Circular Economy is a novel economic model, where every 'asset' is not wasted but reused and upscaled. The Internet of Things-IoT paradigm can underpin the transition to a Circular Economy by enabling fine-grained and continuous asset tracking. However, there are issues related to security and privacy of IoT devices that generate and handle sensitive and personal data. The use of Blockchain technology provides an answer to this issue, however, its application raises issues related to the highly-constrained nature of these networks. In this paper, Edge Computing is presented as a solution to this issue, providing a way in which Blockchain and Edge Computing can be used together to address the constrained nature of IoT. Furthermore, we present the challenges that this combination poses and the opportunities that it brings. We propose an architecture that decreases the IoT devices requirements for memory capacity and increases the overall performance. We also discuss the architecture design and the challenges that it has, comparing it to the traditional Blockchain architecture as well as an Edge Computing architecture for Mobile Blockchain. The paper closes with a discussion and future extensions of our work are presented, as well.
Gabriel Antonio F. Rebello, Igor D. Alvarenga, Igor Jochem Sanz, Otto Carlos M. B. Duarte
Network Function Virtualization (NFV) and Service Function Chaining (SFC) offer flexible end-to-end services that deploy virtual network functions in clouds of competing providers. Orchestration of virtual network functions occurs in a distributed and trustless environment that must tolerate byzantine failures and collusion attacks. This paper proposes BSec-NFVO, a blockchain-based system that secures orchestration operations in virtualized networks, ensuring auditability, non-repudiation and integrity. We propose an NFV-tailored blockchain and a transaction model. BSec-NFVO provides a modular architecture to secure orchestration in a simple and agile way. We develop a prototype of BSec-NFVO for the Open Platform for Network Function Virtualization (OPNFV) with an adaptation of the normal-case of a collusion-resistant consensus protocol. The results show BSec-NFVO incurs low overhead to the cloud orchestrator and presents stable performance as the number of consensus participants increases.
The emerging blockchain technology provides a new paradigm for maintaining data integrity and unforgeability in a distributed manner. However conventional public blockchain systems suffer large consensus latency thus cannot be well applied to Internet of Vehicles (IoV) with the high mobility of vehicles and low latency requirement. In addition, not all messages in IoV should be stored in a global ledger. In this paper, we propose a novel Hierarchical Blockchain (HB) which divides the system into two layers and each layer maintains an exclusive ledger. Sensing information of vehicles are recorded in differnet layer according to its influence scope. Furthermore, based on the transactions recorded in the hierarchical blockchain, we design the proactive file duplicate caching scheme considering not only popularities but influence scopes for the enhancement of overall system performance. Simulation results shows the superiority of the proposed architecture compared with conventional vehicular systems, in terms of failure rate, latency and system utility.
Internet of Things (IoT), an significant support for strategic emerging industries, is re-building industrial systems, such as transportation, healthcare and energy, while a number of new features and requirements like data cross-industry sharding appear in recent years. The emerging Blockchain technology has provided a promising opportunity to break information island and single-domain management in multi-domain IoT systems by leveraging distributed storage. On the other hand, the transaction consensus throughput in the mainstream blockchain systems, such as Ethereum and Fabric, is far from meeting the demand for massive data storage in time in multi-domain IoT systems. In this paper, we design a sharding protocol called MDIoTSP. The protocol first partitions the overall blockchains into many small shards, each of which generally recognized as a micro-blockchain according to the multiple domains, and then make the final consensus by merging the hash digests of the sub-blocks which generated from the shards for the multi-domain IoT blockchains ecosystem specifically. We also develop MicrothingsChains to run MDIoTSP in multi-domain IoT blockchains to prove our assumption that MDIoTSP scales up the transaction consensus throughput near linearly with the number of shards.
Muhammad Saad, Laurent Njilla, Charles Kamhoua, Joongheon Kim · 6 authors
In this paper, we present a new form of attack that can be carried out on the memory pools (mempools) of blockchain-based cryptocurrencies. Towards that end, we study such an attack on Bitcoin mempool and explore its effects on transactions fee paid by legitimate users. We also propose countermeasures to contain such an attack. Our countermeasures include fee-based and age-based designs, which optimize the mempool size and help in countering the effects of DDoS attacks. We further evaluate our designs by simulations and analyze their usefulness in varying attack conditions. Our analyses can be extended to other blockchain-based applications which use memory pools to cache network activities.
