Sybil attack is one of the most serious security threats in distributed systems. This paper proposes an anti-sybil consensus algorithm, which can effectively defend against sybil attacks. This algorithm is an improved version of the PBFT algorithm. It introduces a reputation system, which assigns trust scores to nodes based on their behavior, and uses these trust scores to determine their voting weight in the consensus process. In order to evaluate the performance of the algorithm, the simulation is performed on a blockchain network with different number of nodes and sybil attackers. The results show that the algorithm can effectively defend against sybil attacks. Compared with the existing methods, the anti-sybil consensus algorithm in this paper has several advantages. First, it is lightweight and easy to implement, which makes it suitable for resource-constrained devices. Second, the performance of the improved algorithm has not significantly decreased. In short, the anti-sybil consensus algorithm proposed in this paper provides a practical solution for protecting distributed systems from sybil attacks.
Ahmet Kurt, Abdulhadi Sahin, Ricardo Harrilal-Parchment, Kemal Akkaya
Bitcoin is undoubtedly a great alternative to today's existing digital payment systems. Even though Bitcoin's scalability has been debated for a long time, we see that it is no longer a concern thanks to its layer-2 solution Lightning Network (LN). LN has been growing non-stop since its creation and enabled fast, cheap, anonymous, censorship-resistant Bitcoin transactions. However, as known, LN nodes need an active Internet connection to operate securely which may not be always possible. For example, in the aftermath of natural disasters or power outages, users may not have Internet access for a while. Thus, in this paper, we propose LNMesh which enables offline LN payments on top of wireless mesh networks. Users of a neighborhood or a community can establish a wireless mesh network to use it as an infrastructure to enable offline LN payments when they do not have any Internet connection. As such, we first present proof-of-concept implementations where we successfully perform offline LN payments utilizing Bluetooth Low Energy and WiFi. For larger networks with more users where users can also move around, channel assignments in the network need to be made strategically and thus, we propose 1) minimum connected dominating set; and 2) uniform spanning tree based channel assignment approaches. Finally, to test these approaches, we implemented a simulator in Python along with the support of BonnMotion mobility tool. We then extensively tested the performance metrics of large-scale realistic offline LN payments on mobile wireless mesh networks. Our simulation results show that, success rates up to %95 are achievable with the proposed channel assignment approaches when channels have enough liquidity.
Wenrui Zuo, Aravindh Raman, Raúl J. Mondragón, Gareth Tyson
There has been growing interest in the so-called “Web3” movement. This loosely refers to a mix of decentralized technologies, often underpinned by blockchain technologies. Among these, Web3 social media platforms have begun to emerge. These store all social interaction data (e.g., posts) on a public ledger, removing the need for centralized data ownership and management. But this comes at a cost, which some argue is prohibitively expensive. As an exemplar within this growing ecosytem, we explore memo.cash, a microblogging service built on the Bitcoin Cash (BCH) blockchain. We gather data for 24K users, 317K posts, 2.57M user actions, which have facilitated $6.75M worth of transactions. A particularly unique feature is that users must pay BCH tokens for each interaction (e.g., posting, following). We study how this may impact the social makeup of the platform. We therefore study memo.cash as both a social network and a transaction platform.
Abstract In blockchain networks, topology discovery is a prerequisite when investigating the network characteristics (e.g., performance and robustness), which can provide a deeper comprehension of the behavior of the nodes and topology dynamicity. In this paper, we conduct a longitudinal study on the Bitcoin topology by collecting network snapshots from 2018 to 2022 with Node‐Probe, our topology discovery technique that uses recursive scanning to find all reachable nodes in the Bitcoin network. Using Node‐Probe, we have collected 5‐week‐long snapshots (36‐day‐long snapshots) of the Bitcoin main network and analyzed the network properties, community structure, and topology dynamicity. We confirm that our approach achieves a precision of 99% with a recall of 98% in inferring the topology. Analytical results on community structure show that the Bitcoin network has more communities than what should be expected from a random network. Meanwhile, analytical results on dynamicity indicate that the topology stands firmly on heavy and long‐running nodes. Improving the propagation mechanism using master nodes could improve the propagation delay by proximity compared with the Bitcoin default protocol. Considering a K‐anonymity attack, any transaction from one of the autonomous systems containing only a single Bitcoin node can easily be linked to real users' IP information.
As a promising Internet censorship circumvention technique, refraction networks have attracted the wide attention of researchers in recent years. However, it remains a crucial issue to be tackled, i.e., how to motivate more service providers, known as decoy routers, and clients to join refraction networks, especially with guaranteed security and privacy. To address the issue, we develop a decentralized service auction framework based on the blockchain constructed through clients and decoy routers. Further, we design a multi-stage service auction (MSSA) smart contract composed of multiple functions and events, which are triggered and executed autonomously to complete the tasks, including registration, double auction, first-price sealed auction, and payment clearing. Moreover, we implement the designed MSSA smart contract in the Remix integrated development environment and run a test case on Ethereum virtual machines. The experiment results verify the modest gas and ether cost of the smart contract-based solution and its effectiveness.
Blockchain interoperability promotes value delivery, application expansion, and ecological compatibility across heterogeneous blockchain systems. However, the contract framework and virtual machine construction in these systems are significantly different, and crosschaining becomes a challenging issue for system universality and compatibility. Starting from this problem, in this study, we propose VM-Studio, a crosschain smart contract verification and execution scheme to migrate the virtual machines (VMs) from the origin blockchain to the target blockchain. In our scheme, the migrated VMs are loaded as independent components enclosed in containers. We also design a unified system schedule to enable VM-Studio to allocate transactions into different containers. Loaded with origin blockchain VMs, these containers can accordingly solve crosschain transaction execution and smart contract verification. We implement VM-Studio and evaluate the transaction execution performance in the origin environment with multiple blockchains and the container environment. Experiment results demonstrate that VM-Studio achieves broad universality without compromising the execution performance of original blockchain transactions.
