ABSTRACT This research examines the dynamic linkage between four major cryptocurrencies—Bitcoin, Ethereum, Ripple, and Litecoin—and stock markets in ASEAN-5. The findings revealed that first, linkage testing, in the long run using Engle and Granger co-integration, provided evidence of a relationship among all cryptocurrencies with the stock markets in ASEAN-5, with the exception of Malaysia. Secondly, using the dynamic conditional correlation model, the results showed that time-varying patterns of short-run correlations were found in all relationships. Moreover, the Litecoin linkage with ASEAN-5 markets fluctuated significantly. Further, Bitcoin’s dynamic linkage with the stock markets showed a very high correlation from 2013 to 2015, and then became close to stable until January 2020. Finally, this paper tested the determinants of the linkage cryptocurrencies with financial market factors, consisting of GOLD, CRUDE, FX, and INT. The empirical results showed that GOLD and INT did not affect the degree of linkage with the stock market or cryptocurrency, although both CRUDE and FX impacted it. As for recommendations and policy implications, the cryptocurrencies demonstrated a dynamic linkage with stock markets and exhibited extreme volatility, and therefore the five countries should prepare a policy or regular information regarding cryptocurrencies for investors or policymakers. On the other hand, investors should focus on indicators such as foreign exchange rates and crude oil prices prior to trading.
The growing use of smart contracts in a wide range of transactions has raised a deluge of legal issues, including allocation of liability in such transactions. In many circumstances, using smart contracts involves a range of legal risks that might be distributed beyond the contractual parties to other parties, such as the developers of the smart contract code. While smart contracts have the potential to disrupt the current legal and transactional status quo, notorious occurrences such as attacks on Ethereum or Bitcoin platforms highlight the need to properly dissect the issue of liability and rightly apportion liability where it falls. This also includes working on any lapses in the existing legal and transactional framework to cater for these issues. This article sets out to examine the validity of smart contracts in the light of existing contract law principles. It examined the legal regime and development of smart contracts in Nigeria. It further discussed the problem of allocation of liability associated with smart contracts. It made certain propositions on how these issues could be tackled including the amendment of existing legal framework to aptly provide for and regulate the smart contracts era particularly in Nigeria. The doctrinal method of research was employed to dissect the issues raised and discussed in the article. Relevant texts were scrutinized and analyzed to arrive at the findings and recommendations contained in the article.
Abstract Blockchain-based cloud application (BCP) is an emerging cloud application architecture. By moving trust-critical functions onto blockchain, BCP offers unprecedented function transparency and data integrity. Ethereum is by far the most popular blockchain platform chosen for BCP. In Ethereum, special programs named smart contracts are often used to implement key components for BCP. By design, users can send transactions to smart contracts, which will automatically lead to code execution and state modification. However, unlike regular programs, smart contracts are restricted in execution by gas limit, i.e., a form of runtime resource. If a transaction uses up all available gas, an out of gas exception () will trigger, reverting state until right before that transaction.In this work, we study the out of gas exceptions (or gas exceptions in short) on Ethereum empirically for the very first time. In particular, we collect exception transactions using an instrumented Ethereum client. By investigation, we found gas exceptions stand out in terms of both occurrences and losses. Moreover, we focused on individual contracts and transactions, aiming at discovering and identifying common causing factors triggering these exceptions. At last, we also investigate existing tools in preventing gas exceptions. Our results suggest further research and study in this direction.
Ijazah konvensional mempunyai beberapa kekurangan diantaranya yaitu bisa dipalsukan, membutuhkan tempat pemyimpanan yang aman dan bisa rusak. Oleh karena perlu dibuat teknologi informasi yang bisa mengatasi kekurangan tersebut, salah satunya adalah smart contract pada blockchain Ethereum. Smart contract pada blockchain Ethereum memungkinkan membuat ijazah dengan integritas dan keamanan data yang tinggi, sehingga bisa meminimalisir kerusakan dan pemalsuan ijazah. Akan tetapi blockchain Ethereum memerlukan biaya yang besar dalam menyimpan data yang besar. Pada penelitian ini bertujuan guna mengukur performa dari pengimplementasian IPFS pada smart contract yang dapat membuat biaya transaksi lebih stabil dan murah sebesar 61,95% dibandingkan dengan blockchain Ethereum tanpa mengimplementasikan IPFS. Selain itu, performa pada smart contract yang mengimplementasikan IPFS dapat meningkatkan performa dari Quality of Service (QoS) dengan parameter throughput sebesar 6,04 kali, Packet Loss 39,47%, dan Latency 42,28%.
