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93,175 results · page 3608 of 3,883
Giancarlo Bigi, Andrea Bracciali, Giovanni Meacci, Emilio Tuosto
No abstract is available for this record.
Alex Norta
No abstract is available for this record.
Christian Brenig, Rafael Accorsi, Günter Müller
This paper reports on our research towards an economic analysis of money laundering schemes utilizing cryptocurrencies, which are convertible decentralized virtual currencies based on cryptographic operations. They gain ground as means to offer enterprises and its customers new payment methods, investing opportunities and some are even intended as substitutes for centrally controlled government-issued fiat currencies. Our starting point is the observation that their increasing popularity attracts the attention of practitioners and scholars, particularly because of raising anti-money laundering concerns. Consequently, work has already been conducted in this area, mainly focusing on implications on anti-money laundering efforts. However, we argue that the potential benefits for criminal individuals are an important, yet neglected factor in the dissemination of cryptocurrencies as money laundering instrument. Addressing this issue, the paper firstly presents the structure of the money laundering process and introduces prevailing anti money-laundering controls. This forms the basis for the subsequent analysis of contextual and transactional factors with respect to their influence on the incentives of criminals to utilize cryptocurrencies for money laundering. This aims at providing an answer to the open question, whether cryptocurrencies constitute a driver for money laundering.
Kim‐Kwang Raymond Choo
No abstract is available for this record.
Florian Glaser, Luis Bezzenberger
The advent of Bitcoin in 2009 has not only introduced Cryptocurrencies and lead to a new digitization movement in the financial, especially payments industry but also made way for a new breed of innovative technologies based on decentralized digital currencies. Generally, decentralized consensus systems could change the very nature of how companies, organizations and individuals are built and interact with each other. Decentralized consensus systems, decentralized applications and smart contracts provide the conceptual framework as well as the technological basis to establish predefined, incorruptible protocols and contracts to organize human behavior and interconnectedness. However, the technical protocols and implementations are quite complex and practitioners as well as interdisciplinary researchers not familiar with cryptography, network protocols or decentralized networks are struggling to find access to these concepts and grasp their potential. To fill this gap, we develop a comprehensive taxonomy of decentralized consensus systems in order to provide a tool for researchers and practitioners alike to facilitate classification and analysis of emerging technologies in the field of "Crypto 2.0", the next level of innovation beyond cryptocurrencies.
Sunoo Park, Albert Kwon, Georg Fuchsbauer, Peter Gaži · 6 authors
International audience
Ryan Farell
No abstract is available for this record.
Kevin Delmolino, Mitchell Arnett, Ahmed E. Kosba, Andrew Miller · 5 authors
We document our experiences in teaching smart contract programming to undergraduate students at the University of Maryland, the first pedagogical attempt of its kind. Since smart contracts deal directly with the movement of valuable currency units between contratual parties, security of a contract program is of paramount importance. Our lab exposed numerous common pitfalls in designing safe and secure smart contracts. We document several typical classes of mistakes students made, suggest ways to fix/avoid them, and advocate best practices for programming smart contracts. Finally, our pedagogical efforts have also resulted in online open course materials for programming smart contracts, which may be of independent interest to the community. 1
Angela Walch
No abstract is available for this record.
Duane Wilson, Giuseppe Ateniese
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.
Shayan Eskandari, David Barrera, Elizabeth Stobert, Jeremy Clark
Bitcoin users are directly or indirectly forced to deal with public key cryptography, which has a number of security and usability challenges that differ from the password-based authentication underlying most online banking services. Users must ensure that keys are simultaneously accessible, resistant to digital theft and resilient to loss. In this paper, we contribute an evaluation framework for comparing Bitcoin key management approaches, and conduct a broad usability evaluation of six representative Bitcoin clients. We find that Bitcoin shares many of the fundamental challenges of key management known from other domains, but that Bitcoin may present a unique opportunity to rethink key management for end users.
Luqin Wang, Yong Liu
No abstract is available for this record.
Charles W. Evans
Journal of Anthropology and Archaeology is a peer-reviewed international journal, which publishes original papers promoting theoretical, methodological and empirical developments in the discipline of socio-cultural anthropology.
Max Kubát
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 “What is bitcoin?”. 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.
Aaron W. Baur, Julian Bühler, Markus Bick, Charlotte S. Bonorden
No abstract is available for this record.
Martina Matta, Maria Ilaria Lunesu, Michele Marchesi
In the last decade, Web 2.0 services such as blogs, tweets, forums, chats, email etc. have been widely used as communication media, with very good results. Sharing knowledge is an important part of learning and enhancing skills. Furthermore, emotions may affect decisionmaking and individual behavior. Bitcoin, a decentralized electronic currency system, represents a radical change in financial systems, attracting a large number of users and a lot of media attention. In this work, we investigated if the spread of the Bitcoin’s price is related to the volumes of tweets or Web Search media results. We compared trends of price with Google Trends data, volume of tweets and particularly with those that express a positive sentiment. We found significant cross correlation values, especially between Bitcoin price and Google Trends data, arguing our initial idea based on studies about trends in stock and goods market.
Áron Lászka, Benjamin Johnson, Jens Großklags
No abstract is available for this record.
Nirupama Devi Bhaskar, Wanfeng Chen, LI Hai-li, David Lee Kuo Chuen
No abstract is available for this record.
Zhichao Zhao, T-H. Hubert Chan
Bitcoin is the first decentralized crypto-currency that is cur-rently by far the most popular one in use. The bitcoin trans-action syntax is expressive enough to setup digital contracts whose fund transfer can be enforced automatically. In this paper, we design protocols for the bitcoin voting problem, in which there are n voters, each of which wishes to fund exactly one of two candidates A and B. The win-ning candidate is determined by majority voting, while the privacy of individual vote is preserved. Moreover, the de-cision is irrevocable in the sense that once the outcome is revealed, the winning candidate is guaranteed to have the funding from all n voters. As in previous works, each voter is incentivized to follow the protocol by being required to put a deposit in the sys-tem, which will be used as compensation if he deviates from the protocol. Our solution is similar to previous protocols used for lottery, but needs an additional phase to distribute secret random numbers via zero-knowledge-proofs. More-over, we have resolved a security issue in previous protocols that could prevent compensation from being paid. 1.
William J. Luther
No abstract is available for this record.
Dirk G. Baur, Adrian D. Lee, KiHoon Hong
No abstract is available for this record.
Marcin Andrychowicz, Stefan Dziembowski, Daniel Malinowski, Łukasz Mazurek
No abstract is available for this record.
Joseph Bonneau, Andrew Miller, Jeremy Clark, Arvind Narayanan · 6 authors
No abstract is available for this record.
Loi Luu, Ratul Saha, Inian Parameshwaran, Prateek Saxena · 5 authors
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 — 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 “block withholding attack”. This attack is a topic of debate, initially thought to be ill-incentivized in today’s 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 strategy—that is—in 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.