Are there differences between the sale of an unopened Super Mario Bros. computer game and of the digital collage of 5,000 images? Viewed from the perspective of the doctrine of exhaustion, we can easily conclude that the two transfers have significant differences. The auction of the tangible data carrier of the Super Mario’s 1986 edition (for $660,000) 1 fits well into the doctrine. The auction of the NFT (non-fungible token) representing Beeple’s “Everdays: the First 5000 Days” (for an equivalent of an astounding $69.3 million) 2 seems to be hype with a snowball effect rather than a modern encapsulation of digital exhaustion. Some commentators, 3 including the present author in collaboration with Alexandra Giannapoulou, João Pedro Quintais, and Balázs Bodó, 4 have thoroughly introduced the incompatibility of the NFT mania with the existing copyright status quo, and so – in connection with the present book’s topic – the sale of tokenized information, which is capable of representing information related to digital artworks, is practically excluded from the scope of the exhaustion of the right of distribution. At the same time, NFTs de facto offer a “code-based digital ecosystem that has practical consequences for the copyright-relevant fields of creativeness.” 5 The sale and resale of NFTs is possible; an exchange of information and title to “own” and “trade” information related to copyrightable subject matter is technologically guaranteed. In line with that, a quasi-exhaustion regime has also emerged. As such, the NFT mania can practically evidence the need for and modern technology’s capability of offering digital marketplaces for artworks as well.
Zero knowledge proof system which has received extensive attention since it was proposed is an important branch of cryptography and computational complexity theory. Thereinto, noninteractive zero knowledge proof system contains only one message sent by the prover to the verifier. It is widely used in the construction of various types of cryptographic protocols and cryptographic algorithms because of its good privacy, authentication, and lower interactive complexity. This paper reviews and analyzes the basic principles of noninteractive zero knowledge proof system, and summarizes the research progress achieved by noninteractive zero knowledge proof system on the following aspects: the definition and related models of noninteractive zero knowledge proof system, noninteractive zero knowledge proof system of NP problems, noninteractive statistical and perfect zero knowledge, the connection between noninteractive zero knowledge proof system, interactive zero knowledge proof system, and zap, and the specific applications of noninteractive zero knowledge proof system. This paper also points out the future research directions.
Fabrice Benhamouda, Stephan Krenn, Vadim Lyubashevsky, Krzysztof Pietrzak
Abstract. We design an efficient commitment scheme, and companion zero-knowledge proofs of knowledge, based on the learning with errors over rings (RLWE) problem. In particular, for rings in which almost all elements have inverses, we construct a perfectly binding commitment scheme whose hiding property relies on the RLWE assumption. Our scheme maps elements from the ring (or equivalently, n elements from Fq) to a small constant number of ring elements. We then construct Σ-protocols for proving, in a zero-knowledge manner, knowledge of the message contained in a commitment. We are able to further extend our basic protocol to allow us to prove additive and multiplicative relations among committed values. Our protocols have a communication complexity of O(Mn log q) and achieve a negligible knowledge error in one run. Here M is the constant from a rejection sampling technique that we employ, and can be set close to 1 by adjusting other parameters. Previously known Σ-protocols for LWE-related languages either relied on “smudging ” out the error (which necessitates working over large fields, resulting in poor efficiency) or only achieved a noticeable or even constant knowledge error (thus requiring many repetitions of the protocol).
We present a construction for non-interactive zero-knowledge proofs of knowledge in the random oracle model from general sigma-protocols. Our construction is secure against quantum adversaries. Prior constructions (by Fiat-Shamir and by Fischlin) are only known to be secure against classical adversaries, and Ambainis, Rosmanis, Unruh (FOCS 2014) gave evidence that those constructions might not be secure against quantum adversaries in general. To prove security of our constructions, we additionally develop new techniques for adaptively programming the quantum random oracle.
It is a widely spread belief that crypto-currencies implementing a proof of stake transaction validation system are less vulnerable to a 51% attack than crypto-currencies implementing a proof of work transaction validation system. In this article, we show that it is not the case and that, in fact, if the attacker's motivation is large enough (and this is common knowledge), he will succeed in his attack at no cost.
Proof of Stake Velocity (PoSV) is proposed as an alternative to Proof of Work (PoW) and Proof of Stake (PoS) to secure the peer-to-peer network and conrm transactions of Reddcoin, a cryptocurrency created specically to facilitate social interactions in the digital age. PoSV is designed to encourage both ownership (Stake) and activity (Velocity) which directly correspond to the two main functions of Reddcoin as a real currency: store of value and medium of exchange. Reddcoin can also function as the unit of account in heterogeneous social context. The technological aspects of PoSV are presented after a detailed review of existing designs. The economic aspects of Reddcoin are then analysed. Finally the unique position of Reddcoin as a digital social currency in the competitive landscape of cryptocurrencies is discussed.