While Vehicular Ad-hoc Networks (VANETs) can potentially improve driver safety and traffic mangement efficiency (e.g. through timely sharing of traffic status among vehicles), security and privacy are two ongoing issues that need to be addressed. Hence, security solutions such as conditional privacy-preserving authentication (CPPA) protocols have been proposed. However, CPPA protocols are generally far from being ready for deployment in VANETs, for example due key/certificate management limitations in PKI-based protocols or intractable private key updating in ID-based protocols. Although serveral blockchain-based CPPA (BCPPA) protocols have been proposed to mitigiate these challenges, there still exist some intractabilities such as revoking private key, or frequent interactions, or requiring an idea hardware. Thus, in this paper, we are motivated to propose a novel BCPPA protocol without these existing issues. Specifically, we present a PKI-based solution (using a typical digital signature protocol, such as ECDSA) based on Ethereum (a public blockchain), which is designed to facilitate secure communication in VANETs. In other words, we combine the blockchain technology and a key derivation algorithm to realize an effective certificate management. This reduces the need for participating vehicles to store a large number of private keys. To reduce the verification time cost, our BCPPA suppotrs replacing ECDSA with modified ECDSA for batch verification or directly adopting other PKI-based signatures with batch verification. In addition to introducing the concrete design, we also present the security requirements that our BCPPA protocol can satisfy. We then implement BCPPA in the Ethereum test network (i.e.Rinkeby) and provide simulations using VanetMobiSim and NS-2 to show its feasibility (i.e. milliseconds).
Dhruv Rawat, Gaurav Rana, Jaskaran Singh Bindra, Amit Kumar
The blockchain technology is being deployed in many areas and the banking system is not an exception. It is a new technology and should be introduced in the modern banking system. The aim of this project is to give an overview of blockchain technology with its benefits and emphasizing on the application of this technology in the banking sector. We are going to generate our own cryptocurrency along with a banking system with number of nodes between which we can perform transactions using blockchain. And we are using Ethereum (Online Transaction Management System) for our ongoing project. Now, blockchain is better than the conventional banking systems as, combining shared databases and cryptography, blockchain technology allows multiple parties that may not know each other from different geographical locations to have simultaneous access to a constantly updated digital ledger that cannot be altered. So, we will generate our own virtual nodes (Users who want to transfer money) which will transfer our own cryptocurrency to each other. The blockchain is a ground-breaking innovation that empowers Bitcoin, Litecoin, Dogecoin, and other virtual monetary standards to be open, mysterious, and secure. The blockchain basically is a database about each Bitcoin exchange in detail. Typically known as an open record, the log contains metadata about when and how every exchange occurred. The record is freely available through APIs and deluge destinations. To forestall messing with current and furthermore past exchanges, the database is cryptographically made sure about. Because of Cryptography can edit only the parts of the blockchain that they “own” - by possessing the private keys required to write to the file. It also keeps everyone’s copy of the distributed blockchain is kept in sync. Using blockchain rather than conventional banking system would help in fraud reduction and that too by quiet a lot of margin. Financial institutions spend millions of money per year to keep up with Know your Customer (KYC) and customer due diligence regulations according to a Thomson Reuters Survey. These regulations are meant to help reduce money laundering and terrorism activities by having requirements for businesses to verify and identify their clients. Blockchain would allow an organization to access the verification details of a client by another organization, thus avoiding repetition of the KYC process. Blockchain disruption could be highly transformative in the payments process. It would allow banks higher security with minimal lower costs to process payment between organizations and their clients and even between banks themselves. Blockchain would get rid of all the intermediaries in the payment processing system. Keywords: Blockchain, current transaction system, KYC, online transaction management system, processing system Cite this Article: Dhruv Rawat, Gaurav Rana, Jaskaran Singh Bindra, Amit Kumar. Implementation of blockchain in current transaction systems. International Journal of Data Structures. 2020; 6(1): 31–59p.
This paper aims to identify and model relationships between cryptocurrencies market price changes and topic discussion occurrences on social media. The considered cryptocurrencies are the two highest in value at the moment, Bitcoin and Ethereum. At the same time, topics were realized through a classification of the comments gained from the Reddit social media platform, implementing a Hawkes model. The results highlight that it is possible to identify some interactions among the considered features, and it appears that some topics are indicative of certain types of price movements. Specifically, the discussions concerning issues about government, trading and Ethereum cryptocurrency as an exchange currency, appear to affect Bitcoin and Ethereum prices negatively. The discussions of investment appear to be indicative of price rises, while the discussions related to new decentralized realities and technological applications is indicative of price falls.
