To solve the credibility and supervision lacking problem in the OTC warehouse receipt trading system, a scheme of using smart contract on the blockchain to implement the OTC warehouse receipt trading system is presented. As a distributed ledger, blockchain has the advantages of decentralization, irreversibility and trustworthiness. The warehouse receipt transaction data is recorded on the blockchain, ensuring its safety and credibility. Smart contract is automatically executed code stored on the blockchain, it can directly control the transaction of digital assets. No participant can control and tamper it before the contract is lapsed. In the process of using the Ethereum smart contract to realize warehouse receipt transactions, consensus is reached by the PBFT consensus algorithm, Since the trusted third-party is not needed, the lack of supervision problem is solved. This paper introduces the application of blockchain and smart contract to the OTC warehouse receipt trading system. It includes the design of smart contracts, the verification of smart contracts security. This paper also verifies the feasibility of designing smart contracts by using the instance of listed transactions.
Preboj tehnologije veriĆŸenja blokov je omogocil oĆŸivitev in razvoj pametnih pogodb, ki omenjeni tehnologiji predstavljajo kljucno dodano vrednost. Pametne pogodbe so trenutno v fazi zasnove koncepta in s tem sproĆŸajo veliko zanimanje strokovne javnosti. Prav zaradi zgodnje faze v samem razvoju so izoblikovani vzorci dobrih praks razvoja pametnih pogodb in arhitektur decentraliziranih aplikacij, ki temeljijo na pametnih pogodbah, zelo okrnjeni. Ena od kljucnih lastnosti tehnologije veriĆŸenja blokov je nespremenljivost, ki se odraĆŸa tudi na pametne pogodbe. Taksna lastnost lahko predstavlja izvedbene in varnostne teĆŸave, saj so pametne pogodbe nezamenljive in hkrati nespremenljive v trenutku, ko so namescene v omreĆŸje verig blokov. V magistrskem delu predlagamo arhitekturo ekosistema pametnih pogodb, ki bo ucinkovito omogocala zamenljivost in nadgradljivost pametnih pogodb na platformi Ethereum. Uporabo predlagane arhitekture smo predstavili na primeru resevanja realnega izziva nadgradnje poslovnega procesa implementiranega s pomocjo pametnih pogodb.
Multiple blockchain implementations, such as Ethereum, support the storage and execution of executable code, called smart contracts. Due to the immutability of smart contracts, security updates and new functionalities can currently not be implemented. From this, the main goal of the study is derived: to investigate whether a smart contract can be updated in a decentralised manner. This study adopts a Design Science approach to design a solution that involves a technical aspect to bypass the immutability of a smart contract and a decision-making process to reach a consensus on an update amongst the (anonymous) participants. This thesis presents a design that bypasses the immutability by adopting a proxy smart contract which redirects incoming calls to the most recent version of the smart contract. The decision-making process that we present, is extracted from four illustrative case studies. In this study, a fair stake is implemented as the value at risk: the stake in the process is relative to the value stored on the smart contract. As the results show, the applicability and feasibility of this concept are limited for smart contracts. The design that we present in this study is not viable and should not be implemented by industry.
As of January 2018, there were 1,384 cryptocurrencies available, and the number continues to grow., The term "cryptocurrencies," for now, at least, covers Bitcoin; altcoins, which are simply coins that are variants or forks of Bitcoin when there is a change in the underlying codes; and tokens.Unlike Bitcoin and coins that operate on separate blockchains, tokens are issued and operated on top of a blockchain.Bitcoin enjoys its enviable leading role among all cryptocurrencies, and Ethereum follows Bitcoin in standing.At the present time and for convenience purposes in the confines of this article, the author will refer to Bitcoin as inclusive of other cryptocurrencies.
This chapter covers the theory behind smart contract programming, with a special focus on Truffle, Solidity, and the Ethereum protocol. The chapter is laid out in a fashion that allows it to be used as a reference while weâre coding the games in the later chapters of the book. This chapter is intended for readers who have prior exposure to programming.
