The distributed ledger technology attracts increasing
attention, especially in the fi-nancial industry. The
contribution attempts to provide a brief overview of ongoing
efforts to apply this technological phenomenon on various
aspects of financial services and further investigates the role
of regulation in regard to this technology with primary focus
on the European concept of smart regulation.
Abstrak : Seiring Perkembangan teknologi, Pembelian pulsa sudah mengalami perkembangan pesat diiringi dengan perkembangan internet salah satunya yaitu perkembangan mata uang digital terutama bitcoin. Bitcoin adalah mata uang virtual yang dikembangkan pada tahun 2009 oleh seseorang dengan nama samaran Satoshi Nakamoto. Mata uang ini seperti halnya Rupiah atau Dollar, namun hanya tersedia di dunia digital. Tidak seperti mata uang pada umumnya, bitcoin tidak tergantung dengan mempercayai penerbit utama. Bitcoin menggunakan sebuah database yang didistribusikan dan menyebar ke node-node dari sebuah jaringan P2P ke jurnal transaksi, dan menggunakan kriptografi untuk menyediakan fungsi-fungsi keamanan dasar Lewat aplikasi penjualan pulsa dengan bitcoin ini memudahkan masyarakat membeli pulsa dengan menggunakan bitcoin melalui sarana website yang bisa di akses melalui perangkat komputer ataupun tablet PC yang mendukung web browser yang terkoneksi internet. Kata Kunci : Penjualan, Pulsa, Bitcoin, Codeigniter, PHP, MySQL.
Steve Huckle, Martin White, Rituparna Bhattacharya
In this paper, we discuss an application that uses blockchain technology to transfer fiat money into a cryptocurrency — Ether. A typical use of this technology could be to become a component of a larger system, whereby, after traveling, a customer can exchange leftover foreign currency for their local denomination. However, a more interesting application could be to convert fiat money into a cryptocurrency to facilitate a demonetisation scheme, such as that implemented recently in India. In the latter context, we describe the development of our blockchain application against the ramifications of demonetisation and whether the Indian government could have augmented that scheme through technology such as ours. We discuss why the Indian government has not contemplated such a measure, which also leads to a discussion of whether they might have considered adopting their own cryptocurrency. However, even though the Indian public seems willing to adopt the technology, we find that unlikely. Finally, we show that our application demonstrates that fiat money to cryptocurrency conversion is technically feasible, but the Indian government is unlikely to consider such technology due to issues surrounding monetary sovereignty.
Andrew Miller, Iddo Bentov, Surya Bakshi, Ranjit Kumaresan · 5 authors
Bitcoin, Ethereum and other blockchain-based cryptocurrencies, as deployed today, cannot scale for wide-spread use. A leading approach for cryptocurrency scaling is a smart contract mechanism called a payment channel which enables two mutually distrustful parties to transact efficiently (and only requires a single transaction in the blockchain to set-up). Payment channels can be linked together to form a payment network, such that payments between any two parties can (usually) be routed through the network along a path that connects them. Crucially, both parties can transact without trusting hops along the route. In this paper, we propose a novel variant of payment channels, called Sprites, that reduces the worst-case "collateral cost" that each hop along the route may incur. The benefits of Sprites are two-fold. 1) In Lightning Network, a payment across a path of $\ell$ channels requires locking up collateral for $Θ(\ellΔ)$ time, where $Δ$ is the time to commit an on-chain transaction. Sprites reduces this cost to $O(\ell + Δ)$. 2) Unlike prior work, Sprites supports partial withdrawals and deposits, during which the channel can continue to operate without interruption. In evaluating Sprites we make several additional contributions. First, our simulation-based security model is the first formalism to model timing guarantees in payment channels. Our construction is also modular, making use of a generic abstraction from folklore, called the "state channel," which we are the first to formalize. We also provide a simulation framework for payment network protocols, which we use to confirm that the Sprites construction mitigates against throughput-reducing attacks.
