2008 yılında temelleri atılmış olan Kiripto para kavramı, 2017 yılı Aralık ayı itibari ile 19.060 ABD dolarına ulaşmış ve tanınırlığını arttırmıştır. Bitcoin ve sayıları 2700’ü bulan diğer kripto paralar hızlı kazanç elde etmek isteyen yatırımcıların dikkatini çekmeyi başarmıştır. Bu kapsamda kripto paraların fiyatının nasıl ve ne yönde değişeceği birçok kesim tarafından araştırma konusu olmuştur. Bu çalışmanın amacı, Bitcoin, Ethereum, IOTA ve Ripple gibi farklı altyapısal özellikleri olan kripto paraların gelecek fiyatını geçmişte gerçekleşen fiyatlardan hareketle tahmin etmektir. Çalışmada Deng Ju-Long tarafından 1980’li yıllarda ortaya atılan gri sistem teorisi ile fiyat tahminlemesi yapılmıştır. Çalışmada kullanılan geçmiş fiyatlar 11 günlük süreci kapsamaktadır. Literatüre göre kısa sayılabilecek bu süre modelin diğer modellere görece üstünlüğünü göstermektedir. Elde edilen sonuçlara göre GM(1,1) model ve Rolling-GM(1,1) model sonuçlarının birbirine çok yakın hata oranlarıyla tahmin yaptıkları ve yapılan tahminlere ait hata oranlarının çok düşük olduğu görülmüştür.
With the popularization of intelligent terminals, especially current trends, such as “Industrie 4.0” and the Internet of Things, mobile crowdsensing is becoming one of the promising applications built on smart devices in mobile networks. However, the existing mobile crowdsensing models are mostly based on a centralized platform, which is not fully trusted in reality and results in the existence of fraud and other security problems. Furthermore, the data quality collected through crowdsensing is varied, and the location privacy is difficult to guarantee, especially at the worker selection stage. To solve these two problems, an effective blockchain-based location-privacy-preserving crowdsensing model, CrowdBLPS, is proposed in this article. First, the idea of a blockchain is introduced into this model. The decentralized structure and the consensus approach are applied to realize the nonrepudiation and nontampering of information. Second, to improve the data sensing quality and protect worker privacy, a two-stage approach, including the preregistration stage and the final selection stage, is proposed. Finally, we further implement a prototype on the Ethereum public testing network, and the experimental results show the feasibility, availability, and reliability of CrowdBLPS.
We present "Gasper," a proof-of-stake-based consensus protocol, which is an idealized version of the proposed Ethereum 2.0 beacon chain. The protocol combines Casper FFG, a finality tool, with LMD GHOST, a fork-choice rule. We prove safety, plausible liveness, and probabilistic liveness under different sets of assumptions.
Ethereum, the largest blockchain for running smart contracts, charges the people who send transactions to deploy or invoke smart contracts for thwarting resource abuse. The amount of transaction fee depends on the size of that contract and the operations executed by that contract. Consequently, smart contracts with inefficient code will waste money. In this article, we propose and develop the first tool, namedGasChecker, for automatically identifying gas-inefficient code in smart contracts, and conduct the first empirical study on the prevalence of gas-inefficient code in the deployed smart contracts. More precisely, we first summarize ten gas-inefficient programming patterns and propose a new approach based on symbolic execution (SE) to detect them in the bytecode of smart contracts. To make our approach scalable to analyze millions of smart contracts, we parallelize SE by tailoring it to the MapReduce programming model, and propose a new feedback-based load balancing strategy to effectively utilize cloud resources. Extensive experiments show thatGasCheckerscales well with the increase of workers. The empirical study demonstrates that lots of real smart contracts contain various inefficient code. Manual investigation demonstrates that only 2.5 percent of discovered gas-inefficient instances are false positives.
