Consensus is one of the key problems in blockchains. There are many articles analyzing the performance of threat models for blockchains. But the network stability seems lack of attention, which in fact affects the blockchain performance. This paper studies the performance of a well adopted consensus algorithm, Raft, in networks with non-negligible packet loss rate. In particular, we propose a simple but accurate analytical model to analyze the distributed network split probability. At a given time, we explicitly present the network split probability as a function of the network size, the packet loss rate, and the election timeout period. To validate our analysis, we implement a Raft simulator and the simulation results coincide with the analytical results. With the proposed model, one can predict the network split time and probability in theory and optimize the parameters in Raft consensus algorithm.
Halil Ibrahim Ozercan, Atalay Mert Ileri, Erman Ayday, Can Alkan
Genomics data introduce a substantial computational burden as well as data privacy and ownership issues. Data sets generated by high-throughput sequencing platforms require immense amounts of computational resources to align to reference genomes and to call and annotate genomic variants. This problem is even more pronounced if reanalysis is needed for new versions of reference genomes, which may impose high loads to existing computational infrastructures. Additionally, after the compute-intensive analyses are completed, the results are either kept in centralized repositories with access control, or distributed among stakeholders using standard file transfer protocols. This imposes two main problems: (1) Centralized servers become gatekeepers of the data, essentially acting as an unnecessary mediator between the actual data owners and data users; and (2) servers may create single points of failure both in terms of service availability and data privacy. Therefore, there is a need for secure and decentralized platforms for data distribution with user-level data governance. A new technology, blockchain, may help ameliorate some of these problems. In broad terms, the blockchain technology enables decentralized, immutable, incorruptible public ledgers. In this Perspective, we aim to introduce current developments toward using blockchain to address several problems in omics, and to provide an outlook of possible future implications of the blockchain technology to life sciences.
Open access
Blockchain Technology Applications and Security
Nanocluster Synthesis and Applications
Innovative Microfluidic and Catalytic Techniques Innovation
We compute and compare profitabilities of stubborn mining strategies that are variations of selfish mining. These are deviant mining strategies violating Bitcoin's network protocol rules. We apply the foundational set-up from our previous companion article on the profitability of selfish mining, and the new martingale techniques to get a closed-form computation for the revenue ratio, which is the correct benchmark for profitability. Catalan numbers and Catalan distributions appear in the closed-form computations. This marks the first appearance of Catalan numbers in the Mathematics of the Bitcoin protocol.
Traditional centralized energy systems have the disadvantages of difficult management and insufficient incentives. Blockchain is an emerging technology, which can be utilized in energy systems to enhance their management and control. Integrating token economy and blockchain technology, token economic systems in energy possess the characteristics of strong incentives and low cost, facilitating integrating renewable energy and demand side management, and providing guarantees for improving energy efficiency and reducing emission. This article describes the concept and functionality of token economics, and then analyzes the feasibility of applying token economics in the energy systems, and finally discuss the applications of token economics with an example in integrated energy systems.
Prateesh Goyal, Ravi Netravali, Mohammad Alizadeh, Hari Balakrishnan
Prior research has proposed technical solutions to use peer-to-peer (P2P) content delivery to serve Internet video, showing that it can reduce costs to content providers. Yet, such methods have not become widespread except for a few niche instances. An important challenge is incentivization: what tangible benefits does P2P content delivery offer users who bring resources to the table? In this paper, we ask whether monetary incentives can help attract peers in P2P content delivery systems. We commissioned a professional survey of people around theUnited States to answer several relevant questions. We found that 51% of the 876 respondents--substantially larger than our expectations--answered "yes" to whether they would participate for suitable financial incentives. Encouraged by the results of the survey, we propose Gringotts, a system to structure incentives and securely incorporate P2P delivery into content delivery systems. Gringotts provides a novel Proof of Delivery mechanism that allows content providers to verify correct delivery of their files, and shows how to use cryptocurrency to pay peers while guarding against liars and Sybil attacks.
Aug 2, 2018·Jan Rüth, Torsten Zimmermann, Konrad Wolsing, and Oliver Hohlfeld. 2018. Digging into Browser-based Crypto Mining. In IMC '18: Internet Measurement Conference, October 31-November 2, 2018, Boston, MA, USA. ACM, New York, NY, USA, 7 pages
Jan Rüth, Torsten Zimmermann, Konrad Wolsing, Oliver Hohlfeld
Mining is the foundation of blockchain-based cryptocurrencies such as Bitcoin rewarding the miner for finding blocks for new transactions. The Monero currency enables mining with standard hardware in contrast to special hardware (ASICs) as often used in Bitcoin, paving the way for in-browser mining as a new revenue model for website operators. In this work, we study the prevalence of this new phenomenon. We identify and classify mining websites in 138M domains and present a new fingerprinting method which finds up to a factor of 5.7 more miners than publicly available block lists. Our work identifies and dissects Coinhive as the major browser-mining stakeholder. Further, we present a new method to associate mined blocks in the Monero blockchain to mining pools and uncover that Coinhive currently contributes 1.18% of mined blocks having turned over 1293 Moneros in June 2018.
