While industry has adopted blockchain-based video-streaming platforms, other stakeholders could contribute more to grow the technology and support its implementation. This article reviews current blockchain-based video streaming applications and industrial advancements and identifies today's research activities and future opportunities for investigation.
Ran Zhang, F. Richard Yu, Jiang Liu, Renchao Xie · 5 authors
D2D caching assists mobile edge caching in offloading inter-domain traffic by sharing cached items with nearby users, while its performance relies heavily on caching nodes' sharing willingness. In this article, a Blockchain-based CDM is proposed as an incentive mechanism for the distributed caching system. Under given incentive mechanisms, both D2D and mobile edge caching nodes' willingness is guaranteed by satisfying their expected reward for cache sharing. Besides, for the distributed CDM, content delivery related transactions are executed by smart contracts. To achieve consensus on the transactions and prevent frauds, a consensus protocol among the SCENE is necessary. The pPBFT protocol is proposed to minimize the latency of reaching consensus while guaranteeing its confidence level. We build the model of cache sharing and transaction execution consensus, and we further formulate cache placement and SCENE selection as Markov Decision Process problems. Considering the complexity and dynamics of the problems, a deep reinforcement learning approach is adopted to solve the problems. Simulation results show that, compared to conventional solutions, the proposed schemes achieve efficient traffic offloading, and significantly improve the transaction execution consensus speed.
With the increase of IOT devices worldwide, Software-Defined Networking (SDN) has emerged as a critical tool to optimize and manage congested IP networks. The challenges faced with such networks are achieving optimal resource allocation and traceability. Network operators face network security attacks (eg. MITM) causing a breach in Service-Level Agreements (SLA). Traditional solutions have aimed to improve this using algorithms and additional hardware. This paper presents DecOp, a new methodology in operating a network based on peers instead of a centralized algorithm using Blockchain (BC). BC is a growing technology that is used primarily in the financial industry (eg. BITCON and ETHEREUM) because of its ability to bring dependable consensus amongst several users using distributed ledgers. DecOp makes use of the existing platforms infrastructure to process and store network configurations. This allows for a modular solution that can be implemented and verified with varying platforms. We designed a new method to allocate resources by integrating SDN and BC using the designed Secure Service Contract (SSC) chaincode, Secure Network Operator (SNO) chaincode, and modular communication middleware. This provides a dependable traceability by storing changes to the network state in an immutable ledger. A prototype is developed and tested with Hyperledger Fabric as the BC platform and OpenDaylight as the SDN Controller. Evaluation results focus on system performance versus the BC Network size, from 12 to 40 peers.
This paper proposes a proximity-aware extensions to the current Bitcoin protocol, named Master Node Based Clustering (MNBC). The ultimate purpose of the proposed protocol is to evaluate the security and performance of grouping nodes based on physical proximity. In MNBC protocol, physical internet connectivity increases as well as the number of hops between nodes decreases through assigning nodes to be responsible for propagating based on physical internet proximity.
In Bitcoin and Ethereum, nodes require large storage capacity to maintain all the blockchain data, such as transactions, UTXOs, and account states. As of May 2020, the storage size of the Bitcoin blockchain has expanded to 270 GB, and it will continue to increase. This storage requirement is a major hurdle to becoming a block proposer or validator. Although many studies have attempted to reduce the storage size, in the proposed methods, a node cannot keep all blocks or cannot generate a block. We propose an architecture called Trail that allows nodes to hold all blocks in a small storage and to generate and validate blocks and transactions. Trail does not depend on a consensus algorithm or fork choice rule. In this architecture, a client who issues transactions has the data to prove its own balances and can generate a transaction containing the proof of balances. The nodes in Trail do not store transactions, UTXOs and account balances: they keep only blocks. The blocksize is approximately 8 KB, which is 100 times smaller than that of Bitcoin. Further, the block size is constant regardless of the number of accounts and the number of transactions. Compared to traditional blockchains, clients who issue transactions must store additional data. However, we show that proper data archiving can keep the account device storage size small. Trail allows more users to be block proposers and validators and improves the decentralization of the blockchain.
