Bitcoin's enormous success has inspired the development of alternative blockchains, such as consortium chains. Several cross-chain protocols have been proposed as ways of connecting these universes of individual blockchains in a distributed and secure manner. In this paper, we present Niji, a new cross-chain protocol that allows parties to perform virtual Bitcoin payment securely on a consortium chain, without any trusted third-party or mediators. Our work focuses on the issue that it is difficult for a consortium chain's token to hold a stable market value, and Niji makes it possible for smart contract services to acquire means of payment in the consortium chain. With the Bitcoin payment channel built on the consortium chain, the process from payment to service provision runs autonomously without any interaction between parties. Niji introduces the concept of a transaction template to validate Bitcoin payments efficiently on different blockchains, and it allows a service provider to delegate all of its tasks for verifying state updates to a smart contract on the consortium chain. We also propose a novel bi-directional payment channel adapted for design of the Niji protocol, which can update payments non-interactively between parties. We implemented a prototype of the Niji protocol and conducted an experiment measuring the computational cost and latency that demonstrates the protocol's feasibility on practical platforms.
Neville Grech, Michael Kong, Anton Jurisevic, Lexi Brent · 6 authors
Ethereum is a distributed blockchain platform, serving as an ecosystem for smart contracts: full-fledged inter-communicating programs that capture the transaction logic of an account. Unlike programs in mainstream languages, a gas limit restricts the execution of an Ethereum smart contract: execution proceeds as long as gas is available. Thus, gas is a valuable resource that can be manipulated by an attacker to provoke unwanted behavior in a victim's smart contract (e.g., wasting or blocking funds of said victim). Gas-focused vulnerabilities exploit undesired behavior when a contract (directly or through other interacting contracts) runs out of gas. Such vulnerabilities are among the hardest for programmers to protect against, as out-of-gas behavior may be uncommon in non-attack scenarios and reasoning about it is far from trivial. In this paper, we classify and identify gas-focused vulnerabilities, and present MadMax: a static program analysis technique to automatically detect gas-focused vulnerabilities with very high confidence. Our approach combines a control-flow-analysis-based decompiler and declarative program-structure queries. The combined analysis captures high-level domain-specific concepts (such as "dynamic data structure storage" and "safely resumable loops") and achieves high precision and scalability. MadMax analyzes the entirety of smart contracts in the Ethereum blockchain in just 10 hours (with decompilation timeouts in 8% of the cases) and flags contracts with a (highly volatile) monetary value of over $2.8B as vulnerable. Manual inspection of a sample of flagged contracts shows that 81% of the sampled warnings do indeed lead to vulnerabilities, which we report on in our experiment.
Distributed Ledger Technologies have promising applications in the Internet of Things. However, scalability and support for micropayments remain problems for blockchain-based applications, therefore other alternatives such as IOTA should be considered. This work reports on an experimental evaluation of IOTA on several different IoT platforms. We show that even though the communication overhead to join the IOTA network can be significantly reduced by adapting a proxy-based architecture, the computational overhead remains high. We conclude that IOTA is not currently suitable for battery-powered IoT devices.
This thesis focuses on the issues between a blockchain technology and the new European Union General Data Protection Regulation (GDPR). The Blockchain technology is a rather new technology which potential has been recognised only in the recent years. Essentially, a blockchain is a distributed database in which data is stored in blocks, which form a chronological chain of blocks. Blockchains have many types and possible use cases, but this research focuses on public and permissionless blockchains, which primary objective is to enable individuals to transact with each other without centralised intermediaries. \n \nThe GDPR entered into force on 25 May 2018. The GDPR was not drafted taking account of distributed ledger technologies, such as the blockchain technology, which has raised several points of tension between the regulation and the technology. The primary focus of this thesis is on the conflict between the ‘immutability’ of blockchain technology and the right to erasure under Article 17 of the GDPR. One of the main features of blockchains is the immutability, that is to say, data on old blocks is extremely difficult to modify or delete. This feature seems prima facie to conflict with Article 17 of the GDPR that provides data subjects with the right to request erasure of their personal data under certain conditions. \n \nFirstly, this thesis analyses the current state of the conflict. Before analysing the conflict, the research addresses two essential preliminary questions: the question about anonymisation and personal data and the question about allocation of responsibilities on blockchains. After that, different solutions proposed to reconcile the conflict are analysed to understand the current situation. While public and permissionless blockchains currently may infringe Article 17 of the GDPR, there are potential solutions for the conflict in the future. \n \nThe second purpose of this thesis is to identify relevant legal problems and propose how to address the problems in the future. Blockchain developers should consider data protection obligations already in the design phase. From the legal side, this research has provided flexible interpretations for the legal problems that could help to comply with the right to erasure. There is a need for a flexible approach to the problems between the regulation and the technology.