Este artigo apresenta uma análise sobre a inserção da moeda digital Bitcoin como a mesma é utilizada, tecnologia englobada, suas variações e diversificação de aplicação.
Sierra Ison, Jeremy Hills, Cherie W. Morris, Selina M. Stead
Marine Protected Areas (MPA) are mostly studied from an environmental context. A review of available information identified a lack of knowledge in sustainable mechanisms to finance MPA networks. At the United Nations Ocean Conference in 2017, Fiji reaffirmed its voluntary commitment to make 30% of its inshore and offshore marine area MPAs by 2020 under Sustainable Development Goal 14. The work presented here uses empirical data to explore potential benefits from selected community-based MPAs to recipient local stakeholders. A Willingness to Pay (WTP) and Willingness to Contribute Time (WtCT) method was used to explore the extent to which bottom-up governance systems represent a potential financing mechanism of a MPA network. Results of 115 interviews concluded that proximity to a fishing market, dependence on marine resources, food security, income and international commitments were significant variables influencing stakeholder's WTP and WtCT to manage a MPA. We argue that there is a discrepancy between WtCT and WTP driven by income constraints. Thus, by using WTP and WtCT to support financing of a MPA network, a Provincial Trust Fund (PTF) could promote an equitable and benefits-based contribution. Equally important, a PTF has a polycentric and decentralized governance model, which endorses sustainable management of traditional fishing communities. The conclusions provide insight into a bottom-up approach for long-term financial sustainability of Fiji's national MPA commitments.
Open access
Economic and Environmental Valuation
Coral and Marine Ecosystems Studies
Conservation, Biodiversity, and Resource Management
Jialiang Chang, Bo Gao, Hao Xiao, Jun Sun · 6 authors
Ethereum smart contracts are an innovation built on top of the blockchain technology, which provides a platform for automatically executing contracts in an anonymous, distributed, and trusted way. The problem is magnified by the fact that smart contracts, unlike ordinary programs, cannot be patched easily once deployed. It is important for smart contracts to be checked against potential vulnerabilities. In this work, we propose an alternative approach to automatically identify critical program paths (with multiple function calls including inter-contract function calls) in a smart contract, rank the paths according to their criticalness, discard them if they are infeasible or otherwise present them with user friendly warnings for user inspection. We identify paths which involve monetary transaction as critical paths, and prioritize those which potentially violate important properties. For scalability, symbolic execution techniques are only applied to top ranked critical paths. Our approach has been implemented in a tool called sCompile, which has been applied to 36,099 smart contracts. The experiment results show that sCompile is efficient, i.e., 5 seconds on average for one smart contract. Furthermore, we show that many known vulnerabilities can be captured if user inspects as few as 10 program paths generated by sCompile. Lastly, sCompile discovered 224 unknown vulnerabilities with a false positive rate of 15.4% before user inspection.
Blockchain is receiving ever-growing attention from research and industry and is considered a breakthrough technology. This paper presents an overview of Blockchain Technology and its potential applications in developing countries especially Uganda. It was noted that these nations have the potential to progress, but do not have adequate access to present day technology, primarily due to lack of infrastructure and thus Blockchain Technology will fill the gaps. Fundamentally, these nations need transparency, security, and accountability in their processes, all of which are cornerstones of Blockchain technology. Finally, this paper reveals that due to the support from both government and non-governmental organizations, and the establishment of the Blockchain Association of Uganda, Uganda is ready for Blockchain Technology.
Blockchain and smart contract provide a convenient vehicle to build decentralize applications. Among varies Decenrtalized applications (DAPPs), exchange is one of the most mentioned ones. To fully-decentralized an exchange looks somehow like an utopia. Most works tried to use different methods to solve different problems on this subject. According to our observations, the problems caused by blockchain include 1) Long confirmation time, 2) Vulnerable to front running attack, 3) wasting on-chain resource, all these problems make a blockchain based exchange not user friendly. To deal with the above-mentioned problems, a hybrid centralized and decentralized exchange is presented in this work. By simulating the transaction execution processes and eliminating all the unwanted uncertainties, we are confident that the transactions in the proposed exchange center (EC) will be confirmed and executed well on the blockchain, that is, our system allows users to conclude their trades without need of waiting for a long blockchain confirmation time. In conclusion, a Hybrid Centralized and Decentralized Application (HCDAPP) provides a better-quality service, just like a centralized server; at the same time, it also provides a higher-level security, like a decentralized smart contract.
