative PCR assay9,10. A five gene signature has been reported to predict type 1 reactions at least two weeks before the actual onset of the disease/symptoms11. Anti-LID-1 serology at diagnosis has been shown to have prognostic value for type 2 reaction in M. leprae positive patients12. In the future, more biomarkers may be discovered and once these undergo further evaluations for repeatability and economic feasibility, these will become ready for transfer from laboratory to field. Newer drugs for treating leprosy and its reactions Treatment efficacy and safety of newer drugs to treat the disease, newer combinations of drugs and the myriad periods of interventions that have reported the need for careful investigations for validity and repeatability. The specter of dangerous amounts of drug resistance to M. leprae is of concern and there is a constant need for innovative drugs and drug combinations to successfully kill the bacilli. Newer anti-inflammatory drugs used in other diseases may hence be explored particularly for recalcitrant type 1 and type 2 reactions. Some drugs, such as cyclosporin A, infliximab and methotrexate, have been used in controlling reactions in leprosy, but their efficacy needs to be replicated in larger studies. Lessons to be learnt from other diseases that have signs in common with leprosy The hallmark of leprosy is a decrease or abolition of tactile sensation. Various other conditions cause hypoesthesia, but two important ones, diabetes mellitus, which is a metabolic disease and HIV, which is a viral disease, have both undergone extensive research to prevent hypoesthesia, identify early peripheral nerve dysfunction and regenerate peripheral nerves to restore sensation. Great strides have been made in imaging techniques of peripheral nerves, bioengineering of neural tissue and in deciphering the mechanisms involved in the regeneration of peripheral nerves. Limb prosthesis with robust functions like never before is now becoming available, but few have been used and tested in deformed leprosy patients13. Shoes that are prescribed for patients with diabetic neuropathy are highly functional, more effective in preventing ulcers and aesthetically pleasing compared to the footwear offered to leprosy patients. In the current age of intensive national and global travel, it is important to study the risk and course of MB leprosy with co-existing morbidities such as HIV, tuberculosis, COVID-19 and monkeypox. Both HIV and tuberculosis as co-morbidities with leprosy are of concern because of the resistance the virus and bacteria are acquiring. Surveillance would play a critical role in this context. Specialized areas that require training While physicians, physio and occupational therapists receive reasonable training in leprosy, it is generally not the case with paediatrics, nursing, dentistry and nutrition. Childhood leprosy, besides being a marker for recent transmission, warrants accurate, early diagnosis by paediatricians who are generally poorly trained in leprosy14. When leprosy patients are admitted to a hospital, nursing becomes the focal point of caregiving. Publications related to leprosy nursing are scarce. Gingival recession, tooth loss, chronic pulpitis, periodontitis and dental caries, fissuring and atrophic glossitis, fibrosis and loss of uvula are commonly seen in patients belonging to the pre-MDT era and a substantial number of them have limb deformities15,16. Can leprosy patients with deformed hands maintain oral hygiene? This is an area lacking important information. Malnutrition is common in children of leprosy contacts as well as adults with leprosy, but only a few studies focus on nutrition in leprosy patients in the post-MDT era17. Modifying curriculum in dentistry, paediatrics and nursing must hence be undertaken to remedy these shortcomings. Nurses trained in specialized care of patients with deformity and acute reactions will be better prepared to learn on the job in caring for leprosy patients. Zero leprosy M. leprae has been detected in a wide variety of wild animals. Leprosy-like lesions have been reported in wild chimpanzees and sooty mangabey monkeys (Cercocebus atys)18,19. Armadillos