The article represents VET modernisation problem as pre-technological and occupational pre-high education. The aim is to ground innovative changes priority approaches in educational sub-systems aligned with Sustainable Development Strategy “Ukraine-2020”, Copenhagen Declaration, Bruges Communiqué, Torino Process etc. The article provides characteristics of educational trends emphasising technological education for senior high school students modernisation. Modern approaches on personalisation technological education, professional career guidance for schoolers are envisaged. It grounds the necessity for structural changes in schools based on cooperation with enterprises, VET schools and HEIs. It emphasises the need to modernize VET in accordance with modern economy and education trends. The increasing prestige mechanism for working professions and professional (vocational) education as a whole is revealed. The article defines VET’s aim and its organization-pedagogical conditions, namely: VET schools management decentralization; setting marketing services; implementing VET education quality monitoring system; multi-source financing etc. The specifics for transition to applied training model targeting a person’s needs, national and regional LMs are considered. The attention is drugged to broad use of dual education within employers’ engagement; setting flexible training entities for formal, in-formal and non-formal professional education programs realisation. It specifies the specifics of creating information-educational environments, inclusive education conditions in VET schools. It emphasises competence-based occupational, educational and assessment standards development, designing new hi-tech qualifications, creating a New occupations and professions register, including “green” ones. Inter-disciplinary approach for projecting socio-cultural component of VET content importance is outlined and the need for occupational pre-high education modernization is examined.
Simona Ibba, Andrea Pinna, Maria Ilaria Lunesu, Michele Marchesi · 5 authors
An ICO (Initial Coin Offering) is an innovative way to fund projects based on blockchain. The funding is based on the selling of tokens by means of decentralized applications called smart contracts written in Solidity, a programming language specific for Ethereum blockchain. The ICOs work in a volatile context and it is crucial that the team is capable of handling constant changes. The Agile methods, proven practices enabling to develop software in presence of changing requirements, could be a means for managing uncertainty. The main goals of this work are to understand software engineering activities related to ICOs, recognize the ICOs developed using Agile methods, and make a comparison between ICOs and Agile ICOs. In addition, we perform a deeper analysis of Agile ICOs concerning project planning, software development, and code features. Our work shows that the roles of the people involved in an ICO can be compared to the typical roles of the SCRUM methodology. The majority of Agile ICOs use tool of testing before storing smart contract on blockchain. Finally, the application of volumetric and complexity software metrics shows that the files of Agile ICOs is on average shorter and less complex than in other smart contracts.
Zaynah Dargaye, Antonella Del Pozzo, Sara Tucci-Piergiovanni
The paper presents Pluralize a formal logical framework able to extend the execution of blockchain transactions to events coming from external oracles, like external time, sensor data, human-made declarations, etc. These events are by essence non-reliable, since transaction execution can be triggered by information whose veracity cannot be established by the blockchain. To overcome this problem, the language features a first-order logic and an authority algebra to allow formal reasoning and establish accountability of agents for blockchain-enabled transactions. We provide an accountability model that allows to formally prove the accountability of agents by a formal proof locally executable by each agent of the blockchain.
In the present paper, we investigate connectedness within cryptocurrency markets as well as across the Bitcoin index (hereafter, BPI) and widely traded asset classes such as traditional currencies, stock market indices and commodities, such as gold and Brent oil. A spill over index approach with the spectral representation of variance decomposition networks, is employed to measure connectedness. Results show no significant spillover effects between the nascent market of cryptocurrencies and other financial markets. We suggest that cryptocurrencies are real independent financial instruments that pose no danger to financial system stability. Concerning the connectedness within the cryptocurrency markets, we report a time–frequency–dynamics connectedness nature. Moreover, the decomposition of the total spill over index is mostly dominated by a short frequency component (2–4 days) leading to the conclusion that this nascent market is highly speculative at present. These findings provide insights for regulators and potential international investors.