Blockchain brings a peer-to-peer transaction solution without a trusted third authority over the peer-to-peer network. Proof-of-work (PoW), also called `mining', incents some peers (called miners)to compete for the right of block generation by rewarding a certain mount of cryptocurrency. Hence, PoW undertakes the cryptocurrency creation and block generation in a blockchain based transaction system (BTS). However, in a BTS, the block mining reward (BMR)will be terminated after that the regulated quantity of currency have been minted. Although the voluntarily paid transaction fee is allowed to support BMR, the stable reward for block mining is no longer guaranteed, and which inevitably destroys the sustainability of BTS. In this work, we propose a sustainable reward mechanism (SRM)for block mining in BTS. Specifically, SRM introduces a mandatory transaction fee mechanism with dedicated fee rate determination algorithm. An on-chain public account (PA), which is trust-free but security-provable, is set to collect the dynamic transaction fees. With transaction fee collection under adaptive fee rate setting, PA provides the steady BMR, thus makes blockchain sustainable when the currency creation purposed BMR has been terminated. Numerical results are presented to demonstrate the effectiveness of SRM.
The emergence of a "post-fact" world has seen knowledge being misinterpreted and manipulated to suit diverse purposes. Information from credible sources is often drowned out by `facts' with dubious provenance. It is not enough to simply establish knowledge provenance if this meta-data can be changed afterwards. This paper presents a possible solution using blockchains to manage knowledge provenance. The solution is modelled using a concrete example of knowledge institutions. Variations and extensions to suit other domains are suggested. Particularly, a graph based variation of the blockchain is outlined. We also discuss the impact of our model beyond technology.
An insurance system based on blockchain is proposed for web identity security, which provides two insurance service models for personal web identity security of end users and data security of commercial websites, respectively. Claim evidences are uploaded automatically to the blockchain to keep their authenticity. Smart contracts are automatically applied between insurers and policyholders to build trust between them.
Zhuyun Qi, Yan Zhang, Yi Wang, Jinfan Wang · 5 authors
Blockchain as a novel technology which consists of peer-to-peer network, distributed consensus, cryptography and other fundamental knowledge. Blockchain can help people build trust among untrusted people, which will help people establish new application models in multiple areas. But there are several legacy problems which obstruct the deployment and development of blockchain, the biggest problem is blockchain performance that blockchain cannot process the transactions as much as the centralized server per second. We propose a cascade structure for blockchain, which can accelerate the block generation, enlarge the capacity of the block, reduce the risk of fork and increase the difficulty to launch the 51% attack.
Nazrul M. Ahmad, Abdul Razak, Subarmaniam Kannan, Ibrahim Yusof · 5 authors
Identity Management (IDM) in cloud-based Internet-of-Things (IoT) applications is critical in many businesses. However, most conventional IDM systems are costly and hinder the innovation and greater customer experience. By using blockchain, a new way of managing the identities is proposed. This paper presents an initiative to improve IDM by integrating face recognition approach and blockchain technology in an integrated IoT -cloud application. To illustrate the proposed initiative, a decentralized campus wide printing service is chosen as a use case. In this use case, face recognition is used as an entry point to the service. Since face recognition involves a lot of complex computations and machine learning, this process is executed on a cloudlet, hence minimizing the need for massive data transfer to a distant cloud. Once a user's login information is digitally verified via immutable blockchain, smart contract is deployed to keep track of the user's printing activities. The integration of blockchain in this service has decentralized the IDM, automated the service, and kept the service inexpensive and transparent.
IoT and Edge/Fog Computing
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
This paper discusses the application of the blockchain technology to wireless communications, in particular, for enhancing the security of vehicular communications. The idea that the blockchain will become a key solution for ensuring security and data consistency has long been controversial, even in more traditional areas such as finance or real-estate, for example. In this paper, an analysis of the two opposing sides is put forward and a review of the key aspects that need further evolution to ensure the blockchain's survival is presented. In the context of vehicular communications existing blockchain applications are examined with focus on certificate and reputation management, and message forwarding promotion. In this scope, the future of the blockchain is debated with emphasis on the key limitations of public implementations.
This paper proposes a scheme to use blockchain technology for rideshare services. This paper replaces the centralized authority that matches drivers and riders, with block chain and a matching application that uses two types of coins, which encourages the drivers turning into miners. To evaluate the proposed system, this paper applies the proposed blockchain rideshare service to a case study to simulate and find the least matching probability to make drivers benefit from this system. Furthermore, this paper establishes a mathematical model of the stationary distribution of drivers and calculate the stationary profit of each driver in the blockchain rideshare system.
