Blockchain Papers

Bill Marino, Ari Juels

No abstract is available for this record.

Loi Luu, Duc-Hiep Chu, Hrishi Olickel, Prateek Saxena · 5 authors

Cryptocurrencies record transactions in a decentralized data structure called a blockchain. Two of the most popular cryptocurrencies, Bitcoin and Ethereum, support the feature to encode rules or scripts for processing transactions. This feature has evolved to give practical shape to the ideas of smart contracts, or full-fledged programs that are run on blockchains. Recently, Ethereum's smart contract system has seen steady adoption, supporting tens of thousands of contracts, holding millions dollars worth of virtual coins. In this paper, we investigate the security of running smart contracts based on Ethereum in an open distributed network like those of cryptocurrencies. We introduce several new security problems in which an adversary can manipulate smart contract execution to gain profit. These bugs suggest subtle gaps in the understanding of the distributed semantics of the underlying platform. As a refinement, we propose ways to enhance the operational semantics of Ethereum to make contracts less vulnerable. For developers writing contracts for the existing Ethereum system, we build a symbolic execution tool called Oyente to find potential security bugs. Among 19, 336 existing Ethereum contracts, Oyente flags 8, 833 of them as vulnerable, including the TheDAO bug which led to a 60 million US dollar loss in June 2016. We also discuss the severity of other attacks for several case studies which have source code available and confirm the attacks (which target only our accounts) in the main Ethereum network.

Viktor Jacynycz, Adrian Calvo, Samer Hassan, Antonio A. Sánchez‐Ruiz

No abstract is available for this record.

Joseph Bonneau

No abstract is available for this record.

Karl Wüst, Arthur Gervais

No abstract is available for this record.

Nicola Atzei, Massimo Bartoletti, Tiziana Cimoli

No abstract is available for this record.

Sinclair Davidson, Primavera De Filippi, Jason Potts

Distributed ledger technology, invented for cryptocurrencies, is increasingly understood as a new general-purpose technology for a broad range of economic activities that rely on consensus of a database of transactions or records. However, blockchains are more than just a disruptive new ICT. Rather, they are a new institutional technology of governance that competes with other economic institutions of capitalism, namely firms, markets, networks, and even governments. We present this view of blockchains through a case study of Backfeed, an Ethereum-based platform for creating new types of commons-based collaborative economies.

Sinclair Davidson, Primavera De Filippi, Jason Potts

No abstract is available for this record.

Marko Vukolić

No abstract is available for this record.

Xun Yi, Xuechao Yang, Andrei Kelarev, Kwok‐Yan Lam · 5 authors

Kriptovalute su digitalni novac utemeljen na kriptografiji i decentraliziranom sustavu. Postoje samo u elektroničkom obliku kao jedinstveni digitalni novčići ("tokeni"). Iza njih ne stoji autoritet države niti ih je moguće svojevoljno proizvesti. Rad se fokusira na značajkama, postavkama, razvoju i svim međuodnosima važnih ekonomskih faktora koji utječu na kriptovalute. U prvom poglavlju navedena su obilježja kriptovaluta. Drugo poglavlje daje primjere i govori o primjeni kriptovaluta u svakodnevnom životu. U trećem poglavlju je raspravljano o trenutnim i budućim regulacijama najmoćnijih zemalja svijeta (G20) , kao i njihovoj zajedničkoj suradnji u želji za jedinstvenim i standardiziranim pravilima, a sve u svrhu što kvalitetnijeg nadzora nad kriptovalutama kako bi se spriječile malverzacije i zaštitili potrošači. Četvrto poglavlje govori o inicijalnoj ponudi kovanica, a peto poglavlje je namijenjeno sigurnosti kriptovaluta. Cilj istraživanja je utvrditi koliko je studentska populacija upoznata i usmjerena prema novim oblicima digitalnog novca, koje značajke kriptovaluta smatraju pozitivnima, a koje negativnima i u kojoj su mjeri investirali ili su spremni investirati dio svojih ulaganja u kriptovalute i sl. Metode istraživanja korištene u radu su kompilacija na temelju proučavanja postojeće literature o temi rada, prikupljanje i analiza podataka vezanih uz kriptovalute, ponajprije podataka vezanih uz cijene i tržišnu kapitalizaciju, anketiranje studenata Ekonomskog fakulteta u Rijeci i metoda dedukcije putem koje su pokazane sve važne karakteristike i obilježja kriptovaluta. Na temelju provedene ankete u kojoj je sudjelovalo 90 studenata Ekonomskog fakulteta u Rijeci zaključak toga dijela istraživanja je da je mlada populacija dobro upoznata s kriptovalutama i njenim glavnim značajkama, ali i određenim nedostatkom informiranosti o tehnologiji (trećina studenata nije čula za pojam "blockchain") i nedovoljnoj odlučnosti oko investiranja i trgovanja u kriptovalute. Povrh toga, dokazan je i negativan utjecaj hakerskih napada i određenih kriminalnih radnji, kao i nestabilnost tržišne cijene na povjerenje studenata, ali i ukupne populacije vezane uz globalni financijski sustav u kriptovalute. Ishod istraživanja omogućio je da zaključimo kako su kriptovalute trenutno u ranoj fazi razvoja i nisu se dovoljno implementirale za široku primjenu u trgovini roba i usluga ili općenito kao sredstvo razmjene. Faktor koji je uključen u istraživanje kako bi opisao veličinu, odnosno obujam neke kriptovalute je tržišna kapitalizacija u dolarima. Temeljna ideja ovog rada je informirati čitatelja o pozitivnim i negativnim značajkama koje se se vežu uz kriptovalute. Na taj način čitatelji će biti bolje informirani i educirani o potencijalnom riziku ulaganja u kriptovalute, kao i većoj razini zaštite prilikom posjedovanja neke digitalne valute.

