Blockchain is an innovative distributed ledger technology which has attracted a wide range of interests for building the next generation of applications to address lack-of-trust issues in business. Blockchain as a service (BaaS) is a promising solution to improve the productivity of blockchain application development. However, existing BaaS deployment solutions are mostly vendor-locked: they are either bound to a cloud provider or a blockchain platform. In addition to deployment, design and implementation of blockchain-based applications is a hard task requiring deep expertise. Therefore, this paper presents a unified blockchain as a service platform (uBaaS) to support both design and deployment of blockchain-based applications. The services in uBaaS include deployment as a service, design pattern as a service and auxiliary services. In uBaaS, deployment as a service is platform agnostic, which can avoid lock-in to specific cloud platforms, while design pattern as a service applies design patterns for data management and smart contract design to address the scalability and security issues of blockchain. The proposed solutions are evaluated using a real-world quality tracing use case in terms of feasibility and scalability.
Mobile crowdsensing(MCS) is an emerging pattern which means task initiators attract mobile users sensing with their own devices by some platforms. MCS could exploit idle resources in low cost, while it has lots of flaws, which impede its developments. First, isolations between different MCS systems leads to wastage of social resources. What's more, current MCS always operate in a centralized way, which causes it vulnerable and unbelievable. Blockchain is a promising technology which could supply a credible and transparent environment. This paper construct a blockchain based MCS market and design smart contract for its operation. In our design, platform breaks isolation by blockchain, task initiators and mobile users manage their tasks by smart contract and bargain price with distributed algorithm. By this way, resource could be exploited better, and the market could be more fair. What's more, the paper analyzes Walrasian Equilibrium (WE) in the market, and details how to deploy MCS in blockchain. Evalution results shows that Equilibrium could be found.
Blockchain technologies have grown swiftly in recent years, primarily due to the advent of Bitcoin. Blockchain is a consensus of data structures or blocks programmed for cryptographically storing organized data, which is spread across nodes, so that various operations can be executed on it. Originally blockchain was designed for storing digital coins as system states and now has grown beyond crypto-currencies to support user-defined decentralized autonomous applications or smart contracts with Ethereum. Growing interest from the industry and wide range of applications has triggered development of new blockchain platforms. As the technology is progressing quickly, it is necessary and challenging to have a more profound perspective of what the core technology platforms have to provide in order to establish which blockchain implementation should be leveraged for a particular application. We therefore grasp the key aspects of blockchain and compare how the current blockchain implementations are different from each other, both qualitatively and quantitatively in terms of design architecture, codebase, consensus algorithms and performance. Drawing from the comparison we identify the current challenges as well as performance issues in blockchain adoption, thus suggesting possible solutions and future implementations to improve performance of blockchain and provide subsequent research directions.
Unspent Transaction Output (UTXO) set is the foundational model used in many blockchain systems to represent assets. The benefits of UTXO representation include parallel processing, privacy, etc. However, the increasing size of UTXO set is degrading the access performance and severely brings down the validation speed of blockchain further, especially in resource-constrained scenerios, such as IoT. In this paper, we present a memory-economical storage system for UTXO-based blockchain. Based on the inherent properties of UTXO set, we propose two lossless compression techniques to reduce the memory space occupied by UTXO set. Besides, the database related operations are adopted to make the proposed mechanism easily applied in current blockchain system. Taking Bitcoin as the object of study, our mechanism can deliver 2.9-4.5x memory reduction and orders of magnitude validation speed improvement in resource-constrained situations. This compact system will improve validation performance and extend applied scope of blockchains.
