Devdoot Maji, Ravi Singh Lamkoti, Hitesh Shetty, Bharati Gondhalekar
An estimated 26.3 million students enrolled in Indian higher education in 2018-19 and nearly 9 million graduates annually. A student, whether he is a high school student or an undergraduate, or maybe a postgraduate, generates a lot of certificates that may include results, diplomas, or transcripts during this entire duration of studies. For admission, students need to produce these certificates in institutions or companies. Tracking these certificates and validating their authenticity manually becomes a tedious job. The absence of an appropriate anti-forge system leads to a scenario where it is found that the graduation certificate is forged. To make the data more secure and safe, everything needs to be digitalized with the principle of Confidentiality, Reliability, and Availability. All of these can be achieved with a technology named Blockchain. Briefly, the flow of our system will consist of a Certificate issuer who will generate certificates and those certificates will be validated by a panel within that organization before being sent to a student. Each certificate will have a unique hash key which can be used to validate the authenticity of the certificate by any organization through the portal. The benefit of such a system is that the student also faces less risk of losing or damaging a certificate and the validation of the certificate can also be done quite easily.
First, a big data analysis of the transactions and smart contracts made on\nthe Ethereum blockchain is performed, revealing interesting trends in motion.\nNext, these trends are compared with the public's interest in Ether and\nBitcoin, measured by the volume of online searches. An analysis of the crypto\nprices and search trends suggests the existence of big players (and not the\nregular users), manipulating the market after a drop in prices. Lastly, a\ncross-correlation study of crypto prices and search trends reveals the pairs\nproviding more accurate and timely predictions of Ether prices.\n
The cloud-fog-edge hybrid system is the evolution of the traditional centralized cloud computing model. Through the combination of different levels of resources, it is able to handle service requests from terminal users with a lower latency. However, it is accompanied by greater uncertainty, unreliability, and instability due to the decentralization and regionalization of service processing, as well as the unreasonable and unfairness in resource allocation, task scheduling, and coordination, caused by the autonomy of node distribution. Therefore, this paper introduces blockchain technology to construct a trust-enabled interaction framework in a cloud-fog-edge environment, and through a double-chain structure, it improves the reliability and verifiability of task processing without a big management overhead. Furthermore, in order to fully consider the reasonability and load balance in service coordination and task scheduling, Berger’s model and the conception of service justice are introduced to perform reasonable matching of tasks and resources. We have developed a trust-based cloud-fog-edge service simulation system based on iFogsim, and through a large number of experiments, the performance of the proposed model is verified in terms of makespan, scheduling success rate, latency, and user satisfaction with some classical scheduling models.
There are few topics out there, that seem to create as much confusion and discussion as blockchains. This has a multitude of reasons: (1) A large number of drastically different concepts and systems are unified under the very broad term "blockchain". (2) The topic touches a variety of different fields, including databases, distributed processing, networks, cryptography, and even economics. (3) There exists a large number of different applications of the technology.The goal of this paper is to simplify and structure the discussion of blockchain technology. We first introduce a simple formalization of the basic components, that appear again and again in a variety of blockchain systems. Second, we formalize four important execution models, that express the workflow of a large number of blockchain systems. Third, along the way, the we also discuss certain misconceptions, that constantly reappear in discussions. We believe that a common formalization of the transaction processing behavior of blockchain systems both helps beginners to get into the topic as well as can bring experts from different fields to a common denominator when discussing blockchain systems.
Cloud computing has been widely used in the field of information services. However, large-scale Internet of things (IoT) applications are raising new challenges to cloud computing architecture. Edge computing, which complements cloud computing, is considered to be the way to address these challenges. Volunteer computing, which harvests idle resources in the network can improve the hardware utilization rate and support tens of billions of IoT devices. In view of the limitations of traditional volunteer computing that cannot provide realtime services and has no mechanism to reward services in existing volunteer clouds, this paper presents blockchain-based volunteer edge cloud. A common runtime environment is provided by container technology, and blockchain smart contract is used for critical business steps and computing service payment. Volunteer edge cloud systems based on blockchain is introduced from a top-level perspective, and a prototype system build on Ethereum and KubeEdge is described in detail. On top of the prototype system, we deployed an example IoT application of robot formation control. It demonstrates the benefits of volunteer edge cloud in reducing the complexity of IoT devices, improving the flexibility of software development, and paying the computing service.
