James Bartusek, Andrea Coladangelo, Dakshita Khurana, Fermi Ma
We investigate the round complexity of maliciously-secure two-party quantum computation (2PQC) with setup, and obtain the following results:
- A three-message protocol (two-message if only one party receives output) in the common random string (CRS) model assuming classical two-message oblivious transfer (OT) with post-quantum malicious security. This round complexity is optimal for the sequential communication setting. Under the additional assumption of reusable malicious designated-verifier non-interactive zero-knowledge (MDV-NIZK) arguments for NP, our techniques give an MDV-NIZK for QMA. Each of the assumptions mentioned above is known from the quantum hardness of learning with errors (QLWE).
- A protocol with two simultaneous rounds of communication, in a quantum preprocessing model, assuming sub-exponential QLWE. In fact, we construct a three-round protocol in the CRS model with only two rounds of online communication, which implies the above result. Along the way, we develop a new delayed technique that we call simulation via teleportation, which may be useful in other settings.
In addition, we perform a preliminary investigation into barriers and possible approaches for two-round 2PQC in the CRS model, including an impossibility result for a natural class of simulators, and a proof-of-concept construction from a strong form of quantum virtual black-box (VBB) obfuscation.
Prior to our work, maliciously-secure 2PQC required round complexity linear in the size of the quantum circuit.
The hardness of highly-structured computational problems gives rise to a variety of public-key primitives. On one hand, the structure exhibited by such problems underlies the basic functionality of public-key primitives, but on the other hand it may endanger public-key cryptography in its entirety via potential algorithmic advances. This subtle interplay initiated a fundamental line of research on whether structure is inherently necessary for cryptography, starting with Rudich’s early work (PhD Thesis '88) and recently leading to that of Bitansky, Degwekar and Vaikuntanathan (CRYPTO '17). Identifying the structure of computational problems with their corresponding complexity classes, Bitansky et al. proved that a variety of public-key primitives (e.g., public-key encryption, oblivious transfer and even functional encryption) cannot be used in a black-box manner to construct either any hard language that has NP-verifiers both for the language itself and for its complement, or any hard language (and even promise problem) that has a statistical zero-knowledge proof system - corresponding to hardness in the structured classes NP ∩ coNP or SZK, respectively, from a black-box perspective. In this work we prove that the same variety of public-key primitives do not inherently require even very little structure in a black-box manner: We prove that they do not imply any hard language that has multi-prover interactive proof systems both for the language and for its complement - corresponding to hardness in the class MIP ∩ coMIP from a black-box perspective. Conceptually, given that MIP = NEXP, our result rules out languages with very little structure. Already the cases of languages that have IP or AM proof systems both for the language itself and for its complement, which we rule out as immediate corollaries, lead to intriguing insights. For the case of IP, where our result can be circumvented using non-black-box techniques, we reveal a gap between black-box and non-black-box techniques. For the case of AM, where circumventing our result via non-black-box techniques would be a major development, we both strengthen and unify the proofs of Bitansky et al. for languages that have NP-verifiers both for the language itself and for its complement and for languages that have a statistical zero-knowledge proof system.
Introduction. In the context of reforming the system of local self-government and territorial organization of power, they need to rethink a number of important theoretical postulates of domestic financial science through the prism of improving existing and developing new conceptual approaches to the theoretical substantiation of the finances of the united territorial communities in their territorial communities. After all, the study of OTG finances, with their permanent dominance in local finance, is the basis for effective implementation of the reform of financial decentralization and local development. Moreover, upon completion of the reform, the UGT finances will prevail, completely changing the local finances. Purpose. Given the limited theoretical and practical experience of domestic scientists on the finances of the united territorial communities, the purpose of the article is to find out the place and role of OGF finances in the financial system of the state. Methods. The methods of abstraction, generalization, induction, deduction, synthesis were applied in the study of the role and place of OGF finances in the financial system of the state, as well as the system method. Results. The views of domestic and foreign theorists and practitioners on the scientific substantiation of the financial system of the state and its structural components have been systematized. The LTG finances in its structure and the role for modifications of local finances was determined. This made it possible to identify OTG finances as an area of the financial system and to formulate a science-based approach to their knowledge, while separating OTG budgets, utility and financial institutions and local borrowing in their structure. Discussion. It is advisable to carry out further scientific researches of OGF finances on the basis of the formed theoretical substantiation of OGF finances as an integral part of the financial system of the state with the corresponding structural structure – links that are interconnected and interact.