In this paper we extend the known methodology for fitting stable distributions to the multivariate case and apply the suggested method to the modelling of daily cryptocurrency-return data. The investigated time period is cut into 10 non-overlapping sections, thus the changes can also be observed. We apply bootstrap tests for checking the models and compare our approach to the more traditional extreme-value and copula models.
S. Keshav, W. Golab, B. Wong, S. Rizvi · 5 authors
Distributed consensus is a key enabler for many distributed systems including distributed databases and blockchains. Canopus is a scalable distributed consensus protocol that ensures that live nodes in a system agree on an ordered sequence of operations (called transactions). Unlike most prior consensus protocols, Canopus does not rely on a single leader. Instead, it uses a virtual tree overlay for message dissemination to limit network traffic across oversubscribed links. It leverages hardware redundancies, both within a rack and inside the network fabric, to reduce both protocol complexity and communication overhead. These design decisions enable Canopus to support large deployments without significant performance degradation. The existing Canopus protocol is resilient in the face of node and communication failures, but its focus is primarily on performance, so does not respond well to other types of failures. For example, the failure of a single rack of servers causes all live nodes to stall. The protocol is also open to attack by Byzantine nodes, which can cause different live nodes to conclude the protocol with different transaction orders. In this paper, we describe RCanopus (`resilent Canopus') which extends Canopus to add liveness, that is, allowing live nodes to make progress, when possible, despite many types of failures. This requires RCanopus to accurately detect and recover from failure despite using unreliable failure detectors, and tolerance of Byzantine attacks. Second, RCanopus guarantees safety, that is, agreement amongst live nodes of transaction order, in the presence of Byzantine attacks and network partitioning.
With the increase of web users and applications with real time requests, the ability to identify, track and trace elements of a product as it moves in the supply chain is deemed necessary, and for many industries is even mandated by national or international regulations. Traceability presupposes the integrity and transparency of data that is saved and shared. This is a problem for current technologies, as there are many examples with tampered data and database vulnerabilities that resulted in serious implications and data loss. A solution to this problem can be the decentralization of the system, which will remove the central point of failure. To that effect, blockchain or DLT technologies, an emergent technology that enables the decentralization of a network can be used, by implementing a trustless model to achieve it. Blockchains are tamperproof and transparent, which means that by exploiting blockchain characteristics, traceability can be improved. A model that describes the decentralization process of the supply chain traceability part has been developed for this paper and is later evaluated and compared with the traditional system.
Italian Abstract: Blockchain puo significare anche riorganizzazione dei sistemi di sicurezza sociale. Di qui l'idea di approfondire l'applicazione possibile della blockchain a alcuni istituti previdenziali, tra cui il distacco europeo, l'invalidita e il REI, per definire il quadro delle potenzialita e delle criticita. Nel saggio si studia anche il concetto di smart contract.
English Abstract: Blockchain technologies and smart contracts can be applied to social security systems. The paper is aimed at investigating the possible social fields of such application, the legal consequences, the critical points. Posting and invalidity benefits regimes are examined in light of the possible application of blockchain.
In this paper we extend the known methodology for fitting stable\ndistributions to the multivariate case and apply the suggested method to the\nmodelling of daily cryptocurrency-return data. The investigated time period is\ncut into 10 non-overlapping sections, thus the changes can also be observed. We\napply bootstrap tests for checking the models and compare our approach to the\nmore traditional extreme-value and copula models.\n
Sang‐Min Choi, Jiho Park, Quan Nguyen, André Cronje
We describe \emph{Fantom}, a framework for asynchronous distributed systems. \emph{Fantom} is based on the Lachesis Protocol~\cite{lachesis01}, which uses asynchronous event transmission for practical Byzantine fault tolerance (pBFT) to create a leaderless, scalable, asynchronous Directed Acyclic Graph (DAG). We further optimize the \emph{Lachesis Protocol} by introducing a permission-less network for dynamic participation. Root selection cost is further optimized by the introduction of an n-row flag table, as well as optimizing path selection by introducing domination relationships. We propose an alternative framework for distributed ledgers, based on asynchronous partially ordered sets with logical time ordering instead of blockchains. This paper builds upon the original proposed family of \emph{Lachesis-class} consensus protocols. We formalize our proofs into a model that can be applied to abstract asynchronous distributed system.
