Blockchain Papers

Yunsen Wang

No abstract is available for this record.

V. S. Dhillon, David Metcalf, Max Hooper

In this chapter, we focus on three new technologies that have significantly advanced our understanding of blockchain-enabled applications and opened up several new avenues for research. We begin our discussion with EOS, an Ethereum competitor built with an OS inspired architecture and platform-support design philosophy. It uses a new consensus mechanism called delegated proof-of-stake to enable rapid transaction verification and a continuous cycle of voting for delegates that support the network. The message passing protocols implemented in EOS are very advanced, allowing automated response handlers and action triggers on message delivery. They make up most of the smart contract system. There is also support for parallel lockless execution of smart contract instructions across the network, massively reducing latency in communication and state updates.

Emmanuelle Anceaume, Romaric Ludinard, Maria Potop-Butucaru, Frédéric Tronel

No abstract is available for this record.

Mukesh Thakur

Over past decade cloud services have enabled individuals and organizations to perform different types of tasks such as online storage, email services, on-demand movies and TV shows. The cloud services has also enabled on-demand deployment of applications, at cheap cost with elastic and scalable, fault tolerant system. These cloud services are offered by cloud providers who use authentication, authorization and accounting framework based on client-server model. Though this model has been used over decades, study shows it is vulnerable to different hacks and it is also inconvenient to use for the end users. In addition, the cloud provider has total control over user data which they are able to monitor, trace, leak and even modify at their will. Thus, the user data ownership, digital identity and use of cloud services has raised privacy and security concern for the users. In this thesis, Blockchain and its applications are studied and alternative model for authentication, authorization and accounting is proposed based on Ethereum Blockchain. Furthermore, a prototype is developed which enables users to consume cloud services by authenticating, authorizing and accounting with a single identity without sharing any private user data. Experiments are run with the prototype to verify that it works as expected. Measurements are done to assess the feasibility and scalability of the solution. In the final part of the thesis, pros and cons of the proposed solution are discussed and perspectives for further research are sketched.

Angelica Lo Duca, Clara Bacciu, Andrea Marchetti

No abstract is available for this record.

Yoshiaki Kawase, Shoji Kasahara

No abstract is available for this record.

Sergi Delgado-Segura, Cristina Pérez‐Solà, Guillermo Navarro‐Arribas, Jordi Herrera‐Joancomartí

Bitcoin relies on the Unspent Transaction Outputs (UTXO)
\nset to efficiently verify new generated transactions. Every unspent output,
\nno matter its type, age, value or length is stored in every full node.
\nIn this paper we introduce a tool to study and analyze the UTXO set,
\nalong with a detailed description of the set format and functionality. Our
\nanalysis includes a general view of the set and quantifies the difference
\nbetween the two existing formats up to the date. We also provide an accurate
\nanalysis of the volume of dust and unprofitable outputs included
\nin the set, the distribution of the block height in which the outputs where
\nincluded, and the use of non-standard outputs.

Hanna Hałaburda

Most of the suggested benefits of blockchain technologies do not come from elements unique to the blockchain.

Luciano García‐Bañuelos, Alexander Ponomarev, Marlon Dumas, Ingo Weber

Blockchain technology enables the execution of collaborative business processes involving untrusted parties without requiring a central authority. Specifically, a process model comprising tasks performed by multiple parties can be coordinated via smart contracts operating on the blockchain. The consensus mechanism governing the blockchain thereby guarantees that the process model is followed by each party. However, the cost required for blockchain use is highly dependent on the volume of data recorded and the frequency of data updates by smart contracts. This paper proposes an optimized method for executing business processes on top of commodity blockchain technology. The paper presents a method for compiling a process model into a smart contract that encodes the preconditions for executing each task in the process using a space-optimized data structure. The method is empirically compared to a previously proposed baseline by replaying execution logs, including one from a real-life business process, and measuring resource consumption.

