Blockchains such as Bitcoin and Ethereum execute payment transactions securely, but their performance is limited by the need for global consensus. Payment networks overcome this limitation through off-chain transactions. Instead of writing to the blockchain for each transaction, they only settle the final payment balances with the underlying blockchain. When executing off-chain transactions in current payment networks, parties must access the blockchain within bounded time to detect misbehaving parties that deviate from the protocol. This opens a window for attacks in which a malicious party can steal funds by deliberately delaying other parties' blockchain access and prevents parties from using payment networks when disconnected from the blockchain. We present Teechain, the first layer-two payment network that executes off-chain transactions asynchronously with respect to the underlying blockchain. To prevent parties from misbehaving, Teechain uses treasuries, protected by hardware trusted execution environments (TEEs), to establish off-chain payment channels between parties. Treasuries maintain collateral funds and can exchange transactions efficiently and securely, without interacting with the underlying blockchain. To mitigate against treasury failures and to avoid having to trust all TEEs, Teechain replicates the state of treasuries using committee chains, a new variant of chain replication with threshold secret sharing. Teechain achieves at least a 33x higher transaction throughput than the state-of-the-art Lightning payment network. A 30-machine Teechain deployment can handle over 1 million Bitcoin transactions per second.
Blockchains such as Bitcoin and Ethereum execute payment transactions securely, but their performance is limited by the need for global consensus. Payment networks overcome this limitation through off-chain transactions. Instead of writing to the blockchain for each transaction, they only settle the final payment balances with the underlying blockchain. When executing off-chain transactions in current payment networks, parties must access the blockchain within bounded time to detect misbehaving parties that deviate from the protocol. This opens a window for attacks in which a malicious party can steal funds by deliberately delaying other parties' blockchain access and prevents parties from using payment networks when disconnected from the blockchain. We present Teechain, the first layer-two payment network that executes off-chain transactions asynchronously with respect to the underlying blockchain. To prevent parties from misbehaving, Teechain uses treasuries, protected by hardware trusted execution environments (TEEs), to establish off-chain payment channels between parties. Treasuries maintain collateral funds and can exchange transactions efficiently and securely, without interacting with the underlying blockchain. To mitigate against treasury failures and to avoid having to trust all TEEs, Teechain replicates the state of treasuries using committee chains, a new variant of chain replication with threshold secret sharing. Teechain achieves at least a 33x higher transaction throughput than the state-of-the-art Lightning payment network. A 30-machine Teechain deployment can handle over 1 million Bitcoin transactions per second.
Yu‐Pin Lin, Joy R. Petway, Johnathen Anthony, Hussnain Mukhtar · 7 authors
Blockchain technology, while still challenged with key limitations, is a transformative Information and Communications Technology (ICT) that has changed our notion of trust. Improved efficiencies for agricultural sustainable development has been demonstrated when ICT-enabled farms have access to knowledge banks and other digital resources. UN FAO-recommended ICT e-agricultural infrastructure components are a confluence of ICT and blockchain technology requirements. When ICT e-agricultural systems with blockchain infrastructure are immutable and distributed ledger systems for record management, baseline agricultural environmental data integrity is safeguarded for those who participate in transparent data management. This paper reviewed blockchain-based concepts associated with ICT-based technology. Moreover, a model ICT e-agriculture system with a blockchain infrastructure is proposed for use at the local and regional scale. To determine context specific technical and social requirements of blockchain technology for ICT e-agriculture systems, an evaluation tool is presented. The proposed system and tool can be evaluated and applied to further developments of e-agriculture systems.
