Qingyi Zhu, Seng W. Loke, Rolando Trujillo-Rasúa, Frank Jiang · 5 authors
Distributed Ledger Technologies (DLTs) and blockchain systems have received enormous academic, government, and commercial interest in recent years. This article surveys the integration of DLTs within another life-changing technology, the Internet of Things (IoT). IoT-based applications, such as smart home, smart transport, supply chain, smart healthcare, and smart energy, promise to boost the efficiency of existing infrastructures and change every facet of our daily life. This article looks into the challenges faced by such applications and reviews a comprehensive selection of existing DLT solutions to those challenges. We also identify issues for future research, including DLT security and scalability, multi-DLT applications, and survival of DLT in the post-quantum world.
Roben Castagna Lunardi, Regio A. Michelin, Charles V. Neu, Henry C. Nunes · 6 authors
The Internet of Things (IoT) is transforming our physical world into a complex and dynamic system of connected devices on an unprecedented scale. Connecting everyday physical objects is creating new business models, improving processes and reducing costs and risks. Recently, blockchain technology has received a lot of attention from the community as a possible solution to overcome security issues in IoT. However, traditional blockchains (such as the ones used in Bitcoin and Ethereum) are not well suited to the resource-constrained nature of IoT devices and also with the large volume of information that is expected to be generated from typical IoT deployments. To overcome these issues, several researchers have presented lightweight instances of blockchains tailored for IoT. For example, proposing novel data structures based on blocks with decoupled and appendable data. However, these researchers did not discuss how the consensus algorithm would impact their solutions, i.e., the decision of which consensus algorithm would be better suited was left as an open issue. In this paper, we improved an appendable-block blockchain framework to support different consensus algorithms through a modular design. We evaluated the performance of this improved version in different emulated scenarios and studied the impact of varying the number of devices and transactions and employing different consensus algorithms. Even adopting different consensus algorithms, results indicate that the latency to append a new block is less than 161ms (in the more demanding scenario) and the delay for processing a new transaction is less than 7ms, suggesting that our improved version of the appendable-block blockchain is efficient and scalable, and thus well suited for IoT scenarios.
The problem of peer selection, which randomly selects a peer from a set, is commonplace in Proof-of-Stake (PoS) protocols. In PoS, peers are chosen randomly with probability proportional to the amount of stake that they possess. This paper presents an approach that relates PoS peer selection to Roulette-wheel selection, which is frequently used in genetic and evolutionary algorithms or complex network modelling. In particular, we introduce the use of stochastic acceptance algorithm [6] for fast peer selection. The roulette-wheel selection algorithm [6] achieves O(1) complexity based on stochastic acceptance, whereas searching based algorithms may take O(N ) or O(logN ) complexity in a network of N peers.
With the development of science and technology, human beings cannot live without electricity. The introduction of smart grid systems brings new ideas to break the shackle of existing electricity systems. This paper proposes a mechanism with data monitoring and sharing capabilities based on the consortium blockchain, realizing comprehensive monitoring of smart devices, and promoting the effective sharing of electrical data in smart grids. When a smart device is out of order, the smart contract connected to it will be triggered, and the users can check the running status through the smart phone. This approach allows nodes in the consortium blockchain to request transactions, using the prepaid payment smart contract with time-lock script to protect the consumer right of request nodes. In addition, we use a (t, n) -threshold secret sharing scheme to realize multiparty sharing of electrical data. Paillier encryption arithmetic is used to guarantee the confidentiality of messages in node transaction.