Growing consumer awareness as well as manufacturersâ internal quality requirements lead to novel demands on supply chain traceability. Existing centralized solutions suffer from isolated data storage and lacking trust when multiple parties are involved. Decentralized blockchain-based approaches attempt to overcome these shortcomings by creating digital representations of physical goods to facilitate tracking across multiple entities. However, they currently do not capture the transformation of goods in manufacturing processes. Therefore, the relation between ingredients and product is lost, limiting the ability to trace a productâs provenance. We propose a blockchain-based supply chain traceability system using smart contracts. In such contracts, manufacturers define the composition of products in the form of recipes. Each ingredient of the recipe is a non- fungible token that corresponds to a batch of physical goods. When the recipe is applied, its ingredients are consumed and a new token is produced. This mechanism preserves the traceability of product transformations. The system is implemented for the Ethereum Virtual Machine and is applicable to any blockchain configuration that supports it. Our evaluation reveals that the gas costs scale linearly with the number of products considered in the system. This leads to the conclusion that the solution can handle complex use cases.
Lohkoketjuteknologia tuli tietoisuuteen vuonna 2008, kun sitÀ kÀytettiin maailman ensimmÀisen kryptovaluutan, Bitcoinin taustalla. Lohkoketjun merkitys huomattiin heti, mikÀ nÀkyikin huomattavana mÀÀrÀnÀ muiden kryptovaluuttojen syntymisenÀ. Lohkoketjuteknologiaa voidaan hyödyntÀÀ kryptovaluuttojen lisÀksi myös muihin tarkoituksiin, ja esimerkiksi maailman isoimmat pankit tutkivat lohkoketjuteknologian mahdollisuuksia, mukaan lukien Yhdysvaltain keskuspankki sekÀ Euroopan keskuspankki. TÀmÀn kirjallisuuskatsauksena toteutettavan tutkielman tarkoituksena on antaa pintapuolinen kÀsitys lohkoketjun toimintaperiaatteista, hyödyntÀmiskohteista sekÀ haasteista. Tutkielmassa perehdytÀÀn myöskin lohkoketjuteknologian keskiössÀ oleviin konsensusmekanismeihin, kuten Bitcoinissa kÀytettÀvÀÀn proof-of-work -mekanismiin. Lohkoketjuteknologian perimmÀinen idea on, ettÀ verkon osapuolista jokainen pitÀÀ hallussaan tÀsmÀlleen samaa tietoa. MikÀli tietoja halutaan muuttaa, verkon osapuolien tÀytyy pÀÀstÀ asiasta yhteisymmÀrrykseen eli konsensukseen. TÀmÀn vuoksi olemassa olevia tietoja on todella vaikea muuttaa, mikÀ on yksi lohkoketjuteknologian suurimmista hyödyistÀ. Konsensukseen voidaan pÀÀstÀ eri tavoilla riippuen valitusta konsensusmekanismista. Suurimmat kryptovaluutat kÀyttÀvÀt proof-of-work -mekanismia, eli todistetta tehdystÀ työstÀ, mutta esimerkiksi Ethereum on siirtymÀssÀ kÀyttÀmÀÀn proof-of-stake -mekanismia, eli todistetta panoksesta. KÀytetty konsensusmekanismi on avainasemassa lohkoketjun toiminnassa, ja esimerkiksi Bitcoinin tapauksessa sen kÀyttÀmÀ konsensusmekanismi on syy sen globaalisti merkittÀvÀÀn virrankulutukseen.
Digital currencies and cryptocurrencies have hesitantly started to penetrate the investors, and the next step will be the regulatory risk management framework. We examine the Value-at-Risk and Expected Shortfall properties for Bitcoin and Ethereum, using GARCH methodology and filtered historical simulation. We find the both Bitcoin and Ethereum are subject to a higher risk, therefore, to higher sufficient buffer and risk capital to cover potential losses.