A blockchain is a decentralized ledger where all transactions are recorded. For having a reliable blockchain and double-spending prevention, we need a decentralized consensus and agreement on a blockchain. Bitcoin uses proof-of-work (PoW). It is a cryptographic puzzle that is difficult to solve but easy to verify. However, because of significant latency of proof-of-work for transactions confirmation, this consensus mechanism is vulnerable against double-spending. On the other hand, PoW consumes a significant amount of energy that by growing the network, it becomes a major problematic of this consensus mechanism. In this paper, we introduce an alternative to PoW, because of all its major problems and security issues that may lead to collapsing decentralization of the blockchain, while a full decentralized system is the main purpose of using blockchain technology. The approach we introduce is based on a distributed voting process and called "RDV: Register, Deposit, Vote". Since in RDV algorithm, there is no mining process, so it is appropriate for low-level energy devices and Internet of Things (IoT).
The long-term dependence of Bitcoin (BTC), manifesting itself through a Hurst\nexponent $H>0.5$, is exploited in order to predict future BTC/USD price. A\nMonte Carlo simulation with $10^4$ geometric fractional Brownian motion\nrealisations is performed as extensions of historical data. The accuracy of\nstatistical inferences is 10\\%. The most probable Bitcoin price at the\nbeginning of 2018 is 6358 USD.\n
General Insurance occupies a strong position in today's market. It has a centralized way of operation, which makes it inefficient, less transparent, with trust problems and creates conflicts of interest between insurance companies and policyholders. Furthermore, it's an industry with relative difficulty in innovation, which contrasts with today's services powered by new technologies. New disruptive technologies have the capacity to compromise the value chain of traditional insurance, creating a big problem in its stability and future. Associated to this new kind of technologies, comes a new way of thinking perpetuated by the new generations based on the new trend of sharing economy. They give priority to new technology based services, which are decentralized, more convenient, more price competitive, transparent, and efficient and they prefer services which put the user more in control instead of the current less personalized options. New business models such as Social Insurance, are being developed and powered by new technologies and this new way of thinking. Social Insurance enables people in need of insurance to connect and pool their money and risks. It offers coverage that is cheaper, more transparent, and more relevant to the customer. Members of this type of insurance are both policyholders and underwriters. All these factors compromise the future of traditional insurance companies and their business model. The main goal is to create a new business model in order to adapt insurance companies to the new trend of shared economy. This new business model is going to be focused on health insurance, based in peer to peer communication and is going to be backed up by a business case and a prototype powered by a blockchain database. Blockchain is a decentralized transaction ledger shared amongst all nodes participating in the system. Every node has an updated copy of the database and cannot update it without the consensus of the network, removing the need for having a central authority or trusted third party to monitor the system. Each Blockchain implementation may have its own consensus mechanism (e.g. Proof-of-Work and Proof-of-Stake) to ensure that one node on its own cannot change the database without being validated by the network. Bitcoin is the world's most well-known Blockchain implementation, a public ledger for all transactions made in with a digital currency. However, Blockchain technology can be applied to multiple use cases and industries using Smart Contracts (a collection of code that runs on the network) to define the rules of the business. It fits the purpose for this business model, because it has peer to peer communication by default and has no central authority, making the service more efficient and transparent.
Transactions between individuals have always been a part and parcel of human society for the division of labour made people interdependent. The medium of transaction has also been evolving along with the evolution of society and human consciousness from barter system to commodity money to fiat currency and now to digital currency or cryptocurrency. But since evolution is a form of error correction, the problem of double spending in digital currency was solved by a distributed ledger system called Blockchain. Since 2008 onwards the blockchain technology has been separated from bitcoins to be injected to many other problems related especially to banking transactions. Blockchain technology enables the creation of decentralized currencies, smart contracts and intelligent assets that can be controlled over the Internet
Abstract Blockchains are distributed data structures that are used to achieve consensus in systems for cryptocurrencies (like Bitcoin) or smart contracts (like Ethereum). Although blockchains gained a lot of popularity recently, there are only few logic-based models for blockchains available. We introduce $\mathsf{BCL}$, a dynamic logic to reason about blockchain updates, and show that $\mathsf{BCL}$ is sound and complete with respect to a simple blockchain model.