Feeding external data to a blockchain, a.k.a. data feed, is an essential task to enable blockchain interoperability and support emerging cross-domain applications, notably stablecoins. Given the data-intensive feeds in real life (e.g., high-frequency price updates) and the high cost in using blockchain, namely Gas, it is imperative to reduce the Gas cost of data feeds. Motivated by the constant-changing workloads in finance and other applications, this work focuses on designing a dynamic, workload-aware approach for cost effectiveness in Gas. This design space is understudied in the existing blockchain research which has so far focused on static data placement. This work presents GRuB, a cost-effective data feed that dynamically replicates data between the blockchain and an off-chain cloud storage. GRuB's data replication is workload-adaptive by monitoring the current workload and making online decisions w.r.t. data replication. A series of online algorithms are proposed that achieve the bounded worst-case cost in blockchain's Gas. GRuB runs the decision-making components on the untrusted cloud off-chain for lower Gas costs, and employs a security protocol to authenticate the data transferred between the blockchain and cloud. The overall GRuB system can autonomously achieve low Gas costs with changing workloads. We built a GRuB prototype functional with Ethereum and Google LevelDB, and supported real applications in stablecoins. Under real workloads collected from the Ethereum contract-call history and mixed workloads of YCSB, we systematically evaluate GRuB's cost which shows a saving of Gas by 10% ~ 74%, with comparison to the baselines of static data-placement.
Cryptocurrencies are digital assets which depend upon the use of distributed peer-to-peer networks. The method a new peer uses to initially join a peer-to-peer network is known as bootstrapping. The ability to bootstrap without the use of a centralized resource is an unresolved challenge. In this paper we survey the bootstrapping techniques used by 74 cryptocurrencies and find that censorship-prone methods such as DNS seeding and IP hard-coding are the most prevalent. In response to this finding, we test two other bootstrapping techniques less susceptible to censorship, Tor and ZMap, to determine if they are operationally feasible alternatives more resilient to censorship. We perform a global measurement study of DNS query responses for each the 92 DNS seeds discovered across 42 countries using the distributed RIPE Atlas network. This provides details of each cryptocurrencies' peer-to-peer network topology and also highlights instances of DNS outages and query manipulation impacting the bootstrapping process. Our study also reveals that the source code of the cryptocurrencies researched comes from only five main repositories; hence accounting for the inheritance of legacy bootstrapping methods. Finally, we discuss the implications of our findings and provide recommendations to mitigate the risks exposed.
Bitcoin is a top-ranked cryptocurrency that has experienced huge growth and survived numerous attacks. The protocols making up Bitcoin must therefore accommodate the growth of the network and ensure security.
The pervasiveness of IoT devices makes the delivery mechanism of security updates a challenge. Current IoT systems rely on centralized or brokered paradigms or clouds with huge computational and storage capacities. The existing centralized IoT setups are therefore expensive as the result of factors such as the high costs associated with cloud server and network infrastructures and maintenance. Thus, the need for a fully decentralized peer to peer and secure technology to overcome these problems rises into the realm of existence. Blockchain provides a solution that fulfills the requirements of such a platform. Ideally, the update infrastructure should implement the CIA triad properties (Confidentiality, Integrity, and Availability). In this article, we study how a blockchain application can meet these requirements and propose a novel system to decentrally distribute digital content in a peer-to-peer network using the blockchain technology and smart contracts to overcome the concerns mentioned above. Additionally, in order to prevent the issues stemming from the free-riding challenge in P2P networks (peers refrain to generously share their resources to distribute updates), we exploit a Nash equilibrium micropayment mechanism to grant adequate incentive for peers to participate in distributing IoT update files.
Traditionally in blockchain systems, the sequence of transactions acts as a decentralized ledger where each node in the network is required to store an identical copy. As a result, the storage space required to store the entire blockchain can become prohibitively large. Erasure coding and network coding techniques were previously introduced to mitigate this storage burden. In this work, we first observe that node failures in the network can occur periodically. Next, we take advantage of this property to develop a coding scheme which corrects a predefined set of possible node erasure patterns. By explicitly focusing on certain erasure patterns, proposed codes have lower storage requirements than erasure codes which correct all possible erasure patterns, and moreover, our codes achieve the minimum average storage per node under the given assumptions.