Testing is an important technique to improve the quality of Ethereum smart contract programs. However, current work on testing smart contract only focus on static problems of smart contract programs. A data flow oriented test case generation approach for dynamic testing of smart contract programs is still missing. To address this problem, this paper proposes a novel test case generation approach, called ADF-GA (All-uses Data Flow criterion based test case generation using Genetic Algorithm), for Solidity based Ethereum smart contract programs. ADF-GA aims to efficiently generate a valid set of test cases via three stages. First, the corresponding program control flow graph is constructed from the source codes. Second, the generated control flow graph is analyzed to obtain the variable information in the Solidity programs, locate the require statements, and also get the definition-use pairs to be tested. Finally, a genetic algorithm is used to generate test cases, in which an improved fitness function is proposed to calculate the definition-use pairs coverage of each test case with program instrumentation. Experimental studies are performed on several representative Solidity programs. The results show that ADF-GA can effectively generate test cases, achieve better coverage, and reduce the number of iterations in genetic algorithm.
Ethereum, one of the most popular blockchain platforms, provides financial transactions like payments and auctions through smart contracts. Due to the immense interest in smart contracts in academia, the research community of smart contract security has made a significant improvement recently. Researchers have reported various security vulnerabilities in smart contracts, and developed static analysis tools and verification frameworks to detect them. However, it is unclear whether such great efforts from academia has indeed enhanced the security of smart contracts in reality.
Tai D. Nguyen, Long Hoang Pham, Jun Sun, Yun Lin · 5 authors
Smart contracts are Turing-complete programs that execute on the infrastructure of the blockchain, which often manage valuable digital assets. Solidity is one of the most popular programming languages for writing smart contracts on the Ethereum platform. Like traditional programs, smart contracts may contain vulnerabilities. Unlike traditional programs, smart contracts cannot be easily patched once they are deployed. It is thus important that smart contracts are tested thoroughly before deployment. In this work, we present an adaptive fuzzer for smart contracts on the Ethereum platform called sFuzz. Compared to existing Solidity fuzzers, sFuzz combines the strategy in the AFL fuzzer and an efficient lightweight multi-objective adaptive strategy targeting those hard-to-cover branches. sFuzz has been applied to more than 4 thousand smart contracts and the experimental results show that (1) sFuzz is efficient, e.g., two orders of magnitude faster than state-of-the-art tools; (2) sFuzz is effective in achieving high code coverage and discovering vulnerabilities; and (3) the different fuzzing strategies in sFuzz complement each other.
As the blockchain 2.0 platform, Ethereum's turing complete programming language and smart contract components make it play an important role in the commercialization of blockchain. With the further development of blockchain applications, the privacy and security issues of Ethereum have gradually emerged. To solve this problem, we proposed a blockchain privacy protection model called RZcash in the previous work. It implements the dynamically updateable and verifiable hiding of the asset information in Ethereum, namely the account balance and transaction amount. However, RZcash does not pay attention to the key redundancy problem that may be caused by the creation of secret accounts. In addition, the large size of proofs gives it high communication costs. In response to these problems, we further improve RZcash. For the key redundancy problem, we construct a new signature scheme based on the ciphertext equivalent test commitment. Moreover, we use the Schnorr signature and bulletproof to improve the corresponding proof scheme in RZcash, thereby reducing the size of proof. Based on these improvements, we propose a decentralized payment system, called RZcoin, based on Ethereum. Finally, we implement the algorithm model of RZcoin and evaluate its security and performance. The results show that RZcoin has higher security and Lower communication cost than RZcash.
