Zuqiang Ke, Jongho Seol, Abhilash Kancharla, Nohpill Park
Since the invention of Bitcoin in 2008, there has been a surge in the number of blockchain networks with a variety of heterogeneous designs and functionalities. With the increasing number of blockchain applications and users, it becomes necessary to allow interoperability across isomorphic/heterogeneous blockchains, and further the interoperability is highly demanded in NFT (Non-Fungible Token)-to-NFT trading. This paper proposes a communication model across the blockchains, and an M/Cox/1 queueing model-based model. The cross chain model considers two distinct types of the communication such as atomic swaps and inter-ledger asset transfer. There are two types of communication controls in consideration, namely, Hashed TimeLock Contract (HTLC) for crossing isomorphic chains and Interledger Asset Transfer Protocol (IATP) for crossing heterogeneous chains. In the proposed performance model, a Poisson arrival process is assumed at a rate of λ, and two service rates are assumed to be exponentially distributed at a rate of µ1(asset swap / transfer Pre - Commit and verify) and µ2(transfer commit/rollback), respectively. Lastly, the selection ratio of a communication protocols between IATP and HTLC is assumed to be at a rate of$p$and ($1 -p$), respectively. Extensive numerical simulations are performed to study the impact of communication request arrival rates, communication service rate, communication traffic rates and proportion of the communication protocols on$L$(number of transactions in the system) and W(average waiting time in the system of transaction). This paper will establish a sound theoretical foundation to identify the interrelation and impacts between various design variables on the performance, and ultimately will reveal an optimal solution to a high performance design of cross chain across isomorphic /heterogeneous chains.
In recent years, the media industry has achieved rapid development and experienced three development stages from traditional media to new media and then to the current convergence media. Convergence media has brought about great changes in content production, communication mechanism, operation and maintenance management, but also brought about problems such as declining credibility of the industry, difficulty in confirming content rights, difficulty in protecting user privacy, etc. Research on convergence media based on blockchain can make use of the characteristics of blockchain to design or optimize the media industry. In this paper, we introduced the development of convergence media, blockchain and consensus mechanism, then we described a sustainable convergence media ecology based on blockchain. Furthermore, we designed and implemented a consensus mechanism named proof of efficiency (PoE). After analysis, PoE can provide high security and resist 51% resource attack, sybil attack, etc. The experimental results show that PoE has the characteristics of decentralization, strong consistency, low energy consumption, short average block generation time, high throughput and short block confirmation time; the consensus results of PoE can reflect the node’s ecological characteristics in convergence media which can stimulate the activity of nodes and better solve the generation of the Matthew effect.
Sharding technique is viewed as the most promising solution to improving blockchain scalability. However, to implement a sharded blockchain, developers have to address two major challenges. The first challenge is that the ratio of cross-shard transactions (TXs) across blockchain shards is very high. This issue significantly degrades the throughput of a blockchain. The second challenge is that the workloads across blockchain shards are largely imbalanced. If workloads are imbalanced, some shards have to handle an overwhelming number of TXs and become congested very possibly. Facing these two challenges, a dilemma is that it is difficult to guarantee a low cross-shard TX ratio and maintain the workload balance across all shards, simultaneously. We believe that a fine-grained account-allocation strategy can address this dilemma. To this end, we first formulate the tradeoff between such two metrics as a network-partition problem. We then solve this problem using a community-aware account partition algorithm. Furthermore, we also propose a sharding protocol, named Transformers, to apply the proposed algorithm into the sharded blockchain system. Finally, trace-driven evaluation results demonstrate that the proposed protocol outperforms other baselines in terms of throughput, latency, cross-shard TX ratio, and the queue size of transaction pool.
In this paper, we introduce SwarMED, a decentralized yet high throughput interoperability system for big biomedical data. SwarMED uses Etehreum blockchain for trustless security and Swarm p2p storage to handle high throughput transaction of big data. In SwarMED, we developed an indexing mechanism over the immutable storage of Swarm to achieve high-throughput while sharing millions of patient records and images among multiple parties. SwarMED achieved a high throughput of 250K medical records per second over a private network constructed over LSU-HPC cluster. This high throughput is 9x more comparing to conventional way of using p2p storage in conjunction with blockchain. This high throughput enables the patients to get realtime access to his comprehensive medical history and scientists to gain real-time access to different medical data for collaborative research complying to the constraints posed by existing laws. Our system-level analysis over different design alternatives over different transfer and storage architectures shows that, p2p storage platforms automatically provide significantly better scalability over traditional HTTP with increasing number of clients. Swarm provides 2x more I/O throughput and 10x less latency than IPFS, another p2p storage system making it a better choice for decentralized big data transaction.