Ethereum Private Sidechains are permissioned Ethereum blockchains which allow authorised participants to interact privately using Smart Contracts. Permissioned blockchains are appropriate for use in scenarios in which the list of blockchain participants and the code and state of contracts on the blockchain must be kept secret. Ethereum Registration Authorities are a system of Smart Contracts which can be used to resolve bootstrap information based on domain names to allow Ethereum Private Sidechains to be established between parties which have not previously interacted. This paper presents the architecture, design, and gas usage of a reference implementation for the Ethereum Registration Authority system. It analyses the security properties of the system and shows that it is secure, decentralized, and censorship resistant. The reference implementation gas usage is analysed and shown to be independent of the length of domain name and number of entries in the Smart Contracts.
Ji-Sun Park, Taek-Young Youn, Hye-Bin Kim, Kyung-Hyune Rhee · 5 authors
Internet of Things (IoT)-based devices, especially those used for home automation, consist of their own sensors and generate many logs during a process. Enterprises producing IoT devices convert these log data into more useful data through secondary processing; thus, they require data from the device users. Recently, a platform for data sharing has been developed because the demand for IoT data increases. Several IoT data marketplaces are based on peer-to-peer (P2P) networks, and in this type of marketplace, it is difficult for an enterprise to trust a data owner or the data they want to trade. Therefore, in this study, we propose a review system that can confirm the reputation of a data owner or the data traded in the P2P data marketplace. The traditional server-client review systems have many drawbacks, such as security vulnerability or server administrator's malicious behavior. However, the review system developed in this study is based on Ethereum smart contracts; thus, this system is running on the P2P network and is more flexible for the network problem. Moreover, the integrity and immutability of the registered reviews are assured because of the blockchain public ledger. In addition, a certain amount of gas is essential for all functions to be processed by Ethereum transactions. Accordingly, we tested and analyzed the performance of our proposed model in terms of gas required.
Post-Quantum Cryptography (PQC) attempts to find cryptographic protocols resistant to attacks using Shor polynomial time algorithm for numerical field problems or Grover search algorithm. A mostly overlooked but valuable line of solutions is provided by non-commutative algebraic structures, specifically canonical protocols that rely on one-way trapdoor functions (OWTF). Here we develop an algebraic framework who could be applied to different asymmetric protocols like D-H KE (Diffie-Hellman key exchange), Public Key Encryption, Digital Signature, ZKP (zero-knowledge proof) authentication, Oblivious Transfer, Multi-Party Computing, and so on. The trapdoor one-way functions selected are (a) Triple decomposition Problem (TDP) developed by Kurt, where a known element is factored into a product of three unknown factors and (b) a new version of conjugacy search that we refer from now on as Blind Conjugacy Search Problem (BCSP). Our platform structure is the general linear group GL(d,F_p) d-square non-singular matrices of prime field values. We give support to the fact that this framework is cryptographically secure against classical attacks like linear algebra attacks, length-based attacks, side-channel attacks against square (or duplicate) and multiply (or sum) algorithm, high sensitivity to pseudo random deterministic generators, etc. At same time it is immune against quantum attacks (using Grover and Shor), if the size parameters are carefully selected. Semantic security and IND-CCA2 compliance for this framework is discussed.
The article considers the Swiss model of fiscal municipalization from the ideological and methodological positions of the anthroposociocultural approach. Such components of this approach as historical and genetic methods together with the method of system-structural analysis were applied especially thoroughly and consistently. By means of them it was found that the Swiss model of fiscal decentralization is an attributive part of the construction of public power in Switzerland – municipalization from bottom to top. Special attention is drawn to defining the basic legal features of the Swiss model of fiscal municipalization. It is argued that subsidiarity does not paradigmatically coincide with decentralization: the principle of subsidiarity postulates the sovereignty of the basic territorial collectives and considers the possible conditions for its limitation for general social needs and values. On the contrary, the principle of decentralization has the national level of governance as the starting point and considers the conditions of delegation of certain tasks and competences by the state to the lower levels of public power hierarchy in the principal frames of state sovereignty. Specificity of the principle of subsidiarity in Switzerland is that cantons play dual role from the standpoint of administrative federalism. On the one hand, they are the bearers of sovereignty of public power, including taxation. On the other hand, they are the sole bearers of administrative authority and are obliged to serve national interests, that is, the needs of the entire Swiss Confederation. Paradox is that this service function of the cantons gives them considerable benefits in the inevitable opposition to the Union state, when it comes to provision of services of the entire fiscal system and the entire system of public finance.
