Blockchain Papers

Chunlin Li, Jing Zhang, Xianmin Yang, Youlong Luo

No abstract is available for this record.

Yahya Hassanzadeh-Nazarabadi, Alptekin Kupcu, Oznur Ozkasap

As an append-only distributed database, blockchain is utilized in a vast variety of applications including the cryptocurrency and Internet-of-Things (IoT). The existing blockchain solutions show downsides in communication and storage scalability, as well as decentralization. In this article, we propose LightChain , which is the first blockchain architecture that operates over a Distributed Hash Table (DHT) of participating peers. LightChain is a permissionless blockchain that provides addressable blocks and transactions within the network, which makes them efficiently accessible by all peers. Each block and transaction is replicated within the DHT of peers and is retrieved in an on-demand manner. Hence, peers in LightChain are not required to retrieve or keep the entire ledger. LightChain is fair as all of the participating peers have a uniform chance of being involved in the consensus regardless of their influence such as hashing power or stake. We provide formal mathematical analysis and experimental results (simulations and cloud deployment) to demonstrate the security, efficiency, and fairness of LightChain , and show that LightChain is the only existing blockchain that can provide integrity under the corrupted majority power of peers. As we experimentally demonstrate, compared to the mainstream blockchains such as Bitcoin and Ethereum, LightChain requires around 66 times smaller per node storage, and is around 380 times faster on bootstrapping a new node to the system, and each LightChain node is rewarded equally likely for participating in the protocol.

Maha Kadadha, Hadi Otrok

No abstract is available for this record.

Wenyu Chen, Xue Yang, Haikuo Zhang, Yanzhi Xu · 5 authors

No abstract is available for this record.

Yuhui Zhang, Dejun Yang

The past decade has witnessed an explosive growth in cryptocurrencies, but the blockchain-based cryptocurrencies have also raised many concerns, among which a crucial one is the scalability issue. Suffering from the large overhead of global consensus and security assurance, even the leading cryptocurrencies can only handle up to tens of transactions per second, which largely limits their applications in real-world scenarios. Among many proposals to improve the cryptocurrency scalability, one of the most promising and mature solutions is the payment channel network (PCN), which offers the off-chain settlement of transactions with minimal involvement of expensive blockchain operations. However, transaction failures may occur due to external attacks or unexpected conditions, e.g., an uncooperative user becoming unresponsive. In this paper, we present a distributed robust payment routing protocol RobustPay+to resist transaction failures, which achieves robustness, efficiency, distributedness and approximate optimization. Specifically, we investigate the problem of robust routing in PCNs from an optimization perspective, which is to find a pair of payment paths for a payment request, while minimizing the worst-case transaction fee, subject to the timeliness and feasibility constraints. We present a distributed 2-approximation algorithm for this problem. Moreover, we modify the original Hashed Time-lock Contract (HTLC) protocol and adapt it to the robust payment routing protocol to achieve robustness and efficiency. Extensive simulations demonstrate that RobustPay+significantly outperforms baseline algorithms in terms of the success ratio and the average accepted value.

Tsung-Yi Tang, Li-Yuan Hou, Tyng‐Yeu Liang

With the rise in fog computing, users are no longer restricted to only accessing resources located in central and distant clouds and can request services from neighboring fog nodes distributed over networks. This can effectively reduce the network latency of service responses and the load of data centers. Furthermore, it can prevent the Internet’s bandwidth from being used up due to massive data flows from end users to clouds. However, fog-computing resources are distributed over multiple levels of networks and are managed by different owners. Consequently, the problem of service discovery becomes quite complicated. For resolving this problem, a decentralized service discovery method is required. Accordingly, this research proposes a service discovery framework based on the distributed ledger technology of IOTA. The proposed framework enables clients to directly search for service nodes through any node in the IOTA Mainnet to achieve the goals of public access and high availability and avoid network attacks to distributed hash tables that are popularly used for service discovery. Moreover, clients can obtain more comprehensive information by visiting known nodes and select a fog node able to provide services with the shortest latency. Our experimental results have shown that the proposed framework is cost-effective for distributed service discovery due to the advantages of IOTA. On the other hand, it can indeed enable clients to obtain higher service quality by automatic node selection.