Smart home, as a typical Internet of Things (IoT) application, provides people with a variety of conveniences. Unfortunately, it may suffer from security and privacy issues. Currently, blockchain theory is considered as one of the potential solutions to the IoT security problem. However, according to the rules of blockchain, it requires large storage to store distributed ledgers and undertakes long latency caused by proof of work (PoW), which cannot be performed by resource-constrained IoT devices. To address the issue, we propose a classification-based blockchain architecture with a hierarchical PoW mechanism, which can reduce the storage consumption and decrease the latency. In our architecture, we divide IoT devices into several child nodes by data classification and convert the data storage into partial network storage. Furthermore, we try to set the moderate-cost security grades (SG) to adjust the difficulty of PoW for reduction of latency. Finally, comparing the performance of our scheme with the traditional method and current technology, the proposed architecture not only takes up less storage (i.e., almost 90% reduction) but also increases efficiency (i.e., almost 50% running time saving) while ensuring safety.
Zachary Auhl, Naveen Chilamkurti, Rabei Alhadad, Will Heyne
The consensus mechanism is a core component of Blockchain technology, allowing thousands of nodes to agree on a single and consistent view of the Blockchain. A carefully selected consensus mechanism can provide attributes such as fault tolerance and immutability to an application. The Internet of Things (IoT) is a use case that can take advantage of these unique Blockchain properties. IoT devices are commonly implemented in sensitive domains such as health, smart cities, and supply chains. Resilience and data integrity are important for these domains, as failures and malicious data tampering could be detrimental to the systems that rely on these IoT devices. Additionally, Blockchains are well suited for decentralised networks and networks with high churn rates. A difficulty involved with applying Blockchain technology to the IoT is the lack of computational resources. This means that traditional consensus mechanisms like Proof of Work (PoW) are unsuitable. In this paper, we will compare several popular consensus mechanisms using a set of criteria, with the aim of understanding which consensus mechanisms are suitable for deployment in the IoT, and what trade-offs are required. We show that there are opportunities for both PoW and PoS to be implemented in the IoT, with purpose-made IoT consensus mechanisms like PoSCS and Microchain. Our analysis shows that Microchain and PoSCS have characteristics that are well suited for IoT consensus.
Due to the decentralized and public nature of the blockchain ecosystem, malicious activities on the Ethereum platform impose immeasurable losses on users. At the same time, the transparency of cryptocurrency transactions provides a unique opportunity to analyze illegal activities, such as phishing scams, from a network perspective. Most existing phishing scam detection methods focus primarily on analyzing account interaction networks, which limits their ability to uncover transaction behavior patterns embedded within transaction interactions. To address this, we construct theTransactionSubGraphNetwork (TSGN) by using transaction subgraphs as basic elements and further propose a novel framework for Ethereum phishing account detection. Specifically, we rebuild the graph structures via three well-designed mapping mechanisms, yielding TSGN and its two variants, i.e., Directed-TSGN and Temporal-TSGN, to obtain direction-aware and time-aware transfer flow features. By further incorporating the mapping strategy into transaction multidigraphs, we develop the Multiple-TSGN, which could preserve more transaction flow features while concurrently reducing the time consumption of modeling large-scale networks. TSGN models based on transaction subgraph interactions can capture complex higher-order dependencies, which lay beyond the reach of models that exclusively capture pairwise account interactions. As a general framework, our model can incorporate various feature extraction methods to improve the performance of phishing detection. Extensive experimental results on Ethereum datasets show that our method achieves superior performance in phishing detection, yielding 3.27%$\sim$6.71% relative improvement over previous state-of-the-art.
