Blockchain Papers

Xmaket Digital

No abstract is available for this record.

Xmaket Digital

No abstract is available for this record.

Xmaket Digital

No abstract is available for this record.

Xmaket Digital

No abstract is available for this record.

Xmaket Digital

No abstract is available for this record.

Christian Thiel, Christopher Brown, Mario Hellenkamp, Marius Spancken

Der Abschlussbericht fasst die Ergebnisse des Forschungs- und Entwicklungsprojektes 2015/2016 im Studiengang Master of Science Wirtschaftsinformatik (FH Münster) zur Themenstellung "Kryptowährungen und Smart Contracts" zusammen. Das Projekt analysierte die Einsatzzwecke, Potenziale und Architekturen von Blockchain-Anwendungen. Des Weiteren wurden verschiedene Fragestellungen zum Nutzen der Blockchain-Technologie in modernen Geschäftsprozessen und zu den technischen Herausforderungen mittels der Entwicklung zweier Prototypen betrachtet. Der erste Prototyp realisiert eine eigene Blockchain, in der verschiedene Angriffsszenarien durchgespielt werden können. Der zweite Prototyp realisiert eine Clearinghouse-Anwendung in Form einer verteilten Smart-Contract-Implementierung (in Ethereum). Der Bericht vermittelt einen Überblick über Ansätze, Strukturen, interne Abläufe und Rahmenbedingungen aktueller Blockchain-Implementierungen. Die erzielten Ergebnisse verdeutlichen neben dem Nutzen auch die Besonderheiten und Einschränkungen der Blockchain-Technologie.

Jesús Fernández‐Villaverde, Daniel R. Sanches

Can competition among privately issued fiat currencies such as Bitcoin or Ethereum work? Only sometimes. To show this, we build a model of competition among privately issued fiat currencies. We modify the current workhorse of monetary economics, the Lagos-Wright environment, by including entrepreneurs who can issue their own fiat currencies in order to maximize their utility. Otherwise, the model is standard. We show that there exists an equilibrium in which price stability is consistent with competing private monies, but also that there exists a continuum of equilibrium trajectories with the property that the value of private currencies monotonically converges to zero. These latter equilibria disappear, however, when we introduce productive capital. We also investigate the properties of hybrid monetary arrangements with private and government monies, of automata issuing money, and the role of network effects.

Xmaket Digital

No abstract is available for this record.

Mihails Ļevenčiks

Darba mērķis ir Ethereum decentralizētas programmatūras platformas pētīšana. Darbā tiek pētītas tehnoloģijas uz kurām balstās decentralizētās programmatūras platforma, programmatūras izstrādes process tajā un platformas stiprās un vājās puses. Darba praktiskajā daļā, tiek izveidots decentralizētas kopfinansēšanas sistēmas prototips Ethereum platformā.

Andrew Miller

The past several years have seen the surprising and rapid rise of Bitcoin and other “cryptocurrencies.” These are decentralized peer-to-peer networks that allow users to transmit money, tocompose financial instruments, and to enforce contracts between mutually distrusting peers, andthat show great promise as a foundation for financial infrastructure that is more robust, efficientand equitable than ours today. However, it is difficult to reason about the security of cryptocurrencies. Bitcoin is a complex system, comprising many intricate and subtly-interacting protocol layers. At each layer it features design innovations that (prior to our work) have not undergone any rigorous analysis. Compounding the challenge, Bitcoin is but one of hundreds of competing cryptocurrencies in an ecosystem that is constantly evolving. The goal of this thesis is to formally reason about the security of cryptocurrencies, reining in their complexity, and providing well-defined and justified statements of their guarantees. We provide a formal specification and construction for each layer of an abstract cryptocurrency protocol, and prove that our constructions satisfy their specifications. The contributions of this thesis are centered around two new abstractions: “scratch-off puzzles,” and the “blockchain functionality” model. Scratch-off puzzles are a generalization of the Bitcoin “mining” algorithm, its most iconic and novel design feature. We show how to provide secure upgrades to a cryptocurrency by instantiating the protocol with alternative puzzle schemes. We construct secure puzzles that address important and well-known challenges facing Bitcoin today, including wasted energy and dangerous coalitions. The blockchain functionality is a general-purpose model of a cryptocurrency rooted in the “Universal Composability” cryptography theory. We use this model to express a wide range of applications, including transparent “smart contracts” (like those featured in Bitcoin and Ethereum), and also privacy-preserving applications like sealed-bid auctions. We also construct a new protocol compiler, called Hawk, which translates user-provided specifications into privacy-preserving protocols based on zero-knowledge proofs.