Information-centric networking (ICN) supports efficient data provision and retrieval with in-network caching. The data life cycle over ICN includes atomic data collection, data publication, caching, and retrieval, suffering from various attacks, such as regulation violation and false claim. Existing solutions have not considered regulation compliance and typically focus on the protection of a specific procedure. To solve these problems, we propose a blockchain-based data life cycle protection framework (BDLP), which exploits the transaction and smart contract to provide a trusted and neutral environment in ICN. In BDLP, a special type of node, a data dam blockchain node, is designed to locally control registration and restrict data flow, besides the function of a blockchain node. BDLP consists of five types of transactions (RegT, CollectT, PubT, PayT, and PunT) to achieve accountability and four types of smart contracts (PubSC, PaySC, AccSC, and RepSC) to achieve authentication, regulation compliance, and neutrality. We elaborate on the data retrieval procedure in BDLP and analyze its scalability, demonstrating that BDLP can achieve a low data retrieval permission delay.
Internet-of-Things has emerged to develop smart communities so that real time sensing and decision can improve operational efficiency and quality of lives. However, establishing such infrastructure can be exceptionally intricate due to the vast variety of devices and the implemented technologies. Also, it poses several unique challenges, such as heterogeneity of the infrastructure, type, and scale of deployment, security, privacy, and inter-operability. One primary concern in a smart city environment is the capabilities of typically end-IoT devices which are vulnerable to security threats and prone to confidentiality and integrity breach of data. Blockchain can potentially address these security challenges due to the distributed ledger's inherent properties. In this paper, we propose a decentralized architecture using the Blockchain to provide a secure and resilient smart city infrastructure that can run the ledger service over a distributed network. We consider a permissioned Blockchain, Hyperledger Sawtooth, and to automate and to overcome the infrastructural challenges concerning the smart city deployment, and we provide a systematic methodology that automates the deployment process and saves a significant amount of time. We simulate and deploy a Blockchain-integrated smart city environment using the proposed seamless deployment strategy using our automation module. With the proposed deployment scheme, we improve the Blockchain-based infrastructure development time by 82% compared to the traditional deployment approach.
Service Oriented Architecture is a viable option for developing applications in an Internet of Things (IoT) environment. One important consideration in developing services for an IoT environment is how to incentivize service providers and consumers so that a healthy IoT marketplace can come into practice with a balanced supply and demand for services. We argue that service providers should be specifically incentivized in some form to offer quality services in an IoT environment. In this paper, we present an IoT ecosystem, where each exchange of a service between a service provider and service consumer is logged as a transaction in a distributed ledger. For service sharing, we used OSGi Remote Services implementation of the Eclipse Communication Framework. For the distributed ledger, we used Swirlds Hashgraph. Each OSGi remote service is requested by digitally signing a commitment to use the service and upon service exchange, the signature is logged as a Hashgraph transaction. A proof-of-concept prototype has been implemented with positive results.
IoT devices are quickly becoming a critical source of information about the physical world considered in business processes. Blockchains are a promising platform for such processes if they involve multiple parties with no shared, commonly trusted IT infrastructure. Transacting with a blockchain, however, requires software whose footprint overwhelms many lightweight IoT devices. In this paper we introduce the concept of a blockchain proxy to which an IoT device can offload a large part of this software footprint. The proxy only requires a slim proxy SDK on the device that holds a regular blockchain identity with its own private key, retaining full control of the transactions in the device. We discuss security implications and present cold-chain monitoring as a use case. Preliminary results show significant savings in CPU time and communication bandwidth for the IoT device.
Ronald Doku, Danda B. Rawat, Moses Garuba, Laurent Njilla
The Internet of Things (IoT) and the blockchain are justly regarded as the technology for the future. The blockchain is a Distributed Ledger Technology (DLT) solution which has enormous potential as can be seen in the numerous avenues it has been deployed. Simplistically, it is a decentralized database which can revolutionize the current centralized world we live. IoT is the interconnection of devices with mostly bounded resources. IoT applications are also distributed in nature thereby making it inevitable that the paths of the blockchain and IoT will cross in the future. Blockchain's DLT will eventually play a crucial role in how IoT devices will communicate. The Proof of Work (PoW) mechanism was the original consensus technique introduced in the first blockchain based application (Bitcoin). PoW guaranteed consensus in the network by verifying transactions. However, the PoW had deficiencies. The solving of the PoW puzzle is computationally expensive which has become an impediment in the potential marriage of IoT and blockchain. This predicament arises as IoT devices are plagued with limited resources. In this work, we address this issue by presenting an approach where IoT devices can combine their resources to solve PoW puzzles that they might not have been able to solve on their own. This would ensure a successful merger between the blockchain and the IoT.
