Blockchain Papers

Víctor Pérez, Maximiliano Klemen, Pedro López-García, José F. Morales · 5 authors

No abstract is available for this record.

Thomas Genet, Thomas Jensen, Justine Sauvage

Ethereum is a decentralized blockchain technology equipped with so-called Smart Contracts. A contract is a program whose code is public, which can be triggered by any user, and whose actual execution is performed by miners participating in Ethereum. Miners execute the contract on the Ethereum Virtual Machine (EVM) and apply its effect by adding new blocks to the blockchain. A contract that takes too much time to be processed by the miners of the network may result into delays or a denial of service in the Ethereum system. To prevent this scenario, termination of Ethereum's Smart Contracts is ensured using a gas mechanism. Roughly, the EVM consumes gas to process each instruction of a contract and the gas provided to run a contract is limited. This technique could make termination of contracts easy to prove but the way the official definition of the EVM specifies gas usage makes the proof of this property non-trivial. EVM implementations and formal analysis techniques of EVM's Smart Contracts use termination of contracts as an assumption, so having a formal proof of termination of contracts is crucial. This paper presents a mechanized, formal, and general proof of termination of Smart Contracts based on a measure of EVM call stacks.

Yibin Xu, Yangyu Huang

The exponential growth of the blockchain size has become a major contributing factor that hinders the decentralisation of blockchain and its potential implementations in data-heavy applications. In this paper, we propose segment blockchain, an approach that segmentises blockchain and enables nodes to only store a copy of one blockchain segment. We use \emph{PoW} as a membership threshold to limit the number of nodes taken by an Adversary---the Adversary can only gain at most $n/2$ of nodes in a network of $n$ nodes when it has $50\%$ of the calculation power in the system (the Nakamoto blockchain security threshold). A segment blockchain system fails when an Adversary stores all copies of a segment, because the Adversary can then leave the system, causing a permanent loss of the segment. We theoretically prove that segment blockchain can sustain a $(AD/n)^m$ failure probability when the Adversary has no more than $AD$ number of nodes and every segment is stored by $m$ number of nodes. The storage requirement is mostly shrunken compared to the traditional design and therefore making the blockchain more suitable for data-heavy applications.

Ch. V. N. U. Bharathi Murthy, M. Lawanya Shri, Seifedine Kadry, Sangsoon Lim

Blockchain technology is a distributed ledger with records of data containing all details of the transactions carried out and distributed among the nodes present in the network. All the transactions carried out in the system are confirmed by consensus mechanisms, and the data once stored cannot be altered. Blockchain technology is the necessary technology behind Bitcoin, which is a popular digital Cryptocurrency. “Cloud computing is a practice of using a network of remote servers hosted on the internet to store, manage, and process data, rather than a local server or a personal computer.” It is still facing many challenges like data security, data management, compliance, reliability. In this article, we have mentioned some of the significant challenges faced by the cloud and proposed solutions by integrating it with blockchain technology. We tend to investigate a brief survey on earlier studies focused on blockchain integrating with the cloud to depict their supremacy. In this survey, we have also developed architecture integrating blockchain with cloud revealing the communication between blockchain and cloud.

N. Sánchez-Gómez, Jesús Torres Valderrama, J. A. García-García, Javier Gutiérrez · 5 authors

Blockchain technology promises to spark a real revolution. One of most important concepts associated with this technology is smart contracts, which enable the automatic execution of agreements and augur a world without intermediaries. The conditions and rules of “contracts” are established in a computer codes and trust is enforced by consensus among the participants. One relevant feature associated with smart contract is the immutability property, which establishes the non-alteration of blockchain network data after the clauses of the contract are been approved by all parties or entities involved. For this reason, smart contract development requires more effort and care than the development of other common programs. They require systematic mechanisms to collect requirements and functional specifications. In addition, it is necessary to verify and validate the agreed functionality and the implemented code before they are deployed in the blockchain platform. This article presents a systematic literature review of primary studies in the field of Software Development Life Cycle, focusing on model-based software design and testing in the blockchain domain of smart contracts. This research aims to identify gaps and/or opportunities for further research. After carried out this review, it was observed that no clear methodology exists for evaluating and validating the quality either of this software or the overall development process. This means that software developers may implement smart contract code in which bugs and serious security vulnerabilities appear when the software is delivered to their customers.