A blockchain is a distributed ledger for recording transactions, maintained by many nodes without central authority through a distributed cryptographic protocol. All nodes validate the information to be appended to the blockchain, and a consensus protocol ensures that the nodes agree on a unique order in which entries are appended. Consensus protocols for tolerating Byzantine faults have received renewed attention because they also address blockchain systems. This work discusses the process of assessing and gaining confidence in the resilience of a consensus protocols exposed to faults and adversarial nodes. We advocate to follow the established practice in cryptography and computer security, relying on public reviews, detailed models, and formal proofs; the designers of several practical systems appear to be unaware of this. Moreover, we review the consensus protocols in some prominent permissioned blockchain platforms with respect to their fault models and resilience against attacks. The protocol comparison covers Hyperledger Fabric, Tendermint, Symbiont, R3~Corda, Iroha, Kadena, Chain, Quorum, MultiChain, Sawtooth Lake, Ripple, Stellar, and IOTA.
The hype over bitcoins has been compared to the tulip mania in 17th century Netherlands and it has spawned a host of similar cryptocurrencies. As it has gained in popularity, the law has approached the subject warily, mostly from a regulatory perspective. However, no comprehensive consideration of the fundamental nature of a bitcoin owner’s private law relation to his/her/its bitcoins has been properly conducted. Whether or not bitcoins or other cryptocurrencies achieve mainstream adoption or remain of interest to only a niche audience, this question will inevitably have to be properly addressed. This paper proposes to consider if bitcoins might be recognised as the subject of property rights by Commonwealth courts and if so, what such rights ought to entail. It will begin with a careful consideration of the controversial question of the scope of the law of property before considering bitcoin’s place within the law of property (if any). What is the meaning of property in the common law? What fundamental differences exist between tangible and intangible property? If ownership of bitcoins is worthy of protection, what shape should it take? It suggests that the common law adopts a more expansive view of property than civilian systems and that it is thus able to accommodate bitcoins and other cryptocurrencies within its law of property. However, owing to their unusual nature, legal rights to them must take on a unique and unorthodox form. The code underlying Bitcoin also poses particular challenges to the law which this paper also addresses.
Abstract The I owe you (IOU) credit network Ripple is one of the most prominent alternatives in the burgeoning field of decentralized payment systems. Ripple’s path-based transactions set it apart from cryptocurrencies such as Bitcoin. Its pseudonymous nature, while still maintaining some regulatory capabilities, has motivated several financial institutions across the world to use Ripple for processing their daily transactions. Nevertheless, with its public ledger, a credit network such as Ripple is no different from a cryptocurrency in terms of weak privacy; recent demonstrative deanonymization attacks raise important concerns regarding the privacy of the Ripple users and their transactions. However, unlike for cryptocurrencies, there is no known privacy solution compatible with the existing credit networks such as Ripple. In this paper, we present PathShuffle, the first path mixing protocol for credit networks. PathShuffle is fully compatible with the current credit networks. As its essential building block, we propose PathJoin, a novel protocol to perform atomic transactions in credit networks. Using PathJoin and the P2P mixing protocol DiceMix, PathShuffle is a decentralized solution for anonymizing path-based transactions. We demonstrate the practicality of PathShuffle by performing path mixing in Ripple.
Rituparna Bhattacharya, Martin White, Natalia Beloff
Almost every traveller possesses some amount of leftover foreign currency, either as actual cash or on a travel currency card, at the end of any international trip. However, the means to exchange this leftover currency, coins in particular, is largely inconvenient often leading to considerable amounts discarded or left unused. In this paper, we explore how distributed ledger technology, i.e. blockchain, could be applied to the problem of utilizing this leftover foreign currency. We portray here the drawbacks of the existing systems of foreign currency exchange and delineate the requirements of a potential mobile web application for exchanging this currency by integrating smart kiosk based systems, particularly for handling cash, with a peer-to-peer currency exchange technique based on blockchain that could help to bring such currency back into circulation efficiently.
Mutual Distributed Ledger (MDL, aka blockchain) technology is in an emergent phase. New applications are under development; new uses are being researched; new consortia are being formed to explore MDL applications. Considering appropriate governance structures has had a lower priority so far, but trust in the increasingly popular systems will depend on their incorporating good governance principles. It was the aim of this study to identify those principles, in order to provide a roadmap for developers and users alike.
