The year 2017 saw the rise and fall of the crypto-currency market, followed by high variability in the price of all crypto-currencies. In this work, we study the abrupt transition in crypto-currency residuals, which is associated with the critical transition (the phenomenon of critical slowing down) or the stochastic transition phenomena. We find that, regardless of the specific crypto-currency or rolling window size, the autocorrelation always fluctuates around a high value, while the standard deviation increases monotonically. Therefore, while the autocorrelation does not display signals of critical slowing down, the standard deviation can be used to anticipate critical or stochastic transitions. In particular, we have detected two sudden jumps in the standard deviation, in the second quarter of 2017 and at the beginning of 2018, which could have served as early warning signals of two majors price collapses that have happened in the following periods. We finally propose a mean-field phenomenological model for the price of crypto-currency to show how the use of the standard deviation of the residuals is a better leading indicator of the collapse in price than the time series' autocorrelation. Our findings represent a first step towards a better diagnostic of the risk of critical transition in the price and/or volume of crypto-currencies.
Due to conclusion could not rely on only one test, in this study, we apply various approaches to verify the actuary of VaR model to find out whether VaR model, especially historical VaR and delta normal VaR model, can provide the accurate risk measurement results for cryptocurrencies risk, especially CRIX, BTC, ETH and XRP. We use Kupiec’s POF test, Independence Test - Christoffersen (1998) and Joint Test that widely use for backtesting VaR model. Performance test results for risk measurement by historical VaR provide a fairly accurate over delta normal VaR when we use Kupiec’s POF-test for the accuracy of VaR model. Christoffersen (1998) independence test, the exceptions (failures) of historical VaR and delta normal VaR model show independence exceptions in accordance with an only high confidence level of critical values (0.99). Otherwise, the low confidence level of critical values (0.90 and 0.95) appears dependence exceptions. For the Joint test, we combine POF-test and independence test because each model has different advantages and disadvantages. The results show that historical VaR model is suitable for measuring cryptocurrency risk over delta normal VaR only high confidence level of critical values.
Jun 20, 2018·Proceedings of the IEEE International Conference on Computing, Electronics & Communications Engineering 2018 (IEEE iCCECE '18), to be held between 16-17 August 2018, at University of Essex, Southend, UK, published by IEEE
Securities exchange being digitalised and online, security of information and data has become a major concern. Blockchain (BC) technology, being distributed and immutable in nature, has proved to the "Trust Machine" eliminating the need for third-parties. Authors of this paper investigate how Blockchain can be used to secure stock exchange transactions, with an especial focus to the technological as well as legal aspects of such applications. Considering the intricate operational structure of the securities exchange, the research proposes to design, develop and implement a hybrid BC, customised according to the need of the respective stock exchange. The study suggests that the use of such BC can bring many benefits which the other technologies currently being used cannot offer. However, during the design process of any such application using BC, the relevant laws and regulations of the corresponding country need to be considered.
The amalgamation of information and communication technologies in power industry has led to a revolution known as smart grid (SG). The energy consumers interact with the power utility using a bidirectional communication channel for energy trading in SG ecosystem. However, the traditional energy trading mechanisms strongly rely on trusted third parties which act as a single point of failure. Therefore, it is important to equip SG with a decentralized and secure energy trading system which can execute contracts and handle negotiations among various trading parties. Hence, in this paper, EnergyChain, a blockchain model for storing and accessing the data generated by smart homes in a secure manner is proposed. EnergyChain works in following phases: 1) a miner node is selected on the basis of power capacity of various smart homes, 2) a block creation and validation scheme is presented, and 3) a transaction handling mechanism is designed for secure energy trading. After evaluation, the superiority of EnergyChain is validated. The results obtained show that EnergyChain outperforms the traditional scheme in terms of communication costs and computation time.