Dominik Roeck

Distributed ledger technology (DLT) appears to be one of the most promising technologies in the field of supply chain management (SCM). However, as the technology is still evolving, only limited empirical evidence has been analyzed, managers and scientific scholars alike seek to understand how DLT can help improving SCM. This study aims to shed light into the current DLT applications in SCM to identify the foundation of the technology for SCM and uncover what DLT brings to the table. It develops seven foundational characteristics of DLT in SCM that describe both the nature of DLT and its characteristics for SCM. The study reveals that DLTs are interorganizational information systems that are diverse in their realizations and enable modular platform ecosystems. Nowadays application in SCM build on steady data availability, selective transparency, high authenticity and a source of mutual trust.

Kentaroh Toyoda, Koji Machi, Yutaka Ohtake, Allan N. Zhang

Private Ethereum blockchain-based systems are demanded in many industry sectors. However, the throughput performance of these systems does not meet their expectations. Many researchers have analyzed the performance of private blockchains, but their studies have failed to analyze root causes. In this paper, we perform a deep function-level bottleneck analysis for the private Ethereum blockchain. As the Ethereum client application is developed with golang, we leverage pprof, which is a resource-profiling tool for golang, and custom golang functions to measure the time taken by functions. To easily configure parameters and conduct our test, we code a shell script that automates the building process of a private Ethereum blockchain with docker containers. We conducted a series of experiments and identified the bottleneck function that is called every time a transaction arrives at an Ethereum node. In addition, we also found that the multi-threading is not well utilized, meaning that there is much room for improvement.

Markus Schinle, Christina Erler, Wilhelm Stork

Costs, risks and inefficiencies in Collaborative Networks (CNs) resulting from information asymmetries have been discussed in the scientific community for years. In this work, supply chain networks, as common representative of CNs, are used as object of investigation. Therein, problems and requirements of interorganizational information exchange are elaborated as well as the potential role Distributed Ledger Technology (DLT) could play to address them. As major challenge, convincing all relevant network partners to resolve asymmetric information by sharing sensitive data is identified. To face this issue, the value of shared information is prioritized as a motivational aspect. Finally, we propose a search process to systematically assess the benefits of information sharing in collaborative networks. To coordinate and implement this process regarding the derived requirements of CNs we propose system components based on DLT design patterns.

Caixiang Fan, Sara Ghaemi, Hamzeh Khazaei, Petr Musı́lek

Blockchain has been envisioned to be a disruptive technology with potential for applications in various industries. As more and more different blockchain platforms have emerged, it is essential to assess their performance in different use cases and scenarios. In this paper, we conduct a systematic survey on the blockchain performance evaluation by categorizing all reviewed solutions into two general categories, namely, empirical analysis and analytical modelling. In the empirical analysis, we comparatively review the current empirical blockchain evaluation methodologies, including benchmarking, monitoring, experimental analysis and simulation. In analytical modelling, we investigate the stochastic models applied to performance evaluation of mainstream blockchain consensus algorithms. Through contrasting, comparison and grouping different methods together, we extract important criteria that can be used for selecting the most suitable evaluation technique for optimizing the performance of blockchain systems based on their identified bottlenecks. Finally, we conclude the survey by presenting a list of possible directions for future research.

Qiheng Zhou, Huawei Huang, Zibin Zheng, Jing Bian

Blockchain-based decentralized cryptocurrencies have drawn much attention and been widely-deployed in recent years. Bitcoin, the first application of blockchain, achieves great success and promotes more development in this field. However, Bitcoin encounters performance problems of low throughput and high transaction latency. Other cryptocurrencies based on proof-of-work also inherit the flaws, leading to more concerns about the scalability of blockchain. This paper attempts to cover the existing scaling solutions for blockchain and classify them by level. In addition, we make comparisons between different methods and list some potential directions for solving the scalability problem of blockchain.

Grant Chung, Luc Desrosiers, Manav Gupta, Andrew Sutton · 7 authors

Blockchain scalability can be complicated and costly. As enterprises begin to adopt blockchain technology to solve business problems, there are valid concerns if blockchain applications can support the transactional demands of production systems. In fact, the multiple distributed components and protocols that underlie blockchain applications makes performance optimization a non-trivial task. Blockchain performance optimization and scalability require a methodology to reduce complexity and cost. Furthermore, existing performance results often lack the requirements, load, and infrastructure of a production application. In this paper, we first develop a methodical approach to performance tuning enterprise blockchain applications to increase performance and transaction capacity. The methodology is applied to an enterprise blockchain-based application (leveraging Hyperledger Fabric) for performance tuning and optimization with the goal of bridging the gap between laboratory and production deployed system performance. We then present extensive results and analysis of our performance testing for on-premise and cloud deployments, in which we were able to scale the application from 30 to 3000 TPS without forking the Hyperledger Fabric source code and maintaining a reasonable infrastructure footprint. We also provide blockchain application and platform recommendations for performance improvement.