Scalability has been a bottleneck for major blockchains such as Bitcoin and Ethereum. Despite the significantly improved scalability claimed by several high-profile blockchain projects, there has been little effort to understand how their transactional throughput is being used. In this paper, we examine recent network traffic of three major high-scalability blockchains---EOSIO, Tezos and XRP Ledger (XRPL)---over a period of seven months. Our analysis reveals that only a small fraction of the transactions are used for value transfer purposes. In particular, 96% of the transactions on EOSIO were triggered by the airdrop of a currently valueless token; on Tezos, 76% of throughput was used for maintaining consensus; and over 94% of transactions on XRPL carried no economic value. We also identify a persisting airdrop on EOSIO as a DoS attack and detect a two-month-long spam attack on XRPL. The paper explores the different designs of the three blockchains and sheds light on how they could shape user behavior.
Scalability has been a bottleneck for major blockchains such as Bitcoin and Ethereum. Despite the significantly improved scalability claimed by several high--profile blockchain projects, there has been little effort to understand how their transactional throughput is being used. In this paper, we examine recent network traffic of three major high-scalability blockchains--EOSIO, Tezos and XRP Ledger (XRPL)--over a period of seven months. Our analysis reveals that only a small fraction of the transactions are used for value transfer purposes. In particular, 96% of the transactions on EOSIO were triggered by the airdrop of a currently valueless token; on Tezos, 76% of throughput was used for maintaining consensus; and over 94% of transactions on XRPL carried no economic value. We also identify a persisting airdrop on EOSIO as a DoS attack and detect a two-month-long spam attack on XRPL. The paper explores the different designs of the three blockchains and sheds light on how they could shape user behavior.
Invoice financing has been a steadily growing component of the financing market as a whole for the last few years, and, in 2016, it became the third largest financing market. Nonetheless, the risk of frauds is still very high, and most solutions proposed so far are based on private, proprietary platforms that cannot match the global nature of such a market. Even the most recent proposals based on blockchain are mainly adopting a private, permissioned blockchain due to the lack of confidentiality in public blockchain. In this article, we propose an Invoice financing platform based on a public blockchain supporting both fully open and group-restricted auctioning of invoices. We addressed the confidentiality issue by storing the confidential data encrypted in IPFS and the corresponding hash in the smart contract hosted on Ethereum blockchain. Our blockchain-based solution ensures data confidentiality and benefits from the main properties of the public blockchain required in Invoice financing systems, such as transparency, immutability, trustworthiness, and security. Furthermore, our platform introduces a reputation system based on the past behavior of entities, computed using the blockchain global ledger. Such a reputation system allows insurance companies to modulate the cost of the insurance contracts they offer. This combination guarantees the complete transparency and tamperproofness of a public blockchain, while it allows reducing insurance costs and fraud possibilities.
Introduction. The paradigm of the modern development of economic intelligent systems is associated with the introduction of information technology, technology platforms, protocols, and IoT. Understanding the essence of technological breakthroughs and finding ways to implement technological innovations to digitize economic processes should help solve a number of problematic areas of doing business that focus on improving competitiveness. Methods. The methodological basis of the article was the current principles of the theory of innovation, methods of cognition, which are formed in the main works on the theoretical direction of the theory of organization, theory of organizational behaviour, theory of competition and theory of system analysis. Results. The essence is examined and the feasibility of using blockchain technology to increase the competitiveness of the business and reduce the risks of its business is proved. An idea of the functioning of the blockchain technology has been formed and the advantages based on the principles of invariability and accessibility of the tool have been highlighted, therefore they should work on the safety and efficiency of doing business. The experience of introducing blockchain technology by foreign countries is analyzed, possible applications are identified. The modern vitality of economic intellectual systems requires specialized technical knowledge and skills, understanding of the essence of technological processes and access to databases that allow to combine economic and technological pools of knowledge to achieve business goals. Discussion. Prospects for further research will be concentrated in the field of potential applications of blockchain technology on the Ethereum platform through smart contracts with promising use of artificial intelligence. Keywords: economic intelligent systems, digitalization, blockchain technology, Ethereum platform, smart contract, competitiveness.