Xu Li, Paul T. Russell, Catalina Mladin, Chonggang Wang

Many emerging wireless applications are based on unique requirements such as edge data processing, distributed trust, and automation, which can be provided and enabled by blockchain technology through decentralization, transaction accountability, and smart contract-based automation. This article discusses opportunities and challenges of such blockchain-enabled wireless applications. First, blockchain technology and 5G system architecture are briefly reviewed. Then, an example wireless application use case is presented to illustrate the benefits that blockchain technology can bring to wireless applications. A set of pending research issues addressing some of the challenges faced by blockchain-enabled wireless applications is introduced. As a potential solution, a wireless blockchain middleware architecture (BlockWare) is proposed, based on a blockchain middleware layer connecting wireless applications and underlying blockchain infrastructure. The blockchain middleware layer interacts with various types of blockchain systems on behalf of different wireless applications. Thus, a wireless application does not need to implement complex blockchain functions, rather relying on the blockchain middleware layer and its services to leverage various underlying blockchain systems. This article also points out several research directions for future study, such as inter-blockchain interactions and interoperability, efficient blockchain transaction management, and blockchain-based messaging in future wireless systems such as 5G, beyond 5G, and 6G.

Emanuele Viglianisi, Mariano Ceccato, Paolo Tonella

The peculiar novelty of smart contracts is a computational model where irreversible transactions are stored in a distributed persistent data storage, namely the blockchain. The technical nature of this new type of software opens to new kinds of faults, which require specific test capabilities to be revealed. In this paper we present SOCRATES, an extensible and modular framework to automatically test smart contracts. The distinctive features of SOCRATES are: (1) a collection of composable behaviours that exercise smart contracts in the blockchain; (2) it deploys a society of bots, with the purpose of detecting defects arising from multi-user interactions, which are impossible to reveal when deploying a single bot. Our empirical investigation demonstrates that SOCRATES is able expose both known and previously unknown faults in smart contracts that are actively run in the official Ethereum blockchain. Moreover, we show that a society of multiple bots is more efficient in fault exposure than a single bot alone.

Fatih Rabia, Sara Arezki, Taoufiq Gadi

The Blockchain is one of the recent technologies that have emerged in the last decade. Blockchain has become a topic of many researches in several fields and it was implemented in some industries like finance, energy, health care, and electronic voting. Blockchain presents some great potential solutions that help to tackle difficulties. In this work we will focus on e-voting using blockchain technology. As we all know the voting is a way that leads the governments to approach democracy in their countries by an electoral process. The blockchain voting has replaced the traditional vote paper, also it replaced the voting systems that store data in central database. That gave much efficiency to the blockchain technology through a decentralized system that requires anonymity, confidentiality and transparency.

Peilin Zheng, Quanqing Xu, Zibin Zheng, Zhiyuan Zhou · 6 authors

Blockchain performance cannot meet the requirement nowadays. One of the crucial ways to improve performance is sharding. However, most blockchain sharding research focuses on public blockchain. As for consortium blockchain, previous studies cannot support high cross-shard efficiency, cross-contract flexibility, shard availability, and strict transaction atomicity, which are the essential requirements but also the challenges in consortium blockchain systems. Facing these challenges, we propose Meepo, a systematic study on sharded consortium blockchain. Meepo enhances cross-shard efficiency via the cross-epoch and cross-call. Moreover, a partial cross-call merging strategy is designed to handle the multi-state dependency in contract calls, achieving cross-contract flexibility. Meepo employs a replay-epoch to ensure strict transaction atomicity, and it also uses a backup algorithm called shadow shard based recovery to improve the shard robustness. We implement Meepo on the AliCloud, using 32 shards in maximum, achieving more than 120,000 cross-shard TPS under the workload of 100,000,000 asset transactions.

Ge Chen, Jun Wu, Wu Yang, Ali Kashif Bashir · 6 authors

Nowadays, adopting blockchain technology to Internet of Things has become a trend and it is important to minimize energy consumption while providing a high quality of service (QoS) in Blockchain-based IoT networks. Pre-caching popular and fresh IoT content avoids activating sensors frequently, thus effectively reducing network energy consumption. However, the user equipment in regions covered by base stations will generate distributed and time-varying data requests, hence modeling the base station topology to capturing spatio-temporal request patterns is required for the data storage pre-allocation. Traditional solutions typically fail to pay attention to the topology, resulting in the sensor being activated redundantly. In this paper, we propose Request Graph Convolutional-LSTM to capture the spatio-temporal request patterns in Blockchain-based IoT networks and make predictions. Moreover, a heuristic algorithm based on the predictions is proposed to develop pre-caching strategy, which determines the data and location to be cached to minimize the mean data retrieval latency restricted by the cache space of IoT network entities and the freshness of IoT content. Experiments show that our proposed frame provides a low energy consumption.

