James Meijers, Guntur Dharma Putra, Grammateia Kotsialou, Salil S. Kanhere · 5 authors
Billions of Internet of Things (IoT) devices deployed today collect massive amounts of potentially valuable data. To efficiently utilize this data, markets must be developed where data can be traded in real time. Blockchain technology offers a potential platform for these types of markets. However, previous proposals using blockchain technology either require trusted third parties such as data brokers, or necessitate a large number of on-chain transactions to operate, incurring excessive overhead costs. This paper proposes a trustless data trading system that minimizes both the risk of fraud and the number of transactions performed on chain. In this system, data producers and consumers come to binding agreements while trading data off chain and they only settle on chain when a deposit or withdrawal of funds is required. A credit mechanism is also developed to further reduce the incurred fees. Additionally, the proposed marketplace is benchmarked on a private Ethereum network running on a lab-scale testbed and the proposed credit system is simulated so to analyze its risks and benefits.
As user privacy gains popularity and attention, and starts to shape relations between users and service providers, blockchain based solutions thrive for ways to relax immutability without sacrificing consistency. This work answers that need and presents the first design for a redactable execute-order-validate blockchain, that grants users with the \emph{right to be forgotten}. The design is easy to adopt, as we exemplify by implementing it on top of Hyperledger Fabric. It modifies the block structure and extracts user data from the hash-chain without loosening any correctness or liveness criteria. We evaluate our design and show that it provides compliance with only a minimal performance overhead, making it a feasible add-on to any execute-order-validate blockchain system.
Remigijus Paulavičius, Saulius Grigaitis, Ernestas Filatovas
Since the introduction of Bitcoin, blockchain has attracted tremendous interest from both academia and industry. During the last decade, various large-scale blockchain systems were developed. However, the complexity of large-scale distributed systems makes the performance evaluation process challenging and costly. Here, blockchain simulators give the possibility to repeat complex real-world processes at a low cost. Simulators are easily extensible and can test distributed ledger performance using different settings and parameter variations. This work reviews and summarizes the current status of the state-of-the-art blockchain simulators.
Binh Minh Nguyen, Thang Nguyen, Thieu Nguyen, Ba-Lam Do
Over the last years, many blockchain platforms opt for Delegated Proof-of-Stake (DPoS) consensus protocol for their network deployment. However, using the DPoS, nodes on the network tend to vote for the nodes that are more likely to become block producers after several voting rounds. Hence, with DPoS, the number of block producers is quite small compared to the total number of nodes in the blockchain network. Besides, with DPoS consensus, the distribution of block producers often centralizes into several individual nodes. This paper proposes a novel consensus protocol called Meta-heuristic Proof of Criteria (MPoC) to overcome the disadvantages. Our protocol enables multiple operational criteria to evaluate all blockchain nodes during the block producer selection process. We apply meta-heuristic algorithms to optimize the decentralized level of the node selection based on the set of criteria weights to increase the democracy of the blockchain network.We carry out experiments to evaluate the block producer decentralization of MPoC as compared with DPoS. The achieved results show that our consensus protocol improves the decentralization of block producers as expected. We also show the feasibility of applying different meta-heuristic algorithms to our consensus protocol of blockchain through experiments.
We evaluate and analyze the performance of a local electricity market for energy trading that we implemented on the Ethereum platform. The energy trading is based on a double auction with multiple sellers and multiple buyers; the matched price and volume are determined by a trade reduction mechanism. We benchmark the performance of Ethereum using a systematic blockchain performance evaluation method. Based on this, we propose and analyze an efficient market operation method. In particular, we relate the limits on the scalability and real-time performance of the market to the throughput and latency of the Ethereum platform. We also identify the minimum resources necessary to operate an Ethereum client.
Distributed Ledger Technologies (DLT) and Decentralized File Storages (DFS) are becoming increasingly used to create common, decentralized and trustless infrastructures where participants interact and collaborate in Peer-to-Peer interactions. A prominent use case is represented by decentralized data marketplaces, where users are consumers and providers at the same time, and trustless interactions are required. However, data in DLTs and DFS are usually unstructured and there are no efficient mechanisms to query a certain type of data for the search in the market. In this paper, we propose the use of a Distributed Hash Table (DHT) as a layer on top of DLTs where, once the data are acquired and stored in the ledger, these can be searched through multiple keyword based queries, thanks to the lookup functionalities offered by the DHT. The DHT network is a hypercube overlay structure, organized for an efficient processing of multiple keyword-based queries. We provide the architecture of such solution for a decentralized data marketplace and an analysis based on a simulation that proves the viability of the proposed approach.