Lakshmana Kumar, Shireesha Yeddu

Today, with the use of Internet, a huge volume of data been generated in the form of transactions, logs etc. As assessed, 90% of total volume of data generated since evaluation of Computers is from last 3 years only. It's because of advancements in Data storage, global connectivity with Internet high speed, mobile applications usage and IoT. BigData Technologies aims at processing the BigData for deriving trend analysis and business usage from its BigData information. This paper highlights some of the security concerns that Hadoop implemented in its current version and need for some of the enhancements along with a new methodology such as Electronic Currency (BitCoin) and BlockChain functionality. And also emphasises on why and how BitCoin and BlockChain can fit in Hadoop Eco-Systems and their possible advantages and disadvantages. Especially, in validating and authorizing business transactions with some mathematical cryptographic techniques like hashcode with the help of BlockChain Miners.

Roman Matzutt, Oliver Hohlfeld, Martin Henze, Robin Rawiel · 6 authors

As transaction fees skyrocket today, blockchains become increasingly expensive, hurting their adoption in broader applications. This work tackles the saving of transaction fees for economic blockchain applications. The key insight is that other than the existing "default'' mode to execute application logic fully on-chain, i.e., in smart contracts, and in fine granularity, i.e., user request per transaction, there are alternative execution modes with advantages in cost-effectiveness. On Ethereum, we propose a holistic middleware platform supporting flexible and secure transaction executions, including off-chain states and batching of user requests. Furthermore, we propose control-plane schemes to adapt the execution mode to the current workload for optimal runtime cost. We present a case study on the institutional accounts (e.g., coinbase.com) intensively sending Ether on Ethereum blockchains. By collecting real-life transactions, we construct workload benchmarks and show that our work saves 18%\sim 47%18%-47% per invocation than the default baseline while introducing 1.81%\sim 16.59%1.81%-16.59% blocks delay.

Dimaz Ankaa Wijaya

Bitcoin is a digital payment system empowered by a distributed database called blockchain. The blockchain is an open ledger containing records of every transaction within Bitcoin system maintained by Bitcoin nodes all over the world. Because of its availability and robustness, the blockchain could be utilized as a record-keeping tool for information not related to any Bitcoin transactions. We propose a method of utilizing the blockchain of Bitcoin system to publish information by embedding an arbitrary size of data into Bitcoin transactions. By publishing information using the blockchain, the information also carries the characteristics of Bitcoin transaction: anonymous, decentralized, and permanent. The proposed protocol could be used to extend the functionality of asset management systems which are limited to a maximum of 80 bytes data. The proposed method also offers an efficiency of the transaction fee by 18 percent compared to Bitcoin Messaging protocol.

Gerrit Anders, Patrick Lehner

In many technical systems, such as smart grids, the central issue is to enable multiple devices to solve a resource allocation problem. Because centralized solutions usually struggle with an increasing number of agents, regio-central or completely decentralized mechanisms, which solve the problem in a cooperative manner, are of utmost interest in large-scale systems. In this paper, we present a coalition-based algorithm that allows a multi-agent system to cooperatively solve a single-resource allocation problem. Our approach uses self-organization to dynamically identify groups of agents whose decisions have to be coordinated, while optimistically refraining from coordinating the actions between these coalitions. The basic idea of our algorithm is inspired by the way pressure compensates in gas or fluid pipeline systems. It therefore operates on the basis of an overlay network, i.e., a graph, that defines a topology of possible resource flows as well as resistances in the form of costs of transferring a resource from one agent to another. Throughout this paper, the problem of compensating for imbalances between energy production and consumption in autonomous power management systems serves to illustrate our algorithm and results.

José Gladistone da Rocha, Carlo Kleber da Silva Rodrigues

O protocolo Bitcoin foi proposto há cerca de seis anos e sua adoção para a implementação de um sistema de transações financeiras tem se mostrado crescente em diferentes países no mundo. No entanto, há poucas obras na literatura voltadas ao esclarecimento de todas as etapas que envolvem o processo de negócio desse sistema. Neste contexto, este artigo tem o objetivo de apresentar a modelagem deste processo de negócio bem como detalhar como ocorre o seu processo primário Gerenciar Pagamento. Para tanto, são empregadas técnicas de Engenharia de Software e de Business Process Model and Notation. Os modelos desenvolvidos permitem mapear problemas críticos do sistema, explicitando em quais etapas do processo de negócio eles incidem. Isso viabiliza principalmente a proposição mais efetiva de soluções e otimizações com vistas à maior robustez global do sistema.