Marine transportation is the oldest means of transportation, which is the most useful when the goods to be shipped are in bulk. Travelling through sea means there is high chance of mishappening even when safety regulations are in place, which could result in damage or loss of the ship or the shipments. Thus, Marine insurance is advisable as it covers the hull, cargo, freight and marine liabilities. Any losses or damages sustained during a marine journey must be settled as early as possible through Insurance. The process of declaring and claiming Insurance involves a lot of documentation, which is collected and stored in paper format, and third-party participation. In modern times, there has been a shift towards Digitization in every sector, which means everything is stored in a digital format. One of the key developments in Digitization has been the use of Blockchain technologies which support distributed ledgers, smart contracts, smart properties, storage, etc. Applications, in which there is involvement of money or assets, are reliant on blockchain because of the security, by encryption of data, and performance provided by it. In this paper, we have discussed the challenges and key issues associated with the declaration and claiming of Marine Hull Insurance through the existing system. To resolve these issues, we combine three of the latest technologies in Blockchain, namingly, Private Blockchain, Filecoin Protocol and Smart Contracts. Our proposed system is based on a digital platform, where all documents can be commonly accessed and third-party involvements are removed, resulting in simpler, faster and easier declaration and claiming of marine hull insurances that removes the complications in the present general procedure.
Bitcoin and Ethereum are novel mechanisms for decentralizing the concept of money and computation. Extending decentralization to the human identity concept, we can think of using blockchain for creating a list of verified human identities with a one-person-one-ID property. UniqueID is a Decentralized Autonomous Organization(DAO) for maintaining human identities such that every physical human entity can have no more that one account. One part of this identity is simply the user's claim on one of his unique, permanent, and measurable characteristics -biometrics. Blockchain has proved its integrity as a platform for storing and performing computations on such claims. The biggest challenge here is to ensure that the user has submitted his own valid biometric data. Human verifiers can check if there is any inconsistency in other users' data, by peer-to-peer checks. For preventing bad behavior and centralization in the verification process, UniqueID benefits from novel governance mechanisms to choose verifiers and punish unjust ones. Also, there are incentives for honest verifiers and users by newly generated tokens. We show how the users' privacy can be preserved by using state-of-the-art cryptographic techniques, and so they can use their identity without any concerns for votings, financial and banking purposes, social media accounts, reputation systems etc.
The popularity of blockchain technology continues to grow rapidly in both industrial and academic fields. Most studies of blockchain focus on the improvements of security, usability, or efficiency of blockchain protocols, or the applications of blockchain in finance, Internet of Things, or public services. However, few of them could reveal the concerns of front-line developers and the situations of blockchain in practice. In this article, we investigate how developers use and discuss blockchain with a case study of Stack Overflow posts. We find blockchain is a relatively new topic in Stack Overflow but it is rising to popularity. We detect 13 types of questions that developers post in Stack Overflow and identify 45 blockchain relevant entities (e.g., frameworks, libraries, or tools) for building blockchain applications. These findings may help blockchain project communities to know where to improve and help novices to know where to start.
Isaac Sheff, Xinwen Wang, Andrew C. Myers, Robbert van Renesse
Blockchains offer a useful abstraction: a trustworthy, decentralized log of totally ordered transactions. Traditional blockchains have problems with scalability and efficiency, preventing their use for many applications. These limitations arise from the requirement that all participants agree on the total ordering of transactions. To address this fundamental shortcoming, we introduce Charlotte, a system for maintaining decentralized, authenticated data structures, including transaction logs. Each data structurestructure -- indeed, each block -- specifies its own availability and integrity properties, allowing Charlotte applications to retain the full benefits of permissioned or permissionless blockchains. In Charlotte, a block can be atomically appended to multiple logs, allowing applications to be interoperable when they want to, without inefficiently forcing all applications to share one big log. We call this open graph of interconnected blocks a blockweb. We allow new kinds of blockweb applications that operate beyond traditional chains. We demonstrate the viability of Charlotte applications with proof-of-concept servers running interoperable blockchains. Using performance data from our prototype, we estimate that when compared with traditional blockchains, Charlotte offers multiple orders of magnitude improvement in speed and energy efficiency.
