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.
Friedrich-Alexander-Universität Erlangen-Nürnberg, Lehrstuhl für Wirtschaftsinformatik, insb. im Dienstleistungsbereich, Nürnberg, Germany, Moritz Schindelmann, Philipp Klinger, Freimut Bodendorf
Blockchain capabilities like Ethereum Smart Contracts offer great opportunities to manage cross-organizational business processes due to their trustless and tamperproof nature. However, communication in such processes poses a major issue since there is no direct option for one participating organization to inform other collaborators about their individual progress in their impersonation as a Smart Contract. As that knowledge is vital to execute a cross-organizational process, we design a Smart Contract architecture in which participants express their progress through Blockchain events. Furthermore, we implement a prototype that subscribes to the relevant events of one or more participants and reacts to their occurrence by triggering the subsequent step(s) of the process. Evaluation of the prototype and architecture shows that this does not only avoid unnecessary latency in process communication but also results in a fair cost distribution as each participant is only charged for the expenses of its individual actions.
Subhi Alrubei, Edward A. Ball, Jonathan Rigelsford, Callum. A Willis
The Internet of Things (IoT) is increasingly being utilized, by both businesses and individuals, for many applications. This utilization means increases in the smart devices that are connected to the Internet of Things, which will significantly increase the challenges related to devices' interconnectivity and management, data and user privacy, and network, data, and device security. At the same time, blockchain approaches provide a decentralized, immutable, and peer-to-peer ledger technology that could be the right answer to these challenges. Significant challenges, however, accompany the integration of blockchain into the Internet of Things, since IoT smart devices may suffer from resource and power constraints and blockchain is associated with scalability and delay issues. In this paper, a practical incorporation of blockchain into the Internet of Things is demonstrated using Ethereum Proof of Authority (PoA). This provides performance analyses, which include measurement of the transaction arrival time, the system end-to-end latency for different network implementations over cellular and Wi-Fi, and the average power consumption. This includes the study of the effect of network bandwidth on the stability and synchronization of all nodes on the blockchain network.
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.
Purpose A blockchain is a shared distributed ledger technology that stores the information of every transaction in the network. The blockchain has emerged with a huge diversity of applications not only in the economic but in the non-economical domain as well. Blockchain technology promises to provide a wide range of solutions to the problems faced during implementation of smart cities. It has the potential to build smart contracts more secure, thus eliminating the need for centralized authority. Design/methodology/approach This paper presents a proof-of-concept for a use case that uses an Ethereum platform to build a blockchain network to buy, sell or rent a property. Findings The findings of this study provide an opportunity to create novel decentralized scalable solutions to develop smart cities by enabling paperless transactions. There are enormous opportunities in this distributed ledger technology which will bring a revolutionary change in upcoming years. Originality/value The concept of blockchain along with smart contracts can be used as a promising technology for sharing services which is a common requirement in smart cities. All the blockchain transactions are stored in decentralized shared database. The transaction recorded in decentralized system is immutable, it cannot be altered and hence chance of forgery is negligible.
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.
The present era is witnessing a reuse of hardware IPs to reduce cost. As trustworthiness is an essential factor, designers prefer to use hardware IPs which performed effectively in the past, but at the same time, are still active and did not age. In such scenarios, pay per use licensing schemes suit best for both producers and users. Existing pay per use licensing mechanisms consider a centralized third party, which may not be trustworthy. Hence, we seek refuge to blockchain technology to eradicate such third parties and facilitate a transparent and automated pay per use licensing mechanism. A blockchain is a distributed public ledger whose records are added based on peer review and majority consensus of its participants, that cannot be tampered or modified later. Smart contracts are deployed to facilitate the mechanism. Even dynamic pricing of the hardware IPs based on the factors of trustworthiness and aging have been focused in this work, which are not associated in existing literature. Security analysis of the proposed mechanism has been provided. Performance evaluation is carried based on the gas usage of Ethereum Solidity test environment, along with cost analysis based on lifetime and related user ratings.
Physical Unclonable Functions (PUFs) and Hardware Security
While blockchain technology is best-known for cryptocurrencies, some chains also tout their ability to implement so-called "smart contracts." Ethereum, which bills itself as a "blockchain app platform," defines smart contracts as applications that run exactly as programmed without any possibility of downtime, censorship, fraud or third-party interference (http://www.ethereum.org).
Digital Rights Management and Security
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
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.
Open Educational Resources (OER) play a pivotal role in the traditional teaching learning processes. So far, there are several problems in the conventional OER such as tracking and tracing of OER, proper attribution, sustainability, publishing time and single point of failure due to its centralized nature. This paper proposes a Ethereum blockchain based decentralized and distributed framework to alleviate the problems existing in present OER. In addition Interplanetary File System (IPFS) has been included in this proposed system for storing the hypermedia as distributed way. It reduces the storage time. In this paper, we design distributed and decentralized infrastructure for OER system that remedies all of these drawbacks through the use of the Ethereum blockchain platform.
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.