Paulo Nicolás Carrillo, Pe ntilde a Clara I., de La Rosa Josep Ll.

With the popularization of online games and social networks, the virtual currencies have acquired a boom growing as solution of alternative payment and best adapted to the particular needs of the exchange of goods or virtual services offering faster, more secure and low cost transactions of value. This work proposes a case study to create the Eurakos Next cryptocurrency based on a virtual currency named Eurakos which currently works using digital contracts. The idea is to allow agreements to be signed by two peers and validated by other peers in a mobile social community network using Smart Contracts through the Ethereum framework to take advantage of the Blockchain technology.

Christopher Marks

No abstract is available for this record.

Michel Avital, Roman Beck, John Leslie King, Matti Rossi · 5 authors

The panel focuses on blockchain, the technology behind Bitcoin and Ethereum. The topic has drawn much attention recently in both business and academic circles. The blockchain is a distributed, immutable digital record system that is shared among many independent parties and can be updated only by their consensus. If unbiased and incorruptible blockchain-based information systems become prevalent repositories of our records, trusting other humans with<br/>constructing and maintaining key records to define the resources at our disposal could become unnecessary. In principle, blockchain could provide a decentralized information infrastructure that no one fully controls, thereby no one has absolute power and no one can distort past or current records. The full potential let alone implications of blockchain is still unknown. The panel explores blockchain challenges and opportunities from the IS research perspective.

Robert Leonhard

No abstract is available for this record.

Aggelos Kiayias, Giorgos Panagiotakos

A fundamental open problem in the area of blockchain protocols is whether the Bitcoin protocol is the only solution for building a secure transaction ledger. A recently proposed and widely considered alternative is the \GHOST protocol which, notably, was proposed to be at the core of Ethereum as well as other recent proposals for improved Bitcoin-like systems. % The \GHOST variant is touted as offering superior performance compared to Bitcoin (potentially offering block production speed up by a factor of more than 40) without a security loss. Motivated by this, in this work, we study from a provable security point of view the \GHOST protocol.<br/><br/>We introduce a new formal framework for the analysis of blockchain protocols that relies on trees (rather than chains) and we showcase the power of the framework by providing a unified description of the \GHOST and Bitcoin protocols, the former of which we extract and formally describe. We then prove that \GHOST implements a ``robust transaction ledger'' (i.e., possesses liveness and persistence) and hence it is a provably secure alternative to Bitcoin; moreover, our bound for the liveness parameter is superior to that proven for the bitcoin backbone in line with the original expectation for \GHOST. Our proof follows a novel methodology for establishing that \GHOST is a robust transaction ledger compared to previous works, which may be of independent interest and can be applicable to other blockchain variants.

