Blockchain Papers

J. Mohajeri

No abstract is available for this record.

Molli Noland

An interactive proof involves two parties, the prover and the verifier. The goal of the proof is for the prover to convince the verifier that some instance of a decision problem is true. A zero-knowledge proof is an interactive proof where the only information learned by the verifier of the proof is the outcome of the proof. This thesis contains a theoretical overview of interactive and zero-knowledge proofs and describes experiments with implementations of some of them. Two examples of interactive proofs from number theory are given, a protocol for quadratic non-residues and a protocol for subgroup non-membership. The third example of an interactive proof is a protocol for determining the truth value of a quantified Boolean formula. This interactive proof was implemented and the details of that implementation, plus a test of the implementation derived from game theory, are included. There is also a discussion of quantum interactive proofs. The two examples of perfect zero-knowledge proofs that are included are protocols for quadratic residues and for subgroup membership. These protocols were also implemented, and those details are included. For each protocol, there is a discussion of the complexity status of the problems addressed by the protocol. There is also a brief discussion of the history and applications of interactive and zero-knowledge proofs.

Markus Jakobsson, Claus-Peter Schnorr

We study the notion of meta-proofs, which, as the name indicates, are proofs about proofs. We employ the notion of meta-proofs to produce a highly efficient oblivous proof of correct exponentiation. It is minimum-knowledge independently of whether the input is valid or not, a property that does not hold for many other protocols (that are zero-knowledge only for valid inputs.) This has direct security implications to multiparty protocols, where the protocols we demonstrate — one interactive and one non-interactive — can be employed to obtain protocol robustness at a low cost. As a result of potential independent interest, we show how to turn any standard discrete log signature scheme into a scheme for proving equality of discrete logarithms. We demonstrate our method using the Schnorr signature scheme.

Alfredo De Santis, Giuseppe Persiano, Giovanni Di Crescenzo

No abstract is available for this record.

Oded Goldreich, Amit Sahai, Salil Vadhan

No abstract is available for this record.

Usman Khalil, Owais Ahmed Malik, Wee-Hong Ong, Mueen Uddin

The concept of smart city architecture requires a comprehensive solution that can combine real-time response applications for cyber-physical systems. However, the architecture faces challenges that can obstruct the operations in terms of systems, processes, and data flow as far as the breach risk is concerned. Though the field has been researched with the existence of centralized and distributed architectures to support smart cities. Research gaps regarding security concerns, platform assistance, and resource management continue to persist. This research article presents a novel blockchain-based architecture that proposes expansion in the non-fungible tokens (NFTs) to cater to the expansion of IoT-enabled smart assets. It enables NFTs to employ fog computing for all users and smart devices connected to a fog node in a cyber-physical system. The proposed expansion suggested in Non-Fungible Tokens (NFTs) for IoT assets representation in a cyber-physical system, provides devices and user identification and authentication functionality. The proposed NFT architecture has been designed to provide a smart city solution for cyber-physical systems that ensures robust security features (such as CIA) by introducing new attributes and functions for Owner, User, Fog, and IoT device/s authentication. The validation and rigor of the security services, efficiency, and latency have been achieved by deployments on private and public ledgers. The efficiency, and cost-effectiveness of the suggested functions and components have been evaluated in terms of evaluation cost and time complexity which resulted in promising results, obtained and validated on a testnet. The evaluation cost for the devised mint component was approximately 81%, and devised approve() was approximately 23% more efficient than other solutions.

Giovanni Di Crescenzo, Rafail Ostrovsky

No abstract is available for this record.

Ran Canetti, Oded Goldreich, S. Goldwasser, Silvio Micali

We introduce the notion of Resettable Zero-Knowledge (rZK), a new security measure for cryptographic protocols which strengthens the classical notion of zero-knowledge. In essence, an rZK protocol is one that remains zero knowledge even if an adversary can interact with the prover many times, each time resetting the prover to its initial state and forcing it to use the same random tape. Under general complexity assumptions, which hold for example if the Discrete Logarithm Problem is hard, we construct (non-constant round) Resettable Zero-Knowledge proof-systems for NP constant-round Resettable Witness-Indistinguishable proof-systems for NP constant-round Resettable Zero-Knowledge arguments for NP in the public key model: where veriers have fixed, public keys associated with them. In addition to shedding new light on what makes zero knowledge possible (by constructing ZK protocols that use randomness in a dramatically weaker way than before), rZK has great relevance to applications. Firstly, we show that rZK protocols are closed under parallel and

Amy S. Lee, Ruth Lev Bar‐Or

No abstract is available for this record.