Andrew Miller, Iddo Bentov, Ranjit Kumaresan, Christopher Cordi · 5 authors
Bitcoin, Ethereum and other blockchain-based cryptocurrencies, as deployed\ntoday, cannot scale for wide-spread use. A leading approach for cryptocurrency\nscaling is a smart contract mechanism called a payment channel which enables\ntwo mutually distrustful parties to transact efficiently (and only requires a\nsingle transaction in the blockchain to set-up). Payment channels can be linked\ntogether to form a payment network, such that payments between any two parties\ncan (usually) be routed through the network along a path that connects them.\nCrucially, both parties can transact without trusting hops along the route.\n In this paper, we propose a novel variant of payment channels, called\nSprites, that reduces the worst-case "collateral cost" that each hop along the\nroute may incur. The benefits of Sprites are two-fold. 1) In Lightning Network,\na payment across a path of $\\ell$ channels requires locking up collateral for\n$\\Theta(\\ell\\Delta)$ time, where $\\Delta$ is the time to commit an on-chain\ntransaction. Sprites reduces this cost to $O(\\ell + \\Delta)$. 2) Unlike prior\nwork, Sprites supports partial withdrawals and deposits, during which the\nchannel can continue to operate without interruption.\n In evaluating Sprites we make several additional contributions. First, our\nsimulation-based security model is the first formalism to model timing\nguarantees in payment channels. Our construction is also modular, making use of\na generic abstraction from folklore, called the "state channel," which we are\nthe first to formalize. We also provide a simulation framework for payment\nnetwork protocols, which we use to confirm that the Sprites construction\nmitigates against throughput-reducing attacks.\n
This paper critiques blockchain-based “smart contracts,” which aim to automatically and securely execute obligations without reliance on a centralized enforcement authority. Though smart contracts do have some features that might serve the goals of social justice and fairness, I suggest that they are based on a thin conception of what law does, and how it does it. Smart contracts focus on the technical form of contract to the exclusion of the social contexts within which contracts operate, and the complex ways in which people use them. In the real world, contractual obligations are enforced through all kinds of social mechanisms other than formal adjudication—and contracts serve many functions that are not explicitly legal in nature, or even designed to be formally enforced. I describe three categories of contracting practices in which people engage (the inclusion of facially unenforceable terms, the inclusion of purposefully underspecified terms, and willful nonenforcement of enforceable terms) to illustrate how contracts actually “work.” The technology of smart contracts neglects the fact that people use contracts as social resources to manage their relations. The inflexibility that they introduce, by design, might short-circuit a number of social uses to which law is routinely put. Therefore, I suggest that attention to the social and relational contexts of contracting are essential considerations for the discussion, development, and deployment of smart contracts.
Simone Porru, Andrea Pinna, Michele Marchesi, Roberto Tonelli
The Blockchain technology is reshaping finance, economy, money to the extent that its disruptive power is compared to that of the Internet and the Web in their early days. As a result, all the software development revolving around the Blockchain technology is growing at a staggering rate. In this paper, we acknowledge the need for software engineers to devise specialized tools and techniques for blockchain-oriented software development. From current challenges concerning the definition of new professional roles, demanding testing activities and novel tools for software architecture, we take a step forward by proposing new directions on the basis of a curate corpus of blockchain-oriented software repositories, detected by exploiting the information enclosed in the 2016 Moody's Blockchain Report and teh market capitalization of cryptocurrencies. Ensuring effective testing activities, enhancing collaboration in large teams, and facilitating the development of smart contracts all appear as key factors in the future of blockchain-oriented software development.
The agencies of money gain new currency as new privately owned systems for creating and transferring value occupy the imagination of industry players and regulators, as well as us everyday folk. Experts have predicted the end of cash and coin almost as soon as modern governments standardized their issue. But before there was coin, there were records of transactions warranting other transactions and literally inscribing (in clay, stone, papyrus) the distributed agencies of human interaction. Asking after the infrastructures facilitating that transfer leads to the role of accounting not as a record of monetary interaction, but as that interaction itself. It is precisely a question of the distribution of agency: who shall make entries into the great ledger of human transaction and exchange? As the ledger pluralizes, who controls the cross-referencing, the gateways between newly dispersed accounts?
