PGP is built upon a Distributed Web of Trust in which the trustworthiness of a user is established by others who can vouch through a digital signature for that particular identity. Preventing its wholesale adoption are a number of inherent weaknesses to include (but not limited to) the following: 1) Trust Relationships are built on a subjective honor system, 2) Only first degree relationships can be fully trusted, 3) Levels of trust are difficult to quantify with actual values, and 4) Issues with the Web of Trust itself (Certification and Endorsement). Although the security that PGP provides is proven to be reliable, it has largely failed to garner large scale adoption. In this paper, we propose several novel contributions to address the aforementioned issues with PGP and associated Web of Trust. To address the subjectivity of the Web of Trust, we provide a new certificate format based on Bitcoin which allows a user to verify a PGP certificate using Bitcoin identity-verification transactions - forming first degree trust relationships that are tied to actual values (i.e., number of Bitcoins transferred during transaction). Secondly, we present the design of a novel Distributed PGP key server that leverages the Bitcoin transaction blockchain to store and retrieve Bitcoin-Based PGP certificates. Lastly, we provide a web prototype application that demonstrates several of these capabilities in an actual environment.
In spite of the fact that a lot of virtual currencies have been created in recent years, bitcoin is the best known from all of them and regularly reported in the news. Currency without identified creator is appreciated by its user for non-centralized running, without any chance of governments to influence the money supply. The advantages of bitcoin, such as very quick payments worldwide, stop of inflations caused by governments trying to solve their own problems or high level of transactions privacy are widely mentioned. The aim of the article is not to describe the technical issue of bitcoin and explain how this system works, because it has been widely explained in other articles. The aim is focusing on economic aspects of bitcoin, the technical aspects are mentioned only if necessary. For accomplishing the aim the article is split in two parts. The first part is dedicated to answering the question âWhat is bitcoin?â. It examines whether bitcoin complies with theoretical, empirical and law definition of money. The law definition of money compliance is done for Czech, German and EU law in general, but attitudes of US and Chinese governments are also mentioned. According to the findings, bitcoin cannot be easily considered as money. The second part is focused on store of value money function. Better store of value in comparison with fiat currencies should be important advantage of bitcoin. This function examination is based on volatility calculation for bitcoin and other currencies and assets. Comparing of results shows that volatility (and therefore risk) of bitcoin is significantly higher than of other currencies and assets.
Several new services incentivize clients to compete in solving large computation tasks in exchange for financial rewards. This model of competitive distributed computation enables every user connected to the Internet to participate in a game in which he splits his computational power among a set of competing pools â the game is called a computational power splitting game. We formally model this game and show its utility in analyzing the security of pool protocols that dictate how financial rewards are shared among the members of a pool. As a case study, we analyze the Bitcoin cryptocurrency which attracts computing power roughly equivalent to billions of desktop machines, over 70% of which is organized into public pools. We show that existing pool reward sharing protocols are insecure in our game-theoretic analysis under an attack strategy called the âblock withholding attackâ. This attack is a topic of debate, initially thought to be ill-incentivized in todayâs pool protocols: i.e., causing a net loss to the attacker, and later argued to be always profitable. Our analysis shows that the attack is always well-incentivized in the long-run, but may not be so for a short duration. This implies that existing pool protocols are insecure, and if the attack is conducted systematically, Bitcoin pools could lose millions of dollars worth in months. The equilibrium state is a mixed strategyâthat isâin equilibrium all clients are incentivized to probabilistically attack to maximize their payoffs rather than participate honestly. As a result, a part of the Bitcoin network is incentivized to waste resource competing for higher selfish reward.
Ifigeneia Georgoula, Demitrios E. Pournarakis, Christos Bilanakos, Dionisios N. Sotiropoulos · 5 authors
This paper uses time-series analysis to study the relationship between Bitcoin prices and fundamental economic variables, technological factors and measurements of collective mood derived from Twitter feeds. Sentiment analysis has been performed on a daily basis through the utilization of a state-of-the-art machine learning algorithm, namely Support Vector Machines (SVMs). A series of short-run regressions shows that the Twitter sentiment ratio is positively correlated with Bitcoin prices. The short-run analysis also reveals that the number of Wikipedia search queries (showing the degree of public interest in Bitcoins) and the hash rate (measuring the mining difficulty) have a positive effect on the price of Bitcoins. On the contrary, the value of Bitcoins is negatively affected by the exchange rate between the USD and the euro (which represents the general level of prices). A vector error-correction model is used to investigate the existence of long-term relationships between cointegrated variables. This kind of long-run analysis reveals that the Bitcoin price is positively associated with the number of Bitcoins in circulation (representing the total stock of money supply) and negatively associated with the Standard and Poor's 500 stock market index (which indicates the general state of the global economy).
The buzz surrounding Bitcoin has reached a fever pitch. Yet in academic legal discussions, disproportionate emphasis is placed on bitcoins (that is, virtual currency), and little mention is made of blockchain technologyâthe true innovation behind the Bitcoin protocol. Simply, blockchain technology solves an elusive networking problem by enabling âtrustlessâ transactions: value exchanges over computer networks that can be verified, monitored, and enforced without central institutions (for example, banks). This has broad implications for how we transact over electronic networks. This Note integrates current research from leading computer scientists and cryptographers to elevate the legal communityâs understanding of blockchain technology and, ultimately, to inform policymakers and practitioners as they consider different regulatory schemes. An examination of the economic properties of a blockchain-based currency suggests the technologyâs true value lies in its potential to facilitate more efficient digital-asset transfers. For example, applications of special interest to the legal community include more efficient document and authorship verification, title transfers, and contract enforcement. Though a regulatory patchwork around virtual currencies has begun to form, its careful analysis reveals much uncertainty with respect to these alternative applications.