Khanh Quoc Nguyen, Yi Mu, Vijay Varadharajan

No abstract is available for this record.

Khanh Quoc Nguyen, Feng Bao, Yi Mu, Vijay Varadharajan

No abstract is available for this record.

Carlo Ginzburg

Historian Carlo Ginzburg uses the occasion of his Menachem Stern Lectureship to present a provocative and characteristically brilliant examination of the relation between rhetoric and historiography. In four lectures, based on a wide range of texts -- Aristotle's Poetics; humanist Lorenzo Valla's tract exposing the Donation of Constantine as a forgery; an early 18th-century Jesuit historical account purporting to record the diatribe of a Mariana Island native against Spanish rule; and Proust's commentary on Flaubert's style -- he demonstrates that rhetoric, if properly understood, is related not only to ornament but to historical understanding and truth. Ginzburg discovers a middle ground between the empiricist or positivist view of history, and the current postmodern tendency to regard any historical account as just one among an infinity of possible narratives, distinguished or measured not by the standard of truth, but by rhetorical skill. As a whole, these lectures stake out a position that both mediates and transcends warring factions in the current historiographical debate.

Ransom Richardson, Joe Kilian

No abstract is available for this record.

Uriel Feige, Dror Lapidot, Adi Shamir

In this paper we show how to construct noninteractive zero knowledge proofs for any NP statement under general (rather than number theoretic) assumptions, and how to enable polynomially many provers to give polynomially many such proofs based on a single random string. Our constructions can be used in cryptographic applications in which the prover is restricted to polynomial time.

Stephen L. Ross, John Ýinger

No abstract is available for this record.

Stephen L. Ross, John Ýinger

This chapter reviews the literature on the boundary between urban economics and local public finance, defined as research that considers both a housing market and the market for local public services. The first part of the chapter considers positive theories. This part presents the consensus model of the allocation of households to jurisdictions, which is built on bid functions and household sorting, as well as alternative approaches to this issue. It also examines models of local tax and spending decisions, which exhibit no consensus, and reviews research in which both housing and local fiscal variables are endogenous. The second part of the chapter considers empirical research, with a focus on tax and service capitalization, on household heterogeneity within jurisdictions, and on the impact of zoning. The third part considers normative theories about a decentralized system of local governments. This part examines the extent to which such a system leads to an efficient allocation of households to communities or efficient local public service levels, and it discusses the fairness of local public spending. This review shows that the bidding/sorting framework is strongly supported by the evidence and has wide applicability in countries with decentralized governmental systems. In contrast, models of local public service determination depend on institutional detail, and their connections with housing markets have been largely unexplored in empirical work. Ever since Tiebout (1956), many scholars have argued that decentralized local governments have efficiency advantages over centralized forms. However, a general treatment of this issue identifies four key sources of inefficiency even in a decentralized system: misallocation of households to communities, the property tax, public service capitalization and heterogeneity. Few policies to eliminate these sources of inefficiency have yet been identified. Finally, this review explores the equity implications of household sorting and other features of a decentralized system.

