Follow blockchain research across journals, conferences, and preprint repositories.
13,597 results · page 554 of 567
Christian Masiak, Joern Block, Tobias Masiak, Matthias Neuenkirch · 5 authors
No abstract is available for this record.
Elie Kfoury, David Khoury
No abstract is available for this record.
Andrew Miller, Zhicheng Cai, Somesh Jha
No abstract is available for this record.
Shaun Azzopardi, Joshua Ellul, Gordon J. Pace
No abstract is available for this record.
Yi Zhou, Deepak Kumar, Surya Bakshi, Joshua Mason · 6 authors
Interacting with Ethereum smart contracts can have potentially devastating financial consequences. In light of this, several regulatory bodies have called for a need to audit smart contracts for security and correctness guarantees. Unfortunately, auditing smart contracts that do not have readily available source code can be challenging, and there are currently few tools available that aid in this process. Such contracts remain opaque to auditors. To address this, we present Erays, a reverse engineering tool for smart contracts without the need for source code. Erays takes in smart contract from the Ethereum blockchain and produces high-level pseudocode suitable for manual analysis. We show how Erays can be used to provide insight into several contract properties, such as code complexity and code reuse in the ecosystem. We then leverage Erays to link contracts with no previously available source code to public source code, thus reducing the overall opacity in the ecosystem. Finally, we demonstrate how Erays can be used for reverse-engineering in four case studies: high-value multi-signature wallets, arbitrage bots, exchange accounts, and finally, a popular smart-contract game, Cryptokitties. We conclude with a discussion regarding the value of reverse engineering in the smart contract ecosystem, and how Erays can be leveraged to address the challenges that lie ahead.
Leonardo Alt, Christian Reitwießner
No abstract is available for this record.
Haya R. Hasan, Khaled Salah
There is an immense need of a proof of delivery (PoD) of today's digital media and content, especially those that are subject to payment. Current PoD systems are mostly centralized and heavily dependent on a trusted third party (TTP) especially for payment. Such existing PoD systems often lack security, transparency, and visibility, and are not highly credible, as the TTP can be subject to failure, manipulation, corruption, compromise, and hacking. In this paper, we propose a decentralized PoD solution for PoD of digital assets. Our solution leverages key features of blockchain and Ethereum smart contracts to provide immutable and tamper-proof logs, accountability, and traceability. Ethereum smart contracts are used to orchestrate and govern all interactions and transactions including automatic payments in Ether cryptocurrency between customers, digital-content provider, and the file server hosting the digital content. All entities are incentivized to act honestly, and our solution has a mechanism to handle dispute if arisen among participants. The solution has an off-chain secure download phase involving the file server and customers. Moreover, our solution leverages the benefits of interplanetary file system to store the agreed upon terms and conditions between the smart contract actors. A security analysis of our proposed system has been provided. The full code of the smart contract has been publicly made available on Github.
Jason Paul Cruz, Yuichi Kaji, Naoto Yanai
The role-based access control (RBAC) framework is a mechanism that describes the access control principle. As a common interaction, an organization provides a service to a user who owns a certain role that was issued by a different organization. Such trans-organizational RBAC is common in face-toface communication but not in a computer network, because it is difficult to establish both the security that prohibits the malicious impersonation of roles and the flexibility that allows small organizations to participate and users to fully control their own roles. In this paper, we present an RBAC using smart contract (RBAC-SC), a platform that makes use of Ethereum's smart contract technology to realize a trans organizational utilization of roles. Ethereum is an open blockchain platform that is designed to be secure, adaptable, and flexible. It pioneered smart contracts, which are decentralized applications that serve as “autonomous agents”running exactly as programmed and are deployed on a blockchain. The RBAC-SC uses smart contracts and blockchain technology as versatile infrastructures to represent the trust and endorsement relationship that are essential in the RBAC and to realize a challenge-response authentication protocol that verifies a user's ownership of roles. We describe the RBAC-SC framework, which is composed of two main parts, namely, the smart contract and the challenge-response protocol, and present a performance analysis. A prototype of the smart contract is created and deployed on Ethereum's Testnet blockchain, and the source code is publicly available.