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.
블록체인 환경에서 트릴레마 문제로 불리는 분산성•보안성•확장성을 동시에 만족시키는 것은 어려운 문제이다. 블록체인들은 트릴레마 문제를 위해 많은 합의 알고리즘를 제안한다. 보안성이 높은 작업증명(Proof-of-Work)은 ASIC 채굴기의 등장으로 분산성이 훼손되었다. 몇몇 블록체인은 ASIC 저항 알고리즘을 개발하였다. 우리는 ASIC 채굴기의 등장을 억제하기 위하여 LDPC 디코더와 해시 함수를 결합한 오류-정정 부호 기반의 작업증명(Error-Correction Codes Proof-of-Work, ECCPoW)를 제안하였다. 그리고 ECCPoW를 구현하는 방법을 제안하였다. 이 논문은 ECCPoW의 코어 1.0 버전에 대하여 설명하고 이더리움 환경에 적용하는 방법을 제안한다. 그리고 우리는 ECCPoW가 적용된 이더리움과 기존의 이더리움(Ethash)의 확장성을 평가한다.
Hossam Saad Shady Yasser Hassan Gaber Aya Samy, Ashraf Tammam, Ahmed Fahmy, Bahaa Hasan
Blockchain is one of the most powerful and promising technologies nowadays in the IT industry, One of Blockchain’s main features is the presence of a Consensus Algorithm, which is responsible for maintaining the security and integrity of the entire blockchain network where all the nodes participating in the network reach a certain agreement. However, some algorithms like the Proof-of-Work require very high energy consumption to reach a single agreement by solving a puzzle and provides a low throughput (3-7 transactions/second), thus, it may not be very reliable in blockchain solutions. In this paper, we aim to provide a reliable choice for different business use-cases by proposing a modification in the Istanbul Byzantine Fault Tolerance voting-based algorithm that provides a higher throughput (up to 1140 tx/s), which will be very important to be used in the use case called a letter of credit which is a part of trade finance (relation between exporter, importer and the bank institutions).
Proof of Stake (PoS) has been talked about extensively as an alternative way of reaching consensus in blockchain systems. However, there are few publications on how PoS can be used to create new blocks in detail. The undisputed lead proponent for PoS is Ethereum. However, virtually all discussions regarding PoS for Ethereum are centered on selecting a block using PoS after one or more candidate blocks have already been somehow created. PeerCoin was the first blockchain system that incorporated PoS in block creation. Unfortunately, there is no known documentation on how PoS works in PeerCoin. In this paper, we fill this gap by presenting a detailed explanation of the PeerCoin PoS algorithm based on PeerCoin source code. We also dispel the misconception that PeerCoin PoS is based on Proof of Work (PoW) and hence would consume a lot of energy just like proof of work (PoW). In fact, it resembles PoW only on surface and differs from PoW substantially in terms of how to meet the difficulty target.
Distributed energy, mainly composed of new energy, plays an important role in promoting the development of new energy. At present, the development of distributed energy is greatly hindered by imperfect trading platform and unstable output of new energy. Blockchain is decentralized, autonomous and requires collaborative management. Its own technical characteristics have the inherent advantages of reconstructing the energy system. The alliance chain in the blockchain is more suitable for building a distributed energy trading platform. The paper constructs a distributed energy transaction model based on alliance blockchain, studies the integration mode of blockchain and distributed energy transaction, and explores the application of blockchain in distributed transaction. The paper provides a new idea for optimizing and reconstructing the traditional distributed energy trading platform, and providing decision support for promoting distributed energy trading.
This paper presents a queueing model for mining-based public blockchains and validations with respect to specific yet practical characteristics of public blockchains such as Bitcoin and Ethereum, primarily in terms of transaction queue size and block waiting time, as an alternative solution to the conventional industrial networks for the trustworthiness it offers. A set of variables taken into account in this model lists the network traffic intensity, the maximum number of transactions in a block, the block time, and the transaction arrival rate, to mention a few. The proposed model provides a comprehensive yet fundamental basis to assure and ultimately optimize the design of blockchain technology-based applications in specific terms of performance. Numerical simulations have been conducted and the efficacy of the proposed model is validated in a quantitative yet practical manner versus Bitcoin and Ethereum.