Tinu N. S.

Data analytics has captured attention of both researchers as well as business organizations, since a long time now, as the knowledge or information getting analyzed and evolved is priceless in upbringing the business. Blockchain is the latest technology which is getting adopted at a faster rate due to its unique properties. This paper focuses mainly on data models, and some tools used for data analytics being used in blockchain environment. Public blockchain is an open ledger platform which allows to perform data analytics.

Haoyu Wang, Lina Wang, Zhichao Zhou, Xueqiang Tao · 6 authors

Fog computing makes up for the shortcomings of cloud computing. It brings many advantages, but various peculiarities must be perceived, such as security, resource management, storage, and other features at the same time. This paper investigates the resource contribution model between the fog node and cloud or users when fog computing introduces blockchain. The proposed model practices the reward and punishment mechanism of the blockchain to boost the fog nodes to contribute resources actively. The behavior of the fog node in contributing resources and the completion degree of the task also for contributing resources are packaged into blocks and stored in the blockchain system to form a transparent, open, and tamper-free service evaluation index. The differential game method is employed to model and solve the above process and address the interaction between the optimal resource contribution strategy of the fog node and the optimal benefit under the optimal resource contribution strategy. Indirectly, this service evaluation index also brings long-term economic benefits to fog service providers. Besides, taking advantage of the performance characteristics of the collective maintenance of blockchain and the ability to establish a credible consensus mechanism in an untrusted environment, fog computing nodes, under the proposed architecture, can have specific security protection capabilities.

Authors unavailable

There are many consensus algorithms that exist in parallel computing that involve multiple computing units like virtual machines which make use of available resources and arrive at a single agreeable state for the combined system. This is done on the basis of voting which itself branches into several arrangements like voting, functions of central tendencies, weighted functions of central tendencies etc. Some applications that consensus algorithms try to cover are: deciding on transaction operations (read, write, commit); deciding on node leaders of a system; maintaining replicas in the state of a machine (also called a state machine) and creating consistency between them. Some common algorithms of this type are Proof of Work algorithm (PoW), the practical Byzantine fault tolerance algorithm (PBFT), the proof-of-stake algorithm (PoS) and the delegated proof-of-stake algorithm (DPoS), Paxos algorithm and the Raft consensus algorithm.

Eric Mantelaers, Martijn Zoet, Koen Smit

The current standard in accounting practice is the double-entry approach. Basis of the double-entry approach is that every financial event brings two equal and offsetting entries. Since these financial events are not automatically confirmed by both parties, the accounting quality can be improved. The blockchain mechanism possibly offers a different take on accounting. Based on an experimentation approach, data was collected to compare the double-entry method with the blockchain-based triple-entry method. The results show that the main difference concerns determining the completeness of the financial statement items. In the situation of double-entry accounting, segregation of duties is applied to do so. In the blockchain situation, the underlying mechanism of the blockchain already ensures this.

Filipi Rydzi, Hong‐Linh Truong

The integration of Internet of Things (IoT) and cloud services with edge technologies has enabled the development of many new types of edge services, which leverage blockchain features for cross-organizational, traceable and verifiable records. However, developing such edge services with blockchain features requires not only knowledge about complex blockchain technologies but also how blockchain technologies coexist with edge computing service models and architectures and deployments. In the context of edge service development, coupling edge systems, software models for edge services and blockchain technologies is complex. Thus, a strong collaboration and knowledge sharing for edge systems and blockchain technologies will help addressing many concerns of the developer. However, there is a lack of frameworks for sharing knowledge about blockchain software artefacts and deployments for edge services. In this paper, we present various types of information linking blockchain performance with service deployments at different levels. We represent and associate benchmarked performance information of blockchain operation and blockchain infrastructural services with common edge service interactions and resource deployments. Based on that, we develop a service offering blockchain knowledge to the developer seeking relevant blockchain operation information for their development decisions. We will present a prototype of our framework with benchmarked information obtained from experiments with Ethereum and Hyperledger.

