Incorporating accountability mechanisms in online services requires effective trust management and immutable, traceable source of truth for transaction evidence. The emergence of the blockchain technology brings in high hopes for fulfilling most of those requirements. However, a major challenge is to find a proper consensus protocol that is applicable to the crowdsourcing services in particular and online services in general. Building upon the idea of using blockchain as the underlying technology to enable tracing transactions for service contracts and dispute arbitration, this paper proposes a novel consensus protocol that is suitable for the crowdsourcing as well as the general online service industry. The new consensus protocol is called “Proof-of-Trust” (PoT) consensus; it selects transaction validators based on the service participants' trust values while leveraging RAFT leader election and Shamir's secret sharing algorithms. The PoT protocol avoids the low throughput and resource intensive pitfalls associated with Bitcoin' s “Proof-of-Work” (PoW) mining, while addressing the scalability issue associated with the traditional Paxos-based and Byzantine Fault Tolerance (BFT)-based algorithms. In addition, it addresses the unfaithful behaviors that cannot be dealt with in the traditional BFT algorithms. The paper demonstrates that our approach can provide a viable accountability solution for the online service industry.
Nikos Tsakiris, Panos Hatzipanayotou, Michael S. Michael
Abstract We build a two asymmetric regions model with cross‐border pollution related to production. Each region issues emission permits and revenues from their sales finance public pollution abatement. The decentralized level of emission permits is efficient when permits are interregionally tradable and cross‐border pollution is perfect. This result is robust in a variety of cases—for example, when (i) capital is immobile or internationally mobile or only mobile between the two regions, and (ii) revenue from permits sales is transferred to a federal authority.
SBFT is a state of the art Byzantine fault tolerant permissioned blockchain system that addresses the challenges of scalability, decentralization and world-scale geo-replication. SBFTis optimized for decentralization and can easily handle more than 200 active replicas in a real world-scale deployment. We evaluate \sysname in a world-scale geo-replicated deployment with 209 replicas withstanding f=64 Byzantine failures. We provide experiments that show how the different algorithmic ingredients of \sysname increase its performance and scalability. The results show that SBFT simultaneously provides almost 2x better throughput and about 1.5x better latency relative to a highly optimized system that implements the PBFT protocol. To achieve this performance improvement, SBFT uses a combination of four ingredients: using collectors and threshold signatures to reduce communication to linear, using an optimistic fast path, reducing client communication and utilizing redundant servers for the fast path.
Cyberattacks are nowadays moving rapidly. They are customized, multi-vector, staged in multiple flows and targeted. Moreover, new hacking playgrounds appeared to reach mobile network, modern architectures and smart cities. For that purpose, malware use different entry points and plug-ins. In addition, they are now deploying several techniques for obfuscation, camouflage and analysis resistance. On the other hand, antiviral protections are positioning innovative approaches exposing malicious indicators and anomalies, revealing assumptions of the limitations of the anti-antiviral mechanisms. Primarily, this paper exposes a state of art in computer virology and then introduces a new concept to create undetectable malware based on the blockchain technology. It summarizes techniques adopted by malicious software to avoid functionalities implemented for viral detection and presents the implementation of new viral techniques that leverage the blockchain network.
Bitcoin cryptocurrency system enables users to transact securely and pseudo-anonymously by using an arbitrary number of aliases (Bitcoin addresses). Cybercriminals exploit these characteristics to commit immutable and presumably untraceable monetary fraud, especially via ransomware; a type of malware that encrypts files of the infected system and demands ransom for decryption. In this paper, we present our comprehensive study on all recent ransomware and report the economic impact of such ransomware from the Bitcoin payment perspective. We also present a lightweight framework to identify, collect, and analyze Bitcoin addresses managed by the same user or group of users (cybercriminals, in this case), which includes a novel approach for classifying a payment as ransom. To verify the correctness of our framework, we compared our findings on CryptoLocker ransomware with the results presented in the literature. Our results align with the results found in the previous works except for the final valuation in USD. The reason for this discrepancy is that we used the average Bitcoin price on the day of each ransom payment whereas the authors of the previous studies used the Bitcoin price on the day of their evaluation. Furthermore, for each investigated ransomware, we provide a holistic view of its genesis, development, the process of infection and execution, and characteristic of ransom demands. Finally, we also release our dataset that contains a detailed transaction history of all the Bitcoin addresses we identified for each ransomware.
