Blockchain is a decentralized transaction and data management solution, the technological weapon-of-choice behind the success of Bitcoin and other cryptocurrencies. As the number and variety of existing blockchain implementations continues to increase, adopters should focus on selecting the best one to support their decentralized applications (dApps), rather than developing new ones from scratch. In this paper we present a framework to aid software architects, developers, tool selectors and decision makers to adopt the right blockchain technology for their problem at hand. The framework exposes the correlation between technological decisions and architectural features, capturing the knowledge from existing industrial products, technical forums/blogs, experts' feedback and academic literature; plus our own experience using and developing blockchain-based applications. We validate our framework by applying it to dissect the most outstanding blockchain platforms, i.e., the ones behind the top 10 cryptocurrencies apart from Bitcoin. Then, we show how we applied it to a real-world case study in the insurtech domain.
Abstract This article explores ‘smart contracts’ from first principles: What they are, whether they are properly called ‘contracts’, and what issues they raise for national contract law. A ‘smart’ contract purports to record contractual promises in language which is both intelligible to human beings and (ultimately) executable by machines. The formalisation of contracting language that this entails is, I argue, the most important aspect for lawyers—just as important as the automation of contractual performance. Rather than taking a doctrinal approach focused on the presence of traditional indicia of contract formation, I examine the nature of contracts as legal entities created by words and documents. In most cases, smart contracts will be ‘wrapped in paper’ and nested in a national legal system. Borrowing from the idiom of computer science, I introduce the term ‘contract stack’ to highlight the complex nature of contracts as legal entities incorporating different ‘layers’, including speech acts by the parties in both natural and formal languages as well as mandatory legal rules. It is the interactions within this contract stack that will be most important to the development of contract law doctrines appropriate to smart contracts. To illustrate my points, I explore a few issues that smart contracts might raise for English contract law. I touch on the questions of illegality, jurisdiction, and evidence, but my focus in this paper is on exploring issues in contract law proper. This contribution should be helpful not only to lawyers attempting to understand smart contracts, but to those involved in coding smart contracts—and writing the languages used to code them.
Fatih Ceylan, Ramazan Eki̇nci̇, Osman Tüzün, Hakan Kahyaoğlu
Başta Bitcoin olmak üzere kripto paralar son dönemde çok sık kullanılmaya başlamıştır. “Para birimi” olarak ve “Değer birikim aracı” olarak kabul görmeye başlayan kripto paraların fiyat hareketlerinin analiz edilmesi ihtiyacı ortaya çıkmıştır. Bu piyasaların büyümesi ve küresel entegrasyonu ile birlikte fiyatlarda meydana gelen önemli değişimlerin temelinde spekülatif balonların olup olmadığı finansal istikrar konusunda açıklık ve güvence açısından önem arz etmektedir. Ayrıca kripto para piyasasında meydana gelen spekülatif hareketler piyasa katılımcılarının sürü psikolojisiyle hareket edip etmedikleri sorusunu ortaya çıkarmaktadır. Bu nedenle çalışmada Bitcoin ve Etherium para birimlerinde spekülatif balonların varlığı Philips vd. (2015) tarafından geliştirilen yöntem ile tespit edilmiş ve ne zaman oluştukları tahminlenmiştir. Piyasada balonların olması ve bu balonların süre olarak varlığı sürü psikolojisinin olduğu yönünde bilgi sağlarken, bu piyasada dengeleyici bir spekülasyonun olmadığı yönünde de bir bilgidir. Elde edilen bulgular doğrultusunda Bitcoin ve Etherium kripto para birimlerinde çok sayıda baloncuk olduğu tespit edilmiştir. Özellikle 2017-2018 yılları arasında büyük baloncukların ortaya çıkması bu para birimlerinin spekülatif hareketlere karşı eğilimli olduğunu gösterilmiştir.