Yongjie Bai, Zhi Yang, Hui Li, Han Wang · 6 authors

Blockchain is an emerging distributed storage technology in recent years. It can hold all historical data, transaction records, and other related information from the past by using a self-referencing blockchain data storage structure. Consensus is the core technology of blockchain, which ensures consistency of data of different nodes and also enables the blockchain to have Byzantine fault tolerance. However, most consensus algorithms are serialized. With the increase in the number of nodes, throughput of system decreases rapidly. Proof of Vote (PoV) is an efficient voting-based consensus algorithm. It separates the voting and bookkeeping rights and has a great traffic complexity of . Based on PoV, we propose a more efficient and practical consensus algorithm called Parallel Proof of Vote (PPoV), which allows multiple nodes to generate blocks in parallel within a consensus cycle. Analysis and experiments show that the performance of PPoV is 2-5 times higher than typical BFT consensus as the number of nodes in range of 4-100.

Yu Liu, Junfang Zeng

Blockchain technology, with its distributed ledger, decentralization, high security, no tampering and other features, helps to solve the problems of data source confirmation, traceability and authorized data sharing. The effective utilization of data to achieve automatic governance and trusted decision-making of the city is known as "City Brain". The city brain is the key in smart city development, while the key to build a city brain is data resources. Aiming at the challenges existing in the construction of big data platform, this paper proposes a new solution based on blockchain, establishes the entity model and data model, analyzes the business model, designs the blockchain data platform framework and the cloud-blockchain integrated operation mode, and at last discusses the issues concerned in the application.

Jing Huey Khor, Michail Sidorov, Peh Yee Woon

Although blockchain offers a lot of benefits for the Internet-of-Things (IoT) network in terms of security, there are a number of barriers to its widespread adoption. Since many IoT networks consist of battery-powered devices with limited computing capabilities, one of those adoption barriers is the IoT end node itself. Several articles provided a general survey of the blockchain integration with IoT applications. However, a detailed analysis of this integration is missing, possible challenges are omitted, and no solutions that would enable the integration are presented. Furthermore, none of the surveys focused on reviewing public blockchains for IoT devices with low computational capabilities and limited energy resources. Therefore, the aim of this article is to provide the results of an in-depth study that covers challenges faced by existing public blockchains with IoT device integration. This article looks into resource-constrained IoT device classification and the wireless communication protocols used by them. It examines challenges that are required to be overcome for the successful integration of resource-constrained IoT end nodes with existing public blockchains. It then looks at the proposed solutions and their feasibility. A detailed review of possible security attacks on an IoT blockchain network is provided. As a result, a list of important characteristics that a public blockchain should possess in order to be integrated with a resource-constrained IoT network is proposed. Finally, the requirements for the IoT end nodes themselves are specified.

Joshua Ellul

A decade on since Satoshi’s Bitcoin paper, Blockchain is now considered to be sliding into the trough of Gartner’s hype cycle. Claims in regards to Blockchain and Cryptocurrencies being dead are on the rise, whilst at the same time many claim the contrary. The vague statement encapsulates many different aspects and perspectives of a myriad of use cases, technology and platforms including both the technique as a whole as well as individual instantiations. In this paper, we unpack the statement, break it down, and investigate objectively concrete factors which provide indication in regards to whether Blockchain is dead. We examine metrics including budgets and investment; public company registries and data; community engagement, projects, and source code repositories; academic research and programmes; social media posts; and public interest. We demonstrate metrics individually that indicate the respective measures’ healthy activity and come to the conclusion that the collective statement “Blockchain is dead” does not hold. A clear message extracted from the work proposed herein is that success is achieved where the community comes together rather than works in isolation.

Sotirios Brotsis, Konstantinos Limniotis, Gueltoum Bendiab, Nicholas Kolokotronis · 5 authors

Blockchain and distributed ledger technologies have received significant interest in various areas beyond the financial sector, with profound applications in the Internet of Things (IoT), providing the means for creating truly trustless and secure solutions for IoT applications. Taking into account the weak security defences that the majority of IoT devices have, it is critical that a blockchain-based solution targeting the IoT is not only capable of addressing the many challenges IoT is facing, but also does not introduce other defects, in terms of performance, making its adoption hard to achieve. This paper aims at addressing the above needs by providing a comprehensive and coherent review of the available blockchain solutions to determine their ability to meet the requirements and tackle the challenges of the IoT, using the smart home as the reference domain. Key architectural aspects of blockchain solutions are examined in terms of their ability to withstand various types of common IoT and blockchain attacks, deliver enhanced privacy features, and assure adequate performance levels while processing large amounts of transactions being generated in an IoT environment. The analysis carried out identified that the defences currently provided by blockchain platforms are not sufficient to thwart all the prominent attacks against blockchains, with blockchain 1.0 and 2.0 platforms being susceptible to the majority of them. On the other side, privacy related mechanisms are being supported, to varying degrees, by all platforms investigated; however, each of the them tackles specific only privacy aspects, thus rendering the overall privacy evaluation a challenging task which needs to be considered in an ad-hoc basis. If the underlying consensus protocols performance and fault tolerance is also considered, then only a small number of platforms meet the requirements of our reference IoT domain.

