Feroz Ahmad Ahmad, Prashant Kumar, Gulshan Shrivastava, Med Salim Bouhlel
ON 12 JANUARY 2009 a pseudonymous entity signed a transaction that instructed a distributed network to transfer a small amount of digital currency to Hal Finney, one ofthe key figures of the cypherpunk movement. After a few minutes, the transaction was recorded on a distributed public ledger, permanently updating the balance ofbothparties. This transactionâ the first Bitcoin transactionâmarked the beginning of a new era of decentralized payment systems, ushering in a variety of financial Services that do not depend on any centralized clearinghouse or other financial middleman. Bitcoin is regarded by many as a powerful technological innovation that could disrupt many sectors, in the realm of finance and beyond. But the underlying technology on which the network operates, the Bitcoin blockchain can do much more than that. Just as the internet did in the early-1990s, blockchain technology carries with it a whole new range of promises concerning how decentralization can support and promote individual freedoms and autonomy. Blockchain proponents believe that Bitcoin and other cryptocurrency platforms will revolutionize mechanisms of value exchange in the same way that the internet transformed information sharing, by providing a platform for people to exchange digital resources, in a secure and decentralized manner without the need to rely on any intermediary or trusted authority. But this revolutionary potential also carries with it serious implications for censorship, intellectual property, and the regulated flow of information. A blockchain is a decentralized database of transactions maintained by a distributed network of computers, which all contribute to the verification and the validation of transactions. Once accepted, these transactions are recorded inside a âblockâ of transactions, which incorporates a reference to previous blocks. This creates a long chain of blocksâa âblockchainââthat stores the history of all transactions in a chronological order. Every block contains information about a particular set of transactions, a reference to the preceding block in the blockchain, and the answer to a complex mathematical puzzle that is used to validate the data associated with that block. A copy of the blockchain is stored on every computer in the network, making it virtually impossible for anyone unilaterally to modify the data stored on this decentralized database: if anyone tries to modify any transaction the fraud will be immediately detected by all other network participants.
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Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
Bitcoin is the first and most popular decentralized cryptocurrency to date. In this work, we extract and analyze the core of the Bitcoin protocol, which we term the Bitcoin backbone , and prove three of its fundamental properties which we call Common Prefix , Chain Quality, and Chain Growth in the static setting where the number of players remains fixed. Our proofs hinge on appropriate and novel assumptions on the âhashing powerâ of the protocol participants and their interplay with the protocol parameters and the time needed for reliable message passing between honest parties in terms of computational steps. A takeaway from our analysis is that, all else being equal, the protocolâs provable tolerance in terms of the number of adversarial parties (or, equivalently, their âhashing powerâ in our model) decreases as the duration of a message passing round increases. Next, we propose and analyze applications that can be built âon topâ of the backbone protocol, specifically focusing on Byzantine agreement (BA) and on the notion of a public transaction ledger. Regarding BA, we observe that a proposal due to Nakamoto falls short of solving it, and present a simple alternative which works assuming that the adversaryâs hashing power is bounded by 1/3. The public transaction ledger captures the essence of Bitcoinâs operation as a cryptocurrency, in the sense that it guarantees the liveness and persistence of committed transactions. Based on this notion, we describe and analyze the Bitcoin system as well as a more elaborate BA protocol and we prove them secure assuming the adversaryâs hashing power is strictly less than 1/2. Instrumental to this latter result is a technique we call 2-for-1 proof-of-work (PoW) that has proven to be useful in the design of other PoW-based protocols.
In this chapter we provide an overview of the concept of blockchain technology and its potential to disrupt the world of banking through facilitating global money remittance, smart contracts, automated banking ledgers and digital assets. In this regard, we first provide a brief overview of the core aspects of this technology, as well as the second-generation contract-based developments. From there we discuss key issues that must be considered in developing such ledger based technologies in a banking context.
Chain Of A Lifetime: How Blockchain Technology Might Transform Personal Insurance is the outcome of a research project conducted between August and December 2014 which explored how blockchain technology might transform personal insurance and in particular interactions among individuals and insurance companies over time.