Thomas Dickerson, Paul Gazzillo, Maurice Herlihy, Eric Koskinen
Modern cryptocurrency systems, such as Ethereum, permit complex financial transactions through scripts called smart contracts. These smart contracts are executed many, many times, always without real concurrency. First, all smart contracts are serially executed by miners before appending them to the blockchain. Later, those contracts are serially re-executed by validators to verify that the smart contracts were executed correctly by miners. Serial execution limits system throughput and fails to exploit today's concurrent multicore and cluster architectures. Nevertheless, serial execution appears to be required: contracts share state, and contract programming languages have a serial semantics. This paper presents a novel way to permit miners and validators to execute smart contracts in parallel, based on techniques adapted from software transactional memory. Miners execute smart contracts speculatively in parallel, allowing non-conflicting contracts to proceed concurrently, and "discovering" a serializable concurrent schedule for a block's transactions, This schedule is captured and encoded as a deterministic fork-join program used by validators to re-execute the miner's parallel schedule deterministically but concurrently. Smart contract benchmarks run on a JVM with ScalaSTM show that a speedup of of 1.33x can be obtained for miners and 1.69x for validators with just three concurrent threads.
We present Bitcoin Security Tables computing the probability of success p(z,q,t) of a double spend attack by an attacker controlling a share q of the hashrate after z confirmations in time t.
This paper presents an all-passive negative feedback network that performs autonomous radio-frequency (RF) front-end beam-forming and dynamic beam-tracking toward the direction of the incident RF signal. The proposed feedback network consists of a passive RF signal processing network, voltage rectifiers, and voltage-controlled delay-line phased shifters, all of which are passive-only circuits. The negative feedback loop is realized by passive phase detection, phase-to-voltage conversion, and voltage-controlled phase shifting, achieving a large loop-gain and autonomous operation with zero DC power consumption. The nonlinear behavior of the loop is exploited to substantially expand the array field of view (FoV). A proof-of-concept broadband four-element all-passive self-steering beam-former at 5 GHz with a wide FoV is implemented in a standard 130 nm CMOS process. A high-quality four-element synthesized array factor is measured for the input progressive phase shift φinfrom -180° to 180°. When the proposed negative feedback loop is enabled, the normalized array factor is -2.87/-2.8 dB at φin= +90°/-90° with an input RF power Pin of -17 dBm/element at 5 GHz, achieving >25 dB array factor improvement over the open-loop operation. Moreover, the nonlinear feedback loop allows for significant array factor improvement even at φin= +180°/-180°. The proposed beam-former also achieves high-quality self-steering beamforming from 4 to 5.68 GHz with 34.7% fractional bandwidth. Therefore, the proof-of-concept all-passive self-steering beamformer outperforms the state-of-the-art active designs in terms of beam-forming quality, FoV, and fractional bandwidth. To the best of the authors' knowledge, this is the first demonstration of an all-passive negative feedback network for a broadband and wide FoV self-steering beam-forming with zero DC power consumption.