In the first chapter, To Pool or Not to Pool? Security Design in OTC Markets with Vincent Glode and Christian C. Opp, we study security issuers' decision whether to pool assets when facing counterparties endowed with market power, as is common in over-the-counter markets. Unlike in competitive markets, pooling assets may be suboptimal in the presence of market power --- both privately and socially --- in particular, when the potential gains from trade are large. In these cases, pooling assets reduces the elasticity of trade volume in the relevant part of the payoff distribution, exacerbating inefficient rationing associated with the exercise of market power. Our results shed light on recently observed time-variation in the prevalence of pooling in financial markets. In the second chapter, Selling to Investor Network: Allocations in the Primary Corporate Bond Market, I develop a model of the primary market for corporate bonds, in which an issuer optimally chooses an issuance price and allocations to investors based on their trading connections in the secondary over-the-counter market. Expected secondary market liquidity, which depends on the structure of the trading network in this market, determines investors' demands in the primary market and, in turn, the issuer's revenues. I show that trading by less connected investors has a relatively high negative impact on expected secondary market liquidity and disproportionately reduces the demands of all investors in the primary market. As a result, the issuer can increase her profits by restricting allocations of new bonds only to more connected investors. This explains the commonly observed exclusion of small institutional investors from the primary market, which is often coupled with seemingly underpriced bonds. In the third chapter, Initial Coin Offerings as a Commitment to Competition with Itay Goldstein and Deeksha Gupta, we model Initial Coin Offerings (ICOs) of utility tokens, which are increasingly used to finance the development of online platforms where buyers and sellers can meet to exchange services or goods. Utility tokens serve as the sole medium of exchange on a platform and can be traded in a secondary market. We show that such a financing mechanism allows an entrepreneur to give up monopolistic rents associated with the control of the platform and make a credible commitment to long-run competitive prices. The entrepreneur optimally chooses to have an ICO, rather than operate as a monopolist, only if future consumers of the platform participate in financing. ICOs, therefore, endogenously require crowd-funding to be viable.
With the rise of digitalization, myriad new technologies are currently revolutionizing most, if not all, markets. One such technology that is receiving particular attention from businesses, private market participants, the financial sector, and governments alike is the blockchain. Despite its increasing popularity, most jurisdictions currently fail to adequately regulate it, meaning that businesses cannot exploit the full potential of blockchain technology and its various applications. This article explains how blockchains function and delineates their associated compliance risks. Here, particular attention will be paid to both decentralized cryptocurrencies and stablecoins. How decentralized cryptocurrencies could potentially be abused for money laundering, terrorism financing, and corruption purposes will be illustrated, and different legislation and international approaches to dealing with blockchain technology and cryptocurrencies will be highlighted. Lastly, the impact of blockchain technology and its implications for actors in the digitalized economy will be discussed.
Traditional centralized access control has some shortcomings in robustness, trustworthiness and circulation. Blockchains have the advantages of fault tolerance and trust. Smart contracts have the characteristics of automatic execution and flexible expansion. Tokens can well record credential information and transfer easily. In this paper, blockchain, smart contract and token are integrated and applied to access control to solve the shortcomings of traditional access control. First, access control, blockchain, smart contract and token are briefly described. Second, this paper proposes a solution by giving the general data structure of access control token, elaborating the equivalence, split, merge and verification algorithms of access control token, and explaining the system architecture of token-based access control. Last, this paper uses a token-based access control simulation system to verify that token-based access control has certain comparative advantages in robustness, trustworthiness, circulation, concurrency and so on.