Web3 networks are emerging to replace centrally-governed networking infrastructure. The integrity of the shared public infrastructure of Web3 networks is guaranteed through data sharing between nodes. However, due to the unstructured and highly partitioned nature of Web3 networks, data sharing between nodes in different partitions is a challenging task. In this paper we present the TSRP mechanism, which approaches the data sharing problem through nodes auditing each other to enforce carrying of data between partitions. Reputation is used as an analogue for the likelihood of nodes interacting with nodes from other partitions in the future. The number of copies of data shared with other nodes is inversely related to the nodes’ reputation. We use a real-world trace of Twitter to show how our implementation can converge to an equal number of copies as structured approaches.
Blockchain technology is a unique distributed ledger technology that has been widely used in various areas. With the increase in data on the blockchain and the append-only nature of the blockchain, the traditional blockchain’s full replica storage technique leads to blockchain storage scalability problem. Existing methods prioritize minimizing the storage strain on blockchain nodes while ignoring the availability of data, resulting in a lengthy average response time for users to access the blockchain. To address the shortcomings, this paper proposes an Information-Centric Networking-based blockchain storage architecture. The architecture uses the enhanced resolution system for community division to build blockchain node partitions and store blockchain ledgers in the underlying network. It introduces virtual chain for rapid blockchain indexing and adopts a collaborative block replica deletion algorithm across neighboring partitions, including replica number decision based on blockchain access decay characteristics and replica deletion based on resource relationship. Finally, we compare and analyze the proposed blockchain storage architecture with BC-store and KASARASA, and the results demonstrate that this architecture has significantly lower average access time than others. The replica data volume of this method is reduced by 57.2% compared to the full replica policy, but the access time is only 5.2% slower when compared to the full replica policy, which substantially increases the replica storage utilization.
Bitcoin has made an increasing impact on the world's economy and financial order, which attracted extensive attention of researchers and regulators from all over the world. Most previous studies had focused more on the transaction layer, but less on the network layer. In this paper, we developed BNS(Bitcoin Network Sniffer), which could find and connect nodes in the Bitcoin network, and made a measurement in detail. We collected nearly 4.1 million nodes in 1.5 hours and identified 9,515 reachable nodes. We counted the reachable nodes' properties such as: service type, port number, client version and geographic distribution. In addition, we analyzed the stability of the reachable nodes in depth and found nearly 60% kept stable during 15 days. Finally, we proposed a new approach to infer the Bitcoin network topology by analyzing the Neighbor Addresses of Adjacent Nodes and their timestamps, which had an accuracy over 80%.
As of the end of September 2021, the size of the Bitcoin blockchain has reached 366.9GB and continues to increase at an average annual growth rate of 17.6%. The large-scale demand for storage space constrains new nodes from joining the network, which seriously hinders the development of blockchain technology. In this paper, to explore the data characteristics of the Bitcoin blockchain, we performed a comprehensive statistical experiment on the current 680,000 blocks. The analysis results indicated that in nearly 95% of blocks, the number of spent transaction output (STXO) accounts for more than 67% of the total transaction outputs. Inspired by this feature, we proposed a novel storage scheme to reduce the size of blocks by deleting the transaction data with the STXO ratio over 67% first and compressing fixed-length fields of those transactions. Then, the newly generated block files were deposited to the InterPlanetary File System (IPFS) private network to improve the scalability of the Bitcoin blockchain. The experiments and evalutions showed that the proposed scheme achieved a compression ratio of 96.9% and saved 330GB of storage space for the Bitcoin full nodes while guaranteeing the normal operation of the Bitcoin network.
The blockchain is a distributed database whose data are stored and managed in every node in the network. By design, the information of trade records is difficult to tamper. Therefore, it can deal with the trust problem without a central operator. Blockchain technology has brought about major reform in the financial field and has been paid more and more attention in many fields. The combination of blockchain technology and energy trade seems to have good prospects due to their common features of distribution, diversity and marketization. In this paper, a new decentralized energy trading framework based on blockchain technology is presented and analyzed. In this framework, four basic participators in the market are set, which are the consumer, supplier, speculator (with energy storage capacity) and regulator. In addition, the order format and price clearing mechanisms are designed accordingly. The new framework can accommodate a large number of entities and enable them to achieve better economic benefits. Small examples are used to analyze the framework. It is concluded that this technology has significant under-researched potential to support and enhance the efficiency gains of the energy revolution, and areas for future research are identified.