Alex Kaplunovich, Karuna Pande Joshi, Yelena Yesha

While adopting Blockchain technologies to automate their enterprise functionality, organizations are recognizing the challenges of scalability and manual configuration that the state of art present. Scalability of Hyperledger Fabric is an open challenge recognized by the research community. We have automated many of the configuration steps of installing Hyperledger Fabric Blockchain on AWS infrastructure and have benchmarked the scalability of that system. We have used the UCR (University of California Riverside) Time Series Archive with 128 timeseries datasets containing over 191,177 rows of data totaling 76,453,742 numbers. Using an automated Serverless approach, we have loaded this dataset, by chunks, into different AWS instances, triggering the load by SQS messaging. In this paper, we present the results of this benchmarking study and describe the approach we took to automate the Hyperledger Fabric processes using serverless Lambda functions and SQS triggering. We will also discuss what is needed to make the Blockchain technology more robust and scalable.

Anna Klimenko, Irina Safronenkova

Abstract In the current paper the issues of the workload relocation in the fog- and edge-computing environments are in-question. The workload relocation problem is closely connected to the scheduling problems, yet, outside the cloud there is almost unlimited number of nodes to place the computational tasks. So the search space for the optimization problem grows, and the time of the workload relocation degrades. We emphasize the techniques to limit the set of candidate nodes for the tasks distribution. In the paper two approaches are proposed and considered in terms of time consumption. The simple models are developed with the following simulation. Also the distributed-ledger-based modifications of the techniques are proposed and examined.

Nicolas Lagaillardie, Mohamed Aimen Djari, Önder Gürcan

Fairness is a crucial property for blockchain systems since it affects the participation: the ones that find the system fair tend to stay or enter, the ones that find the system unfair tend to leave. While current literature mainly focuses on fairness for Bitcoin-like blockchains, little has been done to analyze Tendermint. Tendermint is a blockchain technology that uses a committee-based consensus algorithm, which finds an agreement among a set of block creators (called validators), even if some are malicious. Validators are regularly selected to the committee based on their investments. When a validator does not have enough asset to invest, it can increase it with the help of participants that delegate their assets to the validators (called delegators). In this paper, we implement the default Tendermint model and a Tendermint model for fairness in a multi-agent blockchain simulator where participants are modeled as rational agents who enter or leave the system based on their utility values. We conducted experiments for both models where agents have different investment strategies and with various numbers of delegators. In the light of our experimental evaluation, we observed that while, for both models, the fairness decreases and the system shrinks in the absence of delegators, the fairness increases, and the system expands for the second model in the presence of delegators.

Jae-Yun Kim, Jun-Mo Lee, Yeon-Jae Koo, Sang-Hyeon Park · 5 authors

As ethereum blockchain has become popular, the number of users and transactions has skyrocketed, causing an explosive increase of its data size. As a result, ordinary clients using PCs or smartphones cannot easily bootstrap as a full node, but rely on other full nodes such as the miners to run or verify transactions. This may affect the security of ethereum, so light bootstrapping techniques such as fast sync has been proposed to download only parts of full data, yet the space overhead is still too high. One of the biggest space overhead that cannot easily be reduced is caused by saving the state of all accounts in the block's state trie. Fortunately, we found that more than 90% of accounts are inactive and old transactions are hard to be manipulated. Based on these observations, this paper propose a novel optimization technique called ethanos that can reduce bootstrapping cost by sweeping inactive accounts periodically and by not downloading old transactions. If an inactive account becomes active, ethanos restore its state by running a restoration transaction. Also, ethanos gives incentives for archive nodes to maintain the old transactions for possible re-verification. We implemented ethanos by instrumenting the go-ethereum (geth) client and evaluated with the real 113 million transactions from 14 million accounts between 7M-th and 8M-th blocks in ethereum. Our experimental result shows that ethanos can reduce the size of the account state by half, which, if combined with removing old transactions, may reduce the storage size for bootstrapping to around 1GB. This would be reasonable enough for ordinary clients to bootstrap on their personal devices.