Kai Lei, Qichao Zhang, Junjun Lou, Bo Bai · 5 authors
Named data networking (NDN) enables fast and efficient content dissemination in mission-critical unmanned aerial vehicle ad hoc networks (UAANETs); however, its in-network caching mechanism brings a new security challenge: content poisoning. Poisoned content can contaminate the cache on the routers and isolate valid content from the network, leading to performance degradation or denial of service. To mitigate such attacks and enhance network-layer trust of NDN-based UAANETs, this article proposes a novel and systematic framework that integrates interest-key-content binding (IKCB), forwarding strategy, and on-demand verification to efficiently discover poisoned content. To further provide decentralized IKCB store and detect internal attackers, we introduce a lightweight permissioned blockchain system over NDN and develop a scalable adaptive delegate consensus algorithm. Our experimental results have demonstrated that our proposed framework can effectively purge poisoned content with low overhead, and our algorithms achieve great performance to fit UAANETs.
Maximilian Tschuchnig, Dejan Radovanovic, Eduard Hirsch, Oberluggauer Anna-Maria · 5 authors
Conventional data storage methods like SQL and NoSQL offer a huge amount of possibilities with one major disadvantage, having to use a centralized authority. This authority may be in the form of a centralized or decentralized master server or a permissioned peer-to-peer setting. This paper looks at different technologies on how to persist data without using a central authority, mainly looking at permissionless peer-to-peer networks, primarily Distributed Ledger Technologies (DLTs) and a combination of DLTs with conventional databases. Afterwards it is shown how a system like this might be implemented in two prototypes which are then evaluated against conventional databases.
Sanghyeok Kim, Je-Ho Song, Sangyeon Woo, Youngjae Kim · 5 authors
Advances in blockchain technology have made a significant impact on a wide range of research areas due to the features such as transparency, decentralization and traceability. With the explosive growth of blockchain transactions, there has been a growing interest in improving the scalability of blockchain network. Sharding is one of the methods to solve this scalability problem by partitioning the network into several shards so that each shard can process the transactions in parallel. Ethereum places each transaction statically on a shard based on its account address without considering the complexity of the transaction or the load generated by the transaction. This causes the transaction load on each shard to be uneven, which makes the transaction throughput of the network decrease. In this paper, we propose a dynamic load balancing mechanism among Ethereum shards called D-GAS. The D-GAS dynamically balances the transaction load of each shard by relocating the accounts based on the gas consumption to maximize the transaction throughput. Ethereum gas is a unit that represents the amount of computational effort needed to execute operations in a transaction. Benchmarking results show that the D-GAS outperforms existing techniques by up to 12% in transaction throughput and decreases the makespan of transaction latency by about 74% under various conditions.
Ethereum, one of the most popular cryptocurrencies, has attracted increasing attention of people in various fields. As the backbone of Ethereum, its peer-to-peer network has an effect on almost every aspect of the ecosystem. Consequently, it's necessary to understand the topological properties of Ethereum P2P network. In this paper, we conducted a measurement of Ethereum P2P network. Our result shows that the graphs of Ethereum network have a small average shortest path length and a large clustering coefficient, and the degree distribution of nodes does not follow a pure power-law distribution. These indicate that Ethereum network is very close to a small world network. Though there are a large number of stale nodes and useless nodes, Ethereum is still resilient to both random failures and targeted attacks. What's more, we find that there are around one hundred abnormal nodes in the network. The IP addresses of nodes included in the neighbors messages they reply are replaced with their own IP addresses. Those nodes might have a bad influence on network routing.
