Blockchains and other public ledger structures promise a new way to create globally consistent event logs and other records. We make use of this consistency property to detect and prevent man-in-the-middle attacks in a key exchange such as Diffie-Hellman or ECDH. Essentially, the MitM attack creates an inconsistency in the world views of the two honest parties, and they can detect it with the help of the ledger. Thus, there is no need for prior knowledge or trusted third parties apart from the distributed ledger. To prevent impersonation attacks, we require user interaction. It appears that, in some applications, the required user interaction is reduced in comparison to other user-assisted key-exchange protocols.
Benedikt Bünz, Jonathan Bootle, Dan Boneh, Andrew Poelstra · 6 authors
We propose Bulletproofs, a new non-interactive zero-knowledge proof protocol with very short proofs and without a trusted setup; the proof size is only logarithmic in the witness size. Bulletproofs are especially well suited for efficient range proofs on committed values: they enable proving that a committed value is in a range using only 2 log_2(n)+9 group and field elements, where n is the bit length of the range. Proof generation and verification times are linear in n. Bulletproofs greatly improve on the linear (in n) sized range proofs in existing proposals for confidential transactions in Bitcoin and other cryptocurrencies. Moreover, Bulletproofs supports aggregation of range proofs, so that a party can prove that m commitments lie in a given range by providing only an additive O(log(m)) group elements over the length of a single proof. To aggregate proofs from multiple parties, we enable the parties to generate a single proof without revealing their inputs to each other via a simple multi-party computation (MPC) protocol for constructing Bulletproofs. This MPC protocol uses either a constant number of rounds and linear communication, or a logarithmic number of rounds and logarithmic communication. We show that verification time, while asymptotically linear, is very efficient in practice. The marginal cost of batch verifying 32 aggregated range proofs is less than the cost of verifying 32 ECDSA signatures. Bulletproofs build on the techniques of Bootle et al. (EUROCRYPT 2016). Beyond range proofs, Bulletproofs provide short zero-knowledge proofs for general arithmetic circuits while only relying on the discrete logarithm assumption and without requiring a trusted setup. We discuss many applications that would benefit from Bulletproofs, primarily in the area of cryptocurrencies. The efficiency of Bulletproofs is particularly well suited for the distributed and trustless nature of blockchains. The full version of this article is available on ePrint.
An appealing feature of blockchain technology is smart contracts. A smart contract is executable code that runs on top of the blockchain to facilitate, execute and enforce an agreement between untrusted parties without the involvement of a trusted third party. In this paper, we conduct a systematic mapping study to collect all research that is relevant to smart contracts from a technical perspective. The aim of doing so is to identify current research topics and open challenges for future studies in smart contract research. We extract 24 papers from different scientific databases. The results show that about two thirds of the papers focus on identifying and tackling smart contract issues. Four key issues are identified, namely, codifying, security, privacy and performance issues. The rest of the papers focuses on smart contract applications or other smart contract related topics. Research gaps that need to be addressed in future studies are provided. http://aircconline.com/ijcsit/V9N5/9517ijcsit11.pdf
Cryptocurrency, most notably Bitcoin, has continued to attract attention and consequently substantial investment from businesses, consumers, and the media. Understanding what drives consumer adoption of the technology, however, is not understood. This study uses the UTAUT2 technology adoption theory in order to fill this research gap. A conceptual model is built through a review of the technical aspects of cryptocurrency, an analysis of the technology as currency, and finally a review of technology adoption theory to date. UTAUT2 is found to be the most appropriate adoption theory directly dealing with consumer context. The model conceptualised is tested using multiple linear regression analyses on primary survey data. The findings indicate that facilitating conditions have the highest explanatory effect on actual usage ahead of behavioural intention to use cryptocurrency. Behavioural intention was predicted most strongly by hedonic motivation, followed by perceived trust, and social influence. Interestingly, effort expectancy and performance expectancy were found to be non-significant, contrary to much of the studies in related fields. The study also aimed to identify the primary use-case finding that investment was the primary consumer use. Due to characteristics of the sample collected, the studyÕs findings are limited to the South African context.
Since Bitcoin was launched in 2009, several new cryptocurrencies have been initiated with variations to Bitcoin's original design. Although Bitcoin still remains the most prominent actor in the market, some technical problems have been raised to the design of the protocol. The objective of this thesis is to determine whether the newer cryptocurrencies handle the technical problems of Bitcoin, or if they also suffer from the same issues. Instead of evaluating several cryptocurrencies for this comparison, the cryptocurrency Ethereum has been chosen as a proxy for the others. Ethereum was started in 2014, is widely backed in the community and is second in line to Bitcoin when it comes to market capitalization. \n\nAs a basis for the comparative analysis a rigorous study of the Bitcoin and Ethereum protocols have been performed, and parallel descriptions of the systems have been devised. Three technical problem have shaped the focus of the analysis: computational waste, concentration of power and ambiguity of transactions. Real world statistical data has been gathered and synthesized to enlighten the findings in the comparison. The main result of the comparison is that both systems suffer from the same problems to a certain degree, due to the fact that they utilize the same consensus mechanism. However, Ethereum utilizes several newer techniques to try and reduce the severity of these problems compared to Bitcoin, with varying degrees of success.
