Blockchain Papers

Víctor Garcia-Font

No abstract is available for this record.

Pingcheng Ruan, Tien Tuan Anh Dinh, Dumitrel Loghin, Meihui Zhang · 7 authors

Blockchain has come a long way: a system that was initially proposed specifically for cryptocurrencies is now being adapted and adopted as a general-purpose transactional system. As blockchain evolves into another data management system, the natural question is how it compares against distributed database systems. Existing works on this comparison focus on high-level properties, such as security and throughput. They stop short of showing how the underlying design choices contribute to the overall differences. Our work fills this important gap and provides a principled framework for analyzing the emerging trend of blockchain-database fusion. We perform a twin study of blockchains and distributed database systems as two types of transactional systems. We propose a taxonomy that illustrates the dichotomy across four dimensions, namely replication, concurrency, storage, and sharding. Within each dimension, we discuss how the design choices are driven by two goals: security for blockchains, and performance for distributed databases. To expose the impact of different design choices on the overall performance, we conduct an in-depth performance analysis of two blockchains, namely Quorum and Hyperledger Fabric, and two distributed databases, namely TiDB, and etcd. Lastly, we propose a framework for back-of-the-envelope performance forecast of blockchain-database hybrids.

Bin Cao, Shouming Huang, Daquan Feng, Lei Zhang · 6 authors

In this paper, we investigate the impact of network load on the Direct Acyclic Graph (DAG) consensus process for the blockchain enabled Internet of Things. Specifically, Markov chain model has been adopted to illustrate the dynamics in the consensus process for DAG based blockchain networks. The key performance metrics including cumulative weight and transaction confirmation delay are analysed under the unsteady state caused by the fluctuation of transaction arrival rate. The analysis is based on one of the most typical DAGs, Tangle, and the results show that the performance will be affected when the transaction arrival rate fluctuates widely.

Van Thanh Le, Claus Pahl, Nabil El Ioini

Mobile Edge Computing or MEC enables the provision of computation, storage and network resources within close proximity to the mobile users. MEC can host a set of predefined services or it can dynamically deploy services as requests come from the users. In a typical scenario, mobile users identify the closest MEC node to them and interact with it, however, as they are moving the same service needs to be able to follow them in order to provide service continuity. This problem has been already addressed by phone operators, however, as MEC allows third-party service providers to deploy their applications on top of MEC, new challenges arise. High among them are availability and security. In this paper, we present a blockchain based MEC management with the goal of efficiently guaranteeing service continuity in a secure and timely manner. We propose an architecture and its implementation to validate three main scenarios.

Minsu Kwon, Heonchang Yu

In the fourth industrial revolution, blockchain is one of the popular technologies. There are many benefits such as decentralization, persistency and security. A blockchain network can be public or private. Among them, the private blockchain model is applied to the business model. It can be a consortium of networks and is efficiently handled using smart contracts. However, there are many problems in applying the blockchain technology to various environments. One of the concerns is that it does not provide enough performance for many transactions [1]. This paper focuses on improving the performance of Hyperledger Fabric which is reported to be the fastest private blockchain platform [2]. Fabric has various component such as chaincode(smart-contract), endorsing peer, ordering service and committing peer. We propose two optimization method about endorsing peer and ordering service. Firstly, we have improved the procedure of read transactions by distinguishing between read and write transactions in the endorsement phase. We achieved 60% better performance than original read transaction processing. Secondly, we create a new consensus protocol without using an external project. We decreased latency by 80% through ordering service optimization. By combining two optimizations, we improved the overall latency and throughput performance by 20%.

Guiyan Wang, Hongbo Zhang, Bo-Wen Xiao, Yeh‐Ching Chung · 5 authors

Cloud service for education purpose is the critical infrastructure for the smart campus. The state-of-the-art education clouds are usually developed and maintained by individual schools. The isolation nature makes these data being tampered easily, which leads to malicious tampering and information fragmentation. The blockchain is a perfect technology to address these issues. By leveraging the advantages of the public blockchain, consortium blockchain, and private blockchain, we propose EduBloud, a heterogeneous blockchain system empowered education cloud. The system showed higher reliability, lower latency, higher data throughput, and better economic efficiency than homogeneous blockchain implementations.