Since the introduction of the first Bitcoin blockchain in 2008, different\ndecentralized blockchain systems such as Ethereum, Hyperledger Fabric, and\nCorda, have emerged with public and private accessibility. It has been widely\nacknowledged that no single blockchain network will fit all use cases. As a\nresult, we have observed the increasing popularity of multi-blockchain\necosystem in which customers will move toward different blockchains based on\ntheir particular requirements. Hence, the efficiency and security requirements\nof interactions among these heterogeneous blockchains become critical. In\nrealization of this multi-blockchain paradigm, initiatives in building\nInteroperability-Facilitating Platforms (IFPs) that aim at bridging different\nblockchains (a.k.a. blockchain interoperability) have come to the fore. Despite\ncurrent efforts, it is extremely difficult for blockchain customers\n(organizations, governments, companies) to understand the trade-offs between\ndifferent IFPs and their suitability for different application domains before\nadoption. A key reason is due to a lack of fundamental and systematic\napproaches to assess the variables among different IFPs. To fill this gap,\ndeveloping new IFP requirements specification and open-source benchmark tools\nto advance research in distributed, multi-blockchain interoperability, with\nemphasis on IFP performance and security challenges are required. In this\ndocument, we outline a research proposal study to the community to realize this\ngap.\n
It is said that blockchain will contribute to the digital transformation of society in a wide range of ways, from the management of public and private documents to the traceability in various industries, as well as digital currencies. A number of so-called blockchain platforms have been developed, and experiments and applications have been carried out on them. But are these platforms really conducive to practical use of the blockchain concept? To answer the question, we need to better understand what the technology called blockchain really is. We need to sort out the confusion we see in understanding what blockchain was invented for and what it means. We also need to clarify the structure of its applications. This document provides a generic model of understanding blockchain and its applications. We introduce design patterns to classify the platforms. We categorize possible use cases by identifying the structure among applications, and organize the functional, performance, operational and legal requirements for each such case. Based on the categorization and criteria, we evaluated and compared the following platforms: Hyperledger Fabric, Hyperledger Iroha, Hyperledger Indy, Ethereum, Quorum/Hyperledger Besu, Ethereum 2.0, Polkadot, Corda and BBc-1. We have tried to be fair in our evaluations and comparisons, but we also expect to provoke discussion. The intended readers for this document is anyone involved in development of application systems who wants to understand blockchain and their platforms, including non-engineers and non-technologists. The assessments in this document will allow readers to understand the technological requirements for the blockchain platforms, to question existing technologies, and to choose the appropriate platforms for the applications they envision. The comparisons hopefully will also be useful as a guide for designing new technologies.
Cryptocurrencies like Bitcoin and Ethereum, are widely known applications of blockchain technology, have drawn much attention and are largely recognized in recent years. Initially Bitcoin and Ethereum processed 7 and 15 Transactions Per Second (TPS) respectively, whereas VISA and Paypal process 1700 and 193 TPS respectively. The biggest challenge to blockchain adoption is scalability, defined as the capacity to change the block size to handle the growing amount of load. This paper attempts to present the existing scalability solutions which are broadly classified into three layers: Layer 0 solutions focus on optimization of propagation protocol for transactions and blocks, Layer 1 solutions are based on the consensus algorithms and data structure, and Layer 2 solutions aims to decrease the load of the primary chain by implementing solutions outside the chain. We present a classification and comparison of existing blockchain scalability solutions based on performance along with their pros and cons
Rafael Belchior, André Vasconcelos, Miguel Correia, Thomas Hardjono
The emergence of blockchain interoperability is reducing the risk of investing in blockchain by avoiding vendor lock-in, leveraging interoperation, and providing migration capabilities. However, to fully unlock the internet of blockchains, it is necessary to provide enterprise interoperability mechanisms that allow service providers to comply with different regulations, e.g., data privacy regulations. Each blockchain can be reached via a gateway, allowing to interconnect value, to provide different services, and to enable self-sovereignty. To realize this vision, we propose Hermes, a fault-tolerant middleware that connects blockchain networks and is based on the Open Digital Asset Protocol (ODAP). Hermes is crash fault-tolerant by allying a new protocol, ODAP-2PC, with a log storage API that can leverage blockchain to secure logs, providing them transparency, auditability, availability, and non-repudiation. We introduce a use case benefiting from Hermes, digital cross-jurisdiction promissory notes. We show that cross-chain transactions can be achieved securely with Hermes, given that gateways are complying with legal frameworks.