Nick Vogel

Bitcoin’s popularity increased as its value increased and people became excited about the prospect of a trustless, decentralized currency that could be used on the Internet. Within the last two years, however, people and organizations began exploiting the potential of the block chain that powers the bitcoin network. These people realized that the block chain — a transparent public ledger that cannot be altered — can be used for more than digital currency. One such organization calls itself Ethereum and its developers plan to use block chains to allow decentralized autonomous applications to operate free of government censorship or corruption. While such a network would have a profound effect on society — allowing trustless voting, uncensored social networking and the like — its impact on copyrights could be devastating. This paper argues that the emerging, decentralized Internet (also known as Web 3.0) will be the straw that breaks the copyright owner’s back. This paper argues that, with block chain technology and decentralized applications, those buying and selling unauthorized copies of copyrighted material cannot be subject to court injunctions; making enforcement of copyrights nearly impossible on a decentralized Internet. This paper then proposes that copyright holders get out in front of the problem by embracing a decentralized Internet. This can only be done by drastically reducing the price of copyright licenses. In other words, by offering cheap licenses at the dawn of Web 3.0, copyright holders can instill a sense that it’s better to be safe than sorry when it comes to the ongoing struggle between technology and copyrights.

フォン ヤオカイ, 松本 晋一, 穴田 啓晃, 川本 純平 · 5 authors

No abstract is available for this record.

Loi Luu, Jason Teutsch, Raghav Kulkarni, Prateek Saxena

Cryptocurrencies like Bitcoin and the more recent Ethereum system allow users to specify scripts in transactions and contracts to support applications beyond simple cash transactions. In this work, we analyze the extent to which these systems can enforce the correct semantics of scripts. We show that when a script execution requires nontrivial computation effort, practical attacks exist which either waste miners' computational resources or lead miners to accept incorrect script results. These attacks drive miners to an ill-fated choice, which we call the verifier's dilemma, whereby rational miners are well-incentivized to accept unvalidated blockchains. We call the framework of computation through a scriptable cryptocurrency a consensus computer and develop a model that captures incentives for verifying computation in it. We propose a resolution to the verifier's dilemma which incentivizes correct execution of certain applications, including outsourced computation, where scripts require minimal time to verify. Finally we discuss two distinct, practical implementations of our consensus computer in real cryptocurrency networks like Ethereum.

Sergey Plint

The aim of this bachelor's thesis is to assess the current development of cryptocurrencies, present information about their current state of development, introduce to four largest projects (Bitcoin, Ethereum, litecoin, Ripple) and to evaluate functioning of cryptocurrencies and blockchain technology in the context of start-ups and financial institutions. As a part of this work there is also provided an overview of legislation over cryptocurrencies globally, in the context of the European Union and the Czech Republic. Then there are also presented the actual use of technology, cutting-edge start-ups and their products. Finally the thesis evaluates the intersection of startups into different sectors and presents the views of experts working in various fields of economy.

A.J. Roggeveen

In dit artikel worden de mogelijke gevolgen belicht van de introductie van nieuwe en bestaande toepassingen van Bitcoin-technologie. De transnationale, decentrale en gedistribueerde peer-to-peer-structuur van de Bitcoin-technologie en van nieuwe toepassingen hiervan, hebben de potentie om bestaande sociale relaties en instituties te ontregelen. Het krachtenveld waarin maatschappelijke actoren staan kan hierdoor uit balans worden gebracht. De meest radicale van deze nieuwe technologieën is Ethereum. Met name het concept van de Digital Autonomous Organisation (DOA) heeft mogelijkerwijs verregaande consequenties. Ethereum is een ‘contract validating and enforcing system’, een gedistribueerd systeem dat een platform biedt voor autonome computerprogramma’s die in staat zijn om zelfstandig overeenkomsten met rechtspersonen en andere DOA’s aan te gaan en te ontbinden. Ik richt mij op de mogelijkheden van deze toepassingen als nieuwe platformen voor International Financial (Cyber) Crime.