Iddo Bentov, Charles Lee, Alex Mizrahi, Meni Rosenfeld
We propose a new protocol for a cryptocurrency, that builds upon the Bitcoin protocol by combining its Proof of Work component with a Proof of Stake type of system. Our Proof of Activity (PoA) protocol offers good security against possibly practical future attacks on Bitcoin, and has a relatively low penalty in terms of network communication and storage space. We explore various attack scenarios and suggest remedies to potential vulnerabilities of the PoA protocol, as well as evaluate the performance of its core subroutine. 1
Decentralisation and devolution in conducting of public affairs from higher to lower level of government was implemented in Croatia in 2001 in elementary and secondary education, health care, social welfare and firefighting. It was not true decentralization, with the expansion of the local authority, responsibility and financial capabilities, rather mere administrative decentralization, without spreading the autonomy of the local community. Legal decentralization was not accompanied by fiscal decentralization, which involves financial aspects of transfer of public affairs to regional and local government. The degree of fiscal decentralization of certain government is estimated by the proportion of local government involvement in total revenues and expenditures of the general government and the local government share in GDP. None of these indicators in Croatia are reaching the EU average. Financing of decentralized functions from income tax in the past five years indicates enormous problems in financing due to total dependence of local communities on the central government, especially in the area of primary and secondary education. In such circumstances, the local management, responsible for the efficient and economical operation of the management and disposal of funds for decentralization, is facing organizational challenges.
Marcin Andrychowicz, Stefan Dziembowski, Daniel Malinowski, Łukasz Mazurek
Bitcoin is a peer-to-peer cryptographic currency system. Since its introduction in 2008, Bitcoin has gained noticeable popularity, mostly due to its following properties: (1) the transaction fees are very low, and (2) it is not controlled by any central authority, which in particular means that nobody can "print" the money to generate inflation. Moreover, the transaction syntax allows to create the so-called contracts, where a number of mutually-distrusting parties engage in a protocol to jointly perform some financial task, and the fairness of this process is guaranteed by the properties of Bitcoin. Although the Bitcoin contracts have several potential applications in the digital economy, so far they have not been widely used in real life. This is partly due to the fact that they are cumbersome to create and analyze, and hence risky to use. In this paper we propose to remedy this problem by using the methods originally developed for the computer-aided analysis for hardware and software systems, in particular those based on the timed automata. More concretely, we propose a framework for modeling the Bitcoin contracts using the timed automata in the UPPAAL model checker. Our method is general and can be used to model several contracts. As a proof-of-concept we use this framework to model some of the Bitcoin contracts from our recent previous work. We then automatically verify their security in UPPAAL, finding (and correcting) some subtle errors that were difficult to spot by the manual analysis. We hope that our work can draw the attention of the researchers working on formal modeling to the problem of the Bitcoin contract verification, and spark off more research on this topic.
We are calling for comparisons of banking and banking systems from a spatial perspective. Therefore, this paper develops a classification identifying decentralized and centralized banking according to two characteristics: geographical market orientation (regional vs. supraregional) – to determine whether banks facilitate regional savings-investment cycles – and place of decision-making (proximity vs. distance) – to identify whether the flow of soft information is supported in SME lending. The degree of banks’ centralization is also approximated by the spatial concentration of bank employees and shows remarkable explanatory power in Germany, as de-centralized banks increase lending at the expense of centralized banks.
This paper overviews the entire landscape of Bitcoin-like cryptocurrencies. Bitcoin has not emerged out of cryptocurrency competition, but rather became a dominant currency as the first broad market based cryptocurrency. But there are more than a hundred of cryptocurrencies in the market, and some are catching up to Bitcoin. This is a healthy sign of currency competition á la Hayek. Through this competition new technological and security innovations may emerge. In this paper, we point out potential problems with Bitcoin and propose some ideas for an alternative cryptocurrency.
Bitcoin has enabled competition between digital cryptocurrencies and traditional legal tender fiat currencies. Despite rapidly increasing acceptance, so far the affirmation of cryptocurrency as better money has been thwarted by dramatic deflationary price instability. Successful at disposing of any central monetary authority, bitcoin has elected to have a fixed deterministic inelastic monetary policy, establishing itself more as digital gold than as a currency. Price stability could be achieved by dynamically rebasing the outstanding amount of money: the number of cryptocurrency units in every digital wallet is adjusted instead of each single unit changing its value. The apparent awkwardness of this unfamiliar paradigm is discussed at length, proving that its only real novelty is about fairness and effectiveness. Furthermore, suggestions are provided about how to ease the effect of contractionary monetary policy. The proposed monetary base adjustment has neutral impact on the overall wallet wealth, as it does not introduce any arbitrary distortion into the intrinsic value dynamics of the wallet. The adjustment is based on a commodity price index determined with a resilient consensus process that does not rely on central third party authorities. It is posited in this paper that a digital cryptocurrency adopting elastic monetary standard is Hayek Money, so named from the Nobel Prize-winning economist: a good money standard providing stable prices for a new economic era.