Abel O. Gomez Rivera, Deepak K. Tosh, Laurent Njilla
State-of-the-art centralized internet of things (IoT) architectures suffer from scalability issues in terms of both devices and transactions. Centralized architecture infers a central server with finite resources to process the communication demands of large IoT networks. The security of such IoT infrastructures is contingent on the protection of the central server. To address the challenges of security and scalability of transactions, we design and implement an edge-based blockchain network, where a set of edge nodes are incorporated to serve the requests of field devices. The edge nodes of our network offer security and processing functionalities to data transactions made by field devices. Besides the proposed architecture, a proof of concept of our edge-based blockchain platform is implemented to study its feasibility and performance. The platform achieves the fundamental security properties and addresses the transaction scalability issue. Blockchain technology and edge computing have the potential to enable a robust, and flexible architecture for IoT networks while maintaining low latency and high availability. The effectiveness of the proposed architecture is evaluated in a simulated network.
The blockchain technology has broad application prospects in the financial field, public welfare industry, and Internet with its characteristics of decentralization, openness, autonomy, information unchangeability and anonymity. The most prominent problem it faces is the difficulty in reaching a credible consensus quickly. Based on the consensus mechanism of DPoS and PBFT, a new trust blockchain consensus protocol is proposed. This protocol adds trust value attributes to nodes, dynamically classifies node roles, tracks node behaviors in transactions, and scores trust values for the nodes. The node promotion and demotion mechanism is introduced and the roles of nodes are reclassified according to their latest trust values. Results show that the proposed consensus protocol has high efficiency, low consumption, high fault tolerance and dynamic adaptability, which can meet the needs of most alliance chains.
Mazin Debe, Khaled Salah, Muhammad Habib ur Rehman, Davor Svetinović
The omnipresence of Internet of Things (IoT) devices nowadays has resulted in a large amount of data transferred regularly to the cloud. This continuous data transfer degrades the application performance in terms of latency, bandwidth consumption, connectivity, security, privacy, user experiences, and energy efficiency. Fog computing brings cloud services closer to the IoT devices. In public settings, variety of handheld and IoT devices need to connect to public fog nodes in order to access localized compute, storage, and networking capabilities. Therefore, the reputations of publicly available fog nodes become critical. Maintaining a reputation score is one of the popular techniques to ensure trust for fog nodes. This paper introduces a blockchain-based solution to establish trust in public fog nodes that provides services for IoT devices in a decentralized manner. Our proposed solution exploits blockchain smart contracts to compute the reputation in a decentralized manner by capturing and analyzing its past interactions with IoT devices. The solution also penalizes IoT devices that may collude to provide dishonest reputation scores.
The privacy issues become a major problem that should be resolved for the existing centralized online social networks, which have prompted researchers to consider the decentralization framework for online social networks. In this paper, we propose a novel decentralized social networking architecture enhanced by blockchain technology. We use a sharding framework to increase the system scalability, a blockchain system to ensure the data integrity and consistency, a reputation-based authority control method to improve the system security.
Blockchain is very important in finance field and electronic business field, so many researchers are attracted to study the technologies of blockchain. Since the transactions in blockchain takes much time, and they make the blockchain poor efficiency, business processes across organizations require the transactions as soon as possible. Concurrency is attracted much attention and is very important in blockchain field. In this paper, a novel decentralized blockchain network model with high concurrency is proposed. First, the idea of the proposed model is stated. Second, the high concurrency blockchain network model is proposed. Third, the corresponding algorithms are designed according to the proposed model. Furthermore, the experiment is conduced and the results show that proposed model works well.
Several applications can benefit from recording information about the places a mobile entity visits and the length of time it spends there (e.g., shoppers, employees, buses, movable equipment, autonomous robots, etc.). In this paper, we present our approach to recording spatio-temporal information in a secure and inviolable way using a Distributed Ledger Technology. So far in this work, we observe that, although sending data to the blockchain is a heavy process, there are ways that this transaction time does not disrupt the flow of new data such as adding these data to a queue. However, this makes the sending process overall longer. We intend to continue this study by testing different blockchain services and comparing their performances.