Shenbin Zhang, Ence Zhou, Bingfeng Pi, Jun Sun · 6 authors
Blockchain is one of the most popular distributed ledger technologies. In order to solve the trustless problems between enterprises, many permissioned blockchain platforms are proposed in recent years. Hyperledger Fabric is a permissioned blockchain which is comprised of chaincode, endorsing peers, ordering service, committing peers and membership service. Fabric provides identity authentication, transactions encryption and high performance. Hence, decentralized application based on Fabric can be applied among enterprises to implement the immutable and high throughput for transactions. However, some limitations still exist in Fabric framework. This paper surveys the risk of non-deterministic transactions in Fabric, which can be caused by read-write conflict and transactions order dependency. Transactions are judged to be invalid by committing peers when read-write conflict exists. Besides, transactions submission order may be disrupted during endorsing and ordering. Both of the two risks can make the final transaction execution result non-deterministic. Finally, a solution of cache layer on Fabric client is proposed to solve the risk of non-deterministic transactions.
Blockchain techniques are attracting growing interest due to their capability of immutable and anonymous recording without any centralized authority. One of the difficulties blockchain researchers are facing is a lack of ways to verify behaviors of large scale blockchain networks. In this demonstration, we present SimBlock, a blockchain network simulator. It simulates the peer-to-peer network of a public blockchain, e.g., Bitcoin, which consists of thousands of nodes, as well as parameters related to a blockchain and its network are flexibly configurable. SimBlock can also visualize nodes' behavior and block propagation. By giving some example studies, such as exploring better neighbor selection strategies and assessing the influence of relay networks, we show that SimBlock can facilitate blockchain network research.
A blockchain has attracted in many research fields. In this paper, a blockchain-based distributed optimization method for energy management systems (EMSs) is studied. In distributed optimization, the original problem is decomposed, and the local problems are solved by multiple agents. Hence, distributed optimization is appropriate for large-scale multi-agent systems. In this paper, ADMM (Alternating Direction Method of Multipliers) is utilized as one of the powerful methods in distributed optimization. In ADMM, an aggregator is required for collecting the computation result in each agent. Using blockchains, the function of an aggregator can be contained in a distributed ledger, and an aggregator may not be required. As a result, tampering from attackers can be prevented. In this paper, after ADMM and blockchains are summarized, an EMS studied in this paper is introduced. By numerical experiments, the effectiveness and limitation of blockchain-based distributed optimization are clarified from the viewpoints of tamper tolerance and computation time.
Nakul Chawla, Hans Walter Behrens, Darren Tapp, Dragan Boscovic · 5 authors
Blockchain technology and other distributed ledger systems fill an important role in resilient data storage and publication. However, their normally-decentralized methods also bring unique challenges distinct from more traditional approaches. One lies in the replication of data between participating nodes; since no individual node is more trusted than any other, each node maintains its own copy of the entire ledger for the purposes of validating new transactions. Improving how this information is stored and more importantly, how it propagates across the network, are open research questions. In this work, we propose Velocity, a novel block propagation approach based on fountain codes, allowing for better decentralized delivery of blocks and reduced network bottlenecks without sacrificing the security guarantees of the blockchain ledger itself. We also provide an assessment of economic incentives and their impact on participant behavior, showing that the proposed approach is financially beneficial to rational actors. We conclude by showing experimentally that this approach permits for the mining of even larger blocks, thereby increasing transaction throughput of the system compared to existing state of the art methods.
With the rapid development of the internet of things (IoT), traditional industries are setting off a massive wave of digitization. In the era of the Internet of Everything, millions of devices and links in IoT pose more significant challenges to data management. Most existing solutions employ centralized systems to control IoT devices, which brings about the privacy and security issues in IoT data management. Recently, blockchain has attracted much attention in the field of IoT due to its decentralization, traceability, and non-tamperability. However, it is non-trivial to apply the current blockchain techniques to IoT due to the lack of scalability and high resource costs. Different blockchain platforms have their particular advantages in the scenario of IoT data management. In this paper, we propose a cross-chain framework to integrate multiple blockchains for efficient and secure IoT data management. Our solution builds an interactive decentralized access model which employs a consortium blockchain as the control station. Other blockchain platforms customized for specific IoT scenarios run as the backbone of all IoT devices. It is equivalent to opening the off-chain channels on the consortium blockchain. Our model merges transactions in these channels for confirmation based on the notary mechanism. Finally, we implement a prototype of the proposed model based on hyperledge Fabric and IOTA Tangle. We evaluate the performance of our method through extensive experiments. The results demonstrate the effectiveness and efficiency of our framework.