Though Bitcoin currently enjoys a healthy niche, the aspirations of many in the project are grander: to supplant the existing regime of fiat currencies with cryptocurrencies, and to do so outside of normal political channels. Its primary practical obstacle is its purchasing power volatility, arising from a rigid money stock in the face of wide swings in demand. Nevertheless, the historical example of gold, another (much more successful) money commodity with a more or less rigid supply, illuminates the institutional prerequisites for purchasing power stability, economic efficiency, and sustained growth – namely a market of financial intermediaries whose liabilities denominated in the base money themselves circulate as media of exchange. This paper discusses potential benefits and hurdles to establishing financial intermediation in cryptocurrency, as well as the possibility of managing the money supply to create a stable purchasing power cryptocurrency without the need for intermediation at all. Such schemes ultimately require an existing market of intermediaries in order to provide any benefits, the emergence of which governments are for the moment well-positioned to prevent.
We analyze how network effects affect competition in the nascent cryptocurrency market. We do so by examining the changes over time in exchange rate data among cryptocurrencies. Specifically, we look at two aspects: (1) competition among different currencies, and (2) competition among exchanges where those currencies are traded. Our data suggest that the winner-take-all effect is dominant early in the market. During this period, when Bitcoin becomes more valuable against the U.S. dollar, it also becomes more valuable against other cryptocurrencies. This trend is reversed in the later period. The data in the later period are consistent with the use of cryptocurrencies as financial assets (popularized by Bitcoin), and not consistent with "winner-take-all" dynamics.
Cryptocurrencies like Biteoin are transferable digital assets, secured by cryptography. To date, all of them have been created by private individuals, organizations, or firms. Unlike bank account balances, they are not anyone's liability. They are not redeemable for any government fiat money such as Federal Reserve Notes or for any commodity money such as silver or gold coins. The cryptocurrency is thus a of competing private irredeemable monies (or would-be monies). Friedrich A. Hayek (1978a) and other economists over the last 40 years could only imagine how competition among issuers of private irredeemable monies would work. Today we have an actual study. In what follows I will discuss the main economic features of the market. I also discuss whether the is purely a bubble. As an introduction the topic, I offer the following comic verse about the contrast between Biteoin and the physical gold coins of the past: In the past, money's value was judged with our teeth; We bit coins confirm they were real. Now a Bitcoin's just data, no gold underneath. That's okay if it buys you a meal. (1) The Size and Composition of the Cryptocurrency Market Bitcoin rightly gets the lion's share of media attention, but it is not alone in the for cryptocurrencies. The authoritative website CoinMarketCap.com tracks the U.S. dollar price and total market (price per unit multiplied by number of units outstanding) for each of more than 500 traded cryptocurrencies. Bitcoin is the largest by far. On a recent day (March 9, 2015), the site showed Bitcoin trading at $291 per unit, with a cap of $4.05 billion. The second and third largest cryptocurrencies, Ripple and Litecoin, had caps respectively 8.5 percent and 1.8 percent as large. The entire set of non-Bitcoin cryptocurrencies (known as altcoins) had a cap of roughly $619 million, or 15 percent of Bitcoin's. Stated differently, Bitcoin had roughly 87 percent of the market, altcoins 13 percent. In percentage terms, altcoins do a higher share of Bitcoin's business than Bitcoin does of the Federal Reserve Note's business (currently $1.35 trillion in circulation). In trading volume the percentage share of altcoins (led by litecoin and Ripple) has been similar. The cryptocurrency has grown about fourfold in cap over the last 22 months, with altcoins growing faster than Bitcoin. This is seen by comparing recent data the oldest snapshot of the CoinMarketCap site available via the Internet Archive Wayback Machine, which reports data for May 9, 2013. On that date, Bitcoin had a price of $112 per unit, and a cap of $1.2 billion. The two largest altcoins at that time, Litecoin and Peercoin (aka PPCoin), had caps respectively 4.7 percent and 0.4 percent as large. Only 13 altcoins were listed. Jointly their cap was about 6 percent of Bitcoin's, giving Bitcoin 95 percent of the market. Since then, the share of altcoins has doubled, and their cap has grown ninefold. Trading volumes then were not reported. At $4.05 billion, the cap of Bitcoin, as of March 2015, was slightly smaller than the dollar value of the September 2014 monetary bases of the Lithuanian litas ($5.8 billion) and the Guatemalan quetzal ($5.5 billion), but larger than those of the Costa Rican colon ($3.3 billion) and the Serbia dinar ($3.3 billion). (2) The August 2014 figures from the Central Bank of the Bahamas do not provide the monetary base, but count Bahamian dollar currency in circulation at $210 million, less than two-thirds of Ripple's recent cap of around $344 million. Medium of Exchange, Store of Value, and Medium of Remittance Functions The retail use of Bitcoin as a medium of exchange for goods and services is small date, but is growing. In December 2014, Microsoft began accepting bitcoin payments to buy content such as games and videos on Xbox game consoles, add apps and services Windows phones or buy Microsoft software (BBC 2014). …
We study the economics of Bitcoin transaction fees in a simple static partial equilibrium model with the specificity that the system security is directly linked to the total computational power of miners. We show that any situation with a fixed fee is equivalent to another situation with a limited block size. In both cases, we give the optimal value of the transaction fee or of the block size. We also show that making the block size a non binding constraint and, in the same time, letting the fee be fixed as the outcome of a decentralized competitive market cannot guarantee the very existence of Bitcoin in the long-term.