Erik Hillbom, Tobias Tillström

Bitcoin, one of many cryptocurrencies, has in the last couple of years grown into a multi billion dollar industry. It is fully decentralized and utilizes a public ledger (blockchain), which allows for the currency to function without a central authority. As the Bitcoin protocol contains a programming language, it has potential to be used for much more than exchanging currency. This thesis is about exploring the possibility of combining cryptocurrency with a concept called 'smart-contracts'. The term smart-contracts was coined in a paper written by Nick Szabo in 1997, thus predating Bitcoin by 12 years. In contrast to paper based contracts, these are computer protocols facilitating an agreement between parties. We have put extra emphasis on two types of contracts: a generic type called `Double-Deposit- Escrow' (DDE), and one involving `smart-property'. DDE achieves a double deposit escrow within the blockchain, allowing users to perform business with untrusted parties with minimum risk of losing money. Smart-property may be described as the ability of property itself to be part of a contract. By refining Szabo's ideas using current technology, we have implemented a selfenforcing smart-contract executing the trade of smart-property referred to as the Smart-Property Ownership Exchange Protocol (SPOEP). It was implemented in Python and supports anonymous trades using Bitmessage, as well as NFC. We have analyzed our proposed protocol in terms of security and scalability, and compared it with related projects such as Ethereum and Colored coins. There are several viable approaches for creating smart-contracts using cryptocurrency. Albeit not perfect, we have deemed Bitcoin to be the currently most suited cryptocurrency to be used for this purpose.

Siddharth Misra, Vishal Kashyap, Poonacha K.B., Arjun Mukund · 5 authors

Tema ovog rada su kriptovalute. Budući da većina ljudi nije pravodobno upoznata s ovom temom, ovaj rad prikazuje i opisuje kriptovalute te način na koji se upotrjebljuju u svakodnevnom životu. Kriptovalute (eng. cryptocurrency) digitalne su valute dizajnirane kao sredstvo razmjene. Poznate su po tome što su državne agencije i banke isključene iz procesa razmjene. Kriptovalute omogućuju jednostavnu, jeftinu i brzu transakciju na području cijeloga svijeta. Trenutno najisplativije kriptovalute su Bitcoin i Ethereum, a u radu je opisana njihova korisnost, prednosti i mane. Budući da se Bitcoinu predviđa uspješna budućnost i sve je prisutniji i prihvatljiviji na tržištu, u radu su navedeni primjeri iz Hrvatske koji to potvrđuju. Sve veći broj poduzetnika odlučuje se za uvođenje kriptovaluta. U primjerima je obuhvaćen širok spektar djelatnosti, od frizerskih usluga, preko raznih tvrtki koji se bave prodajom računalne opreme, ugostiteljskih usluga preko mogućnosti brzog i lakog podizana gotovine na kripto bankomatima pa sve do plaćanja komunalnih usluga, pa čak i humanitarno djelovanje. Mnogi smatraju da su kriptovalute samo sinonim za prijevare i pranje novca, no programeri tvrde da su kriptovalute samo jedna vrsta tehnologije, alat koji sam po sebi ne može biti ni dobar ni loš, ovisno o tome za što se koristi. Autor ovoga rada proveo je istraživanje o tome kako se može besplatno započeti trgovanje kriptovalutama te je anketom ispitao stavove ispitanika o implementaciji kriptovaluta u društvu.

Pablo Fernández Burgueño

No abstract is available for this record.

Dappfort

Dappfort is a blockchain-focused Web3 development company that helps businesses harness the power of decentralized technologies to build secure, scalable, and future-ready digital solutions. Headquartered in Madurai, India, with additional presence in London, Dappfort works across a broad range of industries — including finance, healthcare, gaming, retail, and supply chain — delivering tailored blockchain and Web3 applications to startups, enterprises, and global organizations. The company’s core services include the design and development of decentralized applications (DApps), crypto exchanges (centralized and decentralized), crypto wallets, NFT marketplaces, DeFi platforms, token creation, smart contract development, and enterprise Web3 integration. Dappfort also expands into related areas such as Web3 e-commerce, AI-powered blockchain solutions, and metaverse experiences, supporting clients from strategy and consulting through deployment and ongoing support. With expertise in major blockchain networks like Ethereum, Solana, Binance Smart Chain, and others, Dappfort positions itself as a full-stack partner for businesses aiming to enter or grow in the decentralized digital economy. While the company promotes a strong innovation- and security-oriented approach, external reviews on third-party platforms show mixed feedback from users about project delivery and quality.