Modern blockchains use smart contracts to implement automatic and decentralized programs, which are the foundations of Decentralized Applications (DApp). The poor performance on general purpose computers has become the bottleneck that limits the blockchain and smart contracts from being widely used. In this paper, we present BPU, a high-performance modularized blockchain processing unit. BPU aims at bringing performance and flexibility to the blockchain and DApp processing. Our design achieves significant speedup compared against the software implementation on an Intel CPU.
Blockchains and distributed ledgers have brought renewed interest in Byzantine fault-tolerant protocols and decentralized systems, two domains studied for several decades. Recent promising works have in particular proposed to use epidemic protocols to overcome the limitations of popular Blockchain mechanisms, such as proof-of-stake or proof-of-work. These works unfortunately assume a perfect peer-sampling service, immune to malicious attacks, a property that is difficult and costly to achieve. We revisit this fundamental problem in this paper, and propose a novel Byzantine-tolerant peer-sampling service that is resilient to Sybil attacks in open systems by exploiting the underlying structure of wide-area networks.
This paper presents an architecture, based on Distributed Ledger Technologies (DLTs) and Decentralized File Storage (DFS) systems, to support the use of Personal Information Management Systems (PIMS). DLT and DFS are used to manage data sensed by mobile users equipped with devices with sensing capability. DLTs guarantee the immutability, traceability and verifiability of references to personal data, that are stored in DFS. In fact, the inclusion of data digests in the DLT makes it possible to obtain an unalterable reference and a tamper-proof log, while remaining compliant with the regulations on personal data, i.e. GDPR. We provide an experimental evaluation on the feasibility of the use of DFS. Three different scenarios have been studied: i) a proprietary IPFS approach with a dedicated node interfacing with the data producers, ii) a public IPFS service and iii) Sia Skynet. Results show that through proper configuration of the system infrastructure, it is viable to build a decentralized Personal Data Storage (PDS).
The global daily data generation is estimated to be more than 2.5 quintillion bytes, and more than 90 percent of the total data produced is generated in the last two years. Most of this data is being generated and controlled by very few centralized agencies in the Web 2.0 internet architecture. This causes issues, including data manipulation, lack of privacy, and data leaks historically and is not just limited to the fields mentioned. This paper proposes a Web 3.0 based architecture which eliminates the centralized agencies and to promote a fully decentralized, secure, and transparent internet. It leverages IPFS, a peer to peer distributed hypermedia transfer protocol. Ethereum and smart contracts create a secure decentralized mechanism for initiating data-based payments. Furthermore, the proposed architecture uses zero-knowledge proofs and proxy re-encryption mechanisms to enhance the privacy of the nodes in the network.
IoT has proven valuable in many industries such as Supply Chain, Shipping and Transportation providing updates on the status of shipments in real time. This has resulted in a large amount of data created by IoT devices that require real time processing. Blockchain has also emerged as a trusted common data storage among multiple participants in IoT systems. However, it is essential to verify the authenticity of data before they go in to the blockchain. Some IoT data must be also encrypted in a secure manner. In this paper, we propose a method to collect sensor data from IoT devices and use blockchain to store and retrieve the collected data in a secure and decentralized fashion. A testbed private blockchain system with Ethereum and Raspberry Pi has been developed to test the feasibility and performance of blockchain-based secure IoT system. We employ private PKI for key management and TPM for storing keys, signing, verifying and encrypting data in a trusted way. We describe the structure of the testbed, decentralized storage system based on Ethereum Swarm and IPFS, TPM configuration processes, smart contract codes, and detailed operation sequences. Performance has been measured with 5000 test transactions in 8 different configurations. The result shows that Ethereum blockchain with Swarm can offer about 9 transactions per second. Encryption and decryption is shown to reduce the performance slightly to about 8 transactions per second. The proposed system can provide a secure IoT Blockchain platform for small industrial applications at low cost.