Hui-Fang Wang, Zhihong Zhang

Blockchain is an underlying technology that initially implemented for Bitcoin. Data consistency, decentralization, and non-tamperability of this technology provide unique proposition values in many applications. However, slow transaction speed, high demand of resources, and scalability have become the bottlenecks that limit the blockchain's applicability. Instead of a chain, IOTA is a network of tangle distributed ledger in order to offer higher scalability and quicker transaction time, compared to blockchain. In this paper, we propose a new TSGP (Tree Solve Graph Problem) tip selection algorithm for IOTA. Our experiments show that our algorithm performs better than tip selection algorithms in the literature. Moreover, increasing the number of transactions plays no impact on the transaction connection speed in our algorithm.

Joshua Ellul, Gordon J. Pace

Developing smart contract decentralised application based systems typically involves writing code for various platforms, from the smart contract code residing on the underlying distributed ledger technology implementation to back end oracles and front end websites or mobile apps. In addition to the different technologies used for the different parts, the programmer is also burdened with implementing communication channels between the various parts. In this paper we propose a unified programming model allowing for developers to build such systems through a single code artifact, using a macroprogramming approach.

Adrian Spătaru, Laura Ricci, Dana Petcu, Barbara Guidi

The applications of Blockchain and Smart Contracts cover all aspects of digital information processing, varying from Asset Management platforms to Online Shops and Digital Identity Management. Several start-up companies and fellow researchers are interested in creating decentralized Clouds using the Blockchain as the mechanism for synchronization, identity management, and payment. This paper presents a conceptual platform exploiting Ethereum Smart Contracts to handle resource scheduling for Cloud Applications, investigates the operational constraints and measures the cost and latency for three scheduling strategies. In addition, it presents the constraints under which instances can be terminated asynchronously, which increases the cost of the transaction. The minimum cost for executing an application is similar to paying 12 hours for a standard Virtual Machine in today's Clouds if the Smart Contracts are deployed on the Ethereum Network, which limits the interest of users with short running applications.

Eder J. Scheid, Timo Hegnauer, Bruno Rodrigues, Burkhard Stiller

The blockchain (BC) world is rapidly becoming a universe of several ledgers designed for a specific purpose, holding data previously stored (i.e., siloed) in centralized databases. The use of different BCs for the same purpose could hamper the frictionless exchange of data or value. On one hand, it is natural that there are competing implementations exploring the benefits of BC. On the other hand, the problem of siloed data re-emerges, with respect to isolated chains. In this regard, BC interoperability is necessary to connect different BCs, exchanging information and assets. Moreover, to foster BC employment, developers must be able to interact with such different BCs without knowing the details of each implementation. This paper presents a novel solution, called Bifröst, to store and retrieve data on different BCs. Bifröst employs a notary scheme, which allows for connectivity to different BCs. The presented prototype is highly modular and currently implements seven adapters to popular BC implementations, including Bitcoin, Ethereum, and Stellar. The developed prototype was evaluated concerning performance, security, and data size to verify the feasibility of such an implementation and assess design decisions taken during its development.

I Gusti Bagus Baskara Nugraha, Yoanes Bandung, Ahmad Zaky

In general, the electronic official documents system is designed with a centralized system and managed by each government agency, so that data and records of official documents process activities are stored in a centralized database and managed by a single organizational unit. However, there are some disadvantages of this centralized system, especially in the workflow of official documents that involve more than one organizational unit. i.e. dependence on third parties which is the sole authority of the official documents data management. If there is a system failure there is a certain period of time, it will increase the activity cycle time and decrease activity time efficiency in the official documents business process. The blockchain-based solution described in this paper is to avoid the occurrence of delay times during the activity cycle time in business processes when a system failure occurs which can cause a decrease in activity time efficiency. Blockchain makes the official documents system become “Trusless Operation” with each participant of different organizational unit having a copy of transaction data through a consensus mechanism. The simulation results show that our system can reduce time delay in activity cycle time during a system failure as long as the number of faulty peers within the tolerance limit so that it can increase the activity time efficiency.