An analysis of the material collected through desktop research, as well as several discussions with practitioners and stakeholders including a conference and webinar on the subject, has revealed that effective governance in MDL systems relies on people rather than software and rests on three pillars:
Architecture: The role of the governance structure, its composition, remit, powers, responsibilities, and its relationship with users, is a critical component.
Accountability: Effective governance of MDLs enhances trust. Trust is enhanced when a governance structure is accountable to its stakeholders, transparent in its decision-making, and subject to periodic audit and third party review.
Action: The governance structure must develop strategic and risk management plans, which are delivered through effective performance management frameworks. Trust can be further enhanced through the use of the voluntary standards market to independently verify performance metrics and the systems established to compile them.
Along the history, people organised in communities needed payment means in order to exchange goods or deliver services. From beads and feathers to metal and paper money they have always improved the way transactions were made. The invention of the Internet opened new doors in the field of payments, through the quick access to information and the emergence of significant international online communities. The members of these communities became aware of the importance of decentralising the way they acquire goods or services, thus eliminating the middlemen. Cryptocurrencies represent the response of these communities to the old centralised means of payment, controlled by the bankers, politicians and interest groups. Our paper aims to analyse the cryptocurrency phenomenon revealing some of its advantages and disadvantages, to increase the awareness on the topic. We based our research on the existing literature, the relevant international databases, the official positions of the financial and regulatory institutions on the analysed matter.
A. Pinar Ozisik, George Bissias, Brian Neil Levine
We make several contributions that quantify the real-time hash rate and therefore the consensus of a blockchain. We show that by using only the hash value of blocks, we can estimate and measure the hash rate of all miners or individual miners, with quanti able accuracy. We apply our techniques to the Ethereum and Bitcoin blockchains; our solution applies to any proof-of-work-based blockchain that relies on a numeric target for the validation of blocks. We also show that if miners regularly broadcast status reports of their partial proof-of- work, the hash rate estimates are signi cantly more accurate at a cost of slightly higher bandwidth. Whether using only the blockchain, or the additional information in status reports, merchants can use our techniques to quantify in real-time the threat of double-spend attacks.
Robert Norvill, Beltrán Borja Fiz Pontiveros, Radu State, Irfan Awan · 5 authors
Smart contracts have recently attracted interest from diverse fields including law and finance. Ethereum in particular has grown rapidly to accommodate an entire ecosystem of contracts which run using its own crypto-currency. Smart contract developers can opt to verify their contracts so that any user can inspect and audit the code before executing the contract. However, the huge numbers of deployed smart contracts and the lack of supporting tools for the analysis of smart contracts makes it very challenging to get insights into this eco-environment, where code gets executed through transactions performing value transfer of a crypto-currency. We address this problem and report on the use of unsupervised clustering techniques and a seed set of verified contracts, in this work we propose a framework to group together similar contracts within the Ethereum network using only the contracts publicly available compiled code. We report qualitative and quantitative results on a dataset and provide the dataset and project code to the research community.
Cryptocurrency systems are purely digital and decentralized systems that use cryptographic principles to confirm transactions. Bitcoin is the first and also the most widespread cryptocurrency. The aim of this article is to introduce Bitcoin system using a language understandable also to readers without computer science education. This article captures the Bitcoin system from three perspectives: internal structure, network and users. Emphasis is placed on brief and clear definitions (system components) and their mutual relationships. A new system view of the stated terms constitutes author's own contribution.