Blockchain technology's main innovation is an electronic public transaction record of integrity without central authority. Beside cryptocurrencies and distributed payment systems, blockchain applications could include areas of finance where a central, trusted third party has traditionally been used, trade reporting, depository receipts, escrow accounts or trade finance. Blockchains can contain set of documents, record assets and help to manage interconnected devices. Emerging applications, such as smart contracts and decentralised autonomous organisations, might in future also permit blockchains to act as automated agents.
The report concludes that blockchain technology could transform the way people manage identities and personal information; blur even further the divide between global and local; influence consumer perception of time; drive honesty and transparency; and, influence consumer perceptions of risk that could change the way insurers support mutualisation. The report highlights how, at the time of writing, most insurance companies do not yet seem ready to experiment with blockchain technology. They find it difficult enough to understand Bitcoin or cryptocurrencies. Non-insurers are more likely to be the first to create insurance or insurance-related applications. Blockchain applications in insurance are likely to start with digital identity systems and management of personal data.
We show that the behaviour of Bitcoin has interesting similarities to stock\nand precious metal markets, such as gold and silver. We report that whilst\nLitecoin, the second largest cryptocurrency, closely follows Bitcoin's\nbehaviour, it does not show all the reported properties of Bitcoin. Agreements\nbetween apparently disparate complexity measures have been found, and it is\nshown that statistical, information-theoretic, algorithmic and fractal measures\nhave different but interesting capabilities of clustering families of markets\nby type. The report is particularly interesting because of the range and novel\nuse of some measures of complexity to characterize price behaviour, because of\nthe IRS designation of Bitcoin as an investment property and not a currency,\nand the announcement of the Canadian government's own electronic currency\nMintChip.\n
This paper explores the recent development of digital currenciesâcurrencies which are creatures of the Internet, self-authenticating, and usable worldwide by members of the general public to engage in the same types of direct, one-to-one transactions that daily occur using government-issued currencies. At present, the most developed digital currency measured by market capitalization is Bitcoin, which will be used as a proxy for the general phenomenon. Not surprisingly, as Bitcoinâs circulation and visibility has increased, so have the number of practical and legal issues surrounding its use. Some of these will be explored in this paper, with a view to considering the utility and viability of such currencies for widespread, global use.
Decrits is a cryptocurrency in development that makes use of a novel consensus algorithm that does not require proof-of-work. This paper describes how the Decrits Consensus Algorithm (DCA) is as trustless as a proof-of-work algorithm while offering superior transaction security at virtually no cost.
This Essay proposes a conceptual framework for the regulation of transactions involving cryptocurrencies. Cryptocurrencies offer tremendous opportunities for innovation and development but are also uniquely suited to facilitate illicit behavior. The regulatory framework suggested herein is intended to support (or at least not impair) cryptocurrenciesâ innovative potential. At the same time, it aims to disrupt cryptocurrenciesâ criminal utility. To achieve these purposes, this Essay proposes a regulatory framework that imposes costs on the characteristics of cryptocurrencies that make them especially useful for criminal behavior (in particular, anonymity) but does not impose costs on characteristics that are at the core of cryptocurrenciesâ generative potential (in particular, the decentralization of value-transfer processes). Using a basic utility model of criminal behavior as a benchmark, this Essay explains how regulatory instruments can be so designed. One such regulatory instrument is proposed as an example â an elective anonymity tax on cryptocurrency transactions in which at least one party is not anonymous.
Bitcoin is a decentralized P2P digital currency in which coins are generated by a distributed set of miners and transaction are broadcasted via a peer-to-peer network. While Bitcoin provides some level of anonymity (or rather pseudonymity) by encouraging the users to have any number of random-looking Bitcoin addresses, recent research shows that this level of anonymity is rather low. This encourages users to connect to the Bitcoin network through anonymizers like Tor and motivates development of default Tor functionality for popular mobile SPV clients. In this paper we show that combining Tor and Bitcoin creates an attack vector for the deterministic and stealthy man-in-the-middle attacks. A low-resource attacker can gain full control of information flows between all users who chose to use Bitcoin over Tor. In particular the attacker can link together user's transactions regardless of pseudonyms used, control which Bitcoin blocks and transactions are relayed to the user and can \ delay or discard user's transactions and blocks. In collusion with a powerful miner double-spending attacks become possible and a totally virtual Bitcoin reality can be created for such set of users. Moreover, we show how an attacker can fingerprint users and then recognize them and learn their IP address when they decide to connect to the Bitcoin network directly.