Nata Goderdzishvili, Eka Gordadze, Nikoloz Gagnidze
In the period of 2006-2011 Georgia enjoyed the status of "world's top reformer" and World Bank recognised that one of the key success factors that made Georgian governments efforts so powerful, is Harnessing Technology [1]. Although eGoventment was not, per se, high political goal and strategic direction for Georgian reformers, but it quickly became the integral part and key enabler of whole public administration reform process. This paper analysis one of the modern and notable example of Georgian innovative and secure eGovernment solution -- property ownership guaranteed by blockchain technology [2]. The analysis highlight prerequisites for implementing such a solution, its main features, system description and core enabled results of blockchain-managed property registration system. The paper makes a generic conclusion that blockchain-based ownership registry is a key driver for both developing and developed information societies (e.g.: Brazil, Sweden) [3] in order to ensure transparency and reliability of government-owned registration systems and increase trust in them, as well as enhance enforcement of rule of law, protection of basic proprietary human rights, reduce costs and increase efficiency and effectiveness of registration process. The aim of this paper is two-fold: to identify the Georgian country-specific solution for legal validity and presumption of proof of property ownership and to add the Georgian experience for a future cross-country comparative studies.
Jong Sou Park, Young Sik Kim, Chang-hak Choi, JangSup Shim
Many interesting news and activities are going on in the field of blockchain (sometimes called, Distributed Ledger Technology) related technologies like cryptocurrency, Initial Coin Offering (ICO), Internet of Things (IoT), Big Data, Artificial Intelligence (AI, mostly Deep Learning). Not only developing countries but also developed countries need to be concerned about applying blockchain technology to their e-government system. Blockchain technology has brought a very deep innovation over conventional Client Server Trusted Third Party intermediary system to pure peer-to-peer (P2P) based smart contract system. This smart contract based peer-to-peer system allow participants to share data which was not possible under Client Server Trusted Third Party system due to architectural monopoly nature of Client Server. Smart contract concept brought logical conditions to share data among participants but it does not provide any definition about data value. This peer-to-peer based data sharing can be practically possible only under definition of value on data shared. If this definition is vague, then it will be very difficult to share data among participants. Also if this definition is clear, data sharing participants can get much benefit from this data sharing. This data sharing will be only effective from blockchain based architecture.
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
The Blockchain technology is a disruptive technology that is changing the societal environment at various levels particularly the financial systems creating a new cryto-economy. There is dominant optimistic and praising view of the potentialities of the decentralized public ledgers. However most of the changes and cutting-edge impact of Blockchain technology remains misunderstood or unknown. This paper aims to propose a more critical perspective of the Blockchain implications highlighting the limitations, the controversies and the drawbacks of public distributed ledgers. An illustration from the monetary system is presented to propose an example of socio-economic implication. By presenting a case regarding the central bank digital currency (CBDC) system, which is now being, introduced as a counter policy against the emergence of the private crypto-currency system. We elaborate what CBDC is trying to solve and yet at the same time what potential problems might arise from this system. We conclude that the introduction of the Blockchain technology should be valued and evaluated in a more thorough way.
Bitcoin und die zugrunde liegende Technologie der Blockchain sind längst keine Randphänomene mehr. Zwar ist Bitcoin in vielerlei Hinsicht neuartig. Das steht aber einer Einordnung als «Geld im weiteren Sinn» bzw. als «Kryptowährung» nicht im Weg. Bitcoin ient zurzeit primär als Spekulationsobjekt, aber auch zur Wertaufbewahrung und als Zahlungsmittel. Während das Bitcoin-System nur die Übertragung von Bitcoins erlaubt, ist die Blockchain von Ethereum, der zweitgrössten Kryptowährung, frei programmierbar and erlaubt die Emission beliebiger «Tokens». Diese können Währungen, Anleihen, Aktien oder beliebige andere Vermögenswerte mit oder ohne vom Emittenten garantierten Wert darstellen. Kryptowährungen haben das Potenzial, einen Digitalisierungsschub im Finanzbereich auszulösen. Um dieses Potenzial zu realisieren, bedarf es aber noch der Klärung verschiedener Rechtsfragen und der Beseitigung rechtlicher Hürden.
We present SBFT: a scalable decentralized trust infrastructure for Blockchains. SBFT implements a new Byzantine fault tolerant algorithm that addresses the challenges of scalability and decentralization. Unlike many previous BFT systems that performed well only when centralized around less than 20 replicas, SBFT is optimized for decentralization and can easily handle more than 100 active replicas. SBFT provides a smart contract execution environment based on Ethereum's EVM byte-code.