Alexe Luca Spataru, Ciprian Pungilă, Marco Radovancovici

No abstract is available for this record.

Ruben Recabarren Velarde

Distributed Ledger Technologies (DLTs) have become an important driving force towards the creation of novel distributed applications aimed at solving problems that range from digital currency tools to self governing digital democracy systems. Our thesis is that Satoshi cryptocurrencies, i.e., Bitcoin and its variants, can be used to endow several popular distributed services with strong privacy, anonymity and censorship resistance properties that evade current solutions. To this end, we first study the design of Satoshi cryptocurrency mining protocols, and discover and document privacy and integrity vulnerabilities of Stratum, the de-facto pooled mining protocol. We have developed tools that exploit these vulnerabilities and have measured their impact and effectiveness under a rigorous academic context. Further, we have designed and implemented Bedrock, a solution that addresses these vulnerabilities. We have evaluated Bedrock in the live Bitcoin ecosystem and show that it achieved orders of magnitude better performance than traditional solutions like TLS and blanket encryption. We further introduce DLSS, a censorship-resistant, distributed ledger storage system that embeds client content into Satoshi transactions and organize it for fast search, recovery and reconstruction among hundreds of millions of financial transactions. DLSS distinguishes and exploits the singularities of different types of communications under censorship conditions. We design, implement and evaluate novel smart contracts tailored to the needs of censored users. For instance, we introduce difficult to censor and undetectable techniques to embed small quantities of data on Satoshi transactions, to be used for communications flowing out of the censored area that need to avoid detection by all-powerful censors. We also introduce techniques that prioritize cost optimization for storing large content flowing into the censored area, where uncensorability is the only priority. Further, we leverage our blockchain-writing constructs to introduce a novel perspective for traditionally hard problems of censorship resistance, private e-mail and secure port-knocking with surreptitious authentication and logging. We prove the security, privacy and anonymity of our smart contracts, and argue they impose unpalatable collateral damage to would-be censors. We build a monitoring and instrumentation framework for evaluating our constructs in the Litecoin cryptocurrency. We evaluate our blockchain-writing constructs by persisting hundreds of MBs of BBC news articles and censored software in the live Litecoin blockchain, where they are available to access for free anywhere in the world. We show that our solutions achieve storage throughput, blockchain utilization, and cost efficiency that improve by 2-4 orders of magnitude on state-of-the-art blockchain-writing solutions.

Lehlogonolo P. I. Ledwaba, Gerhard P. Hancke, Sherrin J. Isaac, Hein S. Venter

The increasing strain on ageing generation infrastructure has seen more frequent instances of scheduled and unscheduled blackouts, rising reliability on fossil fuel based energy alternatives and a slow down in efforts towards achieving universal access to electrical energy in South Africa. To try and relieve the burden on the National Grid and still progress electrification activities, the smart microgrid model and secure energy trade paradigm is considered—enabled by the Industrial IoT (IIoT) and distributed ledger technologies (DLTs). Given the high availability requirements of microgrid operations, the limited resources available on IIoT devices and the high processing and energy requirements of DLT operations, this work aims to determine the effect of native DLT algorithms when implemented on IIoT edge devices to assess the suitability of DLTs as a mechanism to establish a secure, energy trading market for the Internet of Energy. Metrics such as the node transaction time, operating temperature, power consumption, processor and memory usage are considered towards determining possible interference on the edge node operation. In addition, the cost and time required for mining operations associated with the DLT-enabled node are determined in an effort to predict the cost to end users—in terms of fees payable and mobile data costs—as well as predicting the microgrid’s growth and potential blockchain network slowdown.