Bitcoin is a decentralized, open-source cryptocurrency used to make private, peer-to-peer transactions anywhere across the world. Although the individuals involved are (mostly) anonymous, every Bitcoin transaction is a matter of public record; anyone can view every Bitcoin transaction ever made. Following the methodology developed by Evans and Lyons (2002), this paper adapts and estimates a FX microstructure model that emphases order flow, the difference between buyer- and seller-initiated trading volume, to the Bitcoin market Using a data set consisting of all major currency transactions occurring on the Mt. Gox exchange, our results are quite similar to prior microfinance research on traditional currencies insofar order flow is a significant determinant of Bitcoin spot rates.
A soft control of the network activity through varying reward in a proof-of-work (PoW) cryptocurrency is reported. Rewards are the necessity to incent the contributors activities (i.e., mining) in order to maintain the PoW network. Contrary to constant rewarding in a certain period implemented in most of cryptocurrency, such as bitcoin, we propose a network-dependent rewarding model system, primarily including two phases: 1) activities encouraging phase in which higher rewards are issued at higher network activities; and 2) discouraging further increase of activities by reducing rewards. The advantages of this system include 1) fair distribution of rewards among a variety of contributors, and 2) enforcing a limit to the network activity and hence the cost of maintaining the PoW network. This mechanism requires network contributors to show their participation in order to earn maximum rewards, i.e., proof-of-mining.
In the history of money bitcoin represents an outstanding medium of exchange, independent from central authorities. Therefore, it has experienced impressive demand which, combined with inelastic supply, has led to huge price appreciation. Nonetheless, transaction volume has not been increasing accordingly. At the core of this conundrum is the very poor performance of bitcoin as unit of account: dramatic deflationary price instability makes bitcoin just impractical for commerce, but completely unserviceable for salaries, mortgages, and deferred payments in general. Ametrano (2014a) has championed as Hayek Money the proposal to engineer cryptocurrencies with fully automatic algorithmic non-discretionary elastic supply: the monetary rule of pegging to a price index would dynamically rebase the outstanding amount of money and achieve price stability. It is proposed here to implement Hayek Money as multiple coexisting units of account wrapped around the unmodified bitcoin (or any other cryptocurrency). Prices would be stable in terms of these rebased-bitcoin units of account: different coexisting cryptocurrencies all backed by the same bitcoins, each one with its own floating bitcoin-equivalent rebasing index. These cryptocurrencies would define a new monetary standard, with striking resemblance to the gold standard as improved by the compensated dollar proposed by Fisher (1913). In this Fisher Money scenario bitcoin would be digital crypto-gold and exchange rates would be floating, not fixed, being just the relative prices of the respective cryptocurrency price indexes.
This paper is a primer on many topics related to the digital cryptocurrency, Bitcoin. Bitcoins have been developed and advertised as a private digital money. We analyze this claim, generally to conclude that Bitcoins as they presently exist are not money. They are not generally accepted in exchange and do not serve as a unit of account. We test the hypothesis that the value of Bitcoins are determined largely by network externalities, finding very limited data to support this claim. We analyze features of bitcoins, such as their high exchange rate volatility with respect to the U.S. dollar and other currencies. We examine pricing on various exchanges, and how the law of one price works in bilateral and trilateral exchange rates involving Bitcoins. The potential for arbitrage is examined. We look at the use of bitcoins at Overstock.com, and the impact of that decision on Overstock.com stock prices and on the value of Bitcoins. We consider Bitcoins as an asset and examine their contribution to portfolio holdings. We discuss Bitcoinâs use in fraud resembling a Ponzi scheme. Finally, we speculate on the future of Bitcoins and the potential uses for the underlying technology.