Xiwei Xu, H. M. N. Dilum Bandara, Qinghua Lu, Ingo Weber · 6 authors
Blockchains have been applied in different domains to guarantee data integrity and provide a decentralized computational infrastructure for executing smart contracts. Multiple blockchain-related patterns have been summarized by academics and industry practitioners covering different aspects, such as engineering applications on top of a blockchain, structuring smart contracts, and security. The existence of these patterns is both helpful and challenging for designers. Helpful, as the existence of these patterns means that developers do not need to recreate solutions to common problems. Challenging, as the multitude of patterns leaves a designer confused about when to adopt or adapt patterns. In this paper, we propose a decision model that assists developers and architects in selecting appropriate patterns for blockchain-based applications. The selection is based on the characteristics of the use cases and trade-offs implicit in the patterns. We evaluated the proposed decision model based on expert opinion regarding its correctness and usefulness in guiding the architecture design and understanding the rationale of various design decisions.
This paper presents libtxsize, a library to estimate the size requirements of arbitrary Bitcoin transactions. To account for different use cases, the library provides estimates in bytes, virtual bytes, and weight units. In addition to all currently existing input, output, and witness types, the library also supports estimates for the anticipated Pay-to-Taproot transaction type, so that estimates can be used as input for models attempting to quantify the impact of Taproot on Bitcoin's scalability. libtxsize is based on analytic models, whose credibility is established through first-principle analysis of transaction types as well as exhaustive empirical validation. Consequently, the paper can also serve as reference for different Bitcoin data and transaction types, their semantics, and their size requirements (both from an analytic and empirical point of view).
Wei Yao, Fadi P. Deek, Renita Murimi, Guiling Wang
Consensus algorithms are central to blockchain technology and an emerging research area. In this paper, we begin with an overview of the different types and architectures of blockchain networks. Then, with a focus on consortium blockchains, we survey, classify, and assess their principal consensus mechanisms. Furthermore, as consensus mechanisms determine network reliability, enhance performance efficiency, and ensure system security, we conduct a critical analysis of the strengths and weaknesses of consensus algorithms using a taxonomy of three different criteria: reliability, performance, and security. We conclude with insights into current and future research challenges and opportunities in this domain.
Blockchain is a distributed ledger that is decentralized, immutable, and transparent, which maintains a continuously growing list of transaction records ordered into blocks. As the core of blockchain, the consensus algorithm is an agreement to validate the correctness of blockchain transactions. For example, Bitcoin is a public blockchain where each node in Bitcoin uses the Proof of Work (PoW) algorithm to reach a consensus by competing to solve a puzzle. Unlike a public blockchain, a consortium blockchain is an enterprise-level blockchain that does not contend with the issues of creating a resource-saving global consensus protocol. This paper highilights several state-of-the art solutions in consensus algorithms for enterprise blockchain. For example, the HyperLedger by Linux Foundation includes implementing Practical Byzantine Fault Tolerance (PBFT) as the consensus algorithm. PBFT can tolerate a range of malicious nodes and reach consensus with quadratic complexity. Another consensus algorithm, HotStuff, implemented by Facebook Libra project, has achieved linear complexity of the authenticator. This paper presents the operational mechanisms of these and other consensus protocols, and analyzes and compares their advantages and drawbacks.
By design, distributed ledger technologies persist low-level data which makes conducting complex business analysis of the recorded operations challenging. Existing blockchain visualization and analytics tools such as block explorers tend to rely on this low-level data and complex interfacing to provide enriched level of analytics. The ability to derive richer analytics could be improved through the availability of a higher level abstraction of the data. This article proposes an abstraction layer architecture that enables the design of high-level analytics of distributed ledger systems and the decentralized applications that run on top. Based on the analysis of existing initiatives and identification of the relevant user requirements, this work aims to establish key insights and specifications to improve the auditability and intuitiveness of distributed ledger systems by leveraging the development of future user interfaces. To illustrate the benefits offered by the proposed abstraction layer architecture, a regulated sector use case is explored.