The requirement of supporting both latency sensitive and computing intensive Internet of Things (IoT) applications is consistently boosting the necessity for integrating Edge, Fog and Cloud infrastructure. Although there are a number of real-world frameworks attempt to support such integration, they have many limitations from various perspectives including platform independence, security, resource management and multi-application assistance. To address these limitations, we propose a simplified but effective framework, named FogBus for facilitating end-to-end IoT-Fog(Edge)-Cloud integration. FogBus offers a platform independent interface to IoT applications and computing instances for execution and interaction. It not only assists developers in building applications but also helps users in running multiple applications at a time and service providers to manage their resources. In addition, FogBus applies Blockchain, authentication and encryption techniques to secure operations on sensitive data. Because of its lightweight and cross platform software systems, it is easy to deploy, scalable and cost e_cient. We demonstrate the effectiveness of our framework by creating a computing environment with it that integrates finger pulse oximeter as IoT devices with Smartphone-based gateway and Raspberry Pi-based Fog nodes for Sleep Apnea analysis. We also run several experiments on this computing environment varying FogBus settings. The experimental results show that different FogBus settings can improve latency, energy, network and CPU usage of the computing infrastructure.
Aggregate Computing is a promising paradigm for coordinating large numbers of possibly situated devices, typical of scenarios related to the Internet of Things, smart cities, drone coordination, and mass urban events. Currently, little work has been devoted to study and improve security in aggregate programs, and existing works focus solely on application-level countermeasures. Those security systems work under the assumption that the underlying computational model is respected; however, so-called Byzantine behaviour violates such assumption. In this paper, we discuss how Byzantine behaviours can hinder an aggregate program, and exploit application-level protection for creating bigger disruption. We discuss how the blockchain technology can mitigate these attacks by enforcing behaviours consistent with the expected operational semantics, with no impact on the application logic.
Elections conducted on paper consume a lot of resources and contribute to the destruction of forests, which leads to climate deterioration. Moreover, such election process can make it difficult for some people to vote and it often leads to doubts in the validity of counting, in people submitting multiple votes, in ineligible people voting. In several well-known previous examples, doubts in the validity of paper elections lead to the need of recounting and even court battles to decide the validity of the outcome. Having a way to vote online could be an easier and more reliable solution. However, secure and verifiable methods of online voting need to be developed to achieve this.<br><br>Recent online voting experiences in countries such as the United States, India and Brazil demonstrated that further research is needed to improve security guarantees for future elections, to ensure the confidentiality of votes and enable the verification of their integrity and validity. Electronic voting, to be successful, requires a more transparent and secure approach, than the approach that is offered by current electronic voting protocols. Advanced security methods are necessary to introduce effective online voting in the whole world.<br><br>Currently, most online voting systems are centralized, which means that they involve central tallying authorities to take responsibility for verifying, tallying and publishing the final outcome of the election. These previous systems always assume that their central authorities are honest. Otherwise, the published final outcome cannot be trusted. The aim of our new research is to propose and investigate a decentralized ranked choice online voting systems, which never rely on any third party (such as tallying authorities), thereby significantly increasing the confidence and trust of the voters.<br><br>The thesis presents several publicly verifiable online voting systems and indicates the processing steps and stages in the development of a publicity verifiable online voting system from centralized to semi-decentralized, to fully decentralized. By using Homomorphic cryptosystem, proof of zero knowledge and Blockchain technology, the proposed system in this thesis can achieve the following: (1) Flexible voting mechanism: voters can easily rank all candidates; (2) Publicity verifiable: the whole election procedure is transparent and verifiable by voters; (3) Self-tallying: the final outcome of the election can be computed by any individual voter; and (4) Fully decentralized: no tallying authority (or any other trusted third party) involved at all.<br><br>The proposed systems presented in this thesis include protocols developed on Blockchain technology. The technology that is used as the basis for a secure online voting system is ``smart contract over Blockchain', which offers a factor of the integrity of votes and has not been deeply studied in Blockchain technologies to date. The proposed voting protocols ensure confidentiality and preserve the voters' privacy while keeping the election procedures transparent and secure. The underlying Blockchain protocol has not been modified in any way, the voting scheme proposed merely offers an alternative use case of the protocol at hand, which could be presented as the basis for voting systems using Blockchain with further development of the underlying Blockchain protocols.<br><br>
The gaming industry is affected by two key issues---cheating and DDoS attacks against game servers. In this paper, we aim to present a novel yet concrete application of the blockchain technology to address the seemingly disparate problems. Our approach uses blockchain to manage definitive game state and exploits peer consensus on every player action to track modifications to tangible player assets. While a key impediment to adopting blockchain for real-time systems is its high per-operation latency, our approach leverages several optimizations to enable real-time prevention of a large class of cheats where the reported client state is inconsistent with the observed state at the server. Further, blockchain-based games leverage the robust peer-to-peer architecture to successfully defend against DDoS attacks.