Adrián Calvo María, Viktor Jacynycz García

Betfunding es una plataforma de crowdfunding distribuida que usa apuestas en lugar de donaciones para promover la produccion artistica y el trabajo creativo. A diferencia de otras plataformas de crowdfunding, en Betfunding son los inversores quienes proponen un proyecto y buscan creadores mediante la creacion de una recompensa por su trabajo. Cualquier persona puede convertirse en creador de un proyecto si se compromete con los usuarios mediante una fianza. La evaluacion de exito o fracaso de un proyecto lo determinara un tercero de confianza designado al comienzo del proyecto, quepuede ser una persona o un sistema automatico. La aplicacion ha sido desarrollada sobre Ethereum, una tecnologia similar a la que usa Bitcoin que permite gestionar dinero mediante criptomonedas y desarrollar aplicaciones descentralizadas. El uso de la tecnologia de la cadena de bloques y criptomonedas evita la necesidad de una autoridad central de confianza que envie y guarde el dinero cobrando comisiones. En su lugar, esta tarea se realiza a traves de una red P2P de forma transparente y segura.

Wojciech Nowakowski

No abstract is available for this record.

Yoad Lewenberg, Yonatan Sompolinsky, Aviv Zohar

No abstract is available for this record.

Nick Vogel

Bitcoin’s popularity increased as its value increased and people became excited about the prospect of a trustless, decentralized currency that could be used on the Internet. Within the last two years, however, people and organizations began exploiting the potential of the block chain that powers the bitcoin network. These people realized that the block chain—a transparent public ledger that cannot be altered—can be used for more than digital currency. One such organization calls itself Ethereum and its developers plan to use block chains to allow decentralized autonomous applications to operate free of government censorship or corruption. While such a network would have a profound effect on society—allowing trustless voting, uncensored social networking and the like—its impact on copyrights could be devastating. This paper argues that the emerging, decentralized Internet (also known as Web 3.0) will be the straw that breaks the copyright owner’s back. This paper argues that, with block chain technology and decentralized applications, those buying and selling unauthorized copies of copyrighted material cannot be subject to court injunctions; making enforcement of copyrights nearly impossible on a decentralized Internet. This paper then proposes that copyright holders get out in front of the problem by embracing a decentralized Internet. This can only be done by drastically reducing the price of copyright licenses. In other words, by offering cheap licenses at the dawn of Web 3.0, copyright holders can instill a sense that it’s better to be safe than sorry when it comes to the ongoing struggle between technology and copyrights.

Primavera De Filippi

Les devises électroniques décentralisées, comme Bitcoin*, reposent sur un même principe : elles sont émises et gérées sans autorité centrale et ne dépendent d’aucun gouvernement, banque ou autre institution centralisée. Toutes les transactions sont régies par un protocole cryptographique open source et sont enregistrées sur un registre public (ou blockchain) maintenu par un réseau de pairs distribués dans le monde entier. Ce principe initial a été modifié pour de nouvelles applications afin d...

Yonatan Sompolinsky, Aviv Zohar

No abstract is available for this record.

隆一 小嶋

No abstract is available for this record.

Salim Benjamin Youssefzadeh

With the vast increase in smartphones, there have been an increasing number of opportunities growing in the app industry. One in particular is the way we deal with money. There are huge overheads in the current payment systems around the world particularly in the United States, many of which include large transaction fees. Many new businesses have grown to solve these inefficiencies and create a new platform that provides a new user experience, security, and convenience among many other things. However, many of these platforms are still centralized, making them more susceptible to attacks. This thesis goes over the various methods of payments, starting from their origins and discusses their flaws and ways they are being improved. This study explains where payment platforms are going and how they line up against other platforms in terms of security and usability. We look at the origins of credit cards and why the US is lagging behind other countries in credit card security. Digital wallets like PayPal, Venmo, Square, etc. have done a remarkable job, but still have room for improvement in terms of security and usage. I try to solve these problems with the mobile application AnyCoin by bringing one platform that houses different types of digital wallets. The goal of this application was to grow a large user base and collect data off the transaction for future analysis and advertising. This study goes through an in depth analysis on the application from the iv perspective of merchants and consumers to understand what users are looking for in digital wallets. Decentralized platforms and crypto-currencies like Bitcoin have also created different ways to send money by creating a trustless system that does not depend on any central authority. I discuss what Bitcoin is and exactly how it works and the flaws in the current system. Mining is the process that puts Bitcoin into circulation and secures the network. However, as more customized hardware is released, Bitcoin will fall subject to becoming more centralized, and unfortunately become heavy regulated if it is to be used as a currency. Ethereum is a new technology that takes the concepts of Bitcoin and creates a platform for a developer to create a decentralized application. I create a few contracts that show how we can create a decentralized version of PayPal that works using other crypto- currencies. Ethereum is still in its alpha stage and has yet to

Andrés Guadamuz, Christopher T. Marsden

No abstract is available for this record.