Financial portfolio management is the process of constant redistribution of a\nfund into different financial products. This paper presents a\nfinancial-model-free Reinforcement Learning framework to provide a deep machine\nlearning solution to the portfolio management problem. The framework consists\nof the Ensemble of Identical Independent Evaluators (EIIE) topology, a\nPortfolio-Vector Memory (PVM), an Online Stochastic Batch Learning (OSBL)\nscheme, and a fully exploiting and explicit reward function. This framework is\nrealized in three instants in this work with a Convolutional Neural Network\n(CNN), a basic Recurrent Neural Network (RNN), and a Long Short-Term Memory\n(LSTM). They are, along with a number of recently reviewed or published\nportfolio-selection strategies, examined in three back-test experiments with a\ntrading period of 30 minutes in a cryptocurrency market. Cryptocurrencies are\nelectronic and decentralized alternatives to government-issued money, with\nBitcoin as the best-known example of a cryptocurrency. All three instances of\nthe framework monopolize the top three positions in all experiments,\noutdistancing other compared trading algorithms. Although with a high\ncommission rate of 0.25% in the backtests, the framework is able to achieve at\nleast 4-fold returns in 50 days.\n
Olugbemi T. Olaniyan, Mayowa J. Adeniyi, Charles Oluwaseun Adetunji, Omosigho Omoruyi Pius · 7 authors
Abstract Objectives To introduce blockchain technologies, including their benefits, pitfalls, and the latest applications, to the biomedical and health care domains. Target Audience Biomedical and health care informatics researchers who would like to learn about blockchain technologies and their applications in the biomedical/health care domains. Scope The covered topics include: (1) introduction to the famous Bitcoin crypto-currency and the underlying blockchain technology; (2) features of blockchain; (3) review of alternative blockchain technologies; (4) emerging nonfinancial distributed ledger technologies and applications; (5) benefits of blockchain for biomedical/health care applications when compared to traditional distributed databases; (6) overview of the latest biomedical/health care applications of blockchain technologies; and (7) discussion of the potential challenges and proposed solutions of adopting blockchain technologies in biomedical/health care domains.
Open access
3 source records
Blockchain Technology Applications and Security
IoT and Edge/Fog Computing
Innovative Microfluidic and Catalytic Techniques Innovation
Blockchain technology is the underlying technology of bitcoin. The bitcoin can be used to consume and exchange real currencies, because the blockchain can provide credit certificate of online transaction, and all transaction related information is encrypted and stored in the blockchain. So, it is safe and decentralized, and it will reduce the transaction cost and be widely used. Another important feature of blockchain is non-modifiable. Since all transaction related information is recorded in blockchain and not changeable, this feature facilitates the audit work.
This paper looks at the challenges and opportunities of implementing blockchain technology across banking, providing food for thought about the potentialities of this disruptive technology. The blockchain technology can optimize the global financial infrastructure, achieving sustainable development, using more efficient systems than at present. In fact, many banks are currently focusing on blockchain technology to promote economic growth and accelerate the development of green technologies. In order to understand the potential of blockchain technology to support the financial system, we studied the actual performance of the Bitcoin system, also highlighting its major limitations, such as the significant energy consumption due to the high computing power required, and the high cost of hardware. We estimated the electrical power and the hash rate of the Bitcoin network, over time, and, in order to evaluate the efficiency of the Bitcoin system in its actual operation, we defined three quantities: “economic efficiency”, “operational efficiency”, and “efficient service”. The obtained results show that by overcoming the disadvantages of the Bitcoin system, and therefore of blockchain technology, we could be able to handle financial processes in a more efficient way than under the current system.
This paper describes proposed methodology for evaluation of critical systems and prioritization of critical risks and assets identified in highly secured information systems. For different types of information assets or security environments it is necessary to apply different techniques and methods for their prioritization and evaluation. In this article, VECTOR matrix method for prioritization of critical assets and critical risks is explained and integrated into AHP (Analytic Hierarchy Process) technique as a set of fixed criteria for evaluation of defined alternatives. Bitcoin cryptocurrency was compared and evaluated along with other common Internet transaction systems by information security professionals according to defined VECTOR criteria. Also, the newly proposed hybrid AHP model is presented with potential case studies for future research. This article tries to discover security posture of Bitcoin cryptocurrency in the context of information security risks related to the existing most common online payment systems like e-banking, m-banking, and e-commerce