This Article investigates an increasingly important yet under-developed body of law: regulation of virtual currency. At its peak in March of 2014, the daily volume of Bitcoin transactions in United States dollars exceeded $575,000,000. The growing mainstream acceptance of Bitcoin, however, is best illustrated by the growing number of leading merchants that have decided to accept Bitcoin payments. While Bitcoinâs rise as an alternative payment method is well-chronicled, Bitcoinâs impact extends further due to its use as an investment vehicle and its ability to spur the growth of an industry of Bitcoin-based businesses. Despite increasingly widespread use, Bitcoin (and other virtual currencies) have largely operated without the burden of regulation. Why? Like the potentially transformative innovations that preceded Bitcoin, virtual currency raises unique challenges for which existing legal models may be unprepared. As policymakers struggle to catch-up, the effort to develop an appropriate regulatory regime for virtual currency is at a critical juncture.The response in the United States has thus far involved regulatory bodies acting independently to clarify the treatment of virtual currency under a variety of different laws designed to regulate traditional payment systems, financial services, and investments. This Article argues, contrary to this approach, that a narrow focus on the technical application and extension of existing law creates a deficient regulatory regime. Instead, we suggest that policymakers should: (1) engage the various agency stakeholders to promote cross-communication; (2) think more globally about the wide spectrum of issues arising from virtual currency; and (3) embrace the unique and distinct characteristics of virtual currency. In support of this proposition, we show that refocusing on the collection of policy goals advanced by existing law offers policymakers an additional tool to aid in the development of a comprehensive, cohesive, and appropriately-scaled virtual currency regulatory model.
The present paper seeks to effectively address the following question: What Bitcoin looks like? To do so, we regress Bitcoin price on a number of variables (Bitcoin fundamentals recorded in the literature) by applying an ARDL Bounds Testing approach for daily data covering the period from December 2010 to June 2014. Our findings highlight the speculative nature of Bitcoin. We also provide insightful evidence that Bitcoin may be used for economic reasons but there is any sign of being a safe haven. By considering the Chinese trading bankruptcy and the closing of Road Silk by FBI, the contribution of usersâ interest stills sharply dominant, indicating the robustness of our results.
Off-Chain transactions allow for the immediate transfer of Cryptocurrency between two parties, without delays or unavoidable transaction fees. Such capabilities are critical for mainstream Cryptocurrency adaption. They allow for the "Coffee-Coin Criteria"; under which a customer orders a coffee and pays for that coffee in bitcoins. This is not possible with On-Chain transactions today. Unfortunately, all existing Off-Chain transaction protocols are notoriously unreliable The current generation of third-party facilitators are vulnerable to hacker-based attacks. As Mt. Gox tragically demonstrated, centralized-transaction institutions are easy targets for Cryptocurrency thieves. The slightest security flaw in a third-party system will pounced on by hackers, who will proceed to devour it like ants devouring a crab. Under such circumstances, it no wonder that the Public treats most Cryptocurrency services with a constant shadow of suspicion. For Bitcoin to flourish, its anti-hierarchy principles must be applied to safe Off-Chain transactions. First and foremost, we need a new hacker-proof protocol that can easily be executed by any experienced developer. Preferably, the protocol will be open-sourced for full reliability and transparency. This paper presents one such procedure, which allows for he safe transmission of Bitcoin private key control by way of Cryptocubic transactions.
David GarcĂa, Claudio J. Tessone, Pavlin Mavrodiev, Nicolas Perony
What is the role of social interactions in the creation of price bubbles? Answering this question requires obtaining collective behavioural traces generated by the activity of a large number of actors. Digital currencies offer a unique possibility to measure socio-economic signals from such digital traces. Here, we focus on Bitcoin, the most popular cryptocurrency. Bitcoin has experienced periods of rapid increase in exchange rates (price) followed by sharp decline; we hypothesise that these fluctuations are largely driven by the interplay between different social phenomena. We thus quantify four socio-economic signals about Bitcoin from large data sets: price on on-line exchanges, volume of word-of-mouth communication in on-line social media, volume of information search, and user base growth. By using vector autoregression, we identify two positive feedback loops that lead to price bubbles in the absence of exogenous stimuli: one driven by word of mouth, and the other by new Bitcoin adopters. We also observe that spikes in information search, presumably linked to external events, precede drastic price declines. Understanding the interplay between the socio-economic signals we measured can lead to applications beyond cryptocurrencies to other phenomena which leave digital footprints, such as on-line social network usage.