Internet-of-Things (IoT) technologies have gained prevalence in various areas including Smart Vehicles, Smart Buildings, and Smart Health. Especially on these domains, the use of IoT involves certain challenges around security, privacy and trust, which can be characterized as sensitive issues. Blockchain technologies have emerged as the potential solution to address these issues. However, Blockchain can be inefficient in terms of both performance and cost due to high bandwidth overhead and delays. In this paper, we have examined four different popular Blockchain platforms (Hyperledger Fabric, Hyperledger Burrow, Hyperledger Sawtooth, and BigchainDB) to identify what are the overheads around the use of Blockchain and to study whether there is a single optimal solution with respect to time and computation overheads, or if there are trade-offs between the four platforms for IoT applications.
Computing and communication are getting increasingly ubiquitous with the inclusion of sophisticated devices like electric vehicles, smart phones and other house hold appliances. Due to the constant evolution in Internet of Things (IoT), the process of collaboration of these devices at a mass scale in order to provide improved and better services to the society. Traditional mechanisms which are used to sustain privacy and security become incapable from achieving the same for IoT systems having distributed or decentralized topology. Distributed Ledger Technologies (DLT), an emerging digital technology, consists of different kinds of decentralized data structures to ensure immutability by linking blocks using cryptographic measures. DLT has the ability to ensure privacy, security and distributed or decentralized computations with adhering to the constraints of IoT nodes. This study is motivated due to the lack of an in-depth analysis on how the characteristics of DLT can be exploited to secure IoT systems. So, an in depth overview of DLT along with some of the existing solutions to meet security requirements of IoT systems employing DLT have been provided in this paper. With respect to integrating DLT with IoT, this article also highlights the different challenges.
Dimitris Chatzopoulos, Sujit Gujar, Boi Faltings, Pan Hui
Advances in mobile computing have paved the way for new types of distributed applications that can be executed solely by mobile devices on device-to-device (D2D) ecosystems (e.g., crowdsensing). More sophisticated applications, like cryptocurrencies, need distributed ledgers to function. Distributed ledgers, such as blockchains and directed acyclic graphs (DAGs), employ consensus protocols to add data in the form of blocks. However such protocols are designed for resourceful devices that are interconnected via the Internet. Moreover, existing distributed ledgers are not deployable to D2D ecosystems since their storage needs are continuously increasing. In this work, we introduce Mneme, a DAG-based distributed ledger that can be maintained solely by mobile devices and operates via two consensus protocols: Proof-of-Context (PoC) and Proof-of-Equivalence (PoE). PoC employs users' context to add data on Mneme. PoE is executed periodically to summarize data and produce equivalent blocks that require less storage. We analyze the security of Mneme and justify the ability of PoC and PoE to guarantee the characteristics of distributed ledgers: persistence and liveness. Furthermore, we analyze potential attacks from malicious users and prove that the probability of a successful attack is inversely proportional to the square of the number of mobile users who maintain Mneme.
Mohammad Saeid Safaei, Shamsollah Ghanbari, Zhanat Umarova, Zhalgasbek Iztayev
IoT is one of the most important and profitable projects proposed by Kevin Ashton since 1999. One of the most critical issues in maintaining communication between things and protecting the data is the security issue of IoT. So far, different strategies have been made to maintain safe security. In this paper, we provide a Five-Layers model by adding two security layers based on BlockChain. We show that blockchain smart contracts are a solution to enhance IoT security and prevent infiltration into the network.
The interblockchain communication protocol (IBC) is an end-to-end, connection-oriented, stateful protocol for reliable, ordered, and authenticated communication between modules on separate distributed ledgers. IBC is designed for interoperation between heterogenous ledgers arranged in an unknown, dynamic topology, operating with varied consensus algorithms and state machines. The protocol realises this by specifying the sufficient set of data structures, abstractions, and semantics of a communication protocol which once implemented by participating ledgers will allow them to safely communicate. IBC is payload-agnostic and provides a cross-ledger asynchronous communication primitive which can be used as a constituent building block by a wide variety of applications.