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. Security of the Bitcoin network depends on connectivity between the nodes. Higher connectivity yields better security. In this paper we make two observations: (1) current connectivity in the Bitcoin network is too low for optimal security; (2) at the same time, increasing connectivity will substantially increase the bandwidth used by the transaction dissemination protocol, making it prohibitively expensive to operate a Bitcoin node. Half of the total bandwidth needed to operate a Bitcoin node is currently used to just announce transactions. Unlike block relay, transaction dissemination has received little attention in prior work. We propose a new transaction dissemination protocol, Erlay, that not only reduces the bandwidth consumption by 40% assuming current connectivity, but also keeps the bandwidth use almost constant as the connectivity increases. In contrast, the existing protocol increases the bandwidth consumption linearly with the number of connections. By allowing more connections at a small cost, Erlay improves the security of the Bitcoin network. And, as we demonstrate, Erlay also hardens the network against attacks that attempt to learn the origin node of a transaction. Erlay is currently being investigated by the Bitcoin community for future use with the Bitcoin protocol.
Decentralization for data storage is a challenging problem for blockchain-based solutions as the blocksize plays the key role for scalability. In addition, specific requirements of multimedia data calls for various changes in the blockchain technology internals. Considering one of the most popular applications of secure multimedia streaming, i.e., video surveillance, it is not clear how to judiciously encode incentivization, immutability and compression into a viable ecosystem. In this study, we provide a genuine scheme that achieves this encoding for a video surveillance application. The proposed scheme provides a novel integration of data compression, immutable off-chain data storage using a new consensus protocol namely, Proof-of-WorkStore (PoWS) in order to enable fully useful work to be performed by the miner nodes of the network. The proposed idea is the first step towards achieving greener application of blockchain-based environment to the video storage business that utilizes system resources efficiently.
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cs.DC
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
Lachlan J. Gunn, Jian Liu, Bruno Vavala, N. Asokan
Consensus mechanisms used by popular distributed ledgers are highly scalable but notoriously inefficient. Byzantine fault tolerance (BFT) protocols are efficient but far less scalable. Speculative BFT protocols such as Zyzzyva and Zyzzyva5 are efficient and scalable but require a trade-off: Zyzzyva requires only $3f + 1$ replicas to tolerate $f$ faults, but even a single slow replica will make Zyzzyva fall back to more expensive non-speculative operation. Zyzzyva5 does not require a non-speculative fallback, but requires $5f + 1$ replicas in order to tolerate $f$ faults. BFT variants using hardware-assisted trusted components can tolerate a greater proportion of faults, but require that every replica have this hardware. We present SACZyzzyva, addressing these concerns: resilience to slow replicas and requiring only $3f + 1$ replicas, with only one replica needing an active monotonic counter at any given time. We experimentally evaluate our protocols, demonstrating low latency and high scalability. We prove that SACZyzzyva is optimally robust and that trusted components cannot increase fault tolerance unless they are present in greater than two-thirds of replicas.
Kun Wu, Guohao Dai, Xing Hu, Shuangchen Li · 7 authors
Blockchain applications have shown huge potential in various domains. Proof of Work (PoW) is the key procedure in blockchain applications, which exhibits the memory-bound characteristic and hinders the performance improvement of blockchain accelerators. In order to mitigate the "memory wall" and improve the performance of memory-hard PoW accelerators, using Ethash as an example, we optimize the memory architecture from two perspectives: 1) Hiding memory latency. We propose specialized context switch design to overcome the uncertain cycles of repetitive memory requests. 2) Increasing memory bandwidth utilization. We introduce on-chip memory that stores a portion of the Ethash directed acyclic graph (DAG) for larger effective memory bandwidth, and further propose adopting embedded NOR flash to fulfill the role. Then, we conduct extensive experiments to explore the design space of our optimized memory architecture for Ethash, including number of hash cores, on-chip/off-chip memory technologies and specifications. Based on the design space exploration, we finally provide the guidance for designing the memory-bound PoW accelerator. The experiment results show that our optimized designs achieve 8.7% -- 55% higher hash rate and 17% -- 120% higher hash rate per Joule compared with the baseline design in different configurations.