In this paper, I propose a new concept for understanding the role of algorithms in daily life: algorithmic authority. Algorithmic authority is the legitimate power of algorithms to direct human action and to impact which information is considered true. I use this concept to examine the culture of users of Bitcoin, a crypto-currency and payment platform. Through Bitcoin, I explore what it means to trust in algorithmic authority. My study of the Bitcoin community utilizes interview and survey data. I found that Bitcoin users prefer algorithmic authority to the authority of conventional institutions which they see as untrustworthy. However, I argue that Bitcoin users do not have blind faith in algorithms; rather, they acknowledge the need for mediating algorithmic authority with human judgment. I examine the tension between members of the Bitcoin community who would prefer to integrate Bitcoin with existing institutions and those who would prefer to resist integration.
On March 16, 2013, Cyprus announced that it would accept a bailout that required imposing a one-time levy on bank deposits. It has been argued that, by making traditional deposit accounts seem less secure, the bailout announcement prompted some to consider â or reconsider â using the cryptocurrency bitcoin. Relying on rank data for a subset of apps, existing studies maintain that interest in bitcoin increased following the announcement, especially in countries with troubled banks. We argue that (1) focusing on a subset of apps does not allow one to distinguish a general increase in the demand for bitcoin apps from a substitution between bitcoin apps and (2) changes in rank data are a poor predictor of changes in the number of downloads. In order to address these concerns, we collect rank data for all fifteen bitcoin apps available at the time and use an established technique to estimate an index of downloads for each country considered. We find that, while downloads of bitcoin apps increased following the announcement, the observed effect was not especially pronounced in countries thought to have had troubled banking systems at the time.
Arthur Gervais, Hubert Ritzdorf, Ghassan Karame, SrÄjan Äapkun
Given the increasing adoption of Bitcoin, the number of transactions and the block sizes within the system are only expected to increase. To sustain its correct operation in spite of its ever-increasing use, Bitcoin implements a number of necessary optimizations and scalability measures. These measures limit the amount of information broadcast in the system to the minimum necessary. In this paper, we show that current scalability measures adopted by Bitcoin come at odds with the security of the system. More specifically, we show that an adversary can exploit these measures in order to effectively delay the propagation of transactions and blocks to specific nodes for a considerable amount of time---without causing a network partitioning in the system. Notice that this attack alters the information received by Bitcoin nodes, and modifies their views of the ledger state. Namely, we show that this allows the adversary to considerably increase its mining advantage in the network, and to double-spend transactions in spite of the current countermeasures adopted by Bitcoin. Based on our results, we propose a number of countermeasures in order to enhance the security of Bitcoin without deteriorating its scalability.
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Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
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.
Open access
43 source records
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.
Bitcoin is defined as digital money within a decentralized peer-to-peer payment network. It is a hybrid between fiat currency and commodity currency without intrinsic value and independent of any government or monetary authority. This paper analyses the question of whether Bitcoin is a medium of exchange or an asset and more specifically, what is its current usage and what usage will prevail in the future given its characteristics. We analyse the statistical properties of Bitcoin and find that it is uncorrelated with traditional asset classes such as stocks, bonds and commodities both in normal times and in periods of financial turmoil. The analysis of transaction data of Bitcoin accounts shows that Bitcoins are mainly used as a speculative investment and not as an alternative currency and medium of exchange.
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.
La versione italiana di questo documento Ăš disponibile al seguente link: http://ssrn.com/abstract=2731132 The core technology of Bitcoin, the blockchain, has recently emerged as a disruptive innovation with a wide range of applications, potentially able to redesign our interactions in business, politics and society at large. Although scholarly interest in this subject is growing, a comprehensive analysis of blockchain applications from a political perspective is severely lacking to date. This paper aims to fill this gap and it discusses the key points of blockchain-based decentralized governance, which challenges to varying degrees the traditional mechanisms of State authority, citizenship and democracy. In particular, the paper verifies to which extent blockchain and decentralized platforms can be considered as hyper-political tools, capable to manage social interactions on large scale and dismiss traditional central authorities. The analysis highlights risks related to a dominant position of private powers in distributed ecosystems, which may lead to a general disempowerment of citizens and to the emergence of a stateless global society. While technological utopians urge the demise of any centralized institution, this paper advocates the role of the State as a necessary central point of coordination in society, showing that decentralization through algorithm-based consensus is an organizational theory, not a stand-alone political theory.
Blockchains represent a novel application of cryptography and information technology to ag-eold problems of financial record-keeping, and they may lead to far-reaching changes in corporate governance. Many major players in the financial industry have began to invest in this new technology, and stock exchanges have proposed using blockchains as a new method for trading corporate equities and tracking their ownership. This essay evaluates the potential implications of these changes for managers, institutional investors, small shareholders, auditors, and other parties involved in corporate governance. The lower cost, greater liquidity, more accurate recordkeeping, and transparency of ownership offered by blockchains may significantly upend the balance of power among these cohorts.
Christian Decker, Jochen Seidel, Roger Wattenhofer
The Bitcoin system only provides eventual consistency. For everyday life, the time to confirm a Bitcoin transaction is prohibitively slow. In this paper we propose a new system, built on the Bitcoin blockchain, which enables strong consistency. Our system, PeerCensus, acts as a certification authority, manages peer identities in a peer-to-peer network, and ultimately enhances Bitcoin and similar systems with strong consistency. Our extensive analysis shows that PeerCensus is in a secure state with high probability. We also show how Discoin, a Bitcoin variant that decouples block creation and transaction confirmation, can be built on top of PeerCensus, enabling real-time payments. Unlike Bitcoin, once transactions in Discoin are committed, they stay committed.
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