A key performance metric in blockchains is the latency between when a transaction is broadcast and when it is confirmed (the so-called, confirmation latency). While improvements in consensus techniques can lead to lower confirmation latency, a fundamental lower bound on confirmation latency is the propagation latency of messages through the underlying peer-to-peer (p2p) network (inBitcoin, the propagation latency is several tens of seconds). The de facto p2p protocol used by Bitcoin and other blockchains is based on random connectivity: each node connects to a random subset of nodes. The induced p2p network topology can be highly suboptimal since it neglects geographical distance, differences in bandwidth, hash-power and computational abilities across peers. We present Perigee, a decentralized algorithm that automatically learns an efficient p2p topology tuned to the aforementioned network heterogeneities, purely based on peers' interactions with their neighbors. Motivated by the literature on the multi-armed bandit problem, Perigee optimally balances the tradeoff between retaining connections to known well-connected neighbors, and exploring new connections to previously-unseen neighbors. Experimental evaluations show that Perigee reduces the latency to broadcast by $33\%$. Lastly Perigee is simple, computationally lightweight, adversary-resistant, and compatible with the selfish interests of peers, making it an attractive p2p protocol for blockchains.
Ran Zhang, F. Richard Yu, Jiang Liu, Tao Huang · 5 authors
Device-to-Device (D2D) caching assists Mobile Edge Computing (MEC) based caching in offloading inter-domain traffic by sharing cached items with nearby users, while its performance relies heavily on caching nodes' sharing willingness. In this paper, a Blockchain-based Cache and Delivery Market (CDM) is proposed as an incentive mechanism for the distributed caching system. Under given incentive mechanisms, both D2D and MEC caching nodes' willingness is guaranteed by satisfying their expected reward for cache sharing. Besides, for the distributed CDM, content delivery related transactions are executed by smart contracts. To achieve consensus on transactions and prevent frauds, a consensus protocol among the smart contract execution nodes (SCENE) is necessary. To minimize the latency of reaching consensus while guaranteeing its confidence level, we propose partial Practical Byzantine Fault Tolerance (pPBFT) protocol. Further, the model of cache sharing and transaction execution consensus is proposed, and we further formulate caching placement and SCENE selection as Markov Decision Process problems. Due to the complexity and dynamics of the problems, a deep reinforcement learning approach is adopted to solve the problem. The simulation results show that the proposed schemes outperform conventional solutions in terms of traffic offloading, content retrieval latency, and consensus latency.
The Bitcoin Lightning network is a mechanism to enable fast and inexpensive off-chain Bitcoin transactions using peer-to-peer (P2P) channels between nodes that can also be composed into a routing path. Although the resulting possible channel graphs are well-studied, there is no empirical data on the network's reliability in terms of being able to successfully route payments at a given moment in time. In this paper we address this gap and investigate two forms of availability that are a necessary ingredient to achieve such reliability. We first study the Lightning network's ability to route payments of various sizes to nearly every participating node, over most available channels. We establish an inverse relationship between payment volume and success rate and show that at best only about a third of destination nodes can be successfully reached. The routing is hampered by a number of possible errors, both transient and permanent. We then study the availability of nodes in the network longitudinally and determine how long-lived they are. Churn in the network is actually low, and a considerable number of nodes are hosted on cloud providers. By testing node liveness, we find that the propagated network information is relatively often stale, however, both for IP addresses and Tor onion addresses. We provide recommendations how the Lightning network can be improved, including considerations which trade-offs between privacy and decentralization on the one hand and reliability on the other hand should at least be reconsidered by the community developing the Lightning network.