Today, companies use blockchain technology and digital assets for a variety of purposes. This Comment analyzes the digital token. If the Securities and Exchange Commission (SEC) views a digital token as a security, then the issuer of the digital token must comply with the registration and extensive disclosure requirements of federal securities laws.\nTo determine whether a digital asset is a security, the SEC relies on the test that the Supreme Court established in SEC v. W.J. Howey Co. Rather than enforcing a statute or agency rule, the SEC enforces securities laws by applying the Howey test on a fact-intensive case-by-case basis. This Comment takes the position that policymaking by enforcement is harmful to the financial technology industry and perpetuates the lack of clarity surrounding regulation of digital assets.\nThis Comment proposes a solution in which both Congress and the SEC play an integral role: 1) Congress should amend the Securities Act of 1933 and the Securities Exchange Act of 1934 to exclude “digital token” from the definition of “security”; and 2) the SEC should issue an agency rule that creates a grace period for digital tokens to become fully decentralized before the SEC may evaluate whether they are securities.
The Securities and Exchange Commission (SEC) recently took steps to regulate certain forms of cryptocurrency as substitute securities. However, the SEC has not provided clear guidance regarding which forms of cryptocurrency it deems worthy of regulation. This creates a dilemma. While some cryptocurrencies, like those involved in capital-raising via initial coin offerings (ICOs), do indeed seem like securities, others do not. For example, J.P. Morgan is developing a cryptocurrency that appears to be more like fiat currency than a security. This Note discusses how the SEC recently convinced a federal judge that certain ICO-related cryptocurrencies can be considered securities under the Howey test, as well as how the major questions doctrine—which asserts that issues of major importance should not be left to the discretion of federal agencies absent clear congressional guidance—relates to the topic of cryptocurrency regulation. Furthermore, this Note discusses why it is undesirable that the SEC is regulating cryptocurrency without clear guidance from Congress regarding which cryptocurrencies the Commission has the authority to regulate. Because cryptocurrency is such a rapidly developing field, the gray area between forms of cryptocurrency that seem to be securities and those that do not will only become more complex. As a result, piecemeal cryptocurrency regulation will continue to deprive innovators of sufficient guidance regarding issues such as whether their cryptocurrency must be registered with the SEC. Ultimately, this Note argues that the regulation of cryptocurrency—as a developing technology—is a “major question,” and thus Congress should authorize a new commission or sub-agency that can adequately address this varied and everchanging field.
Identity is a tool that identifies a person or group and ensures that they are recognized by others. Personalidentification cards issued by the states to people contain specific information about the person given.Identity systems used for centuries are now digitalized, ID cards with chips and passports with chipshave entered our lives. In the past, only information such as name, surname and place of birth wereincluded in ID cards with chips and passports. But today, in addition to our personal information, itincludes our biometric information such as fingerprints, iris, digital signatures. Blockchain technology,which has entered our lives with the financial sector, offers application areas in different sectors andsubjects. Some of these are IoT (internet of things), security and reliability systems, copyrights, publicand health sectors. In this study, it has been mentioned about the advantages and the features obtainedby using blockchain technology in identity management. The purpose of this study; It is to ensure thesafe use of identity information thanks to the features provided by the block chain such as distributeddatabase called DLT (distributed ledger technology), peer-to-peer transmission, transparency andirreversible records. Also in this study, a software that can simulate blockchain technology was createdand an Android application that reads data with NFC (Near Field Communication) technology wasdeveloped. Thus, the process of adding the data in the ID card or passport to the block chain by readingthe data from NFC with the Android application can be performed.
We show an Ω̃(n^2.5) lower bound for general depth four arithmetic circuits computing an explicit n-variate degree-Θ(n) multilinear polynomial over any field of characteristic zero. To our knowledge, and as stated in the survey [Amir Shpilka and Amir Yehudayoff, 2010], no super-quadratic lower bound was known for depth four circuits over fields of characteristic ≠ 2 before this work. The previous best lower bound is Ω̃(n^1.5) [Abhijat Sharma, 2017], which is a slight quantitative improvement over the roughly Ω(n^1.33) bound obtained by invoking the super-linear lower bound for constant depth circuits in [Ran Raz, 2010; Victor Shoup and Roman Smolensky, 1997]. Our lower bound proof follows the approach of the almost cubic lower bound for depth three circuits in [Neeraj Kayal et al., 2016] by replacing the shifted partials measure with a suitable variant of the projected shifted partials measure, but it differs from [Neeraj Kayal et al., 2016]’s proof at a crucial step - namely, the way "heavy" product gates are handled. Loosely speaking, a heavy product gate has a relatively high fan-in. Product gates of a depth three circuit compute products of affine forms, and so, it is easy to prune Θ(n) many heavy product gates by projecting the circuit to a low-dimensional affine subspace [Neeraj Kayal et al., 2016; Amir Shpilka and Avi Wigderson, 2001]. However, in a depth four circuit, the second (from the top) layer of product gates compute products of polynomials having arbitrary degree, and hence it was not clear how to prune such heavy product gates from the circuit. We show that heavy product gates can also be eliminated from a depth four circuit by projecting the circuit to a low-dimensional affine subspace, unless the heavy gates together account for Ω̃(n^2.5) size. This part of our argument is inspired by a well-known greedy approximation algorithm for the weighted set-cover problem.