Pedro Marcos, Marco Chiesa, Lucas Fernando Müller, Pradeeban Kathiravelu · 7 authors
Autonomous Systems (ASes) can reach hundreds of networks via Internet eXchange Points (IXPs), allowing improvements in traffic delivery performance and competitiveness. Despite the benefits, any pair of ASes needs first to agree on exchanging traffic. By surveying 100+ network operators, we discovered that most interconnection agreements are established through ad-hoc and lengthy processes heavily influenced by personal relationships and brand image. As such, ASes prefer long-term agreements at the expense of a potential mismatch between actual delivery performance and current traffic dynamics. ASes also miss interconnection opportunities due to trust reasons. To improve wide-area traffic delivery performance, we propose Dynam-IX, a framework that allows operators to build trust cooperatively and implement traffic engineering policies to exploit the rich interconnection opportunities at IXPs quickly. Dynam-IX offers a protocol to automate the interconnection process, an intent abstraction to express interconnection policies, a legal framework to digitally handle contracts, and a distributed tamper-proof ledger to create trust among ASes. We build and evaluate a Dynam-IX prototype and show that an AS can establish tens of agreements per minute with negligible overhead for ASes and IXPs.
Thomas Hepp, Alexander Schoenhals, Christopher Gondek, Béla Gipp
Abstract Currently, timestamps are certified by central timestamping authorities, which have disadvantages of centralization. The concept of the decentralized trusted timestamping (DTT) was developed by Gipp et al. to address these drawbacks. The paper provides insights into the architecture and implementation of a decentralized timestamp service taking the integration of multiple blockchain types into account. Furthermore, the components are introduced and the versatile application scenarios are presented. A future direction of research is the evaluation of blockchain technology and their suitability for timestamping.
With the increasing digitalization of the economy, it is becoming increasingly important for organizations to embrace digital innovation. The emergence of blockchain technology exemplifies the disruptive impact of digital innovation and, simultaneously, poses challenges for organizations. Hence, organizations are in transition with regard to fostering its organizational adoption. This kind of adoption is reflected in far-reaching measures in terms of technology, organization, and people. The measures are governed by project management that aligns internal measures with the outside environment. Based on this framework, our research builds on an empirical study to explore the organizational adoption of blockchain technology. We conducted in-depth interviews in 11 cases with experts leading the adoption of blockchain. The objective of our study is to better understand organizational adoption and to explore the factors influencing adoption. Our results uncover a multitude of factors and inherent tensions. The paperâs contributions are twofold. First, our findings can be used as guidelines for organizations planning to adopt digital innovations such as blockchain and to effectively cope with the related phenomena. Second, the factors advance the literature on blockchain by conceptualizing its organizational adoption and aligning the factors to the organizational adoption framework.