Biagio Bossone

The author analyzes the financial system's role in economic growth and stability, addressing several core policy issues associated with financial sector reform in emerging economies. He studies finance's role in the context of a circuit model, with interacting rational, forward-looking, heterogeneous agents. He shows finance to essentially complement the price system in coordinating decentralized intertemporal resource allocation choices made by agents operating with limited information and incomplete trust. He discusses the links between finance and incentives for efficiency and stability in the context of the circuit model. He also identifies incentives and incentive-compatible institutions for reform strategies for financial sectors in emerging economies. Among his conclusions: 1) Circuit theory features important methodological advantages to analyze the role of finance, and to assess structural weaknesses of financial systems under different institutional settings and in different stages of economic development. 2) Incentives for prudence and honesty can protect the stability of the circuit by directing private sector forces unleashed by liberalization. In particular: a) Financial institutions should be encouraged to invest in reputational capital. b) Governments should complement the creation of franchise value by strengthening supervision and by adopting a regulatory regime based on rules designed to align the private incentives of market players with the social goal of financial stability. c) Safety nets to reduce systemic risk should minimize the moral hazard from stakeholders by limiting risk protection and by making the cost of protection sensitive to the risk taken. d) Governments should encourage self-policing in the financial sector. e) Where information and trust are scarce, there is a potential market for them, and governments can greatly improve incentives for optimal provision of information. f) Governments should strengthen the complementarity between the formal and the informal financial sectors. Emphasizing incentives is not to deny the importance of good rules, capable regulators andsupervisors, and strong enforcement measures. It is to suggest that the returns on investments to set up rules, institutions, and enforcement mechanisms can be greater if market players have an incentive to align their own objectives with the social goal of financial stability.

Nelly Hanna

States and elites The culture of the Ottoman period has often been analyzed by using the same criteria applied to the periods before and after it, Mamluk Egypt (1250–1517) and the nineteenth century. This is problematic for two reasons, firstly because of the very different roles played by the state in relation to culture and learning and secondly because of the role of elites in providing models and patterns of culture. The influence of the ruling class in shaping culture can change between one period and another, and can be greater at certain times than at others. When the state is centralized, the ruling class is much more likely to play a dominant role than it is in a decentralized state. The cultural production is more likely to be polished and refined when ruling classes dominate the direction that it takes, and less so when their role is reduced. When the state is decentralized, as it was during the Ottoman period, and the structures at the top are weaker, the cultural forms and patterns from below are more likely to emerge. Therefore, rather than compare this period to those before or after it, we may approach it through the larger framework of its changing social and political structures. In both Mamluk Egypt and Egypt under the rule of Muhammad ’Ali and his descendants (nineteenth century), the state was very centralized and played an active role in financing and shaping culture and in education. Likewise the ruling elites were actively involved in creating cultural models.

Milton Harris, Artur Raviv

No abstract is available for this record.

Daniel Immergluck, Erin Mullen

The declining federal role in economic development in distressed urban areas and concerns over the problems associated with metropolitan decentralization necessitate increased attention to the intrametropolitan distribution of business development programs. We examine the distribution of business loans made by the U.S. Small Business Administration's 504 development company program in the Chicago metro-politan area over a 5-year period and find that, after controlling for firm density, firm size, and industrial mix, higher income areas and outlying zip codes receive more loans than lower income and closer-in areas. We suggest a number of supply-and demand-side explanations for such patterns, call for measures to direct the flow of 504 financing more to lower income areas, and call for examining more loan and subsidy programs for their effects on intrametropolitan business development patterns.

Amit Dar

This summary addresses the reform of vocational education and training in China, reviewing the successful economic reforms pursued since 1978, and its labor market structure. The broad policy of the government is to move to a market system, but the major issue is whether an effective, and efficient market system, can be achieved through a process of small changes, while maintaining the existing structures. Vocational education, and training are analyzed, along with major management, costs, and financing issues. Notable reforms reveal major obstacles, such as the costs involved in improving, and expanding training facilities, as well as institutional capacity development. While decentralization has been devolved to provincial, county, and city levels, greater cost-sharing, and private provision for higher, and secondary level education, and training, are being officially encouraged. In addition, there is an improved coordination through local funding mechanisms for in-service training, from government, enterprises, vocational schools, and other training organizations.

Douglas Jechoutek Barnes

option in sustainable energy. Rusting monuments to past failures attest that this “autonomous” technology must operate within a frame of sustainable energy development where many systems interact – the power sector, financial markets, social systems, institutional structures, policy frameworks, business climates, political environments, service infrastructures, cultural settings and so on. In the matter of financing renewable energy, a novel approach is needed. Unique financial instruments are required to complement new scale economies, cost profiles, risks, and benefits. The World Bank Group is reflecting that shift in perspective through its new renewable energy operations, the Solar Development Corporation, the Renewable Energy and Energy Efficiency Fund, and other mechanisms. At the sectoral level, sustainable renewable energy development demands a return to basics. Sound sectoral reform and rational incentives are necessary to make the power sector a friendly environment for renewables. It is in these areas that the World Bank can make its most important contribution to sustainable energy. The message is becoming clearer; success takes time and demands the patient laying down of an institutional groundwork to support innovative delivery mechanisms. Financing Decentralized Renewable Energy: New Approaches