The number of photographs taken is increasing exponentially each year. This includes the photographs captured by professional as well as non-professional personnel. The ease in accessibility of these work of art over the internet has increased unauthorized use of owner's property without handing them their deserved credit. In addition, the process to take the authorization over the use of the photograph from the respective owner takes a large amount of time as well as money. One of the solutions to this problem is the use of distributed ledger technology known as ‘Blockchain’ in order to keep the decentralized record of ownership. In addition, storing the photograph itself on the decentralized platform can make it more secure. Furthermore, designing a smart contract in which the user and owner can agree on the use of the owner's property can address the problem of unauthorized use. This paper describes the integration of blockchain, distributed storage, and peer-to-peer communication in order to solve the current problem of handling photograph ownership and authorization. Ethereum blockchain is implemented to achieve secure transaction and handling functionality regarding authorization with the help of smart contracts that runs on the blockchain. As the storage layer, the paper discusses the InterPlanetary File System (IPFS) as a distributed database with which the photographs can be stored such that decentralization can be achieved. Only after the verifying the similar image does not exist on the system the image is stored in IPFS. The existence of a duplicate image is done with the implementation of dHash algorithm and hamming distance. Whisper protocol allows the owner of the photograph and user on the Ethereum blockchain to leverage peer-to-peer communication to reach a consensus.
Erick D. Buenrostro, Abel O. Gomez Rivera, Deepak K. Tosh, Jaime C. Acosta · 5 authors
Military technology is ever-evolving to increase the safety and security of soldiers on the field while integrating Internet-of-Things solutions to improve operational efficiency in mission oriented tasks in the battlefield. Centralized communication technology is the traditional network model used for battlefields and is vulnerable to denial of service attacks, therefore suffers performance hazards. They also lead to a central point of failure, due to which, a flexible model that is mobile, resilient, and effective for different scenarios must be proposed. Blockchain offers a distributed platform that allows multiple nodes to update a distributed ledger in a tamper-resistant manner. The decentralized nature of this system suggests that it can be an effective tool for battlefields in securing data communication among Internet-of-Battlefield Things (IoBT). In this paper, we integrate a permissioned blockchain, namely Hyperledger Sawtooth, in IoBT context and evaluate its performance with the goal of determining whether it has the potential to serve the performance needs of IoBT environment. Using different testing parameters, the metric data would help in suggesting the best parameter set, network configuration and blockchain usability views in IoBT context. We show that a blockchain-integrated IoBT platform has heavy dependency on the characteristics of the underlying network such as topology, link bandwidth, jitter, and other communication configurations, that can be tuned up to achieve optimal performance.
To improve mobile users' quality-of-experience (QoE) in the mobile cyber-physical system (MCPS), caching layered-coding contents on edge nodes that are close to mobile users has been advocated as a promising solution, which can efficiently lower the content delivery delay and mitigate the overhead of backhaul network. However, due to the complexity of trust management and the limited caching capacities of edge nodes, designing an efficient edge caching scheme for mobile users becomes a challenge. Meanwhile, the content caching in MCPS also faces some security problems, where edge nodes may return incorrect results or viruses to mobile users, and mobile users would deliberately refuse to pay for caching services. To tackle these problems, we propose a novel blockchain-based trustworthy edge caching scheme for mobile users in MCPS. Specifically, we first exploit blockchain to supervise the caching transactions between the edge nodes and mobile users in a distributed manner, whereby the caching service information cannot be modified and denied by any entities. Furthermore, we devise a trust management mechanism for mobile users to search the trustworthy caching services from diversified edge nodes, where the trust degree of the edge node is real-time evaluated and updated by mobile users based on the quality of caching service. To take full advantage of caching resources, we design a max-min-based resource allocation algorithm, with which the trustworthy edge node could fairly allocate its caching resource based on mobile users' optimal demands. The simulation results show that the presented scheme not only improves the utilities of edge nodes but also increases the QoE of mobile users.