We tested SBFT by running 1 million EVM smart contract transactions taken from a 4-month real-world Ethereum workload. In a geo-replicated deployment that has about 100 replicas and can withstand $f=32$ Byzantine faults our system shows speedups both in throughput and in latency. SBFT completed this execution at a rate of 50 transactions per second. This is a $10\times$ speedup compared to Ethereum current limit of $5$ transactions per second. SBFT latency to commit a smart contract execution and make it final is sub-second, this is more than $10\times$ speedup compared to Ethereum current $>15$ second block generation for registering a smart contract execution and several orders of magnitude speedup relative to Proof-of-Work best-practice finality latency of one-hour.
Bitcoin has attracted everyone's attention and interest recently. Ethereum (ETH), a second generation cryptocurrency, extends Bitcoin's design by offering a Turing-complete programming language called Solidity to develop smart contracts. Smart contracts allow creditable execution of contracts on EVM (Ethereum Virtual Machine) without third parties. Developing correct smart contracts is challenging due to its decentralized computation nature. Buggy smart contracts may lead to huge financial loss. Furthermore, smart contracts are very hard, if not impossible, to patch once they are deployed. Thus, there is a recent surge of interest on analyzing/verifying smart contracts. While existing work focuses on EVM opcode, we argue that it is equally important to understand and define the semantics of Solidity since programmers program and reason about smart contracts at the level of source code. In this work, we develop the structural operational semantics for Solidity, which allows us to identify multiple design issues which underlines many problematic smart contracts. Furthermore, our semantics is executable in the K framework, which allows us to verify/falsify contracts automatically.
Blockchain technologies are central to what has been described as a new ‘smart social contract’. With blockchain, individual cryptographic identity becomes the basis for new forms of money and for a whole suite of restructured social, political and financial transactions. But what do these developments signal for feminist engagements with the money economy? The transparency and pseudonymity that the blockchain provides has been welcomed as a ‘feminist weapon’. But the decentralised technology also legitimises many longstanding assumptions of libertarianism, especially competitive individualism, naturalised social inequality and the stability of value associated with the gold standard. Drawing on popular culture texts, Goldfinger and The Mandibles, this article considers this history, examining the gendered, racialised and sexualised discursive practices that attend representations of gold along with the ‘metallism’ surrounding blockchain-based cryptocurrencies in the contemporary conjuncture. By claiming to represent non-negotiable certainty derived from technology/nature rather than social convention, the fantasy of fundamental value returns, together with related associations of essentialism and authenticity, but anchored in this new context in the technocratic authoritarianism of FinTech. This is part of the background for the ‘new libertarianism’ whose ascendency now overshadows the neoliberalism that has been the focus of critical attention for some decades.
In the modern era, researchers are predicting prices of various kinds of cryptocurrency to understand their trend in the sector of finance. In this paper, we focus on price prediction of cryptocurrencies based on a period, i.e., for the year 2013 to 2018. From our research, we have identified the highest prices for bitcoin for historical dates and trained Long Short-Term Memory Networks to learn and predict the highest rate for a future period. Thus, trend analysis of cryptocurrency prices has been done, and neural networks have been leveraged to determine from time series data and predict future values.
Purpose This paper aims to solve a mining work centralization problem using a gamification-based approach. Design/methodology/approach The authors have developed a simple blockchain application that incorporates a gamification concept into the mining work. Then, they asked some participants in an experiment to use the application for a week and gathered some insights from the responses on questionnaires. Findings The results show that the gamification-based approach distributed mining work among many participants by increasing their motivation to participate mining work. Originality/value The gamification-based approach solves a mining work centralization problem and opens a new direction for future blockchain technologies.
This article seeks to review and identify potential sources of funds for implementation of planned activities within a fisheries co-management arrangement in the southern Lake Malawi, Mangochi District. In this review, we use secondary sources on fisheries co-management at both national and international levels. With adoption of the co-management or participatory fisheries management as it is alternatively called in Malawi, consideration of sustainable financing mechanisms is essential for implementation of planned activities by the local fisheries management authorities and beach village committees within a decentralization framework. Potential revenue sources include development of a fisheries fund and establishment of a benefit sharing mechanism with reference to a district user fee. Other sources include fees charged for conducting fisheries research on the lake, membership fee for joining beach village committees, levies on fish marketing and fees charged for use of facilities especially jetties, store rooms and fish processing facilities on a beach. The revenue collection is recommended as one of the incentives for co-management partners to ensure implementation of activities like law enforcement, licensing, training, community outreach services and research. We recommend that the legal provisions on the establishment of a fisheries fund and revenue sharing be implemented to ensure availability of funds for the fisheries sector. In addition, the existing by-laws with outlined financing mechanisms should be approved by the appropriate authorities.