infected with M. leprae are found in the southern United States and in South American countries and play a small role as reservoirs for the transmission of leprosy to humans20. As long as, this type of transmission exists, a world with zero leprosy is unlikely. However, infection of M. leprae in laboratory animals has opened up opportunities for in-depth investigations on the bacilli. M. leprae-infected armadillos have become extremely useful in leprosy neuropathy research, providing insights into the reprogramming and fate of Schwann cells when denervation occurs, thereby granting opportunities to discover novel therapeutic targets for delaying or preventing nerve destruction21,22. Leprosy stigma Leprosy stigma remains a problem in several parts of India. There have been plenty of reports on stigma and ways to measure it, but reports on successful outcomes are few23. Future focus should be on investigating and promoting factors that have proved useful in bringing down the level of stigma. Poverty, illiteracy, ageing and visible deformities enhance stigma24. Integrating leprosy into the general healthcare system appears to have brought down the level of stigma25. Integration appears to have worked more successfully in a relatively poor and illiterate state than in an affluent and literate state26. Stigma reduction that is a byproduct in specialized hospitals of excellence where service is sought by wealthier populations and where discounted care is provided to leprosy patients needs reporting. Leprosy prophylaxis The WHO advocates administering a single dose of rifampicin to reduce the risk of leprosy, in contacts of leprosy patients, after excluding leprosy and tuberculosis in them27. It is an attractive concept, especially when the risk of inducing resistance in Mycobacteriumtuberculosis is small28. Reports on long-term microbiological consequences of a single-dose antibiotic are scarce. A short-term study on the effects of a single-dose antibiotic prophylaxis on normal oral microflora reported that it can induce selection of resistant strains29. In the recent past, antimicrobial resistance to leprosy and tuberculosis has been growing30-32. It is critical to continue to evaluate the long-term beneficial effect of this chemoprophylaxis against the risk of microbiological consequences. However, it may not be wise to extend this chemoprophylaxis to other populations where comorbidity with tuberculosis and HIV is substantial. M. leprae, armadillos and liver regeneration M. leprae has some amazing properties – it is the only bacillus that selectively invades human peripheral nervous tissue, it has an extraordinarily lengthy doubling time, a long incubation period and it defies culture in a laboratory medium. It has added one more surprising property in conjunction with 9-banded armadillos. It regenerates liver tissue. M. leprae induces hepatocyte proliferation and a proportionate increase of vasculature, and the biliary system. It does so without accompanying fibrosis or tumorigenesis. This hepatogenesis, if it can be replicated in human beings, holds promise for patients with liver destruction awaiting organ transplants, conditions such as cirrhosis33. Conclusions An excerpt from Dr. Abdul Kalam, a wise ex-President of India, addressing a national conference on the elimination of leprosy gives the ultimate solution in eliminating leprosy – ‘Real cure for the elimination of leprosy lies in the development of the region, that means developing the district, and the State. The development approach would provide for the people better amenities, clean drinking water, better hygiene and sanitation, better education and awareness, better healthcare and nutritious food resulting in a livable environment. This holistic approach is the vital need for eliminating leprosy in endemic regions’34. The proof that this has worked can be found in the developed nations of the world. The current Prime Minister of India envisions that India would become a developed nation in 25 years and once that vision is realized, the end to leprosy in India would become a reality. Financial support & sponsorship: None. Conflicts of Interest: None.