Resumen. Este artículo analiza la implementación de un esquema de reducción de riesgo de desastres asociados a la actividad petroquímica en la ciudad de Coatzacoalcos, en un contexto de descentralización de la gestión de riesgos. El trabajo aborda el papel de las asociaciones público-privadas y el ambiente institucional en torno a las labores locales de protección civil y gestión de riesgos. El artículo identifica los ámbitos de acción de agentes públicos y privados, y analiza el marco legal, los acuerdos políticos informales y las regulaciones fuera del ámbito legal que permiten la colaboración de estos agentes. El estudio muestra que la funcionalidad de estas asociaciones se basa en formas de confianza y colaboración que no tienen como base los principios del marco normativo establecido por el Estado y los acuerdos internacionales en la materia. El estudio concluye que los beneficios y derechos adquiridos a través de redes personales constituyen el apoyo central de este ambiente institucional. Abstract. This paper analyzes the chemical hazards-related disaster risk reduction (drr) scheme in the petrochemical industry oriented city of Coatzacoalcos (Mexico) in the context of political decentralization. This work addresses the role of public-private partnerships, as well as the institutional environment around civil protection and chemical risk management. The paper identifies the scopes of action of public and private agents, and analyzes the legal framework, the informal political agreements and the non-legal regulations that allow these agents’ collaboration. The study shows that the functionality of these partnerships is based on forms of trust that do not rely entirely on the normative framework established by State organizations and international agreements; the trust that underlies their schemes of collaboration is relatively autonomous from the bureaucratic side of this institutional environment. The study concludes that the benefits and rights accessed through personal networks are the core of the institutional environment around risk governance.
Tyler Crain, Vincent Gramoli, Mikel Larrea, Michel Raynal
This paper introduces a deterministic Byzantine consensus algorithm that relies on a new weak coordinator. As opposed to previous algorithms that cannot terminate in the presence of a faulty or slow coordinator, our algorithm can terminate even when its coordinator is faulty, hence the name weak coordinator. The key idea is to allow processes to complete asynchronous rounds as soon as they receive a threshold of messages, instead of having to wait for a message from a coordinator that may be slow. The resulting algorithm assumes partial synchrony, is resilience optimal, time optimal and does not need signatures. Our presentation is didactic: we first present a simple safe binary Byzantine consensus algorithm, modify it to ensure termination, and finally present an optimized reduction from multivalue consensus to binary consensus that may terminate in 4 message delays. To evaluate our algorithm, we deployed it on 100 machines distributed in 5 datacenters across different continents and compared its performance against the randomized solution from Mostefaoui, Moumem and Raynal [PODC14] that terminates in O(1) rounds in expectation. Our algorithm always outperforms the latter even in the presence of Byzantine behaviors. Our algorithm has a subsecond average latency in most of our geo-distributed experiments, even when attacked by a well-engineered coalition of Byzantine processes.
Tyler Crain, Vincent Gramoli, Mikel Larrea, Michel Raynal
This paper presents a new Byzantine consensus algorithm targeting consortium blockchains. To this end, it first revisits the consensus validity property by requiring that the decided value satisfies a predefined predicate, which does not systematically exclude a value proposed only by Byzantine processes, thereby generalizing the validity properties found in the literature. Then, the paper presents a simple and modular Byzantine consensus algorithm that relies neither on a leader, nor on signatures, nor on randomization. It features the fastest multivalued reduction to binary consensus we know of and a time optimal binary Byzantine consensus algorithm. The multivalued reduction runs multiple instances of binary consensus concurrently, which result in a bitmask that is then applied to a vector of multivalued proposals to filter out a valid proposed value that is decided. To ensure eventual decision deterministically, the underlying binary consensus algorithm assumes eventual synchrony.
Anh Dinh, Ji Wang, Sheng Wang, Gang Chen · 12 authors
Today's storage systems expose abstractions which are either too low-level (e.g., key-value store, raw-block store) that they require developers to re-invent the wheels, or too high-level (e.g., relational databases, Git) that they lack generality to support many classes of applications. In this work, we propose and implement a general distributed data storage system, called UStore, which has rich semantics. UStore delivers three key properties, namely immutability, sharing and security, which unify and add values to many classes of today's applications, and which also open the door for new applications. By keeping the core properties within the storage, UStore helps reduce application development efforts while offering high performance at hand. The storage embraces current hardware trends as key enablers. It is built around a data-structure similar to that of Git, a popular source code versioning system, but it also synthesizes many designs from distributed systems and databases. Our current implementation of UStore has better performance than general in-memory key-value storage systems, especially for version scan operations. We port and evaluate four applications on top of UStore: a Git-like application, a collaborative data science application, a transaction management application, and a blockchain application. We demonstrate that UStore enables faster development and the UStore-backed applications can have better performance than the existing implementations.