Ying Liu, Kai Zheng, Paul Craig, Yuexuan Li · 6 authors
In this paper we describe an evaluation to test the reliability of a blockchain based Internet of Things application using a continuous-time Markov chain model. The factors affecting the reliability in our system include the number of devices, the reliability of individual devices, and the underlying consensus algorithm etc. The effect of some factors on overall system reliability is tested, and we find that the total number of devices has the most significant factor to affect overall system reliability. So that we can improve system reliability according to the affecting factors.
Modern communication technologies and cryptographic technologies have pushed social networks into the virtual world, but they have also ensured the real existence of social proximity. In the evaluation of social proximity, some decentralized scenarios require the participants bootstrapping tust, and the existing authentication key exchange scheme can hardly satisfy the above requirements. In this study, we have designed a homomorphic hash and Blockchain based authenticated key exchange protocol with privacy protection, and prove its security under the standard model based on hash one-way, discrete logarithm and Blockchain transaction-level security assumption, and discussed the attack that the proposed scheme can resist. Compared with the existing scheme, the proposed scheme does not need the default Unit of Trust, is safer and more flexible, suitable for the scenarios that require strangers to bootstrap trust.
Aug 1, 2018·2018 17th IEEE International Conference On Trust, Security And Privacy In Computing And Communications/ 12th IEEE International Conference On Big Data Science And Engineering (TrustCom/BigDataSE)
Emerging blockchain systems have been widely adopted in sharing economy, such as e-commerce, to allow mutually distrustful parties to transact fairly without trusted parties. Most blockchain systems, however, lack transactional privacy protection. All transactions, including trading relationship between pseudonyms and content transacted, are exposed on the blockchain. Although many existing privacy protection methods on the blockchain have been proposed, it is difficult to find a trade-off between keeping speed and protecting privacy of transactions. To address this limitation, we propose a novel privacy-preserving method RZKPB that does not store financial transactions in clear on the blockchain, thus retaining transactional privacy from the public's view. Meanwhile, these transactions are as proofs to solve disputes between trading partners. RZKPB ensures fairness and privacy of transactions between participants without adding a new trusted party and breaking the verifying protocol on the blockchain. We take the e-commerce as an example in sharing economy to introduce RZKPB in our paper. Our experimental results show that compared with existing privacy-preserving methods based on the blockchain, RZKPB is more efficient under different settings.
Designing blockchain architecture is still an open question and encounters a lot of challenges such as scalability, security, high utilization and so on. In this paper, we propose Chameleon, a scalable and adaptive permissioned blockchain architecture. We adopt the principles of non-forking, high security, scalable and high utilization to design the Chameleon to be suitable for next generation blockchain architecture. In Chameleon, we introduce credit value which can only be acquired through honest behavior to enhance the security of the consensus algorithm. We also introduce the QoS of transactions to meet the various needs of different users. While previous work using sharding to improve the scalability, they either store all transactions in every area or just work independently, it either causes too much redundant data or low resource utilization. Combined with the cloud storage, Chameleon partition the nodes into different area according to different scenario, every area process their own transactions and can also cooperate with each other dynamically to improve transaction throughput and resource utilization.
... Recent years have shown a surge of interest from various enforcement agencies to remedy commercial behaviour exploiting the increasing information and power asymmetries between consumers and firms. What is particularly notable about this rise in attention is that enforcement actions demonstrate clear interactions between different legal fields that are traditionally applied and enforced in isolation. The present article will focus in particular on the growing interaction between competition, data protection, and consumer law. The Italian Competition, Communications and Data Protection Authority opened a joint ‘big data’ sector inquiry in May 2017 that not only aims to identify potential competition concerns but also to define ‘a regulatory framework able to foster competition in the markets of the digital economy, to protect privacy and consumers, and to promote pluralism within the digital ecosystem’.1 The Bundeskartellamt (German competition authority) announced its preliminary assessment in the Facebook competition investigation in December 2017, reaching the view that Facebook’s collection and use of data from third-party sources is abusive. According to the Bundeskartellamt, Facebook’s terms of service violate data protection provisions and thereby constitute abuse of dominance under competition law as well.2 On the basis of its new competence in the area of consumer protection,3 the Bundeskartellamt also opened two sector inquiries into online price comparison websites and smart TVs in October and December 2017, respectively. The sector inquiry into comparison websites aims to uncover possible violations of consumer law and to identify possible deficits in the enforcement of consumer rights that so far mainly takes place in individual private court proceedings.4 The sector inquiry into smart TVs investigates how producers of smart TVs handle user data. In particular, the Bundeskartellamt is looking to clarify to what extent smart TV manufacturers collect, use and pass on personal data, and whether individuals are appropriately informed of these practices in the contract terms.5