Befekadu G. Gebraselase

Network slicing is the crucial enabler of the new emerging 5G and beyond network generations. It facilitates the facility to compose logical networks over shared physical infrastructures. From the implementation perspective of view, slice isolations and sharing become very challenging. It introduces challenges to provide secure information to the subscribers and enables users to modify and configure the registrations while following the service level agreement. To this aim, we introduce a blockchain as a service, in which the distributed ledger technologies provide security and accessibility to the end-users while removing a third-party involvement. Additionally, it allows tenants and subscribers to manage the slice information as necessary without violating the agreement. The primary advantage of including blockchain in architecture is using it to slice isolation and sharing.

S.C. Saxena, Bharat Bhushan, Mohd Abdul Ahad

No abstract is available for this record.

Huawei Huang, Wei Kong, Sicong Zhou, Zibin Zheng · 5 authors

To draw a roadmap of current research activities of the blockchain community, we first conduct a brief overview of state-of-the-art blockchain surveys published in the past 5 years. We found that those surveys are basically studying the blockchain-based applications, such as blockchain-assisted Internet of Things (IoT), business applications, security-enabled solutions, and many other applications in diverse fields. However, we think that a comprehensive survey toward the essentials of blockchains by exploiting the state-of-the-art theoretical modelings, analytic models, and useful experiment tools is still missing. To fill this gap, we perform a thorough survey by identifying and classifying the most recent high-quality research outputs that are closely related to the theoretical findings and essential mechanisms of blockchain systems and networks. Several promising open issues are also summarized for future research directions. We hope this survey can serve as a useful guideline for researchers, engineers, and educators about the cutting-edge development of blockchains in the perspectives of theories, modelings, and tools.

Xin Cong, Lingling Zi, Ding‐Zhu Du

The current blockchain deployment solutions rely on a continuous connectivity network. Unfortunately, the delay tolerant network does not meet this condition. Therefore, we construct a novel blockchain transaction framework with discrete token negotiation called DTNB, which can be deployed on the delay tolerant network to provide transaction services. Specifically, we present the structure of add-chains by modifying the existing block structure. Then, we design a mining qualification determining scheme to achieve fair transactions, including discrete token generation algorithm and mining qualification attribution algorithm, and this scheme avoids the problem that nodes with more stakes in the PoS and DPoS algorithms can obtain mining qualifications with a higher probability. Furthermore, we present two mining schemes and also design a fork processing algorithm, which ensures that blocks on the add-chain generated by the local network can be appended to the main chain with the equal probability. Finally, we design the second consensus algorithm to avoid the problem of false and repeated transactions of the blocks on the add-chains in the local network. Theoretical analysis shows three properties of DTNB, including safety, reliability and activeness, and the experimental simulations demonstrate DTNB has advantages in throughput, block generation time and fork rate.

Abdullah Ahmad Zarir, Gustavo A. Oliva, Zhen Ming Jiang, Ahmed E. Hassan

Ethereum is a blockchain platform that hosts and executes smart contracts. Executing a function of a smart contract burns a certain amount of gas units (a.k.a., gas usage). The total gas usage depends on how much computing power is necessary to carry out the execution of the function. Ethereum follows a free-market policy for deciding the transaction fee for executing a transaction. More specifically, transaction issuers choose how much they are willing to pay for each unit of gas (a.k.a., gas price). The final transaction fee corresponds to the gas price times the gas usage. Miners process transactions to gain mining rewards, which come directly from these transaction fees. The flexibility and the inherent complexity of the gas system pose challenges to the development of blockchain-powered applications. Developers of blockchain-powered applications need to translate requests received in the frontend of their application into one or more smart contract transactions. Yet, it is unclear how developers should set the gas parameters of these transactions given that (i) miners are free to prioritize transactions whichever way they wish and (ii) the gas usage of a contract transaction is only known after the transaction is processed and included in a new block. In this article, we analyze the gas usage of Ethereum transactions that were processed between Oct. 2017 and Feb. 2019 (the Byzantium era). We discover that (i) most miners prioritize transactions based on their gas price only, (ii) 25% of the functions that received at least 10 transactions have an unstable gas usage (coefficient of variation = 19%), and (iii) a simple prediction model that operates on the recent gas usage of a function achieves an R-Squared of 0.76 and a median absolute percentage error of 3.3%. We conclude that (i) blockchain-powered application developers should be aware that transaction prioritization in Ethereum is frequently done based solely on the gas price of transactions (e.g., a higher transaction fee does not necessarily imply a higher transaction priority) and act accordingly and (ii) blockchain-powered application developers can leverage gas usage prediction models similar to ours to make more informed decisions to set the gas price of their transactions. Lastly, based on our findings, we list and discuss promising avenues for future research.