Decentralized Finance is the new socioeconomic system growing with an extremely fast pace and changing the way financial interactions are being conducted. In comparison with the growing importance of digital assets and blockchain technology, there is still little understanding of Decentralized Finance as a system. In this thesis we analyze transaction datasets from Bitcoin and Ethereum blockchains to obtain a comprehensive understanding of digital assets -from studying the behaviour of each part to investigating the whole structure and deriving the relations between micro and macro properties of the cryptocurrency systems. Using the Complex Networks approach we explained the system's overall structure and dynamics, and uncovered the mechanism behind network formation. It was found that there is fitness preferential attachment among nodes in the bitcoin network that leads the system to scale-free behaviour. We proposed the quantifiable definition of fitness and supported our finding by simulating a synthetic network and reproducing the main properties of the bitcoin network. After having a good understanding about the structure of the system, we zoom in into its parts by studying the behavioral patterns among the system's users (people). We develop the methodology based on Machine Learning models to define distinct behavioral types in the cryptocurrency systems and find that despite differences between the bitcoin and ethereum systems, there are four common strategies that users follow in both markets. Based on our finding, we model the dynamics of people's behaviour in market as an Absorbing Markov Chain. This approach allowed us to present the behavioral switches in a comprehensive and intuitive way. Moreover, we were able to obtain the predictions on the longevity of users in the system according to their behaviour. Finally, we use the Granger causality test to derive the relations between all system characteristics. We attempt to explain the effect of behavioral switches on the structural properties and price; we find that indeed, switches of users from certain behavioral groups causes a change in price which affects the size of the network as well. We hope that the work and results presented in this thesis will advance the understanding of the new field of Decentralized Finance and expect that the research approach and methodologies developed for this study will be helpful to investigate various complex systems as well.
Property taxes are one of the most essential taxes for the local authorities in any country. They are the main source for providing the municipality with finance in order to provide public goods and services. The last decade of unstable fiscal policy induced the necessity to readdress the role and the potential for reform or modernization of these sort of taxes. Considering the ever-growing thirst for larger expenses and going forward with fiscal decentralization process in North Macedonia, the local governments are confronted with the need to secure more finances. Therefore, the goal is to examine the current structure of property taxes in North Macedonia, compare them to some countries in Europe and finally to propose actions regarding some changes in local tax policy in order to improve the tax collection. Those changes should follow the growing inequalities among citizens in the country. In most developed countries the volume of property tax involves real estate and personal property, like vehicles, movable household items. Even some countries take into consideration the ownership of real estate in other countries around the world in order to really detect the wealth of some people. The last reaction from the central government in order to overcome the gap in local budgets (the government borrowed 50.000.000 euros) was with intention to reduce the level of debt in most of the local municipalities and to secure their everyday functioning. Since then there are a lot of discussions in direction of better functioning of local governments through better collection of local revenues.