Blockchain, a distributed and democratically-sustained public register of the transactions of the digital currency "Bitcoin", proposed by Satoshi Nakamoto a pseudonym of a hided developer in 2009, has been the driver of a huge number of initiatives devoted to develop and implement a peer-to-peer distributed database, and with no central authority created as an open source software. Expansion of Bitcoin, as well as other digital currencies, has been due to lower transaction costs, high security protocols and lack of inflation with respect to fiat money and no need of a clearing entity or a central bank. Although, environmental issues related to the use of this currency and, in particular, in the energy consumes, have been raised by the scientific community, but no signals of limiting factors have been detected until now. The hidden in the wings blockchain technology has been recognized the driver of innovation in various fields, contributing to create a more sustainable world. The purpose of this paper is to describe both the recent trends in the applications of the blockchain technology in the cryptocurrencies market and the new projects considering the environmental sustainability (energy consumption, materials depletion) and social impacts. The contribute of blockchain in reducing and accelerating bureaucracy and incentivizing environmentally friendly behaviour, has been discussed. Although the environmental issues related to the energy consumed in Bitcoin mining may scare companies in adopting the new technology, there is no evidence of limiting factors or carrying capacity of the entire system. In future the development of a less energy intensive alternative for validating the blocks to stack in the distributed database, would render the blockchain the ideal candidate for the applicability of sustainability paradigms in the economic, environmental and social sectors.
Many critical applications are designed on the distributed structure using the blockchain technology to ensure the availability, immutability, and security. However, these applications are facing the storage problem owing to the data volume growth of transaction. The number of transactions and its size in a block is growing in the blockchain day by day because of the feature of immutability and append-only. The growing nature of transactions in a block is not only making the problem for storage but also in access to the block transactions. In this paper, we propose an IPFS based blockchain storage model to solve the storage problem of transaction in a block along with access of transaction of a particular block. In the propose storage model, the miners stores transaction on IPFS distributed file system storage and get the returned IPFS hash of transaction into the block of the blockchain. The feature of the IPFS network and its resultant hash reduce the size of transactions in a block. To secure access of transaction for a particular block content-addressed (IPFS hash) storage technique has been proposed. We have applied this scheme on a transaction which includes image storage on IPFS and hash storage into the blockchain. In this paper, we have also proposed the content-addressed technique in contrast to the location addressed for the access of transaction. To implement the framework we have used anaconda python, python flask, and IPFS.
Invoice discounting is a market with a double-digit potential growth rate in Europe and worldwide in the next years. The main benefit of invoice discounting is the acceleration of cash flow from customers to suppliers: suppliers get advance payments from the bank, rather than waiting for the customers to pay. Hence, thanks to the quick availability of capital, businesses can invest in expansion and growth. More specifically, one of the most relevant problems today is how to provide better and faster invoice discounting services while preventing the double spending and maintaining the risk low. The blockchain frameworks have the potential to provide the right solution and thus to revolutionize the invoice discounting process. The benefits for suppliers, customers and financial institutions are related to the increased transparency added to the whole discounting process and the following risk reduction for the banks due to the capability to enhance the entire process and to reduce the double spending. In our paper, we introduce a blockchain-based invoice discounting system, called Distributed Ledger Invoice, and we propose a novel assessment method for evaluating currently available blockchain solutions for the invoice discounting scenario. Moreover, we also discuss two main issues regarding the information accessibility and the interoperability. In particular, since blockchain is still an emerging technology interoperability is a key factor for the blockchain adoption in inter-banking processes, where different blockchains solutions might be used. In this work we propose a decoupling layer, based on the Attribute-Based Access Control language, to unify the access control to reserved information across heterogeneous blockchains.
Summary Selecting which blockchain participants can decide upon a new block is a difficult problem. Consortium blockchains need the participants to be predetermined while public blockchains incentivize all participants to waste their resources to decide every block. In this paper, we introduce the community blockchain that allows potentially all participants to decide upon “some” block while restricting the set of participants deciding upon “one” block. To this end, we propose a blockchain reconfiguration, a Byzantine consensus protocol that allows to dynamically change the set of blockchain participants deciding upon the upcoming blocks. The resulting blockchain, called ComChain , is resilience optimal and transitions through different configurations of participants recorded in dedicated blocks so that each configuration decides upon its subsequent transaction blocks. We evaluate an implementation that adds reconfiguration to the Red Belly Blockchain and demonstrates its practical performance in a distributed system.