Shuai Wang, Chengyu Zhang, Zhendong Su

The term “smart contracts” has become ubiquitous to describe an enormous number of programs uploaded to the popular Ethereum blockchain system. Despite rapid growth of the smart contract ecosystem, errors and exploitations have been constantly reported from online contract systems, which has put financial stability at risk with losses totaling millions of US dollars. Most existing research focuses on pinpointing specific types of vulnerabilities using known patterns. However, due to the lack of awareness of the inherent nondeterminism in the Ethereum blockchain system and how it affects the funds transfer of smart contracts, there can be unknown vulnerabilities that may be exploited by attackers to access numerous online smart contracts.
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\nIn this paper, we introduce a methodical approach to understanding the inherent nondeterminism in the Ethereum blockchain system and its (unwanted) influence on contract payments. We show that our new focus on nondeterminism-related smart contract payment bugs captures the root causes of many common vulnerabilities without relying on any known patterns and also encompasses recently disclosed issues that are not handled by existing research. To do so, we introduce techniques to systematically model components in the contract execution context and to expose various nondeterministic factors that are not yet fully understood. We further study how these nondeterministic factors impact contract funds transfer using information flow tracking. The technical challenge of detecting nondeterministic payments lies in discovering the contract global variables subtly affected by read-write hazards because of unpredictable transaction scheduling and external callee behavior. We show how to augment and instrument a contract program into a representation that simulates the execution of a large subset of the contract behavior. The instrumented code is then analyzed to flag nondeterministic global variables using off-the-shelf model checkers.
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\nWe implement the proposed techniques as a practical tool named NPChecker (Nondeterministic Payment Checker) and evaluate it on 30K online contracts (3,075 distinct) collected from the Ethereum mainnet. NPChecker has successfully detected nondeterministic payments in 1,111 online contracts with reasonable cost. Further investigation reports high precision of NPChecker (only four false positives in a manual study of 50 contracts). We also show that NPChecker unveils contracts vulnerable to recently-disclosed attack vectors. NPChecker can identify all six new vulnerabilities or variants of common smart contract vulnerabilities that are missed by existing research relying on a “contract vulnerability checklist.”

Ruhi Taş, Ömer Özgür Tanrıöver

Blockchain technology is being used in many areas, during last few years. Furthermore, different application opportunities are still been investigated. Blockchain relies on and permits to implement the concept of Decentralized Application (DApps). This makes the applications more transparent, distributed and flexible. The complexity of blockchain and its integration problems require expertise that differs from traditional application development approaches. Within this context, this paper presents our experience in building a DApp with one of the most popular blockchain based platforms called Ethereum.

Halvdan Haugsbakken, Inger Langseth

Blockchain technology is argued to be the next “big” digital technology trend that will challenge a number of organizations, including higher education institutions. In contrast, higher education institutions have a history of being slow to adopt new digital technologies in the organizational apparatus. The question that remains discussing is whether universities will approach blockchain technologies in ways that are different from traditional research and education. This paper intends to discuss three particular ways in which blockchain may challenge higher education institution. The paper questions whether blockchain technologies can democratize and automate learning process, reduce costly bureaucracy and be adopted in higher education institutions. In sum, the intent is to invite to a discussion on blockchain and address whether or in what ways higher education institutions should adopt blockchain technologies as a digital technology.

Yang, Lei, Xuechao Wang, Vivek Bagaria, Gerui Wang · 8 authors

Bitcoin is the first fully-decentralized permissionless blockchain protocol to achieve a high level of security, but at the expense of poor throughput and latency. Scaling the performance of Bitcoin has a been a major recent direction of research. One successful direction of work has involved replacing proof of work (PoW) by proof of stake (PoS). Proposals to scale the performance in the PoW setting itself have focused mostly on parallelizing the mining process, scaling throughput; the few proposals to improve latency have either sacrificed throughput or the latency guarantees involve large constants rendering it practically useless. Our first contribution is to design a new PoW blockchain Prism++ that has provably low latency and high throughput; the design retains the parallel-chain approach espoused in Prism but invents a new confirmation rule to infer the permanency of a block by combining information across the parallel chains. We show security at the level of Bitcoin with very small confirmation latency (a small constant factor of block interarrival time). A key aspect to scaling the performance is to use a large number of parallel chains, which puts significant strain on the system. Our second contribution is the design and evaluation of a practical system to efficiently manage the memory, computation, and I/O imperatives of a large number of parallel chains. Our implementation of Prism++ achieves a throughput of over 80,000 transactions per second and confirmation latency of tens of seconds on networks of up to 900 EC2 Virtual Machines.