We propose a blockchain-based, distributed protocol for enabling the deployment of Internet-of-Things (IoT) networks on-demand on top of IoT devices. Specifically, the proposed protocol leverages blockchain technology to: 1) enable distributed and secure authentication, registration, and management of participatory IoT devices; 2) provide fast discovery of IoT resources and scalable and secure instantiation of IoT networks-on-demand; and 3) manage payment operations and ensure reliable fund transfers among the network entities. The proposed protocol relies on a peer-to-peer network communication infrastructure to allow communications among the IoT devices in a distributed manner and uses a self-recovery/self-healing mechanism to ensure robustness against device failure and maliciousness. The protocol also introduces and uses a reputation system to monitor registered devices to keep track of their service delivery quality so that their service delivery reputations could be leveraged for future device selection and mapping. We implemented and evaluated the proposed protocol intensively using simulations and showed that it scales well with network parameters, is resilient to faulty devices, and is robust to 51% attack.
A content delivery network (CDN) uses distributed cache servers to reduce the content delivery latency to end users. In recent years, CDN providers adopt a new content caching strategy that allows end users to share their storage/bandwidth resources. Two core questions need to answer in this strategy: (1) how to incentivize end users to contribute their resources? (2) how to facilitate transparent, secure content trading among end users?We propose a new CDN solution, called SmartSharing, where users contribute their over-the-top (OTT) devices as mini-cache servers. To incentivize end users to contribute resources, SmartSharing uses game theory and an Expectation-Maximization (EM) algorithm to determine the content delivery schedule and the pricing scheme. To facilitate content trading among end users, SmartSharing uses smart contracts in Ethereum to create a transparent and safe transaction platform. We thoroughly evaluate the performance of SmartSharing with real-world trace-driven simulation as well as a prototype using content metadata and the derived pricing scheme.
Increasing presence of distributed energy resources (DERs) is evolving electricity distribution system to decentralized and active networks. Utilising the data emerging from such networks is an essential step for developing sustainable future energy systems, as such systems must be closely monitored and managed to avoid blackouts and failures. The datasets within energy systems are very large, must be immutable, are often interrelated, yet owned by competing organisations. How then should these datasets be stored and shared? This is the main focus of my research. To provide a reliable way of collecting, storing, sharing, and analysing energy systems data, I propose to use the newly emerging distributed ledger technology. I will work towards developing a middleware-like platform over distributed ledgers, which would aim to provide a reliable data storage solution for immutable energy datasets, while also maintaining relationships between the datasets and addressing the read and write latency and scalability problems of the present distributed ledgers.
Edge cache service (ECS), as a prospective edge network service paradigm, can significantly reduce the data transmission latency and improve the Quality of Service (QoS) of digital content providers by offloading content data to edge devices in the network. Compared to centralized content service, ECS can provide digital content from nearby edge devices via a high-speed wireless network with fewer hops. However, how to motivate edge devices to share their cache resource and ensure the reliability of content data under the diversity of device behavior remains a challenging issue. In this article, we aim to design an ECS framework for cache resource trading and digital content sharing in the edge network. By using blockchain-based credentials, we first provide the cache resource trading mechanism for the trading between the content provider and edge devices. Then, we give a double auction mechanism for digital content trading between edge devices. The experimental results show the proposed framework can greatly improve the matching efficiency of cache resources and reduce the data transmission overhead in edge networks.
Johannes Sedlmeir, Hans Ulrich Buhl, Gilbert Fridgen, Robert Keller
Abstract When talking about blockchain technology in academia, business, and society, frequently generalizations are still heared about its – supposedly inherent – enormous energy consumption. This perception inevitably raises concerns about the further adoption of blockchain technology, a fact that inhibits rapid uptake of what is widely considered to be a groundbreaking and disruptive innovation. However, blockchain technology is far from homogeneous, meaning that blanket statements about its energy consumption should be reviewed with care. The article is meant to bring clarity to the topic in a holistic fashion, looking beyond claims regarding the energy consumption of Bitcoin, which have, so far, dominated the discussion.