The advent of the Blockchain together with the appearance of the Ethereum platform gave rise to the realization of Szabo's original idea, allowing the implementation of intelligent contracts. Blockchain by itself is a database with certain special characteristics but the potential that this technology acquires with the implementation of intelligent contracts leads us to the conceptualization of intelligent property, internet of things, artificial intelligence, intelligent cities, tokenization of physical assets and properties. This last concept also triggers the possibility of issuing tokens linked to undertakings with sustainable development objectives or "green tokens". The tokenization of digital goods has developed naturally, but the pitfalls -more mental than legal and technological- are present in the tokenization of physical assets, and we will address them in this paper. Del Castillo Ionov says: "tokenization involves taking an asset and, using blockchain technology, issuing tokens representative of that asset, facilitating its negotiation, the enjoyment of the rights of that asset and its governance". We believe that the tokenization of physical assets will allow a new field of action, marketing, transmission, circulation of rights and wealth, as well as a new range of opportunities not only for all legal operators but also for the great mass of capital investors interested in sustainable development, as well as for the home retail investor.
Abstract The charity organizations in China lack transparency and the supervision to them is difficult to achieve, which has a negative impact on the willingness of the people to donate. Blockchain as a underlying technology of Bitcoin system provides a new solution for the charity system in terms of technology. This paper proposed a charity system based on blockchain technology and expounds the design pattern, architecture and operational process of the platform. Some core functions of the charity platform have been realized and verified on Ethereum in this article. We hope to increase the transparency of charities to enhance the public’s trust in charities and promote the development of philanthropy by blockchain-based charity system.
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.
Utz Nisslmueller, Klaus-Tycho Foerster, Stefan Schmid, Christian Decker
Cryptocurrency off-chain networks such as Lightning (e.g., Bitcoin) or Raiden\n(e.g., Ethereum) aim to increase the scalability of traditional on-chain\ntransactions. To support nodes in learning about possible paths to route their\ntransactions, these networks need to provide gossip and probing mechanisms.\nThis paper explores whether these mechanisms may be exploited to infer\nsensitive information about the flow of transactions, and eventually harm\nprivacy. In particular, we identify two threats, related to an active and a\npassive adversary. The first is a probing attack: here the adversary aims to\ndetect the maximum amount which is transferable in a given direction over a\ntarget channel by actively probing it and differentiating the response messages\nit receives. The second is a timing attack: the adversary discovers how close\nthe destination of a routed payment actually is, by acting as a passive\nman-in-the middle and analyzing the time deltas between sent messages and their\ncorresponding responses. We then analyze the limitations of these attacks and\npropose remediations for scenarios in which they are able to produce accurate\nresults.\n
Fake education certificates or fake degree is one of the major concerns in higher education. This fraud can be minimized if there is a tamper-proof and confidential registry of certificates wherein not one but multiple certified authorities verifies and stores the issued certificate in immutable repositories with proper privacy maintained. Secondly, there should be a mechanism for retrieving the authentic certificate without much cost and time. Blockchain is an immutable, shared, distributed ledger without the control of a single centralized authority that fits very well for the discussed use case. The proposed work, PrivateCertChain, has implemented the idea for university having multiple affiliated colleges, by deploying and verifying digitally signed e-certificate on Ethereum Blockchain. Multiple affiliated colleges can serve as the miners for verifying the signature of the issuer. For privacy concerns, the content of the certificate will be hashed and this hashed value will be stored in Blockchain along with the roll number of the certificate holder. Once the transaction hash is generated, it will be converted to QR code. The QR code is shared with the respective owner of the certificate and it will also serve as the credential of the certificate. Thus, anyone having the credential can view the authentic certificate which is kept on the blockchain, by scanning QR through the dedicated application designed for verification. The proposed solution can be a foolproof mechanism against all frauds as it guards for integrity, confidentiality, authenticity, and privacy of educational certificates.
Open access
Blockchain Technology Applications and Security
IoT and Edge/Fog Computing
Advanced Steganography and Watermarking Techniques
Peter Robinson, Raghavendra Ramesh, John Brainard, Sandra Johnson
Atomic Crosschain Transaction technology allows composable programming across private Ethereum blockchains. It allows for inter-contract and inter-blockchain function calls that are both synchronous and atomic: if one part fails, the whole call graph of function calls is rolled back. It is not based on existing techniques such as Hash Time Locked Contracts, relay chains, block header transfer, or trusted intermediaries. BLS Threshold Signatures are used to prove to validators on one blockchain that information came from another blockchain and that a majority of the validators of that blockchain agree on the information. Coordination Contracts are used to manage the state of a Crosschain Transaction and as a repository of Blockchain Public Keys. Dynamic code analysis and signed nested transactions are used together with live argument checking to ensure execution only occurs if the execution results in valid state changes. Contract Locking and Lockability enable atomic updates.