Andrea Sabbioni, Carlo Mazzocca, Armir Bujari, Rebecca Montanari · 5 authors
Edge computing and the Internet of Things (IoT) are inextricably linked, and much work has been devoted to strengthening their symbiotic relationship, providing better coverage and quality of service. These solutions are typically vertically tailored, provider-specific and bound to work within one administrative domain, as they presume direct deployment and ownership of the resources controlled in a centralised fashion. This model has effectively created a myriad of physically interconnected elements, logically broken down into separate domain-specific islands, each possibly applying different security/privacy policies, device and process control mechanisms, service access and provisioning schemes etc. To address this data and service balkanization phenomena, complex and time-consuming interactions between multiple providers are required to set up and operate federation of resources across domains and/or providers. Without loss of generality, we envision a scenario where stakeholders in a Smart Tourism ecosystem participate in resource federations to enrich their services and exploit complementarities. In this context, we present a decentralized architecture, relying on Distributed Ledger Technology (DLT), providing a flexible and effective federated access control mechanism to data and services.
Ambre Toulemonde, Loic Besson, Louis Goubin, Jacques Patarin
The blockchain is a new technology that attracts several actors since 2009, and in particular in the financial domain with the emergence of cryptocurrencies such as the well-known Bitcoin. In a blockchain, seen also as a distributed ledger or a chain of blocks, the participants use a consensus protocol to add new data into the ledger. For example, in the Bitcoin Proof-of-Work consensus protocol, the participants have to unnecessarily invest a huge amount of energy to add a new block of transactions, and therefore to also win the coin associated to this block. Several consensus protocols have been proposed to overcome this waste and resource intensive process. In this paper, we present a new consensus protocol for blockchain technologies called Useful Work (UW). Our UW protocol is based on the Proof-of-Stake and Proof-of-Work mechanisms where the computing work is dedicated to useful problems. The participants get a chance to win coins after performing honest and useful work for a submitted problem. We present a high-level description of our UW protocol that is configurable and propose some variants of the protocol. We discuss also some new and well-known issues that our protocol prevents.
Data protection and privacy is a major concern in the Internet of Things (IoT) ecosystem, and the excessive use of IoT devices may risk the security of the network. Blockchain solutions are used to enhance the trustworthiness and eliminate the need for trusted third parties by providing mechanisms to reach consensus in a network of trustless participants. The consensus algorithms employed by blockchain architectures ensure the integrity of the data stored in the blockchain, the resiliency of the network and manage the security of devices. However, current solutions are compute intensive affecting the performance of the network and consuming much energy. In this work, we introduce a consensus algorithm for offering secure distributed consensus among IoT devices without affecting the performance of the network. The algorithm is inspired by existing solutions, employs decentralised identities, verifiable credentials and a decentralised trust management mechanism to guarantee security, privacy and trustworthiness of transactions. Finally, our algorithm combines technologies for operating in a distributed manner which favors the scalability and allow the effective integration in large scale networks.
María Isabel Rojo-Rivas, Daniel Díaz-Sánchez, Florina Almenárez, Andrés Marín
Blockchain has been a revolution in the past few years. Beyond the new currencies that were created around different incarnations of the blockchain concept, there are many other contributions that provide interesting services as a data linked structure using a decentralized network that provide a high level of security. Companies have developed many projects to incorporate blockchain into their business logic pursuing to incorporate other related services as persistence of large volumes of data, privacy or anonymity of transactions, distributed data processing, security (confidentiality, integrity, and availability), document management or micro messages in real time. Nevertheless, as it will be discussed in this article, current blockchains do not meet the needs of companies in many aspects, leading to a scarce or superficial adoption. This article introduces Kriper, a blockchain that aims at meeting corporate world needs by responding with a community-based, open blockchain that may also be segregated and private for certain uses whereas it provides a permissioned distributed storage and micro message lightweight services.