This chapter explores the overall costs of the Wesleyan Methodist chapel estate, and the impact which this financial challenge had upon the Connexion, drawing comparisons with other approaches including that of Anglicanism. Chapel construction triggered the movement’s 1760s financial crisis, and led to the decentralization of responsibility for chapel debt, though with some national oversight. This succeeded in keeping total chapel debt manageable. The scale and timing of chapel construction reflected membership growth, but in some regions did not keep pace. Resources were available, from the growing number of wealthier Methodists, and sometimes from Connexional grants. But there were tensions between the ambitions of local societies and concerns over debt, and between ensuring accessibility to the Gospel, and dependence on the wealthy. By 1800, chapel financing formed part of a complex Connexional financial regime.
Countries like Estonia, Norway or Australia developed electronic voting systems, which could be used to realize parliamentary elections with the help of personal computers and the Internet. These systems are completely different in their design and their way to solve the same problem. In this thesis, we analyze some of the largest real-world systems, describe their building blocks and their general design to focus on possible problems in these electronic voting systems. Furthermore, we present a template for an e-voting system, which we designed to try to fulfill the preliminaries and requirements of a secure electronic voting system. We use the experiences and the building blocks of existing systems to combine them to another more secure system. Afterwards, we compare our concept with real-world systems to evaluate the fulfillments of the requirements. Conclusively, we discuss the occurring problems when designing a secure system. Peer-to-peer networks provide many advantages, like decentralization, which might be applicable to electronic voting systems. Therefore, we take a look on the distributed database called blockchain and the usage in a peer-to-peer voting system. Our contribution to this topic is a modification of the proof-of-stake, which enables the usage of common devices, like smartphones or tablets, for the blockchain verification and inclusion of new ballots to the chain. This proof does not need much computing power and has a lower carbon footprint than the proof-of-work in the Bitcoin protocol.
We correct the double spend race analysis given in Nakamoto’s foundational Bitcoin article and find the exact closed-form formula for the probability of success of a double spend attack using the regularized incomplete beta function. We give the first proof of its exponential decay on the number of confirmations, often cited in the literature, and find an asymptotic formula. Larger number of confirmations are required compared to those given by Nakamoto. We also compute this probability conditional to the knowledge of the time of the confirmations. This provides a finer risk analysis than the classical one.
OBJECTIVE: To illustrate the ability of hierarchical Bayesian spatio-temporal models in capturing different geo-temporal structures in order to explain hospital risk variations using three different conditions: Percutaneous Coronary Intervention (PCI), Colectomy in Colorectal Cancer (CCC) and Chronic Obstructive Pulmonary Disease (COPD). RESEARCH DESIGN: This is an observational population-based spatio-temporal study, from 2002 to 2013, with a two-level geographical structure, Autonomous Communities (AC) and Health Care Areas (HA). SETTING: The Spanish National Health System, a quasi-federal structure with 17 regional governments (AC) with full responsibility in planning and financing, and 203 HA providing hospital and primary care to a defined population. METHODS: A poisson-log normal mixed model in the Bayesian framework was fitted using the INLA efficient estimation procedure. MEASURES: The spatio-temporal hospitalization relative risks, the evolution of their variation, and the relative contribution (fraction of variation) of each of the model components (AC, HA, year and interaction AC-year). RESULTS: Following PCI-CCC-CODP order, the three conditions show differences in the initial hospitalization rates (from 4 to 21 per 10,000 person-years) and in their trends (upward, inverted V shape, downward). Most of the risk variation is captured by phenomena occurring at the HA level (fraction variance: 51.6, 54.7 and 56.9%). At AC level, the risk of PCI hospitalization follow a heterogeneous ascending dynamic (interaction AC-year: 17.7%), whereas in COPD the AC role is more homogenous and important (37%). CONCLUSIONS: In a system where the decisions loci are differentiated, the spatio-temporal modeling allows to assess the dynamic relative role of different levels of decision and their influence on health outcomes.