Jian An, Danwei Liang, Xiaolin Gui, Yang He · 6 authors
With the popularization of intelligent terminals, crowdsensing has become increasingly prominent because of its advantages, such as low cost, high convenience, and fast speed in conducting tasks. However, the quality of the data collected through crowdsensing is varied and is difficult to evaluate. Furthermore, the existing crowdsensing quality control methods are mostly based on a central platform, which is not completely trusted in reality and results in the existence of fraud and other problems. To solve these two questions, a crowdsensing quality control model based on a two-consensus blockchain is proposed in this paper. First, the idea of a blockchain is introduced into this model. The credit-based verifier selection mechanism and the two-consensus approach are proposed to realize the nonrepudiation and nontampering of information in crowdsensing. Then, to help task publishers obtain higher-quality sensing data, the methods of node matching and QGE are proposed. The former method uses the idea of the calculation of matching degree to select workers, and the latter uses the idea of clustering and fuzzy theories to evaluate the quality of the sensing data. Finally, the experiments show that the running time of the block generation in our model is acceptable, and comparing with the other methods, our model can acquire data of higher ioj.
Driven by the technology of mobile Internet of things and the wide demand of sharing economy, the development of smart locks is changing with each passing day. Current schemes rely on the open network architecture which has security vulnerabilities, privacy leaks, vulnerability to various attacks and other security risks. We propose an end-to-end succinct non-interactive offline authentication scheme based on blockchain technology(BC-SNOA). Using blockchain techniques such as anonymity, ellipticcurve cryptography, workload consensus, and privacy-preserving zero-knowledge proof, the BC-SNOA implements one-time pad to improve confidentiality, offline authentication to avoid network remote intrusions and the risk of network services interruptions. It is difficult to replicate and crack because of the in chip calculation of workloads and mathematical problems. Compared with current smart locks which extract biometric verification information and control by network services, the BC-SNOA scheme is likely to accomplish beneficial properties such as high verification performance and more secure, and also makes simple hardware implementations possible.
Blockchain Technology Applications and Security
Cryptography and Data Security
Advanced Steganography and Watermarking Techniques
Fatih Ceylan, Ramazan Eki̇nci̇, Osman Tüzün, Hakan Kahyaoğlu
Cryptocurrencies, especially Bitcoin, have been used very often recently. The need for analyzing the price movements of the cryptocurrencies, which are accepted as “a currency” and “a store of value”, has emerged. With the growth and global integration of these markets, whether there are speculative bubbles on the basis of significant changes in prices is important in terms of openness and security in respect of financial stability. In addition, speculative movements in the cryptocurrencies market raise the question of whether market participants act with herd mentality. For this reason, in the study, the presence of speculative bubbles in Bitcoin and Etherium is analyzed by using Philips et al. (2015) method and estimated when they were formed. While the presence of bubbles in the cryptocurrencies market and the existence of these bubbles as a duration of herd mentality, it is also known that there is no balancing speculation in this market. According to the findings, a large number of bubbles were found in the Bitcoin and Etherium cryptocurrencies. The emergence of large bubbles, especially between the years 2017-2018, has shown that these cryptocurrencies are prone to speculative movements.
Data is of unprecedented importance today. The most valuable companies of today treat data as a commodity, which they trade and earn revenues. To facilitate such trading, data marketplaces have emerged. Present data marketplaces are inadequate as they fail to satisfy all the desirable properties - fairness, efficiency, security, privacy and adherence to regulations. In this article, we propose a blockchain enabled data marketplace solution that fulfills all required properties. We outline the design, show how to design such a system and discuss the challenges in building a complete data marketplace.
Abstract This article analyses ongoing changes in the supply of alternative media of payments (MOPs). The comparison between old (cash and deposits) and new (cryptocurrencies and central bank digital currencies) MOPs is based on a novel definition of money where a MOP has three properties: the first two are the standard functions of medium of exchange (liquidity costs) and store of value (opportunity costs) and the third is the novel function of store of information (privacy costs). Given such properties and that the evolution of the different MOPs likely depends on individual preferences, the relevance of experimental economics is highlighted.