Sukrit Kalra, Seep Goel, Mohan Dhawan, Subodh Sharma
A smart contract is hard to patch for bugs once it is deployed, irrespective of the money it holds. A recent bug caused losses worth around $50 million of cryptocurrency. We present ZEUS-a framework to verify the correctness and validate the fairness of smart contracts. We consider correctness as adherence to safe programming practices, while fairness is adherence to agreed upon higher-level business logic. ZEUS leverages both abstract interpretation and symbolic model checking, along with the power of constrained horn clauses to quickly verify contracts for safety. We have built a prototype of ZEUS for Ethereum and Fabric blockchain platforms, and evaluated it with over 22.4K smart contracts. Our evaluation indicates that about 94.6% of contracts (containing cryptocurrency worth more than $0.5 billion) are vulnerable. ZEUS is sound with zero false negatives and has a low false positive rate, with an order of magnitude improvement in analysis time as compared to prior art.
Pedro Bação, António Portugal Duarte, Hélder Sebastião, Srdjan Redžepagić
This paper investigates the information transmission between the most important cryptocurrencies -Bitcoin, Litecoin, Ripple, Ethereum and Bitcoin Cash. We use a VAR modelling approach, upon which the Geweke’s feedback measures and generalized impulse response functions are computed. This methodology allows us to fully characterize the direction, intensity and persistence of information flows between cryptocurrencies. At the availabledata granularity, most of information transmission is contemporaneous, that is, it occurs within a day. However, it seems that there are some lagged feedback effects, mainly from other cryptocurrencies to Bitcoin. The generalized impulse-response functions confirm that there is a strong contemporaneous correlation and that there is not much evidence of lagged effects. The exception appears to be related to the overreaction of Bitcoin returns to contemporaneous shocks
Leopoldo Catania, Stefano Grassi, Francesco Ravazzolo
Cryptocurrencies have recently gained a lot of interest from investors, central banks and governments worldwide. The lack of any form of political regulation and their market far from being “efficient”, require new forms of regulation in the near future. From an econometric viewpoint, the process underlying the evolution of the cryptocurrencies’ volatility has been found to exhibit at the same time differences and similarities with other financial time-series, e.g. foreign exchanges returns. This short note focuses on predicting the conditional volatility of the four most traded cryptocurrencies: Bitcoin, Ethereum, Litecoin and Ripple. We investigate the effect of accounting for long memory in the volatility process as well as its asymmetric reaction to past values of the series to predict: 1 day, 1 and 2 weeks volatility levels.
Guglielmo Maria Caporale, Timur Zekokh
This paper aims to select the best model or set of models for modelling volatility of the four most popular cryptocurrencies, i.e. Bitcoin, Ethereum, Ripple and Litecoin. More than 1000 GARCH models are fitted to the log returns of the exchange rates of each of these cryptocurrencies to estimate a one-step ahead prediction of Value-at-Risk (VaR) and Expected Shortfall (ES) on a rolling window basis. The best model or superior set of models is then chosen by backtesting VaR and ES as well as using a Model Confidence Set (MCS) procedure for their loss functions. The results imply that using standard GARCH models may yield incorrect VaR and ES predictions, and hence result in ineffective risk-management, portfolio optimisation, pricing of derivative securities etc. These could be improved by using instead the model specifications allowing for asymmetries and regime switching suggested by our analysis, from which both investors and regulators can benefit.
Jethin Abraham, Daniel Higdon, John B. Nelson, Juan G. Ibarra
In this paper, we present a method for predicting changes in Bitcoin and Ethereum prices utilizing Twitter data and Google Trends data. Bitcoin and Ethereum, the two largest cryptocurrencies in terms of market capitalization represent over \$160 billion dollars in combined value. However, both Bitcoin and Ethereum have experienced significant price swings on both daily and long term valuations. Twitter is increasingly used as a news source influencing purchase decisions by informing users of the currency and its increasing popularity. As a result, quickly understanding the impact of tweets on price direction can provide a purchasing and selling advantage to a cryptocurrency user or a trader. By analyzing tweets, we found that tweet volume, rather than tweet sentiment (which is invariably overall positive regardless of price direction), is a predictor of price direction. By utilizing a linear model that takes as input tweets and Google Trends data, we were able to accurately predict the direction of price changes. By utilizing this model, a person is able to make better informed purchase and selling decisions related to Bitcoin and Ethereum.