Ikuo Magaki, Moein Khazraee, Luis Vega Gutierrez, Michael Taylor

GPU and FPGA-based clouds have already demonstrated the promise of accelerating computing-intensive workloads with greatly improved power and performance. In this paper, we examine the design of ASIC Clouds, which are purpose-built datacenters comprised of large arrays of ASIC accelerators, whose purpose is to optimize the total cost of ownership (TCO) of large, high-volume chronic computations, which are becoming increasingly common as more and more services are built around the Cloud model. On the surface, the creation of ASIC clouds may seem highly improbable due to high NREs and the inflexibility of ASICs. Surprisingly, however, large-scale ASIC Clouds have already been deployed by a large number of commercial entities, to implement the distributed Bitcoin cryptocurrency system. We begin with a case study of Bitcoin mining ASIC Clouds, which are perhaps the largest ASIC Clouds to date. From there, we design three more ASIC Clouds, including a YouTube-style video transcoding ASIC Cloud, a Litecoin ASIC Cloud, and a Convolutional Neural Network ASIC Cloud and show 2-3 orders of magnitude better TCO versus CPU and GPU. Among our contributions, we present a methodology that given an accelerator design, derives Pareto-optimal ASIC Cloud Servers, by extracting data from place-and-routed circuits and computational fluid dynamic simulations, and then employing clever but brute-force search to find the best jointly-optimized ASIC, DRAM subsystem, motherboard, power delivery system, cooling system, operating voltage, and case design. Moreover, we show how data center parameters determine which of the many Pareto-optimal points is TCO-optimal. Finally we examine when it makes sense to build an ASIC Cloud, and examine the impact of ASIC NRE.

Ikuo Magaki, Moein Khazraee, Luis Vega Gutierrez, Michael Taylor

GPU and FPGA-based clouds have already demonstrated the promise of accelerating computing-intensive workloads with greatly improved power and performance. In this paper, we examine the design of ASIC Clouds, which are purpose-built datacenters comprised of large arrays of ASIC accelerators, whose purpose is to optimize the total cost of ownership (TCO) of large, high-volume chronic computations, which are becoming increasingly common as more and more services are built around the Cloud model. On the surface, the creation of ASIC clouds may seem highlyimprobable due to high NREs and the inflexibility of ASICs. Surprisingly, however, large-scale ASIC Clouds have already been deployed by a large number of commercial entities, to implement the distributed Bitcoin cryptocurrency system. We begin with a case study of Bitcoin mining ASIC Clouds, which are perhaps the largest ASIC Clouds to date. From there, we design three more ASIC Clouds, including a YouTube-style video transcoding ASIC Cloud, a Litecoin ASIC Cloud, and a Convolutional Neural Network ASIC Cloud and show 2-3 orders of magnitude better TCO versus CPU and GPU. Among our contributions, we present a methodology that given an accelerator design, derives Pareto-optimal ASIC Cloud Servers, by extracting data from place-and-routed circuits and computational fluid dynamic simulations, and then employing clever but brute-force search to find the best jointly-optimized ASIC, DRAM subsystem, motherboard, power delivery system, cooling system, operating voltage, and case design. Moreover, we show how data center parameters determine which of the many Pareto-optimal points is TCO-optimal. Finally we examine when it makes sense to build an ASIC Cloud, and examine the impact of ASIC NRE.

Yu Zhang, Jiangtao Wen

No abstract is available for this record.

Shoji Kasahara, Jun Kawahara

In Bitcoin system, transactions are prioritized according to attributes such as the remittance amount and transaction fees, and transactions with low priority are likely to wait for confirmation. Because the demand of micro payment in Bitcoin is expected to increase due to low remittance cost, it is important to quantitatively investigate how the priority mechanism of Bitcoin affects the transaction-confirmation time. In this paper, we analyze the transaction-confirmation time by queueing theory. We model the transaction priority mechanism of Bitcoin as a priority queueing system with batch service, deriving the mean transaction-confirmation time. Numerical examples show how the demand of transactions of low remittance amount affects the transaction-confirmation time. We also consider the effect of the maximum block size on the transaction-confirmation time.