In order to build a local electricity market (LEM), community members can trade electricity peer-to-peer (P2P) with their neighbors. This paper proposes a Hierarchical Bidding and Transaction Structure based on blockchain (HBTS). First, combined with the multi-agents, each microgrid corrects the estimated cost probability distribution of other microgrids by Bayesian theorem, making its probability closer to the accurate probability. Second, for maximize the benefits of the microgrid, this paper uses the Nash equilibrium in the Cournot model to find the optimal quotation and output of different bidding strategies for the microgrid under different power demand conditions. Then the exchange of electricity translates into an exchange of digital proof of electricity purchases and sales of electricity on the Hyperledger Fabric, ensuring the security of the transaction process and the irreparable modification of ledgers. Finally, we verify the effectiveness of the bidding strategy through experiments, and analyze the transaction process.
In this paper, we present Low-Bandwidth Distributed Applications Framework (LDAF)-an application-aware gateway for communication-constrained Internet of things (IoT) devices. A modular approach facilitates connecting to existing cloud backend servers and managing message formats and APIs' native application logic to meet the communication constraints of resource-limited end devices. We investigated options for positioning the LDAF server in fog computing architectures. We demonstrated the approach in three use cases: (i) a simple domain name system (DNS) query from the device to a DNS server, (ii) a complex interaction of a blockchain-based IoT device with a blockchain network, and (iii) difference based patching of binary (system) files at the IoT end devices. In a blockchain smart meter use case we effectively enabled decentralized applications (DApp) for devices that without our solution could not participate in a blockchain network. Employing the more efficient binary content encoding, we reduced the periodic traffic from 16 kB/s to ~1.1 kB/s, i.e., 7% of the initial traffic. With additional optimization of the application protocol in the gateway and message filtering, the periodic traffic was reduced to ~1% of the initial traffic, without any tradeoffs in the application's functionality or security. Using a function of binary difference we managed to reduce the size of the communication traffic to the end device, at least when the binary patch was smaller than the patching file.
Fuelled by the success (and hype) around cryptocurrencies, distributed ledger technologies (DLT), particularly blockchains, have gained a lot of attention from a wide spectrum of audience who perceive blockchains as a key to carry out business processes that have hitherto been cumbersome in a cost and time effective manner. Governments across the globe have responded to this promising but nascent technology differently - from being apathetic or adopting a wait-and-watch approach: letting the systems shape themselves, to creating regulatory sandboxes and sponsoring capacity building, or in some instances (arguably) over-regulating and attempting to put the blockchain genie back in the bottle. Possible government role spans across a spectrum: regulating crypto-currencies and initial coin offerings (ICO), formulating regulatory frameworks for managing the adoption of blockchains, particularly in critical infrastructure industries, facilitating capacity building, and finally, embracing blockchain technology in conducting the activities of the government itself - be it internally, or in using them to deliver public services. In this paper we survey the last, namely, the use of blockchain and associated distributed ledger technologies in the government technology (GovTech) stack, and discuss the merits and concerns associated with the existing initiatives and approaches.
Muriel Figueredo Franco, Eder J. Scheid, Lisandro Zambenedetti Granville, Burkhard Stiller
Network Functions Virtualization (NFV) is transforming the way in which network operators acquire and manage network services. By using virtualization technologies to move packet processing from dedicated hardware to software, NFV has introduced a new market focused on the offer and distribution of Virtual Network Functions (VNF). Infrastructure Providers (InP) can benefit from an NFV market by providing their infrastructures to fulfill demands of end-users that, in turn, acquire VNFsas- a-Service (VNFaaS). In this context, solutions that promote the competition between InPs can lead to lower prices, while increasing VNF performance to accommodate specific demands of end-users. In this paper, BRAIN, a blockchain-based reverse auction is presented to introduce an auditable solution in which InPs can compete to host VNFs taking into account the demands of each particular end-user. Such a solution helps reduce costs involved in VNF's commercialization and also monetize NFVenabled infrastructures. BRAIN is supported by a case study that provides evidence of the solution's feasibility and effectiveness. A discussion regarding blockchain advantages and drawbacks in this use-case (e.g., , additional costs and time) concludes this paper.