Internet of Things (IoT), Supply Chain monitoring, and other distributed applications rely on messaging protocols for data exchange. Contemporary IoT and enterprise deployments widely use the publish-subscribe messaging model because of its resource-efficiency. However, the systems with publish-subscribe messaging model employ a centralized architecture, wherein the data from all the publishers in the application network flows via a central broker to the subscribers. Such a centralized architecture makes the publish-subscribe messaging model susceptible to Byzantine failures. For example, it provides an opportunity for the organization that owns the broker to tamper with the data. In this work, we contribute Trinity, a novel distributed publish-subscribe broker with Byzantine fault-tolerance and blockchain-based immutability. Trinity distributes the data published to one of the brokers in the network to all the brokers in the network, and stores the data in an immutable ledger through the use of blockchain technology. Through the use of consensus protocols and distributed ledger technology, Trinity can guarantee ordering, fault-tolerance, persistence and immutability across trust boundaries.Our evaluation results show that Trinity consumes minimal resources. To the best of our knowledge, Trinity is the first framework that combines the components of the blockchain technology with the publish-subscribe messaging model. Furthermore, we plan to use Trinity in a real-world use case for increasing the transparency of racial profiling.
Managing the privileges of occupants and visitors of large commercial buildings to access different building areas, control systems and equipment therein is a challenging task. The best practice today involves giving long-term building occupants, for example employees working in the building, access privileges to their organization areas and requiring visitors to be escorted by them. This approach is conservative and inflexible. Ideally, an automated solution is needed to manage access delegations; however, traditional role-based access control models are unwieldy in that they require the specification of all roles and their relative authority, which is a challenge in large buildings home of multiple organizations and numerous visitors. In this paper, we present a methodology based on blockchain smart contracts to describe, grant, and revoke fine-grained permissions for building users in a decentralized fashion. This method supports access control using resource description framework (RDF) graphs and implements two APIs for client applications. Leveraging the metadata of a real building, we have applied the proposed method to manage privileges in some realistic use-cases and shown that it can greatly reduce the administration overhead while providing fine-grained access control.
This work explores a new low-latency distributed ledger structure based on bounded width directed acyclic graphs (DAGs). In this design, each user has their own blockchain traceable back to a common root. These individual chains mutually witness each other to confirm transactions and form a global partially ordered set of events. The number of witness hashes required to establish new blocks is defined as the “DAG width”. This width has an upper bound which of the total number of users in the system, though the actual number of witnesses required is usually far less. In this paper we mathematically model the expected DAG width using analytical techniques from the near miss birthday problem and simulate expected widths for expected network latency and user activity.
Muhammad Anas Imtiaz, David Starobinski, Ari Trachtenberg, Nabeel Younis
Efficient and reliable propagation of blocks is vital for ensuring the scalability of the Bitcoin network. As a result, several schemes have been proposed over the last few years to speed up the block propagation, most notably the compact block protocol (BIP 152). Despite this, we show experimental evidence that (i) the vast majority (97%) of Bitcoin nodes exhibit intermittent network connectivity (churn), and (ii) this churn results in significant numbers of unsuccessful compact blocks, roughly twice the figure for continuously connected nodes. Specifically, we conduct experiments on the Bitcoin network that show that churn results in a 135% average increase in block propagation time (i.e., 336.57 ms vs 142.62 ms), and can lead to as high as an 800-fold increase in the worst case. To effect our analysis, we develop a statistical model for churn based on empirical network data, and use this model to actuate the live test nodes on the Bitcoin network. The performance of the system is measured by means of a novel framework that we develop for logging the internal behavior of a Bitcoin node and share for public use.
Blockchain and AI are promising techniques for next-generation wireless networks. Blockchain can establish a secure and decentralized resource sharing environment. AI can be explored to solve problems with uncertain, time-variant, and complex features. Both of these techniques have recently seen a surge in interest. The integration of these two techniques can further enhance the performance of wireless networks. In this article, we first propose a secure and intelligent architecture for next-generation wireless networks by integrating AI and blockchain into wireless networks to enable flexible and secure resource sharing. Then we propose a blockchain empowered content caching problem to maximize system utility, and develop a new caching scheme by utilizing deep reinforcement learning. Numerical results demonstrate the effectiveness of the proposed scheme.