Recently, coded blockchain systems have been proposed to encode blockchain into coded fragments and distributively store them. These fragments can be collected and decoded to obtain the original blockchain only when needed. This reduces the storage requirement of blockchains and makes it possible to incorporate blockchain in wireless Internet-of-Things (IoT) systems. However, transmitting such coded fragments consumes nonnegligible resource in wireless networks. Hence, this article studies the storage and transmission tradeoff for coded blockchains, and formulates the coded fragments assignment using an integer linear program (ILP). In particular, a$Q$-hop localization property is proposed to ensure that any device is able to collect sufficient coded fragments for decoding within$Q$-hop neighbors. This article then proposes an efficient heuristic algorithm that is built upon the solution to the relaxed ILP. Apart from these, this article studies regrowing blockchains, where nodes dynamically join and leave the networks, and proposes an algorithm to adjust the coded fragments assignments. Simulation results show that the performance of the proposed heuristic algorithm is close to that of the ILP, and only a small portion of nodes need to recalculate their assignments when using the proposed adjustment algorithm in the regrowing blockchains.
<strong>The most accepted cryptographic money is the bitcoin, which is highly attracting the traders and investors for making buy or sell decisions. However, the prediction of the bitcoin prices is challenging due to its higher voltality. In this work, a new bitcoin prediction model is introduced with three major phases: Pre-processing, Feature Extraction and Prediction. The collected bit coin data corresponding to minute-by-minute and hour-by-hour data is subjected to pre-processing. From the pre-processed data, the original features are extracted along with the features based on technical indicators. Average True Range (ATR), Exponential Moving Average (EMA) and Relative Strength Index (RSI) are the technical indicators computed. All the extracted features are subjected to prediction phase, where the optimized Neural Network (NN) model is used. To make the prediction more accurate, the training of NN is carried out by the renowned Elephant Herding Optimization (EHO) via tuning the weight. Finally, the algorithmic analysis is carried out by varying the window size.</strong>
Blockchain technology has recently witnessed a rapid proliferation across multiple industries and has the potential to evolve as a popular energy transaction platform for grid operators and general users. The current proof-of-work consensus algorithm used by many blockchain protocols suffer from vulnerabilities such as the majority attacks problem and strip mining. The algorithm often requires specialized application-specific hardware and involves energy-intensive computation, making it an unlikely candidate for power grid applications. On the other hand, the proof-of-stake consensus algorithm is susceptible to the well-known nothing-at-stake vulnerability issue, making it equally unlikely to be used in large-scale secured energy transactions. An energy-efficient locational marginal pricing-based hybrid proof-of-work, proof-of-stake consensus algorithm is proposed to mitigate such risks. The hybrid consensus algorithm uses an optimized market-based energy pricing model to select the mining and forging nodes. A detailed framework of the hybrid consensus algorithm is provided, along with an overview of its potential application to record large volumes of energy transactions and execute obligatory smart-contract agreements.
Bishakh Chandra Ghosh, Tanay Bhartia, Sourav Kanti Addya, Sandip Chakraborty
With the increasing adoption of private blockchain platforms, consortia operating in various sectors such as trade, finance, logistics, etc., are becoming common. Despite having the benefits of a completely decentralized architecture which supports transparency and distributed control, existing private blockchains limit the data, assets, and processes within its closed boundary, which restricts secure and verifiable service provisioning to the end-consumers. Thus, platforms such as e-commerce with multiple sellers or cloud federation with a collection of cloud service providers cannot be decentralized with the existing blockchain platforms. This paper proposes a decentralized gateway architecture interfacing private blockchain with end-users by leveraging the unique combination of public and private blockchain platforms through interoperation. Through the use case of decentralized cloud federations, we have demonstrated the viability of the solution. Our testbed implementation with Ethereum and Hyperledger Fabric, with three service providers, shows that such consortium can operate within an acceptable response latency while scaling up to 64 parallel requests per second for cloud infrastructure provisioning. Further analysis over the Mininet emulation platform indicates that the platform can scale well with minimal impact over the latency as the number of participating service providers increases.
Trust can best be understood as a relational attribute between (1) a social actor and other actor(s) (interpersonal trust) and / or (2) actors and institutions (institutional or systemic trust) and (3) institutions and (trusting) actors (trust as shared expectations), where institutional frameworks define the nature and strength of trust relationships between different actors.
