We study distributed declarative workflow execution in an adversarial setting.In this setting, parties to an agreed-upon workflow do not trust each other to follow that workflow, or suspect the other party might misrepresent proceedings at a later time.We demonstrate how distributed declarative workflow execution can be implemented as smart contracts, guaranteeing (I) enforcement of workflow semantics, and (II) an incontrovertible record of workflow execution history.Crucially, we achieve both properties without relying on a trusted third party.The implementation is based on the Ethereum blockchain, inheriting the security properties (I) and (II) from the guarantees given by that chain.A recurring challenge for both the implementation and the analysis is the cost of operations on Ethereum: This cost must be minimised for honest parties, and an adversary must be prevented from inflicting extra cost on others.
So far we have discussed the Ethereum architecture, Solidity programming, and the Ethereum client, including setting it up and compiling, running, and debugging Dapps. That’s a lot of work, isn’t it? In this chapter, let’s discuss two leading frameworks, Truffle and Embark, that will provide a set of tools and boilerplate code for scaffolding Dapps for Ethereum. The frameworks will do much of the work themselves and leave you with only a few tasks.
Public key server is a simple yet effective way of key management in secure end-to-end communication. To ensure the trustworthiness of a public key server, transparent log systems such as CONIKS employ a tamper-evident data structure on the server and a gossiping protocol among clients in order to detect compromised servers. However, due to lack of incentive and vulnerability to malicious clients, a gossiping protocol is hard to implement in practice. Meanwhile, alternative solutions such as EthIKS are not scalable. This paper presents Trusternity, an auditing scheme relying on Ethereum blockchain that is easy to implement, scalable and inexpensive to operate.
Cryptocurrency, or digital currency that utilizes blockchain technology and cryptography to encode transactions, has excited many with the promise of minimizing governance. Although the structure of cryptocurrency is inherently decentralized, cryptocurrency relies upon complex relationships between different actors with various functions and roles.. The execution of cryptocurrency thus depends on the mutually satisfying interactions of these actors, who form the basis for non-technical governance structures.\nThis paper investigates the extent to which technical governance mitigates traditional governance problems by examining the governance structures of two cryptocurrencies. It first gives background into the origin and technical value proposition of cryptocurrency, as well as governance theory, before analyzing Bitcoin and Ethereum to understand whEther technology mitigates actors’ motivations. This paper finds that despite cryptocurrency’s promise of minimizing governance, both Bitcoin and Ethereum rely heavily on trust networks, indicating that elements of non-technical governance are, in fact, crucial to their effectiveness.
We analyse the triangle of Initial Coin Offerings (ICO) and cryptocurrencies, namely Bitcoin and Ethereum. So far, little is known about the relationship between ICOs, bitcoin and Ether prices. Hence, we employ both bitcoin and Ether prices but also the ICO amount to measure the future development of raised capital in ICOs. First, our results indicate that an ICO has an influence on the subsequent ICO. Second, not only bitcoin prices but also Ether prices play a considerable role with regard to the output of ICO campaigns. However, the effect of Ethereum is of shorter duration on ICO compared to Bitcoin on ICO. A further finding is that the cryptocurrency Bitcoin positively influences Ether. The implications of these findings for investors and entrepreneurial firms are discussed.
The ZK-STARK technology, published by Ben-Sasson et al. in ePrint 2018/046 is hailed by many as being a viable, efficient solution to the scaling problem of cryptocurrencies. In essence, a ZK-STARK proof uses a Merkle-tree to compress the data that needs to be verified, thus greatly reduces the communication overhead between the prover and the verifier. We propose MARVELlous a family of cryptographic algorithms specifically designed for STARK efficiency. The family currently includes the block cipher Jarvis and the hash function Friday. The design of Jarvis is inspired by the design of Rijndael, better known as the AES. By doing so we create a cipher with similar properties to those of Rijndael which allows us to reuse the wide-trail strategy to argue the resistance of the design against differential and linear cryptanalysis and focus our efforts on resistance against algebraic attacks. Friday is a Merkle-Damgard based hash function instantiated with Jarvis as its compression function thus it inherits its security properties up to the birthday bound. Jarvis and Friday have been suggested to be used in the Ethereum protocol by Ben-Sasson in Ethereum's Devcon IV. In this paper, we instantiate versions of Jarvis offering 128, 160, 192 and 256-bit security (both state- and key-size) which are used to implement Friday. We warmly invite the community to study and assess the security of the designs.