Peter Eklund, Roman Beck

Blockchain systems (more precisely Distributed Ledger Technologies (DLTs)) represent a different digital ecosystem compared with traditional computer systems. One major difference are the performance and scalability factors which will be discussed and analytically investigated in this paper. In doing so, we provide guidance for defining a research agenda focusing on the investigation of the crucial role of scalability for blockchain systems. System performance -- measured in terms of (1) consensus response time (blockchain network latency or time to convergence/agreement); (2) number of transactions per second or throughput, and (3) computing (and power) resources consumed -- can be understood by considering the design dimensions of a blockchain system, namely: (i) the type of blockchain system needed from a requirements perspective which in turn determines; (ii) the complexity of the consensus protocol used; (iii) the topography of the traffic flow on the network; (iv) the performance and complexity of the domain-specific language that implements smart contracts; and (v) by the anticipated growth in size and complexity of the distributed ledger itself.

Kai Li, Yuzhe Tang, Qi Zhang, Cheng Xu · 5 authors

Modern Blockchains support the execution of user programs, called smart contracts. As a trusted computing platform, smart contracts bring decentralization, computation integrity, open access and information transparency to average users on the Internet. However, running smart-contract programs leads to high costs, known as Gas. Such costs prevent the use of smart contracts in data-intensive application scenarios, such as high-frequency trading and transparency logging. This paper addresses the Gas-based cost effectiveness in the most consuming layer of a smart contract, namely data storage. We present GRuB, a dynamic data-replication framework that monitors the smart-contract workload and makes online replication decisions. A new online algorithm is proposed that provides constant-bounded 'competitiveness' in Gas. To further save Gas, the workload monitor and decision maker are run off the Blockchain and with security against the forging of workload trace being monitored. A GRuB prototype is built, including a smart-contract component on Ethereum and an off-chain middleware on top of Google LevelDB. The cost evaluation under the YCSB workloads shows that GRuB can converge quickly to changing workloads and save Gas significantly compared with static replication schemes. Two case studies are conducted for data-intensive applications, including high-frequency trading and transparency logging, in which running GRuB leads to affordable Gas.

Kai Li, Yuzhe Tang, Jiaqi Chen, Zhehu Yuan · 6 authors

Feeding external data to a blockchain, a.k.a. data feed, is an essential task to enable blockchain interoperability and support emerging cross-domain applications, notably stablecoins. Given the data-intensive feeds in real life (e.g., high-frequency price updates) and the high cost in using blockchain, namely Gas, it is imperative to reduce the Gas cost of data feeds. Motivated by the constant-changing workloads in finance and other applications, this work focuses on designing a dynamic, workload-aware approach for cost effectiveness in Gas. This design space is understudied in the existing blockchain research which has so far focused on static data placement. This work presents GRuB, a cost-effective data feed that dynamically replicates data between the blockchain and an off-chain cloud storage. GRuB's data replication is workload-adaptive by monitoring the current workload and making online decisions w.r.t. data replication. A series of online algorithms are proposed that achieve the bounded worst-case cost in blockchain's Gas. GRuB runs the decision-making components on the untrusted cloud off-chain for lower Gas costs, and employs a security protocol to authenticate the data transferred between the blockchain and cloud. The overall GRuB system can autonomously achieve low Gas costs with changing workloads. We built a GRuB prototype functional with Ethereum and Google LevelDB, and supported real applications in stablecoins. Under real workloads collected from the Ethereum contract-call history and mixed workloads of YCSB, we systematically evaluate GRuB's cost which shows a saving of Gas by 10% ~ 74%, with comparison to the baselines of static data-placement.

Suyash Gupta, Jelle Hellings, Mohammad Sadoghi

The recent surge in blockchain applications and database systems has renewed the interest in traditional Byzantine Fault Tolerant consensus protocols (BFT). Several such BFT protocols follow a primary-backup design, in which a primary} replica coordinates the consensus protocol. In primary-backup designs, the normal-case operations are rather simple. At the same time, primary-backup designs place an unreasonable burden on primaries and allows malicious primaries to affect the system throughput substantially, however. To resolve this situation, we propose the MultiBFT paradigm, a protocol-agnostic approach towards improving the performance of primary-backup consensus protocols. At the core of MultiBFT is an approach to continuously order the client-transactions by running several instances of the underlying BFT protocol in parallel. We bring forth our paradigm to two well-established BFT protocols and demonstrate that the rendered parallelized protocols are not only safe and live but also significantly outperform, up to $2\times$, their original non-parallelized forms. Further, we show that our MultiBFT paradigm reaches a throughput of up to $320$K transactions per second.