We propose and compare two approaches to identify smart contracts as token systems by analyzing their public bytecode. The first approach symbolically executes the code in order to detect token systems by their characteristic behavior of updating internal accounts. The second approach serves as a comparison base and exploits the common interface of ERC-20, the most popular token standard. We present quantitative results for the Ethereum blockchain, and validate the effectiveness of both approaches using a set of curated token systems as ground truth. We observe 100% recall for the second approach. Recall rates of 89% (with well explainable missed detections) indicate that the first approach may also be able to identify "hidden" or undocumented token systems that intentionally do not implement the standard. One possible application of the proposed methods is to facilitate regulator' tasks of monitoring and policing the use of token systems and their underlying platforms.
Proponents of Distributed Ledger Technology (DLT) claim it could have an impact greater than the internet; a breakthrough defying organisational boundaries by securely storing data across trustless entities. This would allow decisions to be made on verifiable data in an automated manner without the costs imposed by middlemen, with a corresponding economy-wide impact. Despite this potential, real-world application is embryonic with public and private sectors rapidly seeking exploitation opportunities. This research seeks to understand how DLT might apply to the Defence Support Network (DSN), the mechanism used to sustain UK Armed Forces with materiel and equipment. Drawing on academic and commercial models, a framework was produced for evaluating DLT use cases which measures utility, ease of implementation and impact. Using a functionalist research paradigm, interviews were conducted with DLT and DSN experts on potential use cases, the data from which was then analysed against a lightweight version of the evaluation framework. Results show that use cases involving codification, certification and supply chain provenance merit further investigation. The research concluded with recommendations that the DSN should pilot DLT use cases, but these should be carefully selected utilising an evaluation framework due to DLT's emergent nature.
Abstract Current generations of cryptocurrencies are not money, but future ones may be. While Bitcoin performs poorly as a store of value, it is actually on par with the Venezuelan bolívar over the last decade, and the Argentinian peso over the decade from 1986. I evaluate arguments in favour of central banks issuing digital fiat currency—intended to replace cash—and digital fiat money—intended to replace money more broadly. Digital fiat currency appears a natural step forward, but digital fiat money would be a bad idea as it makes the central bank responsible for the entire money supply.
Recently, cybersecurity becomes more and more important due to the rapid development of Internet. However, existing methods are in reality highly sensitive to attacks and are far more vulnerable than expected, as they are lack of trustable measures. In this paper, to address the aforementioned problems, we propose a blockchain-based cybersecurity framework, termed as Sapiens Chain, which can protect the privacy of the anonymous users and ensure that the transactions are immutable by providing decentralized and trustable services. Integrating semantic analysis, symbolic execution, and routing learning methods into intelligent auditing, this framework can achieve good accuracy for detecting hidden vulnerabilities. In addition, a revenue incentive mechanism, which aims to donate participants, is built. The practical results demonstrate the effectiveness of the proposed framework.
In recent years, blockchain-based techniques have been widely used in cybersecurity, owing to the decentralization, anonymity, credibility and not be tampered properties of the blockchain. As one of the decentralized framework, Sapiens Chain was proposed to protect cybersecurity by scheduling the computational resources dynamically, which were owned by Computational Resources Owners (CROs). However, when CROs in the same pool attack each other, all CROs will earn less. In this paper, we tackle the problem of prisoner's dilemma from the perspective of CROs. We first define a game that a CRO infiltrates another pool and perform an attack. In such game, the honest CRO can control the payoffs and increase its revenue. By simulating this game, we propose to apply Zero Determinant (ZD) strategy on strategy decision, which can be categorized into cooperation and defecting. Our experimental results demonstrate the effectiveness of the proposed strategy decision method.
Eberhard Hechler, Martin Oberhofer, Thomas Schaeck
Most people believe that the paper from 2008 by Satoshi Nakamoto, a pseudonym used by a yet unknown author, introduced the concept of blockchain. However, the key idea is actually 17 years older. The first mentioning of key blockchain concepts goes back to 1991 when Stuart Haber and Scott Stornetta described the concept of a cryptographically secured chain of blocks for the first time.