Abstract The philosophy of blockchain technology is concerned, among other things, with blockchain ontology, how it might be characterised, how it is being created, implemented, and adopted, how it operates in the world, and how it evolves over time. This paper concentrates on whether Bitcoin/blockchain can be considered a complex system and, if so, whether it is a chaotic one. Beyond mere academic curiosity, a positive response would raise concerns about the likelihood of Bitcoin/blockchain entering a 2010‐Flash‐Crash‐type of chaotic regime, with catastrophic consequences for financial systems based on it. The paper starts by highlighting the relevant details of the Bitcoin/blockchain ecosystem formed by the blockchain itself, bitcoin end users (payers and payees), capital gains seekers, miners, full nodes maintainers, and developers, and their interactions. Then the Information Theory of Complex Systems is briefly discussed for later use. Finally, the blockchain is investigated with the help of Crutchfield's Statistical Complexity measure. The low non‐null statistical complexity value obtained suggests that the blockchain may be considered algorithmically complicated but hardly a complex system and unlikely to enter a chaotic regime.
Bitcoin is traded on exchanges which use an open limit order book. This paper investigates the microstructure of various bitcoin markets with respect to liquidity and private information processing. The markets are found to be fairly liquid, providing liquidity at a stable rate throughout the 24 hours trading period. The spread itself as well as the proportion attributed to adverse selection costs are high suggesting that private information is an important aspect in the bid-ask spread.
Daniel Augot, Hervé Chabanne, Thomas Chenevier, William R. George · 5 authors
We present an identity management scheme built into the Bitcoin blockchain, allowing for identities that are as indelible as the blockchain itself. Moreover, we take advantage of Bitcoin's decentralized nature to facilitate a shared control between users and identity providers, allowing users to directly manage their own identities, fluidly coordinating identities from different providers, even as identity providers can revoke identities and impose controls.
Open access
3 source records
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
Monies are typically categorized as commodity or fiat, depending on whether the item in question is intrinsically worthless. In the case of bitcoin, it is not so clear. I consider the superficial subjective value argument often put forward by non-monetary economists and a more sophisticated payments technology argument. After dismissing both, I argue that there are two reasonable views on the value of bitcoin. One might claim bitcoin lacks intrinsic worth, in which case its value depends on foresight and coordination. Alternatively, one might claim that bitcoin has intrinsic worth, even if no one else accepts it, because some users have peculiar preferences. In either case, the existence of bitcoin calls into question the practical relevance of the regression theorem.
Questo studio si propone di analizzare il complesso delle novità introdotte al sistema dei pagamenti e al trasferimento di diritti da Distributed Ledger e Blockchain, in una prospettiva che tenga conto delle applicazioni di mercato di queste innovazioni tecnologiche e della tutela giuridica degli interessi economici e delle posizioni soggettive che ne derivano. In particolar modo, l’opera vuole stimolare la discussione volta alla definizione di un quadro normativo socialmente adeguato che sostenga l’efficienza di questi strumenti in un’ottica di scambio economico globalizzato.
Massimo Bartoletti, Stefano Lande, Livio Pompianu, Andrea Bracciali
Modern cryptocurrencies exploit decentralised blockchains to record a public and unalterable history of transactions. Besides transactions, further information is stored for different, and often undisclosed, purposes, making the blockchains a rich and increasingly growing source of valuable information, in part of difficult interpretation. Many data analytics have been developed, mostly based on specifically designed and ad-hoc engineered approaches. We propose a general-purpose framework, seamlessly supporting data analytics on both Bitcoin and Ethereum --- currently the two most prominent cryptocurrencies. Such a framework allows us to integrate relevant blockchain data with data from other sources, and to organise them in a database, either SQL or NoSQL. Our framework is released as an open-source Scala library. We illustrate the distinguishing features of our approach on a set of significant use cases, which allow us to empirically compare ours to other competing proposals, and evaluate the impact of the database choice on scalability.
Blockchain technology as a whole is experiencing a dramatic rise in adoption, in no small part due to the developer-friendly Ethereum network. While the number of smart-contract powered distributed applications (Dapps) continues to rise, they face many of the same challenges all new technologies face as they are introduced to a market. By modeling the consumer adoption of blockchain technology and analyzing scholarly literature on supply-side factors affecting the diffusion of technology, we seek to prove the growth of a Dapp can be accelerated using abstraction, whole product planning, and complementaries.
Building on the groundswell of scholarly, practitioner, cultural, and investor interest in Decentralized Autonomous Organizations (DAOs), the aim of this paper is to delineate the structure of a multidisciplinary research agenda on DAOs, as encapsulated in the edited volume Decentralized Autonomous Organizations (DAOs): Innovation and Vulnerability in the Digital Economy, highlighting therein the main areas of research promise and avenues of further enquiry. As such, the paper attempts to serve as a form of shorthand-guidebook for researchers interested in the domain of DAOs.