Crowdsourcing is a process wherein an individual or an organisation utilizes\nthe talent pool present over the Internet to accomplish their task. The\nexisting crowdsourcing platforms and their reputation computation are\ncentralised and hence prone to various attacks or malicious manipulation of the\ndata by the central entity. A few distributed crowdsourcing platforms have been\nproposed but they lack a robust reputation mechanism. So we propose a\ndecentralised crowdsourcing platform having an immutable reputation mechanism\nto tackle these problems. It is built on top of Ethereum network and does not\nrequire the user to trust a third party for a non malicious experience. It also\nutilizes IOTAs consensus mechanism which reduces the cost for task evaluation\nsignificantly.\n
Blockchain is a secure and distributed ledger structure and each block is a cryptographic hash of some other factors like a timestamp. The chain is formed by linking the blocks and distributed data is present on multiple computers. The blockchain made system are more fault-tolerant and has high availability even in times of database failures. Though Linux is considered a benchmark for security, it is susceptible to various attacks. With the use of blockchain, Linux logs can be made more transparent among multiple root users and secured by hosting the logs on a decentralized Ethereum blockchain which is customized as per the requirement. It has been observed that in a scenario with multiple root users working simultaneously on same system, transparency between multiple root users can be compromised if some appropriate changes are made in few lines containing the history, Hence, with the help of Ethereum blockchain and log monitoring using log monitors, it is much easier to track the intrusions to identify the source of unauthorized access to logs or changes in them.
Gracie Carter, Ben Chevellereau, Hossain Shahriar, Sweta Sneha
The healthcare system in the United States is unique. From payor to provider, patients have the freedom of choice. This creates a complicated and profitable paradigm of care. Legislation defines government expectations of data exchange; however, the methods are left to the discretion of the stakeholders. Today, devices and programs are not built to unified standards, thus they do not share data easily. This communication between software is known as interoperability. We address the health data interoperability by leveraging Fast Health Interoperable Resource (FHIR) standard, a viewer of FHIR called OpenPharma, and Blockchain technology. Our proof of concept, called "OpenPharma Blockchain on FHIR" (OBF), is interoperable by design and grants clinicians access to patient records using a combination of data standards, distributed applications, patient-driven identity management, and the Ethereum blockchain. OBF is a trustless, secure, decentralized, and vendor-independent method for information exchange. It is easy to implement and places the control of records with the patients.
Itay Tsabary, Matan Yechieli, Alex Manuskin, Ittay Eyal
Smart Contracts and transactions allow users to implement elaborate constructions on cryptocurrency blockchains like Bitcoin and Ethereum. Many of these constructions, including operational payment channels and atomic swaps, use a building block called Hashed Time-Locked Contract (HTLC). In this work, we distill from HTLC a specification (HTLC-Spec), and present an implementation called Mutual-Assured-Destruction Hashed Time-Locked Contract (MAD-HTLC). MAD-HTLC employs a novel approach of utilizing the existing blockchain operators, called miners, as part of the design. If a user misbehaves, MAD-HTLC incentivizes the miners to confiscate all her funds. We prove MAD-HTLC's security using the UC framework and game-theoretic analysis. We demonstrate MAD-HTLC's efficacy and analyze its overhead by instantiating it on Bitcoin's and Ethereum's operational blockchains. Notably, current miner software makes only little effort to optimize revenue, since the advantage is relatively small. However, as the demand grows and other revenue components shrink, miners are more motivated to fully optimize their fund intake. By patching the standard Bitcoin client, we demonstrate such optimization is easy to implement, making the miners natural enforcers of MAD-HTLC. Finally, we extend previous results regarding HTLC vulnerability to bribery attacks. An attacker can incentivize miners to prefer her transactions by offering high transaction fees. We demonstrate this attack can be easily implemented by patching the Bitcoin client, and use game-theoretic tools to qualitatively tighten the known cost bound of such bribery attacks in presence of rational miners. We identify bribe opportunities occurring on the Bitcoin and Ethereum main networks where a few dollars bribe could yield tens of thousands of dollars in reward (e.g., \$2 for over \$25K).
A content delivery network (CDN) uses distributed cache servers to reduce the content delivery latency to end users. In recent years, CDN providers adopt a new content caching strategy that allows end users to share their storage/bandwidth resources. Two core questions need to answer in this strategy: (1) how to incentivize end users to contribute their resources? (2) how to facilitate transparent, secure content trading among end users?We propose a new CDN solution, called SmartSharing, where users contribute their over-the-top (OTT) devices as mini-cache servers. To incentivize end users to contribute resources, SmartSharing uses game theory and an Expectation-Maximization (EM) algorithm to determine the content delivery schedule and the pricing scheme. To facilitate content trading among end users, SmartSharing uses smart contracts in Ethereum to create a transparent and safe transaction platform. We thoroughly evaluate the performance of SmartSharing with real-world trace-driven simulation as well as a prototype using content metadata and the derived pricing scheme.