Elizabeth Burland

The decisions that students make about their educational attainment have profound impacts on their future economic, demographic, and social outcomes. These decisions, however, do not happen in a vacuum. There is a long tradition of research that studies inequality in educational decisionmaking and the various factors that contribute to creating, or reducing, this inequality. However, inequality in educational attainment persists. This dissertation takes a multimethod approach to identifying sources of inequality and evaluating policies aimed at reducing it. In three distinct empirical chapters, this dissertation extends the literature on educational decision making, expanding our knowledge of how inequality is created and maintained. The first empirical paper, evaluates two “free tuition” policy designs, informing policy conversations about how to reduce economic inequality in selective college attendance. Proposed “free college” policies vary widely in design. The simplest set tuition to zero for everyone. More targeted approaches limit free tuition to those who demonstrate need through an application process. We experimentally test the effects of these two models on the schooling decisions of low-income students. An unconditional free tuition offer from a large public university substantially increases application and enrollment rates. A free tuition offer contingent on proof of need has a much smaller effect on application and none on enrollment. These results are consistent with students placing a high value on financial certainty when making schooling decisions. The second paper focuses on the role of social context in shaping student decision making. There is a long history of sociological research that identifies the essential role of social forces in shaping educational attainment; however, siblings have been understudied as a direct mechanism contributing to educational decision making, overshadowed by the focus on parents and institutions. Using longitudinal qualitative interviews with 36 high-achieving high school seniors from families with low incomes, I explore the unique role that older siblings play in shaping the postsecondary decision making of their younger siblings. I find that the support provided by siblings is distinct from other social resources. The intensity of the relationship, and the internal and external relevance, or the fact the information shared is recent and personalized to the students’ circumstances, each make this relationship unique. By studying only parents or considering only the role of parent educational or economic circumstances in contributing to inequality, we ignore an important source of heterogeneity in the lives of students from families with low incomes. The final empirical chapter describes gaps in postsecondary educational attainment between urban, rural, and suburban communities using student-level longitudinal data from the full population of Michigan public high school students. Using several recent high school cohorts, I document rates of college attendance, college selectivity, and bachelor’s degree completion overall and within subgroups, providing updated estimates for urbanicity gaps in college attainment. I find that there is less racial and economic inequality in college outcomes within rural areas; however, it does not come from improved outcomes among racially minoritized students or those from families with low incomes. Students in rural areas from traditionally advantaged groups have substantially lower rates of college attainment than their suburban and city peers. Therefore, while media narratives about White, rural students falling behind are not inaccurate, they tell an incomplete story. This chapter highlights some key areas for policy intervention to better target the distinct needs of students.

Agha Usama Hasan

The UK Government's Climate Change Act (CCA) aims to achieve a net zero greenhouse gas emission by 2050. Supermarkets, being among the most energy-intensive non-residential buildings, play a pivotal role in this endeavour. This research delves into the influence of climate change on supermarket buildings, exploring methodologies to mitigate its impact and assessing its effects on operational energy and carbon emissions. The United Nations has emphasized the built environment's significant contribution to global CO2 emissions, necessitating urgent action. Using a quantitative approach, this study employs the TAS – EDSL software to simulate energy consumption, carbon emission, and building regulations for various supermarket case studies. The research also evaluates the performance of these buildings across different UK climates and emission scenarios, incorporating EU Zebra2020 tool metrics. The primary challenge encountered was the scarcity of literature specifically targeting the UK supermarket industry in the context of climate change. The research underscores the importance of balancing energy consumption, carbon emissions, and future climate adaptations, especially given the industry's nZEB target by 2050. The findings of this study serve as a beacon for all non-residential buildings, bridging the knowledge gap between climate change, building futureproofing, and emission reduction strategies. The research underscores the importance of long-term planning, continuous monitoring of energy-intensive buildings, and the holistic approach of reducing emissions across a building's lifespan. This research aims to guide policymakers and building designers in future-proofing structures, emphasizing the need for energy-efficient measures and the integration of renewable technologies. The overarching goal is to foster the creation of sustainable, climate-resilient buildings for future generations.

Hu S, Tingshuo Gu, Pan Pan, Zhengquan Zhang

In this paper, we first trace the evolution of cryptography from symmetric- and public-key primitives to the emerging paradigm of privacy computing. We systematically examine three pillars, namely, zero-knowledge proofs, fully homomorphic encryption, and secure multi-party computation, by highlighting their models, algorithms, and performance frontiers. The second half narrows the lens to recent deployed systems. In particular, we introduce the Plonk zk-SNARK powering Ethereum layer-2 roll-ups, and present a state-of-the-art privacy-preserving Vickrey auction algorithm. These case studies illustrate how privacy-computing techniques are transitioning from theory to production-grade blockchain applications.

Michele Ciampi, Yu Xia

No abstract is available for this record.