Fuqin Wang, Yijiang Chen, Ruochen Wang, Akindipe Olusegun Francis · 7 authors

This article investigates how choosing a different hash function might affect the overall performance of a blockchain. We focus on the selection of hash function for Ethereum and carry out extensive experiments to evaluate the performance change after the replacement of hash function. Our findings indicate that some performance metrics of a blockchain might be significantly affected by the hash function used. This suggests that selection of a specific hash function may not be a trivial decision for designing a blockchain.

Ronghua Xu, Gowri Ramachandran, Yu Chen, Bhaskar Krishnamachari

To promote the benefits of the Internet of Things (IoT) in smart communities and smart cities, a real-time data marketplace middleware platform, called the Intelligent IoT Integrator (I3), has been recently proposed. While facilitating the easy exchanges of real-time IoT data streams between device owners and third-party applications through the marketplace, I3 is presently a monolithic, centralized platform for a single community. Although the service oriented architecture (SOA) has been widely adopted in the IoT and cyber-physical systems (CPS), it is difficult for a monolithic architecture to provide scalable, inter-operable and extensible services for large numbers of distributed IoT devices and different application vendors. Traditional security solutions rely on a centralized authority, which can be a performance bottleneck or susceptible to a single point of failure. Inspired by containerized microservices and blockchain technology, this paper proposed a BLockchain-ENabled Secure Microservices for Decentralized Data Marketplaces (BlendSM-DDM). Within a permissioned blockchain network, a microservices based security mechanism is introduced to secure data exchange and payment among participants in the marketplace. BlendSM-DDM is able to offer a decentralized, scalable and auditable data exchanges for the data marketplace.

Sukhpal Singh Gill, Shreshth Tuli, Minxian Xu, Inderpreet Singh · 18 authors

Cloud computing plays a critical role in modern society and enables a range of applications from infrastructure to social media. Such system must cope with varying load and evolving usage reflecting societies interaction and dependency on automated computing systems whilst satisfying Quality of Service (QoS) guarantees. Enabling these systems are a cohort of conceptual technologies, synthesized to meet demand of evolving computing applications. In order to understand current and future challenges of such system, there is a need to identify key technologies enabling future applications. In this study, we aim to explore how three emerging paradigms (Blockchain, IoT and Artificial Intelligence) will influence future cloud computing systems. Further, we identify several technologies driving these paradigms and invite international experts to discuss the current status and future directions of cloud computing. Finally, we proposed a conceptual model for cloud futurology to explore the influence of emerging paradigms and technologies on evolution of cloud computing.

Zhiqin Zhu, Guanqiu Qi, Mingyao Zheng, Jian Sun · 5 authors

No abstract is available for this record.

James Kempf, Sambit Nayak, Remi Robert, Jim Feng · 9 authors

In this paper, we describe a virtual services marketplace, called Nubo, designed to connect buyers of virtual services (or tenants) with providers of those services on a cloud computing platform. The marketplace is implemented as a collection of distributed microservices along with a marketplace portal that runs as a Web application. The heart of Nubo is the Saranyu tenant and service management microservice. Saranyu is a decentralized application (dApp) built on top of the J.P. Morgan Quorum blockchain. Tenant and service accounts are represented as static (nonnegotiable) smart contracts written in the Solidity language. Quorum provides a tamper evident and tamper resistant distributed ledger, whereby multiple cloud and service providers can co-operate to provide service resources to tenants in a trustworthy fashion. Services offer resources consisting of a collection of attributes describing what the tenant can consume, and tenants subscribe to service resources through the Nubo Marketplace portal. The Service Manager microservice provides multitenant support for containerized services built for deployment and orchestration using Docker that were originally not designed to be managed through Saranyu. We discuss our design goals for Nubo, describe the overall architecture, discuss some details on how Saranyu uses the blockchain and smart contracts, and provide comprehensive performance and scalability data measured on the Saranyu REST API. The results indicate Saranyu is competitive with published results for comparable operations on the Havana release of OpenStack Keystone, but Saranyu provides a much richer collection of tenant and service management functionality than Keystone.