Tooba Faisal, Nicolas T. Courtois, Antoaneta Serguieva
The use of blockchains is growing every day, and their utility has greatly expanded from sending and receiving crypto-coins to smart-contracts and decentralized autonomous organizations. Modern blockchains underpin a variety of applications: from designing a global identity to improving satellite connectivity. In our research we look at the ability of blockchains to store metadata in an increasing volume of transactions and with evolving focus of utilization. We further show that basic approaches to improving blockchain privacy also rely on embedding metadata. This paper identifies and classifies real-life blockchain transactions embedding metadata of a number of major protocols running essentially over the bitcoin blockchain. The empirical analysis here presents the evolution of metadata utilization in the recent years, and the discussion suggests steps towards preventing criminal use. Metadata are relevant to any blockchain, and our analysis considers primarily bitcoin as a case study. The paper concludes that simultaneously with both expanding legitimate utilization of embedded metadata and expanding blockchain functionality, the applied research on improving anonymity and security must also attempt to protect against blockchain abuse.
Open access
2 source records
cs.CR
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
Jun 18, 2018·Andrew Burnie, 2018. Exploring the Interconnectedness of Cryptocurrencies using Correlation Networks. In Cryptocurrency Research Conference 2018 (Anglia Ruskin University, 2018). Anglia Ruskin University, Cambridge, UK
Correlation networks were used to detect characteristics which, although fixed over time, have an important influence on the evolution of prices over time. Potentially important features were identified using the websites and whitepapers of cryptocurrencies with the largest userbases. These were assessed using two datasets to enhance robustness: one with fourteen cryptocurrencies beginning from 9 November 2017, and a subset with nine cryptocurrencies starting 9 September 2016, both ending 6 March 2018. Separately analysing the subset of cryptocurrencies raised the number of data points from 115 to 537, and improved robustness to changes in relationships over time. Excluding USD Tether, the results showed a positive association between different cryptocurrencies that was statistically significant. Robust, strong positive associations were observed for six cryptocurrencies where one was a fork of the other; Bitcoin / Bitcoin Cash was an exception. There was evidence for the existence of a group of cryptocurrencies particularly associated with Cardano, and a separate group correlated with Ethereum. The data was not consistent with a token's functionality or creation mechanism being the dominant determinants of the evolution of prices over time but did suggest that factors other than speculation contributed to the price.
This study investigates the relationship between blockchain technology and the financial market. The US and China are used as case studies for the 2008–2016 period using fully modified least square and Toda-Yamamoto causality technique. The estimates show that blockchain technology has positive and significant relationship with the financial market in the US and China. In other words, the higher the levels of blockchain innovation in these countries, the more developed the financial markets. This suggests that the presence of blockchain innovation in financial markets spurs financial development. Blockchain innovation is therefore a positive significant factor for well-developed financial markets. The findings also indicate that macroeconomic factors such as lagged financial development, GDP per capita, the growth rate of GDP, FDI and trade openness have significant and positive relationship with financial development in the two countries. Among the institutional variables, government effectiveness has significant and positive effects only in the US.
We study how attempts to regulate cryptocurrencies, or at least to mitigate the harm they do, are misdirected. We started by looking at how one might blacklist stolen bitcoin, and find that two established legal principles – the nemo dat rule and the Clayton's case precedent -- make tracing crime proceeds much simpler than researchers previously thought; they support a first-in first-out rule for taint tracking, which turns out to be much more efficient. However once we published initial results and were approached by theft victims, we discovered a more serious problem. Many bitcoin exchanges do not now give their customers actual bitcoin, but rather do off-chain transactions with other exchange customers or transact on customers' behalf with outsiders. Except where customers withdraw cryptocurrency into self-hosted wallets, the ownership of these assets is unclear. The number of off-blockchain transactions has increased enormously in the last eighteen months; we can't find good figures but the volume is sufficient to raise serious concerns and the practice falls under e-money regulations that are not being enforced. In short, the security, economics and regulatory problems of cryptocurrencies in 2018 turn out to be rather different from those described in the academic literature. The real problem is that we are seeing the emergence of a shadow banking system. Cryptocurrencies do not solve the underlying problems that made bank regulation necessary, and we sadly predict that many of the familiar second-order problems will also reappear. We discuss the implications for regulating cryptocurrencies and smart contracts more generally, and suggest eight things that regulators and central banks might usefully do.