There is a lot of excitement around Blockchain technology and its ability to disrupt many traditional industries and business practices. First invented as a part of Bitcoin’s underlying infrastructure, Blockchain technology offers a platform for decentralized and transparent transaction management between untrusting parties. Many believe this aspect of blockchain can revolutionize traditional supply chain practices typically involving many untrusting entities from the time raw material extraction to the final consumption of a finished product by the end consumer. While there have been many claims regarding its obvious benefits in Supply chain management, there are only few technical applications developed so far that are useful in real world scenarios. In this thesis, we review different real-world implementations of block chain technology in the supply chain domain, especially those that leverage smart contracts. Smart contract is a computer protocol that facilitates, verifies, enforces performance of a contract digitally using Blockchain technology. Since smart contracts are trackable, irreversible and allow performance of credible transactions without third parties, it can be deployed effectively to replace existing supply chain mechanisms that require working with an intermediate entity such as a bank that often comes with a price tag for their services. In this thesis, we present a framework to enable sale of goods between untrusting entities typically in different geographies leveraging smart contract technology that can effectively replace the "letter of credit" payment mechanism. An novel algorithm for dispute resolution is developed and a decentralized app (Dapp) is built and deployed on Ethereum block chain using smart contracts developed in Solidity. Last, we discuss the effectiveness of such a system, potential drawbacks or known security threats that may hinder the adoption of such an app in the real world.
The protocol for cryptocurrencies can be divided into three parts, namely consensus, wallet, and networking overlay. The aim of the consensus part is to bring trustless rational peer-to-peer nodes to an agreement to the current status of the blockchain. The status must be updated through valid transactions. A proof-of-work (PoW) based consensus mechanism has been proven to be secure and robust owing to its simple rule and has served as a firm foundation for cryptocurrencies such as Bitcoin and Ethereum. Specialized mining devices have emerged, as rational miners aim to maximize profit, and caused two problems: i) the re-centralization of a mining market and ii) the huge energy spending in mining. In this paper, we aim to propose a new PoW called Error-Correction Codes PoW (ECCPoW) where the error-correction codes and their decoder can be utilized for PoW. In ECCPoW, puzzles can be intentionally generated to vary from block to block, leading to a time-variant puzzle generation mechanism. This mechanism is useful in repressing the emergence of the specialized mining devices. It can serve as a solution to the two problems of recentralization and energy spending.
Ethereum is one of the most popular blockchain systems that supports more than half a million transactions every day. Whereas it remains mysterious what the transaction pattern is and how it evolves over time. In this paper, we study the evolutionary behavior of Ethereum transactions from a temporal graph point of view. It shows that there is no evidence that changes in average triplet closure duration is related to prices. We observe the macroscopic and microscopic burstiness of Ethereum transactions. We analyze the Gini indexes of the transaction graphs and the user wealth in which Ethereum is found to be very unfair since the very beginning, in a sense, “the rich is already very rich”.
Mayra Samaniego, Sara Hosseinzadeh Kassani, Cristian Espana, Ralph Deters
Computer-Aided Diagnosis (CAD) systems have emerged to support clinicians in interpreting medical images. CAD systems are traditionally combined with artificial intelligence (AI), computer vision, and data augmentation to evaluate suspicious structures in medical images. This evaluation generates vast amounts of data. Traditional CAD systems belong to a single institution and handle data access management centrally. However, the advent of CAD systems for research among multiple institutions demands distributed access management. This research proposes a blockchain-based solution to enable distributed data access management in CAD systems. This solution has been developed as a distributed application (DApp) using Ethereum in a consortium network.
Web-based public participatory GIS (PPGIS) has been used by governmental organizations to facilitate people's contribution to decision-making processes. However, these applications do not provide an open and transparent environment for public participation. This study suggests that PPGISs should be developed as decentralized applications (DApp) based on Ethereum blockchain technology to have a fully open, transparent, and accountable environment for public participation. In a blockchain-based PPGIS, the collected data are securely saved on the blockchain. The validity of the data, replicated on the nodes of the peer-to-peer blockchain network, is ensured through a consensus process without any central control. The data is tamper-free and immutable. Additionally, the data is openly accessible to institutions and citizens. A prototype PPGIS was developed as a DApp through which users can participate in the site selection of urban facilities. Using the application, they compare and rank different criteria. The system solves an analytic hierarchy process to calculate the weights of the criteria. A suitability map is generated afterward and published to be used by both citizens and decision-makers. The feasibility of the application, along with the issues that need to be considered while using blockchain technology for urban planning and development, are thoroughly discussed.