The last years have experienced an effervescence in the field of monetary innovation, concerning both complementary currencies and cryptocurrencies. The scenario of innovation has been intensively investigated with regard to economic and socio-political aspects. Against the peculiar multidimensionality of the phenomenon, the paper argues that the analysis should take the opportunity of grasping a cobelonging between the economic and the social. Whether they seem related to a proliferation of new forms of sociality (as in many experiences of complementary currencies) or to a disquieting desocialization (as in certain domains of the cryptocurrencies' world), the social dimensions of the new monies can be fruitfully analyzed by focusing on how they are consonant with certain basic conceptions of economic life. After a brief discussion of this point with regard to complementary currencies, the above-mentioned theoretical approach is used to investigate the cybernetic ethos of cryptocurrencies. The analysis shows that the socio-technical imaginaries of some cryptocurrencies (with particular regard to Bitcoin) call into question the relationship between human and non-human agency and are complicit with certain ideas of economic life, one of whose main traits concerns the demand for unconditionally "assuring" the economic and for denying the dimension of uncertainty.
This article presents an example of how globalization and digitization force states to rely on international organization. Examining tax policy with respect to cryptocurrency—an innovative, global technology—the implication is that a state levying taxes on cryptocurrency must turn to international monitoring and enforcement regimes to support effective taxation. Based on Margaret Levi’s theory of predatory rule, I submit a theory of “co-predation” to explain international cooperation with respect to taxation of novel, cross-border technologies such as cryptocurrency. The Automatic Exchange of Information (AEOI), an anti-tax evasion framework promulgated by the OECD, serves as an example of international cooperation. A comparison of cryptocurrency taxation in Russia and Belarus finds that, where effective tax policy is at stake, states are enjoined to commit to international cooperation through AEOI. The article concludes by considering implications for legitimacy, quasi-voluntary compliance, and strategic tax policy.
WHO was informed on 31 December 2019 of cases of unknown cause pneumonia in Wuhan City, China. On 7 January 2020 Chinese authorities reported a novel coronavirus as the cause and was temporarily labeled "2019-nCoV." Coronaviruses (CoV) are a wide family of viruses which cause diseases ranging from common cold to more serious illnesses. A novel coronavirus (nCoV) is a new strain not previously found in humans. Countries around the globe have stepped up their surveillance to quickly detect any new 2019-nCoV cases. Blockchain is developing into a safe and efficient network for secure data sharing in applications such as the financial industry, operations management, food industry, energy market, the Internet of Things and healthcare. In this paper, we are using blockchain technology as a mean to share authentic data, tracking of relevant information and help speed up the treatment process. At the same time it will preserve person’s identity. Timely deployment and suitable implementation of the proposed model have the opportunity to curb COVID-19 transmissions and associated mortality, especially in environments with inadequate access to testing facilities. This work will also facilitate in the treatment of other infectious diseases. Smart contract have been designed and implemented using the ethereum blockchain platform which has been presented in this paper. This work would facilitate multiple stakeholders who are involved within the medical system to curb the transmission of this disease.
Kepler Concordia, a new scientific and musical instrument enabling players to explore the solar system and other data within immersive extended-reality (XR) platforms, is being designed by a diverse team of musicians, artists, scientists and engineers using audio-first principles. The core instrument modules will be launched in 2019 for the 400th anniversary of Johannes Kepler's Harmonies of the World, in which he laid out a framework for the harmony of geometric form as well as the three laws of planetary motion. Kepler's own experimental process can be understood as audio-first because he employed his understanding of Western Classical music theory to investigate and discover the heliocentric, elliptical behaviour of planetary orbits. Indeed, principles of harmonic motion govern much of our physical world and show up at all scales in mathematics and physics. Few physical systems, however, offer such rich harmonic complexity and beauty as our own solar system. Concordia is a musical instrument that is modular, extensible and designed to allow players to generate and explore transparent sonifications of planetary movements rooted in the musical and mathematical concepts of Johannes Kepler as well as researchers who have extended Kepler's work, such as Hartmut Warm. Its primary function is to emphasise the auditory experience by encouraging musical explorations using sonification of geometric and relational information of scientifically accurate planetary ephemeris and astrodynamics. Concordia highlights harmonic relationships of the solar system through interactive sonic immersion. This article explains how we prioritise data sonification and then add visualisations and gamification to create a new type of experience and creative distributed-ledger powered ecosystem. Kepler Concordia facilitates the perception of music while presenting the celestial harmonies through multiple senses, with an emphasis on hearing, so that, as Kepler wrote, ‘the mind can seize upon the patterns’.