Ramón Alcarria, Borja Bordel, Tomás Robles, Diego R. Martín · 5 authors
Resource consumption in residential areas requires novel contributions in the field of consumer information management and collaborative mechanisms for the exchange of resources, in order to optimize the overall consumption of the community. We propose an authorization system to facilitate access to consumer information and resource trading, based on blockchain technology. Our proposal is oriented to the Smart communities, an evolution of Community Energy Management Systems, in which communities are involved in the monitoring and coordination of resource consumption. The proposed environment allows a more reliable management of monitoring and authorization functions, with secure data access and storage and delegation of controller functions among householders. We provide the definition of virtual assets for energy and water resource sharing as an auction, which encourages the optimization of global consumption and saves resources. The proposed solution is implemented and validated in application scenarios that demonstrate the suitability of the defined consensus mechanism, trustworthiness in the level of provided security for resource monitoring and delegation and reduction on resource consumption by the resource trading contribution.
The popularity of smart cars is increasing around the world as they offer a wide range of services and conveniences.These smart cars are equipped with a variety of sensors generating a large amount of data, many of which are sensitive. Besides, there are multiple parties involved in a lifespan of a smart car ,such as manufacturers, car owners, government agencies, and third-party service providers who also produce data about the vehicle. In addition to managing and sharing data amongst these entities in a secure and privacy-friendly way which is a great challenge itself, there exists a trust deficit about some types of data as they remain under the custody of the car owner(e.g. satellite navigation and mileage data) and can easily be manipulated. In this paper, we propose a blockchain supported architecture enabling the owner of a smart car to create an immutable record of every data, called the auto biography of a car, generated within its lifespan. We also explain how the trust about this record is guaranteed by the immutability characteristic of the blockchain. Furthermore, the paper describes how the proposed architecture enables a secure and privacy-friendly sharing of smart car data between different parties in a secure yet privacy-friendly manner.
Blockchain-based platforms are emerging to provide solutions for technical and governance challenges associated with genomic data sharing. Providing capabilities for distributed data stewardship and participatory access control along with effective ways for enforcement of the data access agreements and data ownership are among the major promises of these platforms.
Tomás Robles, Borja Bordel, Ramón Alcarria, Diego Sánchez-de-Rivera
Blockchain enables the creation of distributed ledgers as a type of database that is shared, replicated, and synchronized among the members of a network. In this paper we analyze how distributed ledgers can be used for empowering end-users to self-manage their own data, enabling third parties to access those data under a cryptographic management model. We propose a use case where both blockchain and smart contracts are employed by using cryptographic technology to enable user empowerment of data management in AmI. Finally, we analyze strengths and weaknesses of the proposed scenario.
Interest in cryptocurrencies has skyrocketed since their introduction a decade ago, with hundreds of billions of dollars now invested across a landscape of thousands of different cryptocurrencies. While there is significant diversity, there is also a significant number of scams as people seek to exploit the current popularity. In this paper, we seek to identify the extent of innovation in the cryptocurrency landscape using the open-source repositories associated with each one. Among other findings, we observe that while many cryptocurrencies are largely unchanged copies of Bitcoin, the use of Ethereum as a platform has enabled the deployment of cryptocurrencies with more diverse functionalities.
Cryptocurrency has been a trending topic over the past decade, pooling tremendous technological power and attracting investments valued over trillions of dollars on a global scale. The cryptocurrency technology and its network have been endowed with many superior features due to its unique architecture, which also determined its worldwide efficiency, applicability and data intensive characteristics. This paper introduces and summarises the interactions between two significant concepts in the digitalized world, i.e., cryptocurrency and Big Data. Both subjects are at the forefront of technological research, and this paper focuses on their convergence and comprehensively reviews the very recent applications and developments after 2016. Accordingly, we aim to present a systematic review of the interactions between Big Data and cryptocurrency and serve as the one stop reference directory for researchers with regard to identifying research gaps and directing future explorations.