Philipp Frauenthaler, Marten Sigwart, Christof Spanring, Stefan Schulte
Current blockchain technologies provide very limited means of interoperability. In particular, solutions enabling blockchains to verify the existence of data on other blockchains are either very costly or are not fully decentralized. To overcome these limitations, we introduce Testimonium, a novel blockchain relay scheme that applies a validation-on-demand pattern and the on-chain execution of Simplified Payment Verifications to enable the verification of data across blockchains while remaining fully decentralized. Evaluating the scheme for Ethereum-based blockchains shows that Testimonium achieves a cost reduction of up to 92% over existing solutions. As such, the scheme lays a strong foundation for generic blockchain interoperability. For instance, it enables the development of an atomic-commit protocol for distributed transactions across blockchains.
We investigate the behaviour of cryptocurrencies using data for bitcoin, ethereum and ripple which account for over 70% of the cryptocurrency market. We demonstrate that $α$-stable distribution is an appropriately sufficient model for highly speculative cryptocurrencies which outperforms other heavy tailed distributions that are used in financial econometrics. We find that the maximum likelihood method proposed by DuMouchel (1971) produces estimates that fit the cryptocurrency return data much better than the quantile based approach of McCulloch (1986) and sample characteristic method by Koutrouvelis (1980). The empirical results show that the leptokurtic feature presented in cryptocurrency return data can be captured by an $α$-stable distribution. The findings highlight that $α$-stable distribution is not only parsimonious with its four free parameters but also a creative model that is close to reality. This paper covers early reports and literature on cryptocurrencies and stable distributions.
Digitalization and Blockchain have fundamentally transformed the structure of the monetary system. The first wave of cryptocurrencies such as Bitcoin, Ethereum or Ripple have failed to gain relevance in terms of their share in monetary transactions. This was due to systemic deficiencies leading to extreme volatility, limited capacity and limited transparency, which have reduced their ability to fulfil the basic functions of money and hence their attractiveness as a medium of exchange. More recently, stable coins have entered the scene which were specifically designed to deal with the issue of volatility by tying the digital currency to an underlying set of assets. Hence the outlook for digital currencies has improved significantly. Although, the widespread of stable coins have has not been significant, the announcement of Facebook Libra and Telegram Gram with the huge number of billions of users raises the probability that this project will successfully reach global scale in a relatively short period of time. This means that a fully stable currency is made available to the people of developing countries, where governments are generally unable to manage the stability of their local currencies, which can lead to a digital dollarization. Meanwhile, the discussion around the introduction of central bank digital currencies (CBDC) as a possible response has continued more intensively. Introduction of a digital currency issued by the central bank will lead to a direct competition for bank deposits between Central Bank and Commercial banks which eventually lead banking system toward full reserve structure.