Bitcoin created as an academic article in 2008 and realized first transaction in 2009 is a digital/electronic currency which is designed on computer and built from calculating an algorithm. It developed rapidly and skyrocketed its market value in last two years by increasing its number of users and demand. The system designed by the pseudonymous person is not depend on neither any government nor a guarantor or an audit institution that the classical monetary system has. The transactions are realizing peer-to-peer network system and the cost of transaction is almost nothing. On the other hand Bitcoin inholds some of problems stemming from its uncontrollable features by any authority such as government, central banks etc. However the system which can be defined as a interdisciplinary study is a good sample in respect of digital innovations. In this study; emerge of Bitcoin, its features, place in World and Turkish economy, transaction methods are researched and worked on a SWOT analysis for new digital currency.
This paper presents an agent-based artificial cryptocurrency market in which heterogeneous agents buy or sell cryptocurrencies, in particular Bitcoins. In this market, there are two typologies of agents, Random Traders and Chartists, which interact with each other by trading Bitcoins. Each agent is initially endowed with a finite amount of crypto and/or fiat cash and issues buy and sell orders, according to her strategy and resources. The number of Bitcoins increases over time with a rate proportional to the real one, even if the mining process is not explicitly modelled. The model proposed is able to reproduce some of the real statistical properties of the price absolute returns observed in the Bitcoin real market. In particular, it is able to reproduce the autocorrelation of the absolute returns, and their cumulative distribution function. The simulator has been implemented using object-oriented technology, and could be considered a valid starting point to study and analyse the cryptocurrency market and its future evolutions.
We study decentralized cryptocurrency protocols in which the participants do not deplete physical scarce resources. Such protocols commonly rely on Proof of Stake, i.e., on mechanisms that extend voting power to the stakeholders of the system. We offer analysis of existing protocols that have a substantial amount of popularity. We then present our novel pure Proof of Stake protocols, and argue that they help in mitigating problems that the existing protocols exhibit.
On February 2014, $650.000.000 worth of Bitcoins disappeared. Currently it is unclear whether hackers or MtGox, the largest Bitcoin exchange, are to be blamed. In either case, the anonymous and unregulated nature of the Bitcoin system makes it practically impossible for innocent victims to get their money back. We have investigated the technical possibilities, solutions and implications of introducing a regulatory framework based on redlisting Bitcoin accounts. Despite numerous proposals, the Bitcoin community has voiced a strong opinion against any form of regulation. However, most of the discussions were based on speculations rather than facts. We strive to contribute a scientific foundation to these discussions and illuminate the path to crypto-justice.
The financial crisis has led to a widespread loss of trust in financial intermediaries of all kinds, perhaps helping to open the way towards the general acceptance of alternative technologies. This paper briefly summarises the crypto-currency phenomenon, separating the âcurrencyâ issues from the potential technology benefits. With respect to crypto currencies, the paper argues that these canât undermine the ability of central banks to conduct monetary policy. They do, however, raise consumer protection and bank secrecy issues. The valuation of Bitcoins and price volatility issues are discussed, as well as electronic theft, contract failures, etc., all of which could result in large losses to users and hence ultimate costs to the taxpayer (e.g. the failure to provide adequate private pensions resulting in increased reliance on public pensions). The anonymity features of the crypto-currencies also facilitate tax evasion and money laundering, both of which are major public policy concerns. The technology associated with crypto-currencies, on the other hand, could ultimately shift the entire basis of trust involved in any financial transaction. It is an innovation that creates the ability to carry out transactions without the need for a trusted third party; i.e. a move towards trust-less transactions. This mechanism could work to eliminate the role of many intermediaries, thereby reducing transactions costs by introducing much needed competition to incumbent firms. The generic issues that policy makers need to examine are summarised.