Ari Juels, Ahmed E. Kosba, Elaine Shi

Thanks to their anonymity (pseudonymity) and elimination of trusted intermediaries, cryptocurrencies such as Bitcoin have created or stimulated growth in many businesses and communities. Unfortunately, some of these are criminal, e.g., money laundering, illicit marketplaces, and ransomware. Next-generation cryptocurrencies such as Ethereum will include rich scripting languages in support of smart contracts, programs that autonomously intermediate transactions. In this paper, we explore the risk of smart contracts fueling new criminal ecosystems. Specifically, we show how what we call criminal smart contracts (CSCs) can facilitate leakage of confidential information, theft of cryptographic keys, and various realworld crimes (murder, arson, terrorism). We show that CSCs for leakage of secrets (a la Wikileaks) are efficiently realizable in existing scripting languages such as that in Ethereum. We show that CSCs for theft of cryptographic keys can be achieved using primitives, such as Succinct Non-interactive ARguments of Knowledge (SNARKs), that are already expressible in these languages and for which efficient supporting language extensions are anticipated. We show similarly that authenticated data feeds, an emerging feature of smart contract systems, can facilitate CSCs for realworld crimes (e.g., property crimes). Our results highlight the urgency of creating policy and technical safeguards against CSCs in order to realize the promise of smart contracts for beneficial goals.

Henry Kim, Marek Laskowski

An interesting research problem in our age of Big Data is that of determining provenance. Granular evaluation of provenance of physical goods--e.g. tracking ingredients of a pharmaceutical or demonstrating authenticity of luxury goods--has often not been possible with today's items that are produced and transported in complex, inter-organizational, often internationally-spanning supply chains. Recent adoption of Internet of Things and Blockchain technologies give promise at better supply chain provenance. We are particularly interested in the blockchain as many favoured use cases of blockchain are for provenance tracking. We are also interested in applying ontologies as there has been some work done on knowledge provenance, traceability, and food provenance using ontologies. In this paper, we make a case for why ontologies can contribute to blockchain design. To support this case, we analyze a traceability ontology and translate some of its representations to smart contracts that execute a provenance trace and enforce traceability constraints on the Ethereum blockchain platform.

Jack Pettersson, Robert Edström

We show how dependent and polymorphic types can make smart contract development safer. This is demonstrated by using the functional language Idris to describe smart contracts on the Ethereum platform. In particular, we show how one class of common errors can be captured at compile time using dependent types and algebraic side effects. We also bring type annotations to the realm of smart contracts, helping developers to circumvent another class of common errors. To demonstrate the feasibility of our solutions, we have extended the Idris compiler with a backend for the Ethereum Virtual Machine. While we find that the functional paradigm might not be the most suitable for the domain, our approach solves the identified problems and provides advantages over the languages in current use.

Karen Elliott, Fabio Massacci, Chan-Nam Ngo, Julian Williams

No abstract is available for this record.

Fan Zhang, Ethan Cecchetti, Kyle Croman, Ari Juels · 5 authors

Smart contracts are programs that execute autonomously on blockchains. Their key envisioned uses (e.g. financial instruments) require them to consume data from outside the blockchain (e.g. stock quotes). Trustworthy data feeds that support a broad range of data requests will thus be critical to smart contract ecosystems. We present an authenticated data feed system called Town Crier (TC). TC acts as a bridge between smart contracts and existing web sites, which are already commonly trusted for non-blockchain applications. It combines a blockchain front end with a trusted hardware back end to scrape HTTPSenabled websites and serve source-authenticated data to relying smart contracts. TC also supports confidentiality. It enables private data requests with encrypted parameters. Additionally, in a generalization that executes smart-contract logic within TC, the system permits secure use of user credentials to scrape access-controlled online data sources. We describe TC’s design principles and architecture and report on an implementation that uses Intel’s recently introduced Software Guard Extensions (SGX) to furnish data to the Ethereum smart contract system. We formally model TC and define and prove its basic security properties in the Universal Composability (UC) framework. Our results include definitions and techniques of general interest relating to resource consumption (Ethereum’s “gas” fee system) and TCB minimization. We also report on experiments with three example applications. We plan to launch TC soon as an online public service.