Blockchain is an emerging decentralized data collection, sharing, and storage technology, which have provided abundant transparent, secure, tamper-proof, secure, and robust ledger services for various real-world use cases. Recent years have witnessed notable developments of blockchain technology itself as well as blockchain-enabled applications. Most existing surveys limit the scopes on several particular issues of blockchain or applications, which are hard to depict the general picture of current giant blockchain ecosystem. In this paper, we investigate recent advances of both blockchain technology and its most active research topics in real-world applications. We first review the recent developments of consensus and storage mechanisms and communication schema in general blockchain systems. Then extensive literature review is conducted on blockchain-enabled Internet of Things (IoT), edge computing, federated learning, and several emerging applications including healthcare, COVID-19 pandemic, online social network, and supply chain, where detailed specific research topics are discussed in each. Finally, we discuss the future directions, challenges, and opportunities in both academia and industry.
James Lembke, Srivatsan Ravi, Pierre-Louis Roman, Patrick Eugster
Software-defined wide area networking (SD-WAN) enables dynamic network policy control over a large distributed network via network updates . To be practical, network updates must be consistent (i.e., free of transient errors caused by updates to multiple switches), secure (i.e., only be executed when sent from valid controllers), and reliable (i.e., function despite the presence of faulty or malicious members in the control plane), while imposing only minimal overhead on controllers and switches. We present SERENE: a protocol for se cure and re liable ne twork updates for SD-WAN environments. In short: Consistency is provided through the combination of an update scheduler and a distributed transactional protocol. Security is preserved by authenticating network events and updates, the latter with an adaptive threshold cryptographic scheme. Reliability is provided by replicating the control plane and making it resilient to a dynamic adversary by using a distributed ledger as a controller failure detector. We ensure practicality by providing a mechanism for scalability through the definition of independent network domains and exploiting the parallelism of network updates both within and across domains. We formally define SERENE’s protocol and prove its safety with regards to event-linearizability. Extensive experiments show that SERENE imposes minimal switch burden and scales to large networks running multiple network applications all requiring concurrent network updates, imposing at worst a 16% overhead on short-lived flow completion and negligible overhead on anticipated normal workloads.
Recent years have witnessed growing consolidation of web operations. For example, the majority of web traffic now originates from a few organizations, and even micro-websites often choose to host on large pre-existing cloud infrastructures. In response to this, the "Decentralized Web" attempts to distribute ownership and operation of web services more evenly. This paper describes the design and implementation of the largest and most widely used Decentralized Web platform --- the InterPlanetary File System (IPFS) --- an open-source, content-addressable peer-to-peer network that provides distributed data storage and delivery. IPFS has millions of daily content retrievals and already underpins dozens of third-party applications. This paper evaluates the performance of IPFS by introducing a set of measurement methodologies that allow us to uncover the characteristics of peers in the IPFS network. We reveal presence in more than 2700 Autonomous Systems and 152 countries, the majority of which operate outside large central cloud providers like Amazon or Azure. We further evaluate IPFS performance, showing that both publication and retrieval delays are acceptable for a wide range of use cases. Finally, we share our datasets, experiences and lessons learned.
Yaçine Merrad, Mohamed Hadi Habaebi, Elfatih A. A. Elsheikh, Fakher Eldin M. Suliman · 7 authors
Consensus protocols stand behind the success of blockchain technology. This is because parties that distrust each other can make secure transactions without the oversight of a central authority. The first consensus protocol emerged with Bitcoin. Since then, many others have appeared. Some of them have been implemented by official blockchain platforms, whereas others, for the time being, remain as proposals. A blockchain consensus is a trade-off. The new solutions promise to overcome the known drawbacks of blockchain, but they may also bring new vulnerabilities. Moreover, blockchain performance metrics are not clearly defined, as some metrics, such as delay and throughput, which are key factors for the efficiency of standard networks, are purposely constrained by most mainstream blockchain platforms. The main body of this paper consolidates knowledge of blockchains, focusing on the seminal consensus protocols in large-scale market capitalization platforms, and how consensus is achieved for large-scale, decentralized, blockchain architectures. The benefits, limitations, and tradeoffs, as well as the subsequent trend in current consensus development, and its limitations as a general paradigm, are highlighted. The paper also sheds light on overlooked potential performance metrics, and it proposes some novel solutions to some of the identified problems.