Correlation networks were used to detect characteristics which, although\nfixed over time, have an important influence on the evolution of prices over\ntime. Potentially important features were identified using the websites and\nwhitepapers of cryptocurrencies with the largest userbases. These were assessed\nusing two datasets to enhance robustness: one with fourteen cryptocurrencies\nbeginning from 9 November 2017, and a subset with nine cryptocurrencies\nstarting 9 September 2016, both ending 6 March 2018. Separately analysing the\nsubset of cryptocurrencies raised the number of data points from 115 to 537,\nand improved robustness to changes in relationships over time. Excluding USD\nTether, the results showed a positive association between different\ncryptocurrencies that was statistically significant. Robust, strong positive\nassociations were observed for six cryptocurrencies where one was a fork of the\nother; Bitcoin / Bitcoin Cash was an exception. There was evidence for the\nexistence of a group of cryptocurrencies particularly associated with Cardano,\nand a separate group correlated with Ethereum. The data was not consistent with\na token's functionality or creation mechanism being the dominant determinants\nof the evolution of prices over time but did suggest that factors other than\nspeculation contributed to the price.\n
Chuka Oham, Raja Jurdak, Salil S. Kanhere, Ali Dorri · 5 authors
In this paper, we propose a partitioned BlockChain based Framework for Auto-insurance Claims and Adjudication (B-FICA) for CAVs that tracks both sensor data and entity interactions with two-sided verification. B-FICA uses permissioned BC with two partitions to share information on a need to know basis. It also uses multi-signed transactions for proof of execution of instructions, for reliability and auditability and also uses a dynamic lightweight consensus and validation protocol to prevent evidence alteration. Qualitative evaluation shows that B-FICA is resilient to several security attacks from potential liable entities. Finally, simulations show that compared to the state of the art, B-FICA reduces processing time and its delay overhead is negligible for practical scenarios and at marginal security cost.
Jianli Pan, Jianyu Wang, A. MARIA HESTER, Ismail AlQerm · 6 authors
The emerging Internet of Things (IoT) is facing significant scalability and security challenges. On the one hand, IoT devices are "weak" and need external assistance. Edge computing provides a promising direction addressing the deficiency of centralized cloud computing in scaling massive number of devices. On the other hand, IoT devices are also relatively "vulnerable" facing malicious hackers due to resource constraints. The emerging blockchain and smart contracts technologies bring a series of new security features for IoT and edge computing. In this paper, to address the challenges, we design and prototype an edge-IoT framework named "EdgeChain" based on blockchain and smart contracts. The core idea is to integrate a permissioned blockchain and the internal currency or "coin" system to link the edge cloud resource pool with each IoT device' account and resource usage, and hence behavior of the IoT devices. EdgeChain uses a credit-based resource management system to control how much resource IoT devices can obtain from edge servers, based on pre-defined rules on priority, application types and past behaviors. Smart contracts are used to enforce the rules and policies to regulate the IoT device behavior in a non-deniable and automated manner. All the IoT activities and transactions are recorded into blockchain for secure data logging and auditing. We implement an EdgeChain prototype and conduct extensive experiments to evaluate the ideas. The results show that while gaining the security benefits of blockchain and smart contracts, the cost of integrating them into EdgeChain is within a reasonable and acceptable range.
We propose definitions and implementations of "S-money" - virtual tokens designed for high value fast transactions on networks with relativistic or other trusted signalling constraints, defined by inputs that in general are made at many network points, some or all of which may be space-like separated. We argue that one significant way of characterising types of money in space-time is via the "summoning" tasks they can solve: that is, how flexibly the money can be propagated to a desired space-time point in response to relevant information received at various space-time points. We show that S-money is more flexible than standard quantum or classical money in the sense that it can solve deterministic summoning tasks that they cannot. It requires the issuer and user to have networks of agents with classical data storage and communication, but no long term quantum state storage, and is feasible with current technology. User privacy can be incorporated by secure bit commitment and zero knowledge proof protocols. The level of privacy feasible in given scenarios depends on efficiency and composable security questions that remain to be systematically addressed.