Xiwei Xu, Cesare Pautasso, Liming Zhu, Vincent Gramoli · 7 authors

Blockchain is an emerging technology for decentralized and transactional data sharing across a large network of untrusted participants. It enables new forms of distributed software architectures, where components can find agreements on their shared states without trusting a central integration point or any particular participating components. Considering the blockchain as a software connector helps make explicitly important architectural considerations on the resulting performance and quality attributes (for example, security, privacy, scalability and sustainability) of the system. Based on our experience in several projects using blockchain, in this paper we provide rationales to support the architectural decision on whether to employ a decentralized blockchain as opposed to other software solutions, like traditional shared data storage. Additionally, we explore specific implications of using the blockchain as a software connector including design trade-offs regarding quality attributes.

Alexander Chepurnoy, Mario Larangeira, Alexander Ojiganov

Bitcoin is the first successful decentralized global digital cash system. Its mining process requires intense computational resources, therefore its usefulness remains a disputable topic. We aim to solve three problems with Bitcoin and other blockchain systems of today by repurposing their work. First, space to store a blockchain is growing linearly with number of transactions. Second, a honest node is forced to be irrational regarding storing full blocks by a way implementations are done. Third, a trustless bootstrapping process for a new node involves downloading and processing all the transactions ever written into a blockchain. In this paper we present a new consensus protocol for Bitcoin-like peer-to-peer systems where a right to generate a block is given to a party providing non-interactive proofs of storing a subset of the past state snapshots. Unlike the blockchain systems in use today, a network using our protocol is safe if the nodes prune full blocks not needed for mining. We extend the GKL model to describe our Proof-of-Work scheme and a transactional model modifications needed for it. We provide a detailed analysis of our protocol and proofs of its security.

Wei‐Tek Tsai, R. Blower, Yan Zhu, Lian Yu

Blockchain (BC) has received significant attention recently. This paper presents system-related issues for BCs for financial applications. This paper first presents the design of a BC without consideration of any application scenarios, and issues such as performance, security, performance and scalability lead to specific BC designs. Sample BC scenarios are analyzed and these lead to additional BC designs. Specifically, two new kinds of BC emerge: for storing information at transactional level, for storing account information. By splitting traditional BCs into these two BCs allow one to optimize the system with respect to scalability and privacy.

Fu Hou, Xinjun Mao

Summary With the rapid development and application of cloud computing, there exist plenty of clouds that are distributed on the open Internet, decentralized in the management, evolving with various services providing diverse functionalities and QoS. Moreover, because of the potential correlativity of cloud services and the dynamic of tenants' requirements, these services in multiple clouds are expected to be effectively managed in an autonomic and transparent way so that tenants can obtain continuous and efficient services. To this end, this paper proposes an approach based on self‐organizing multi‐agent system to achieving cross‐clouds services management, including the service provision at the tenant‐end and services aggregation at the cloud‐end. In this approach, the clouds services are managed by a series of autonomous agents that are capable of autonomously accessing managed services. They can interact with each other to obtain macro‐level services aggregation in terms of self‐organization to adapt to the changes of both tenants' requirements and cloud services. The paper details the architecture, mechanisms, and algorithms to implement the aggregation and provision of services in cross‐clouds. We also develop relevant cross‐clouds services management platform called as CCloudMan, with which several experiments based on the public data sets have been conducted and the experimental results show the efficiency and usability of our proposed approach. Copyright © 2016 John Wiley & Sons, Ltd.

Renlord Yang

© 2016 Renlord Yang

Hitesh Malviya

We need to shift our perspective of blockchain, from just the programmable ledger, to a networked infrastructure of computing machinery. Doing so, we could easily visualize how computer programs will operate over this new infrastructure, which is presently being used for transaction validations. We cannot take the cloud computing analogy literally because the blockchain infrastructure can’t replace cloud computing completely. Although, it unbundles and democratizes cloud computing. Thus, companies and individual consumers can soon keep their data in distributed cloud network based on highly secure blockchain technology.