Iago Sestrem Ochôa, Rafael Alexandre Piemontez, Lucas M. C. e Martins, Valderi Reis Quietinho Leithardt · 5 authors

Blockchain technology has aroused the interest of researchers as it ensures security and privacy in decentralized applications. One of the platforms currently used for the development of new blockchain-based solutions is the Ethereum network. This article presents an experimental analysis of the scalability of this network to identify its cost and performance for several contracts in a simulated private Ethereum network. The results obtained demonstrate that storage operations for large amounts of data can prevent the use of blockchain due to the high cost of gas charged for this type of operation. The experiments also pointed out that processing operations which do not store information have a small cost of gas.

Michael Coblenz, Reed Oei, Tyler Etzel, Paulette Koronkevich · 9 authors

Blockchain platforms are coming into broad use for processing critical transactions among participants who have not established mutual trust. Many blockchains are programmable, supporting smart contracts, which maintain persistent state and support transactions that transform the state. Unfortunately, bugs in many smart contracts have been exploited by hackers. Obsidian is a novel programming language with a type system that enables static detection of bugs that are common in smart contracts today. Obsidian is based on a core calculus, Silica, for which we proved type soundness. Obsidian uses typestate to detect improper state manipulation and uses linear types to detect abuse of assets. We describe two case studies that evaluate Obsidian's applicability to the domains of parametric insurance and supply chain management, finding that Obsidian's type system facilitates reasoning about high-level states and ownership of resources. We compared our Obsidian implementation to a Solidity implementation, observing that the Solidity implementation requires much boilerplate checking and tracking of state, whereas Obsidian does this work statically.

Xiang Fu, Wang Huaimin, Shi Peichang, Xue Ouyang · 5 authors

Summary The blockchain is a distributed ledger that records all transactions and operations in a shared manner. Public blockchains such as Bitcoin realize decentralization at the cost of mining overhead, which is not suitable for real‐life scenarios requiring high throughput. Techniques such as the consortium blockchain improve efficiency through partial decentralization. However, the consensus algorithms used in the existing state‐of‐the‐art consortium blockchains face many challenges when dealing with commercial applications. For example, the high communication overhead hinders the scalability of PBFT‐based consensus algorithms even though they are efficient at small scale. Hashgraph, one of the most popular Directed Acyclic Graph‐based (DAG‐based) consensus algorithms, achieves good performance in scalability; however, it does not allow users' dynamic participation. To deal with these challenges, we propose Jointgraph, a Byzantine fault‐tolerance consensus algorithm for consortium blockchains based on DAG. In Jointgraph, transactions are packed into events and validated by no less than 2/3 of all members. A supervisor is introduced in our design, who monitors member behaviors and improves consensus efficiency. Simulation results demonstrate that Jointgraph outperforms Hashgraph in both throughput and latency.

Praveen Fernando, Jin Wei

Cloud architecture has become a valuable solution for different applications, such as big data analytics, due to its high-degree of availability, scalability and strategic value. However, there still remain challenges in managing cloud architecture, in areas such as cloud security. In this paper, we exploit software-defined networking (SDN) and blockchain technologies to secure cloud management platforms from a networking perspective. We develop a blockchain-powered SDN-enabled networking infrastructure in which the integration between blockchain-based security and autonomy management layer and multi-controller SDN networking layer is defined to enhance the integrity of the control and management messages. Furthermore, our proposed networking infrastructure also enables the autonomous bandwidth provisioning to enhance the availability of cloud architecture. In the simulation section, we evaluate the performance of our proposed blockchain-powered SDN-enabled networking infrastructure by considering different scenarios.