After the meteoric rise in price, and subsequent public interest, of the cryptocurrency Bitcoin, a developing body of work has begun examining its impact on society. In recent months, as Bitcoin's price has rapidly declined, uncertainty and distrust have begun to overshadow early enthusiasm. In this late-breaking work, we investigated one of the largest and most important Bitcoin online communities, the r/Bitcoin Reddit forum. A vocal subgroup of users identify themselves as "true Bitcoiners", and justify their continued devotion to Bitcoin. These subreddit participants explained and justified their trust in Bitcoin in three primary ways: identifying characteristics of beneficial versus harmful Bitcoin users, diminishing the importance of problems, and describing themselves as loyal to Bitcoin over time.
Apr 29, 2019·The 3rd International Workshop on Integrating Edge Computing, Caching, and Offloading in Next Generation Networks (INFOCOM workshop IECCO 2019), At Paris, France
Edge computing is a novel paradigm designed to improve the quality of service for latency sensitive cloud applications. However, the state-of-the-art edge services are designed for specific applications, which are isolated from each other. To better improve the utilization level of edge nodes, public resource sharing among edges from distinct service providers should be encouraged economically. In this work, we employ the payment channel techniques to design and implement EdgeToll, a blockchain-based toll collection system for heterogeneous public edge sharing. Test-bed has been developed to validate the proposal and preliminary experiments have been conducted to demonstrate the time and cost efficiency of the system.
Blockchain technology is developing at a rapid pace. For consumers that are only interested in simplifying processes and reducing costs by using a blockchain solution a new problem has occurred. It is not only necessary to select the appropriate solution, but also to configure and operate considering blockchain interoperability with different chains. For the industry, there is a need for solutions based on open standards. This paper proposes a Policy-based Blockchain Agnostic Framework that not only connects different blockchains but also facilitates their configuration and operation. Moreover, a case study is presented considering the cold-chain supply-chain, where each actor defines its policies based on blockchain requirements.
Social networking sites have given users unprecedented opportunities for the generation and dissemination of content. A variety of social networking sites exist for different purposes, to afford users a range of anonymous and non-anonymous options for self-expression, and the ability to be a part of a virtual community. These “affordances” enable users to create and share content; however, the ability to partially or wholly detach user identity from the content has resulted in unique challenges for content access and content attribution. This paper proposes a framework for secure, trustworthy social networking that also creates value for user-generated content by using a blockchain-enhanced framework for social networking. This work explains the application of such a framework for collocated spaces of robots and IoT devices and identifies key challenges that result as a consequence of merging social networking sites and blockchain technology.
Distributed ledgers have received significant attention as a building block for cryptocurrencies and have proven to be also relevant in several other fields. In cryptocurrencies, this abstraction is usually implemented by grouping transactions in blocks that are then linked together to form a blockchain. Nodes need to exchange information to maintain the status of the chain but this process consumes significant network resources. Unfortunately, naively reducing the number of messages exchanged can have a negative impact in performance and correctness, as some transactions might not be included in the chain.
Alejandro Ranchal Pedrosa, Maria Potop-Butucaru, Sara Tucci-Piergiovanni
Bitcoin, the most popular blockchain system, does not scale even under very optimistic assumptions. Lightning networks, a layer on top of Bitcoin, composed of one-to-one lightning channels make it scale to up to 105 Million users. Recently, Duplex Micropayment Channel factories have been proposed based on opening multiple one-to-one payment channels at once. Duplex Micropayment Channel factories rely on time-locks to update and close their channels. This mechanism yields to situation where users funds time-locking for long periods increases with the lifetime of the factory and the number of users. This makes DMC factories not applicable in real-life scenarios.
In blockchain, every full node has to store all history transactions in block bodies. However, with the rapid growth of transactions, the storage bloating problem has emerged, and made it challenging for a mobile system to afford the storage and synchronization overhead. This paper proposes to downsample block bodies to reduce the nodes' storage. By downsampling block bodies by M times, only about 1/M of the block bodies with high information entropy are downloaded and stored. Performance analysis demonstrates that the proposed downsampling nodes and full nodes have similar broadcast accuracy with appropriate M. The simulation results show that the proposed algorithm can provide a better cost-effective choice for nodes between broadcast accuracy and storage.