Yukun Liu, Aleh Tsyvinski
Abstract We establish that cryptocurrency returns are driven and can be predicted by factors that are specific to cryptocurrency markets. Cryptocurrency returns are exposed to cryptocurrency network factors but not cryptocurrency production factors. We construct the network factors to capture the user adoption of cryptocurrencies and the production factors to proxy for the costs of cryptocurrency production. Moreover, there is a strong time-series momentum effect, and proxies for investor attention strongly forecast future cryptocurrency returns.
Anastasia Mavridou, Áron Lászka
Blockchain-based distributed computing platforms enable the trusted execution of computation - defined in the form of smart contracts - without trusted agents. Smart contracts are envisioned to have a variety of applications, ranging from financial to IoT asset tracking. Unfortunately, the development of smart contracts has proven to be extremely error prone. In practice, contracts are riddled with security vulnerabilities comprising a critical issue since bugs are by design non-fixable and contracts may handle financial assets of significant value. To facilitate the development of secure smart contracts, we have created the FSolidM framework, which allows developers to define contracts as finite state machines (FSMs) with rigorous and clear semantics. FSolidM provides an easy-to-use graphical editor for specifying FSMs, a code generator for creating Ethereum smart contracts, and a set of plugins that developers may add to their FSMs to enhance security and functionality.
Bikramaditya Singhal, Gautam Dhameja, Priyansu Sekhar Panda
The era of Blockchain applications has just begun. Ethereum is here to be the defacto Blockchain platform for building decentralized applications. We already learned in the previous chapters that public Blockchain use cases are not just limited to cryptocurrencies, and the possibilities are only limited by your imagination! Ethereum has already made inroads in many business sectors and works best not only for public Blockchain use cases, but also for the private ones. Ethereum has already set a benchmark for Blockchain platforms and must be studied well to be able to envision how usable decentralized applications can be built with or without using Ethereum. Today, it is possible to build Blockchain applications with minimal knowledge of cryptography, game theory, mathematics or complex coding, and computer science fundamentals, thanks to Ethereum.
Huijuan Zhang, Chengxin Jin, Hejie Cui
No abstract is available for this record.
Debajani Mohanty
According to Forbes, “Ethereum is the first generic blockchain platform that allows users to easily create and deploy their decentralized and trustless applications. It has created incredible opportunities in the fintech space.” This chapter will introduce you to the entire ecosystem of Ethereum. Later chapters will discuss its specific components in more detail.
Xuechao Yang, Xun Yi, Surya Nepal, Fengling Han
No abstract is available for this record.
Pandian Raju, Soujanya Ponnapalli, Evan Kaminsky, Gilad Oved · 7 authors
No abstract is available for this record.
Alex Biryukov, Dmitry Khovratovich, Sergei Tikhomirov
Identity is a fundamental concept for the financial industry. In order to comply with regulation, financial institutions must verify the identity of their customers. Identities are currently handled in a centralized way, which diminishes users' control over their personal information and threats their privacy. Blockchain systems, especially those with support for smart contracts (e.g., Ethereum), are expected to serve as a basis of more decentralized systems for digital identity management. We propose a design of a privacy-preserving KYC scheme on top of Ethereum. It would let providers of financial services leverage the potential of blockchain technology to increase effciency of customer onboarding while complying with regulation and protecting users' privacy.
Stephan Haarmann, Kimon Batoulis, Adriatik Nikaj, Mathias Weske
No abstract is available for this record.
Haoli Sun, Hua Song, Ence Zhou, Bingfeng Pi · 6 authors
No abstract is available for this record.
Jakub Zakrzewski
No abstract is available for this record.