The cryptocurrency market has become increasingly accessible and significant to the financial markets. This is understood by not only major financial firms, governments, and investors, but also the individual market participants globally. We delve into the history of cryptocurrency to begin our examination of the Bitcoin, Ethereum and Litecoin. Understanding the circumstances of their humble beginning, the purpose it served, and the path of their evolution, helps us to create a fuller understanding of its functions, its limitations, and the drivers of its value. This enables us to identify key market factors and variables for deployment within a robust approach for pricing and product offerings associated with Bitcoin, Ethereum and Litecoin. In order to fully capture the volume, variety, and velocity of data associated with these cryptocurrencies, the use of machine learning can provide an advantageous approach to model development for cryptocurrency pricing. This paper provides the development of a promising initial prototype pricing model for Bitcoin, Ethereum and Litecoin. Our proposed pricing models resulted in an average 7% difference between actual and predicted price for Bitcoin and Ethereum, and a 4% difference for Litecoin along a timeline, through the use of machine learning and deep learning, artificial neural networks using the contributing factors of key variables and how they influence and capture pricing and investor behaviour. We also identify theinclusion of additional datasets, such as sentiment market data into the model, along with larger exploration of Blockchain and raw transaction mining to increase the accuracy and forecasting ability of the model.
In technological issues and evolutions of the same, Blockchain and Project Ethereum are some of the most current presented, focused on the economic area, its developments unleash vast areas of applications and for that fact, their applications and knowledge are important. In this context, this article aims to present a study on the technologies and their applicability, using the year of experience of the author in the mining method and its monitoring in the market of cryptomoedas in the last year as study data, is finalized with validations of the investments made during the study time informed.
With the explosion of Bitcoin, various cryptocurrencies are beginning to garner incredible amounts of attention from speculators and institutional investors alike. Simultaneously, the rise in the number of occurrences of cyber ransom attacks has proven to be an increasingly relevant part of the conversation in the formative years of the Bitcoin ecosystem, as hackers demand payments be in the form of bitcoin. To test the relative impact of these different ransom events on the price of bitcoin, this paper conducts an event study to quantify the reaction by investors upon revelation of the news. In addition, it examines differences between Bitcoin and two other cryptocurrencies, Ethereum and Litecoin, to control for any liquidity effects of victims buying up large sums of bitcoin. The findings of the study indicate that following the ransom events there is a positive price reaction, supporting the claim that investors in Bitcoin generally perceive these events as good news. This could have a profound effect on the development and further adoption of cryptocurrencies, as regulators try to determine whether or not to intervene.
We describe our efforts towards building a tool that automatically verify high-level functional properties of Ethereum smart contracts against its formal specification that can be given using four different methods: an invariant over contract state or three different types of trace properties. A model of runtime system, the source code of smart contract together with its specification is translated into SMT-solver formula and checked for counter example. We tested the method on simplified version of notorious TheDAO smart-contract, called MiniDAO. Our proof-of-concept tool was able to find a functional property violation of MiniDAO in just several seconds. We believe that the proposed method is indeed useful and deserves deeper investigation.
We present a proof of concept implementation of an integration strategy for connecting CAD with Blockchain. We explain the components of most blockchains and the value they bring to the built environment ecosystem, the potential impact a complete integration might have and we demonstrate the first two of four levels of integration we have identified between CAD and blockchain technologies. For the purposes of the paper we use Rhino / Grasshopper and Ethereum as the two components of integration.
Представлено аналіз технології блокчейн та виконано дослідження криптографічної стійкості її найбільш популярних реалізацій. Визначено вразливі місця реалізацій технології та запропоновано практичні рекомендації щодо усунення визначених недоліків.
We introduce FairSwap -- an efficient protocol for fair exchange of digital goods using smart contracts. A fair exchange protocol allows a sender S to sell a digital commodity x for a fixed price p to a receiver R. The protocol is said to be secure if R only pays if he receives the correct x. Our solution guarantees fairness by relying on smart contracts executed over decentralized cryptocurrencies, where the contract takes the role of an external judge that completes the exchange in case of disagreement. While in the past there have been several proposals for building fair exchange protocols over cryptocurrencies, our solution has two distinctive features that makes it particular attractive when users deal with large commodities. These advantages are: (1) minimizing the cost for running the smart contract on the blockchain, and (2) avoiding expensive cryptographic tools such as zero-knowledge proofs. In addition to our new protocols, we provide formal security definitions for smart contract based fair exchange, and prove security of our construction. Finally, we illustrate several applications of our basic protocol and evaluate practicality of our approach via a prototype implementation for fairly selling large files over the cryptocurrency Ethereum.
The characteristics of the "blockchain" technology and especially its decentralized nature lead to the notion of neutrality, censorship resistance, and absolute truths, which makes the concept interesting for many different domains, such as finance, supply chain management, or the energy sector - of course also for the healthcare area (eHealth). Blockchains also offer the possibility for well-known access points for a distributed system with easy to use and simple to integrate programming interfaces, which makes it interesting as a central point for electronic healthcare data exchange in a distributed environment. This paper presents a concept for integrating and sharing distributed personal healthcare records based on smart contracts implemented on an Ethereum blockchain.