Blockchain is an emerging technology for decentralized transactional data sharing networks of untrusted participants. Monitoring and alerting are crucial functionalities when it comes to blockchain projects running in production. In the meantime, different blockchain monitoring systems lack detailed and real-time metrics. In addition to that, the adoption of different DLTs (Distributed Ledger Technologies) is poor. To solve this problem, we propose a realtime-based information framework to monitor blockchain applications. Our monitoring framework is not only a log-based method but also gathers other system metrics (e.g., CPU throughput, latency). The main benefits of our approach are lower configuration setup, more detailed metrics, and, larger DLTs adoption than the existing monitoring tools. We implement the framework to monitor three well-known blockchain systems. The experimental results show that our framework can make a detailed and realtime monitoring of blockchain projects.
Software-Defined Networking (SDN) separates network data plane and control plane, thus facilitates the introduction of control approaches in centralised and distributed modes. In this context, data plane should be remotely accessible for software-based control. In addition, physically-distributed control plane architectures should maintain secure communications between the SDN control plane elements. Securing distributed SDN is one of the applications that can take benefit from the use of Blockchain technology. In this paper, we achieve the security between the SDN controllers using Blockchain based smart contracts. We propose the use of smart contracts that embedded the SDN rules. We show different scenarios invoking smart contracts that are developed to secure the distributed SDN and to avoid unauthorised access and DoS attacks.
Xi Li, Zehua Wang, Victor C. M. Leung, Hong Ji · 6 authors
The paths leading to future networks are pointing towards a data-driven paradigm to better cater to the explosive growth of mobile services as well as the increasing heterogeneity of mobile devices, many of which generate and consume large volumes and variety of data. These paths are also hampered by significant challenges in terms of security, privacy, services provisioning, and network management. Blockchain, which is a technology for building distributed ledgers that provide an immutable log of transactions recorded in a distributed network, has become prominent recently as the underlying technology of cryptocurrencies and is revolutionizing data storage and processing in computer network systems. For future data-driven networks (DDNs), blockchain is considered as a promising solution to enable the secure storage, sharing, and analytics of data, privacy protection for users, robust, trustworthy network control, and decentralized routing and resource managements. However, many important challenges and open issues remain to be addressed before blockchain can be deployed widely to enable future DDNs. In this article, we present a survey on the existing research works on the application of blockchain technologies in computer networks and identify challenges and potential solutions in the applications of blockchains in future DDNs. We identify application scenarios in which future blockchain-empowered DDNs could improve the efficiency and security, and generally the effectiveness of network services.
A lot of hard work and years of research are still needed for developing successful Blockchain (BC) applications. Although it is not yet standardized, BC technology was proven as to be an enhancement factor for security, decentralization, and reliability, leading to be successfully implemented in cryptocurrency industries. Fog computing (FC) is one of the recently emerged paradigms that needs to be improved to serve Internet of Things (IoT) environments of the future. As hundreds of projects, ideas, and systems were proposed, one can find a great R&D potential for integrating BC and FC technologies. Examples of organizations contributing to the R&D of these two technologies, and their integration, include Linux, IBM, Google, Microsoft, and others. To validate an integrated Fog-Blockchain protocol or method implementation, before the deployment phase, a suitable and accurate simulation environment is needed. Such validation should save a great deal of costs and efforts on researchers and companies adopting this integration. Current available simulation environments facilitate Fog simulation, or BC simulation, but not both. In this paper, we introduce a Fog-Blockchain simulator, namely FoBSim, with the main goal to ease the experimentation and validation of integrated Fog-Blockchain approaches. According to our proposed workflow of simulation, we implement different Consensus Algorithms (CA), different deployment options of the BC in the FC architecture, and different functionalities of the BC in the simulation. Furthermore, technical details and algorithms on the simulated integration are provided. We validate FoBSim by describing the technologies used within FoBSim, highlighting FoBSim's novelty compared to the state-of-the-art, discussing the event validity in FoBSim, and providing a clear walk-through validation. Finally, we simulate case studies, then present and analyze the obtained results, where deploying the BC network in the fog layer shows enhanced efficiency in terms of total run time and total storage cost.