BACKGROUND: Personal health record (PHR) security, correctness, and protection are essential for health and medical services. Blockchain architecture can provide efficient data retrieval and security requirements. Exchangeable PHRs and the self-management of patient health can offer many benefits to traditional medical services by allowing people to manage their own health records for disease prevention, prediction, and control while reducing resource burdens on the health care infrastructure and improving population health and quality of life. OBJECTIVE: This study aimed to build a blockchain-based architecture for an international health record exchange platform to ensure health record confidentiality, integrity, and availability for health management and used Health Level 7 Fast Healthcare Interoperability Resource international standards as the data format that could allow international, cross-institutional, and patient/doctor exchanges of PHRs. METHODS: The PHR architecture in this study comprised 2 main components. The first component was the PHR management platform, on which users could upload PHRs, view their record content, authorize PHR exchanges with doctors or other medical health care providers, and check their block information. When a PHR was uploaded, the hash value of the PHR would be calculated by the SHA-256 algorithm and the PHR would be encrypted by the Rivest-Shamir-Adleman encryption mechanism before being transferred to a secure database. The second component was the blockchain exchange architecture, which was based on Ethereum to create a private chain. Proof of authority, which delivers transactions through a consensus mechanism based on identity, was used for consensus. The hash value was calculated based on the previous hash value, block content, and timestamp by a hash function. RESULTS: The PHR blockchain architecture constructed in this study is an effective method for the management and utilization of PHRs. The platform has been deployed in Southeast Asian countries via the Asia eHealth Information Network (AeHIN) and has become the first PHR management platform for cross-region medical data exchange. CONCLUSIONS: Some systems have shown that blockchain technology has great potential for electronic health record applications. This study combined different types of data storage modes to effectively solve the problems of PHR data security, storage, and transmission and proposed a hybrid blockchain and data security approach to enable effective international PHR exchange. By partnering with the AeHIN and making use of the network's regional reach and expert pool, the platform could be deployed and promoted successfully. In the future, the PHR platform could be utilized for the purpose of precision and individual medicine in a cross-country manner because of the platform's provision of a secure and efficient PHR sharing and management architecture, making it a reasonable base for future data collection sources and the data analytics needed for precision medicine.
Otabek Sattarov, Azamjon Muminov, Cheol Won Lee, Hyun Kyu Kang · 8 authors
The net profit of investors can rapidly increase if they correctly decide to take one of these three actions: buying, selling, or holding the stocks. The right action is related to massive stock market measurements. Therefore, defining the right action requires specific knowledge from investors. The economy scientists, following their research, have suggested several strategies and indicating factors that serve to find the best option for trading in a stock market. However, several investors’ capital decreased when they tried to trade the basis of the recommendation of these strategies. That means the stock market needs more satisfactory research, which can give more guarantee of success for investors. To address this challenge, we tried to apply one of the machine learning algorithms, which is called deep reinforcement learning (DRL) on the stock market. As a result, we developed an application that observes historical price movements and takes action on real-time prices. We tested our proposal algorithm with three—Bitcoin (BTC), Litecoin (LTC), and Ethereum (ETH)—crypto coins’ historical data. The experiment on Bitcoin via DRL application shows that the investor got 14.4% net profits within one month. Similarly, tests on Litecoin and Ethereum also finished with 74% and 41% profit, respectively.
Decentralized applications development on the Ethereum platform is becoming very popular in last few years. However, it requires developer to have knowledge and skills to integrate large number of components, such as smart contracts programming, IPFS decentralized storage, RPC calls or True for smart contracts management and various JavaScript libraries (e.g. Web3.js, TrueContract, JS-IPFS). This makes the development process very complex and dicult. At the same time, the developer has multiple front-end frameworks available, which however lack the ability to easily integrate the majority of previously mentioned components. To solve this problem, there are integration tools which address above issues and are intended to support a comprehensive development of decentralized applications (e.g. Drizzle, Vortex, Web3-React). The paper focuses on these integration tools and analyses the code complexity of decentralized application development using such tools. The analysis of code complexity was performed using multiple code complexity metric assessment methods.
Our current banking system is based on a central server where every branch is connected to each other. If the server made any changes to the data of a branch then other branches get affected. In this system, Corruption can be easily occurred because of unauthorized access which is totally insecure in transaction systems. But, Blockchain is a secure system where the transactional history regarding crypto-currency cannot be modified or destructed. Since 2008, Blockchain has gained immense interest due to exclusion of third-party organization participation in monitoring of the transactions. Ethereum is a protocol which is based on Blockchain technology and has several benefits over other crypto-currency based system and is best suited for creating a secure lending system. Every Ethereum based system runs on 'Smart-Contracts' which are lines of code and makes the system automated. As the system gets automated, proper algorithms can make the system reliable and secure as each and every step of the system is maintained and executed by the algorithm inside the Smart-Contracts. Blockchain systems work with peer-to-peer networks and also uses a consensus algorithm that's why there is no possibility of data modification.