Diese Arbeit untersucht die Möglichkeiten, einen exemplarischen kaufmĂ€nnischen Prozess mit verschiedenen Akteuren auf der Ethereum-Plattform abzubilden. Das Wissen ĂŒber die Funktionsweise der Blockchain-Technologie stellt die Grundlage fĂŒr die Bearbeitung dar. Unter BerĂŒcksichtigung der Besonderheiten verteilter Systeme hinsichtlich der Datenhaltung sowie des Datenschutzes wird ein Konzept fĂŒr die Abwicklung eines Warenan- bzw. Verkaufs entwickelt. Darin wird die Integration eines zusĂ€tzlichen Systems zur Speicherung von Daten vorgestellt, das sich kryptografischer Funktionen der Ethereum-Plattform bedient. FĂŒr wichtige Teile des Systems werden zudem Implementierungshinweise gegeben.
Jan 1, 2018·Proceedings of the ... Annual Hawaii International Conference on System Sciences/Proceedings of the Annual Hawaii International Conference on System Sciences
Hua Song, Ence Zhou, Bingfeng Pi, Jun Sun · 6 authors
Battery swapping is a solution of electric vehicle (EV) battery refueling. For EV owners, the battery information and transactionâs correctness, openness, traceability and immutability is difficult to get guarantee in traditional centralized system. The trust lacking between EV owners and swapping station is caused, and becomes a big challenge to EVâs rapid development. An objective mechanism based on decentralized blockchain system is proposed to manage battery swapping and solve the trust lacking issue. With this solution, both batteryâs life-cycle information and all operations histories are permanently saved in blockchain network. All key logics are driven by smart contracts, the battery price calculation and the digital currency exchange between EV owners and station are realized by smart contracts automatically and accurately. A primary prototype based on Ethereum is analyzed and implemented to illustrate the feasibility of managing battery swapping and refueling based on blockchain system to solve the trust lacking issue.
In this paper, we provided a general insight into the burgeoning cryptocurrency market. Having inspected the capabilities of cryptocurrencies as investment assets, we saw value in developing a price prediction model in this highly volatile market. Ether was chosen as the subject due to its unparalleled potential amongst its competitors. Driven by the similarities presented between cryptocurrency and stock, coupled with evidence of hidden states in the financial market, this paper conducted the first application of the Hidden Markov Model to the cryptocurrency space. Our main objectives were to first model the time series data of Ether since its establishment, then use the trained model to forecast future closing prices of Ether before finally devising an investment strategy. HMM was used to solve three fundamental problems namely the Evaluation Problem, Learning Problem and Decoding Problem. Given 936 observations of daily Ether prices obtained from Yahoo Finance, 80% of this data was used as a training set while the remaining 20% was used as the testing set. The Forward algorithm and Baum-Welch algorithm helped obtained the model parameters. Thereafter, Viterbi algorithm decoded the likely state sequence of the observations. Using Mean Absolute Percentage Error as the indication of forecasting power, the selected Hidden Markov Model (HMM) has 3 states and 3 mixtures of Gaussian distribution, with the lowest MAPE of 4.63568. Via Monte Carlo simulations, our HMM investment strategy produced a superior weekly return of 5.68% as compared to 3.94% for the ânaĂŻveâ strategy. This indicated the successful adaptation of HMM in the cryptocurrency market despite limitations from the inherent assumption. Future extensions to the paper could include the use of more model inputs, account for transaction fees and consider the heavy correlation between cryptocurrencies. We also anticipate that our findings require re-validation over time given the rapidly evolving nature of the market.
KĂ€esolevas bakalaureusetöös tutvustatakse plokiahela tehnoloogiat ning selle kahte erinevat platvormi, Ethereum ja Hyperledger Fabric, mis on loodud vĂ€ga erinevate rakenduste loomiseks kasutades just plokiahela tehnoloogiat. Peale selle luuakse mĂ”lemat platvormi kasutades sarnane rakendus, millele jĂ€rgneb vĂ”rdlus. Esiteks, annab vĂ”rdlus lugejale ĂŒlevaate, kuidas antud platvormid ĂŒksteisest arhitektuuri ning kasutajamugavuse poolest erinevad. Teiseks nĂ€itab, kuidas erineb nende platvormide abil rakenduste loomine ning mille poolest erinevad lĂ”putöö raames loodud rakendused.