Aristidis G. Anagnostakis, Νικόλαος Γιαννακέας, Markos G. Tsipouras, Euripidis Glavas · 5 authors
In this paper we investigate the essential minimum functionality of the autonomous blockchain, and the minimum hardware and software required to support it in the micro-scale in the IoT world. The application of deep-blockchain operation in the lower-level activity of the IoT ecosystem, is expected to bring profound clarity and constitutes a unique challenge. Setting up and operating bit-level blockchain mechanisms on minimal IoT elements like smart switches and active sensors, mandates pushing blockchain engineering to the limits. “How deep can blockchain actually go?” “Which is the minimum Thing of the IoT world that can actually deliver autonomous blockchain functionality?” To answer, an experiment based on IoT micro-controllers was set. The “Witness Protocol” was defined to set the minimum essential micro-blockchain functionality. The protocol was developed and installed on a peer, ad-hoc, autonomous network of casual, real-life IoT micro-devices. The setup was tested, benchmarked, and evaluated in terms of computational needs, efficiency, and collective resistance against malicious attacks. The leading considerations are highlighted, and the results of the experiment are presented. Findings are intriguing and prove that fully autonomous, private micro-blockchain networks are absolutely feasible in the smart dust world, utilizing the capacities of the existing low-end IoT devices.
Roman Matzutt, Benedikt Kalde, Jan Pennekamp, Arthur Drichel · 6 authors
Popular cryptocurrencies continue to face serious scalability issues due to their ever-growing blockchains. Thus, modern blockchain designs began to prune old blocks and rely on recent snapshots for their bootstrapping processes instead. Unfortunately, established systems are often considered incapable of adopting these improvements. In this work, we present CoinPrune, our block-pruning scheme with full Bitcoin compatibility, to revise this popular belief. CoinPrune bootstraps joining nodes via snapshots that are periodically created from Bitcoin's set of unspent transaction outputs (UTXO set). Our scheme establishes trust in these snapshots by relying on CoinPrune-supporting miners to mutually reaffirm a snapshot's correctness on the blockchain. This way, snapshots remain trustworthy even if adversaries attempt to tamper with them. Our scheme maintains its retrospective deployability by relying on positive feedback only, i.e., blocks containing invalid reaffirmations are not rejected, but invalid reaffirmations are outpaced by the benign ones created by an honest majority among CoinPrune-supporting miners. Already today, CoinPrune reduces the storage requirements for Bitcoin nodes by two orders of magnitude, as joining nodes need to fetch and process only 6 GiB instead of 271 GiB of data in our evaluation, reducing the synchronization time of powerful devices from currently 7 h to 51 min, with even larger potential drops for less powerful devices. CoinPrune is further aware of higher-level application data, i.e., it conserves otherwise pruned application data and allows nodes to obfuscate objectionable and potentially illegal blockchain content from their UTXO set and the snapshots they distribute.
lockchain stores a series of transactions in form of a sequence of linked blocks. Hence, the concept of ledger is easily maintained. Transactions and interactions that take place among participants accessing the distributed and decentralized blockchain network are holding through ledger. In a student management system (SMS), vital information can be highly shared and well protected at the same time. This paper proposes a model for using blockchains to implement fully functional SMS that maintains students’ records, course registrations record and student marks. The proposed model adds more security via the use of hashing and data readily available with decentralized data storage. In addition, the use of ledger-based system to maintain SMS data introduces reliable and highly trusted model.
Nitin Awathare, Sourav Das, Vinay J. Ribeiro, Umesh Bellur
A Blockchain system such as Ethereum is a peer to peer network where each node works in three phases: creation, mining, and validation phases. In the creation phase, it executes a subset of locally cached transactions to form a new block. In the mining phase, the node solves a cryptographic puzzle (Proof of Work-PoW) on the block it forms. On receiving a block from another peer, it starts the validation phase, where it executes the transactions in the received block in order to ensure all transactions are valid. This execution also updates the blockchain state, which must be completed before creating the next block. A long block validation time lowers the system's overall throughput and brings the well known Verifier's dilemma into play. Additionally, this leads to wasted mining power utilization (MPU).
Alexandr Kuznetsov, Inna Oleshko, Vladyslav Tymchenko, Konstantin Lisitsky · 6 authors
A blockchain, or in other words a chain of transaction blocks, is a distributed database that maintains an ordered chain of blocks that reliably connect the information contained in them. Copies of chain blocks are usually stored on multiple computers and synchronized in accordance with the rules of building a chain of blocks, which provides secure and change-resistant storage of information. To build linked lists of blocks hashing is used. Hashing is a special cryptographic primitive that provides one-way, resistance to collisions and search for prototypes computation of hash value (hash or message digest). In this paper a comparative analysis of the performance of hashing algorithms that can be used in modern decentralized blockchain networks are conducted. Specifically, the hash performance on different desktop systems, the number of cycles per byte (Cycles/byte), the amount of hashed message per second (MB/s) and the hash rate (KHash/s) are investigated. The comparative analysis of different hashing algorithms allows us to choose the most suitable candidates for building decentralized systems type of blockchain.