This thesis focuses on the integration of smart contracts into the Bazo Blockchain with the goal of creating a platform for decentralized applications. Smart contracts are programs that are stored on a blockchain and can be triggered by transactions. Smart contracts offer opportunities in automation and bring along advantages provided by blockchains such as immutability, public visibility of transactions and decentralization. As blockchains are trust-less protocols, it is guar- anteed that smart contracts are executed as intended. The integration of smart contracts was solved by implementing a virtual machine that executes the instructions sent by a transaction. This stack based virtual machine uses byte arrays as base type, which enables the virtual machine to deal with numbers of arbitrary length. Working with elements of arbitrary size requires taking the length of the elements into account, when calculating the gas cost, in addition to the base cost of the instruction type. Furthermore, the virtual machine was embedded within the mining application, which required to alter the blockchain protocol and the mining application. As a result, smart contracts can be deployed and transactions that call functions of smart contracts can be executed. Calling a smart contract function leads to the execution of the contract in the virtual machine and persisting the result in the blockchain. The Bazo Blockchain contin- ues to be a research project, this means it’s not ready for production use due to complex setup and handling. Follow-up theses could simplify the development of smart contracts for the Bazo Blockchain by creating a high-level programming language that can be compiled to Bazo virtual machine instructions.
We study the relationship between Bitcoin and traditional payment systems and the financial sector. The payment systems we will do the study with are Visa, MasterCard, Western Union, American Express and PayPal. We study whether Bitcoin returns, Bitcoin transaction volume, unique Bitcoin addresses and Bitcoin google searches have any relationship with the returns of the traditional payment companies. In addition we also study whether the same variables have any explanatory relationship with the financial sector. We find that the relationship between Bitcoin and payment systems is very weak, which indicates that investors that typically invest in these companies doesn’t see Bitcoin as a serious competitor. However, number of unique Bitcoin addresses has a negative relationship with the abnormal returns of most of the payment companies.
Peter Pennefather, West Suhanic, Fatima Lakha, Deborah I. Fels
An inclusive systemic design is specified for publishing data derived from personal private health records, owned and curated by patients. The design is specified with an example of a digital scrapbook of private personal records of care for medically significant pain. This scrapbook is designed to aggregate private records of patient pain experiences and of the care and accommodations they access. The design also specifies how to store, access and analyze those private records through distributed ledgers and how qualitative and quantitative data derived from that private data can be published as a common pool resource with polycentric governance.
A blockchain is a datastructure that is an append-only chain of blocks. Each\nblock contains a set of transaction and has a cryptographic link back to\nits predecessor. The cryptographic link serves to protect the integrity of\nthe blockchain. A key property of blockchain systems is that it allows mu-\ntually distrusting entities to reach consensus over a unique order in which\ntransactions are appended. The most common usage of blockchains is in\ncryptocurrencies such as Bitcoin.\nIn this thesis we use blockchain technology to design a scalable architec-\nture for a storage system that can provide strong data integrity and ensure the\npermanent availability of the data. We study recent literature in blockchain\nand cryptography to identify the desired characteristics of such a system. In\ncomparison to similar systems, we are able to gain increased performance by\ndesigning ours around a permissioned blockchain, allowing only a predefined\nset of nodes to write to the ledger. A prototype of the system is built on top\nof existing open-source software. An experimental evaluation using different\nquorum sizes of the prototype is also presented.
Blockchain is the technology behind the Bitcoin, it was introduced in the year 2009 by an anonymous person named Satoshi Nakamoto. This technology showed a new way in which financial transaction are possible without any centralized entity involved along with the participating entity. Blockchain technology can be useful in managing supply chain effectively using distributed ledger technology. Distributed ledger spans the identical copy of it"s ledger which is spanned across all the node in the blockchain network.
Bu çalışmada her geçen gün ilgiyle izlenmeye devam edilen sanal para birimi Bitcoin’de çoklu balonların varlığı Phillips, Shi ve Yu (2015) tarafından geliştirilen GSADF birim kök testi ve kritik değerlerin tespitinde her türlü değişen varyans problemini hesaba katarak işlem yapan Harvey, Leybourne, Sollis ve Taylor (2016) tarafından geliştirilen metot takip edilerek araştırılmıştır. Veri seti 16.07.2010 ve 31.12.2017 tarihleri arasında günlük bazdaki 24 saatlik ortalama Bitcoin fiyatlarından oluşmaktadır. Yapılan analizler sonucunda söz konusu veri aralığının büyük bir kısmında Bitcoin fiyatlarında çoklu balonların varlığı görülmüştür