With the increase in popularity of cryptocurrencies, it is becoming extremely crucial to predict what the prices of the currencies are going to be in the future. This paper uses a dataset that consists of over 1500 cryptocurrencies with their prices starting from their initiation till May, 2018. A lot of the effort went into getting the data set ready before predicting the future prices of all the cryptocurrencies, i.e., making sure that the cryptocurrencies were stationary time-series. Beginning with learning about the ARIMA model and the conditions to run the model successfully, first validation of the model is done. An average accuracy of 86.424 is observed for 95% of the currencies are observed. After this validation, forecasting is performed on these cryptocurrencies and the percentage change of the price is calculated.
This article examines the potential uses for Bitcoin and Blockchain technology in libraries. This article will also explore legal aspects of smart contracts as a means for paying for electronic resources.
This paper provides the first comprehensive survey of methods for inserting arbitrary data into Bitcoin’s blockchain. Historical methods of data insertion are described, along with lesser-known techniques that are optimized for efficiency. Insertion methods are compared on the basis of efficiency, cost, convenience of data reconstruction, permanence, and potentially negative impact on the Bitcoin ecosystem.
The Transport Layer Security (TLS) protocol is a de facto standard of secure client-server communication on the Internet. Its security can be diminished by a variety of attacks that leverage on weaknesses in its design and implementations. An example of a major weakness is the public-key infrastructure (PKI) that TLS deploys, which is a weakest-link system and introduces hundreds of links (i.e., trusted entities). Consequently, an adversary compromising a single trusted entity can impersonate any website. Notary systems, based on multi-path probing, were early and promising proposals to detect and prevent such attacks. Unfortunately, despite their benefits, they are not widely deployed, mainly due to their long-standing unresolved problems. In this paper, we present Persistent and Accountable Domain Validation (PADVA), which is a next-generation TLS notary service. PADVA combines the advantages of previous proposals, enhancing them, introducing novel mechanisms, and leveraging a blockchain platform which provides new features. PADVA keeps notaries auditable and accountable, introduces service-level agreements and mechanisms to enforce them, relaxes availability requirements for notaries, and works with the legacy TLS ecosystem. We implemented and evaluated PADVA, and our experiments indicate its efficiency and deployability.
Wireless Sensor networks (WSN) today suffer from a lack of security adapted to their multiple constraints, to which authentication and trust management solutions such as PGP only partially responds. On the one hand, the constraints of autonomy and co-operation of the nodes necessary to guarantee the coherence of the network do not require a distributed solution. On the other hand, the constraints of energy consumption and the low computing power of the nodes require the use of algorithms of low complexity (Zhang2014) . To our knowledge, no solution can answer both these problems at the same time. We are proposing a new solution for securing WSNs named BATMAN (Blockchain Authentication and Trust Module in Ad-hoc Networks) to reply to these challenges. We present a model of centralized management for authentication and trust, implementable on the Tezos blockchain, and evaluate through simulation the confidence estimators proposed here.
Recently, mesh networking and blockchain are two of the hottest technologies in the telecommunications industry. Combining both can reformulate internet access and make connecting to the Internet not only easy, but affordable too. Hyperledger Fabric (HLF) is a blockchain framework implementation and one of the Hyperledger projects hosted by The Linux Foundation. We evaluate HLF in a real production mesh network and in the laboratory, quantify its performance, bottlenecks and limitations of the current implementation. We identify the opportunities for improvement to serve the needs of wireless mesh access networks. To the best of our knowledge, this is the first HLF deployment made in a production wireless mesh network.
Hung Dang, Tien Tuan Anh Dinh, Dumitrel Loghin, Ee‐Chien Chang · 6 authors
Existing blockchain systems scale poorly because of their distributed consensus protocols. Current attempts at improving blockchain scalability are limited to cryptocurrency. Scaling blockchain systems under general workloads (i.e., non-cryptocurrency applications) remains an open question. In this work, we take a principled approach to apply sharding, which is a well-studied and proven technique to scale out databases, to blockchain systems in order to improve their transaction throughput at scale. This is challenging, however, due to the fundamental difference in failure models between databases and blockchain. To achieve our goal, we first enhance the performance of Byzantine consensus protocols, by doing so we improve individual shards' throughput. Next, we design an efficient shard formation protocol that leverages a trusted random beacon to securely assign nodes into shards. We rely on trusted hardware, namely Intel SGX, to achieve high performance for both consensus and shard formation protocol. Third, we design a general distributed transaction protocol that ensures safety and liveness even when transaction coordinators are malicious. Finally, we conduct an extensive evaluation of our design both on a local cluster and on Google Cloud Platform. The results show that our consensus and shard formation protocols outperform state-of-the-art solutions at scale. More importantly, our sharded blockchain reaches a high throughput that can handle Visa-level workloads, and is the largest ever reported in a realistic environment.