Amit Sahai, Salil Vadhan

. We give several efficient transformations for manipulating the statistical difference (variation distance) between a pair of probability distributions. The effects achieved include increasing the statistical difference, decreasing the statistical difference, "polarizing" the statistical relationship, and "reversing" the statistical relationship. We also show that a boolean formula whose atoms are statements about statistical difference can be transformed into a single statement about statistical difference. All of these transformations can be performed in polynomial time, in the sense that, given circuits which sample from the input distributions, it only takes polynomial time to compute circuits which sample from the output distributions. By our prior work (see FOCS 97), such transformations for manipulating statistical difference are closely connected to results about SZK, the class of languages possessing statistical zero-knowledge proofs. In particular, some of the transformation...

Paul H. Edelman

In these pages,' Steven Lubet recently reviewed A Tour of Calculus, by David Berlinski.2 Inspired by both beauty of calculus and Berlinski's description of it, Lubet waxes poetic on many parallels between law and calculus. It is completely understandable--even admirablethat one might be led to ruminations on relationship between calculus and one's own discipline. There is little doubt that subject of calculus stands as one of great intellectual feats of Western thought. It has had profound implications for physics, engineering, economics and many other disciplines-so why not law? Alas, these philosophical musings would be more persuasive had Professor Lubet better understood what it was that he was writing about. Lubet's errors come in two types. first is just a misunderstanding of history, but it is a misunderstanding that unfortunately forms basis for an entire section of his review. second type of error is more fundamentally mathematical: he does not distinguish between a definition and a theorem. Just as Lubet draws legal lessons from calculus, we can draw legal parallels from his mistakes. While some of these might be comforting, others will be more unsettling. As noted by Lubet, development of calculus was done more or less simultaneously in mid-17th century by Sir Isaac Newton and Gottfried Wilhelm Leibniz. Leibniz based much of his development of subject on idea of an infinitesimal, a class of numbers that are smaller than any other number. According to Lubet, the `infinitesimals' turn out to be a futile fiction, notwithstanding Liebnitz's [sic] own endorsement of them. In 1734, Bishop Berkeley that they do not and cannot exist.3 Lubet goes on in Part III to draw a number of legal parallels to this discrediting of idea of infinitesimals. While legal conclusions he draws from these events may well be true, Lubet cannot base them on invalidity of infinitesimals: fact of matter is that Leibniz was right. To be fair to Lubet, ultimate vindication of Leibniz's belief in infinitesimals is hidden in a footnote by Berlinski: The development of [non-Archimedean] fields by logician Abraham Robinson in twentieth century has made possible development of calculus entirely along lines anticipated by Leibnitz [sic].4 Nevertheless, anyone with serious mathematical training would not have needed Berlinski's footnote; Lubet's error highlights danger of relying on secondhand knowledge of a field quite different from one's own. Moreover, culpability aside, Lubet has lost foundation for legal insights he draws from purported invalidity of infinitesimals. And what of supposed proof' of Bishop Berkeley? Berlinski writes that [w]riting in 1734, Bishop Berkeley wasted no time in attacking very idea of infinitesimals, and later says that [1]ooking backward, we can see that Berkeley was entirely correct,5 but never claims that Bishop Berkeley proved conclusively anything about existence of infinitesimals. Indeed, he couldn't have, since by appropriately generalizing idea of a number, Abraham Robinson was able to define them. Lubet should be more careful in using term proof' in context of mathematics. Lubet sees more parallels between computation of area under a curve and way that legal trials proceed by means of accretion of detail.6 Surprisingly, Lubet doesn't draw obvious parallel, that just as sum of more and more rectangles gives better and better approximations for area under a curve, as a trial proceeds evidence presented gives a better and better approximation of truth. He instead focuses on error in mathematical approximation: An integral combines rectangles until limit of error approaches zero, but error-zone never actually becomes zero. …