As the first blockchain platform to support smart contracts, Ethereum has gained popularity and breeds various cybercrimes. Many phishing accounts on Ethereum take advantage of the blockchain’s anonymity to participate in illegal acts. To this end, to solve the transaction security problem caused by phishing accounts on Ethereum, this brief proposes a network embedding-based phishing account detection model. Firstly, we crawl the history of transactions from both labeled phishing and non-phishing accounts and use a new method to build these transactions as a transaction network, where each transaction edge is accompanied by additional transaction information for all source nodes of the target node. Then we propose a new random walk-based network embedding algorithm named bias2vec to obtain the embeddings of nodes as the feature inputs. Finally, we classify the accounts into phishing and non-phishing ones by different classifiers such as lightGBM and XGBoost. Experiments show that our proposed phishing account detection model achieves effective detection performance under different classifiers.
Jie Xu, Qingyuan Xie, Sen Peng, Cong Wang · 5 authors
Although existing schemes improve blockchain throughput by allowing concurrent blocks to be appended to the blockchain, little attention has been devoted to adjusting blockchain throughput dynamically and deduplicating transactions between concurrent blocks. In this article, we propose AdaptChain, an adaptive scaling blockchain with transaction deduplication. When the transaction demand of users in the network is high, the blockchain expands to meet the demand; when the transaction demand is low, the blockchain shrinks to save communication and storage costs. Our transaction deduplication mechanism ensures that no duplicate transactions are added to the blockchain, thereby improving bandwidth utilization and achieving higher effective throughput. Besides, we randomly split the mining power of the system to achieve mining power load balancing and resist attacks. We formally analyze the blockchain security and implement the proposed prototype on Amazon EC2. Experimental results show that AdaptChain achieves dynamic and higher effective blockchain throughput.
Lianna Zhao, Andrew Culleny, Müller, Sebastian, Olivia Saay · 5 authors
This paper discusses congestion control and inconsistency problems in DAG-based distributed ledgers and proposes an additional filter to mitigate these issues. Unlike traditional blockchains, DAG-based DLTs use a directed acyclic graph structure to organize transactions, allowing higher scalability and efficiency. However, this also introduces challenges in controlling the rate at which blocks are added to the network and preventing the influence of spam attacks. To address these challenges, we propose a filter to limit the tip pool size and to avoid referencing old blocks. Furthermore, we present experimental results to demonstrate the effectiveness of this filter in reducing the negative impacts of various attacks. Our approach offers a lightweight and efficient solution for managing the flow of blocks in DAG-based DLTs, which can enhance the consistency and reliability of these systems. Index
Kevin Coutinho, NeerajKumari Khairwal, Pornpit Wongthongtham
Blockchain is a revolutionary technology that is constructively transforming many traditional industries, including financial services. Blockchain demonstrates immense potential in bringing substantial benefits to the remittance industry. Although the remittance industry has crossed the mark of USD 600 billion in 2021, remittance cost is still substantially high, around 6% on average, indirectly limiting financial inclusion and promoting de-risking. The involvement of multiple intermediaries in global remittances makes cross-border payments more expensive. Many projects, including Ripple and Stellar, employ blockchain technology to provide alternative infrastructure for cross-border payments. However, the decentralization of blockchain networks in both solutions is debatable. This paper examines the market characteristics impacting remittance cost, a prominent factor driving the evolution of the remittance industry. A truly decentralized blockchain framework viz. LayerOneX, which provides remittance services at a reduced cost, is proposed in this paper. Devices with low computation and memory capacity can act as transaction validators in this solution. A universal wallet across homogeneous and heterogeneous blockchains is proposed to facilitate fast and inexpensive remittance services. Thus, a novel framework for true decentralization of blockchain-based remittance services, resulting in reduced cost and, therefore, better financial inclusion, is proposed in this paper.
Blockchain can effectively deal with the security and trust issues in Internet of Things (IoT) due to its salient features including decentralization, immutability, traceability, openness, and transparency. However, most IoT devices have too limited computing, storage, and bandwidth resources to maintain the complete operation of a blockchain system. To this end, we propose a hierarchical blockchain framework called HLOChain for IoT scenarios. First, according to computing and storage capabilities, the IoT devices are classified into three levels, i.e., high, medium, and low. They are deployed on different layers. In this way, a hierarchical blockchain architecture is designed. Second, we propose a lightweight proof of random (PoR) consensus mechanism to provide low-energy block mining, so that even the medium nodes can participate in the consensus task. Third, in order to reduce the ledger storage overhead, we design a blockchain storage optimization strategy based on the account model. Finally, the security analysis demonstrates that our HLOChain is secure against double-spend attack, Sybil attack, and so on. The experimental evaluation shows that our HLOChain achieves better performance in ledger storage cost, consensus computing cost, throughput, and transaction confirmation latency.
D. Palanikkumar, G Arun, R Arunadevi, S. Gayathri · 5 authors
Human lives now include a significant amount of social media usage. Social media is used to create communities, strengthen bonds, and stay in touch with distant friends. A single server, which performs all significant processing, serves as the hub of a centralized system. Thus, a centralized server becomes an easy target for hackers. Decentralized social networks can provide a more secure environment where users may exercise more privacy control through distribution of information processing across many machines. This study proposes a system where the Web3 Library is used to implement the decentralized network. This provides a social graph with all devices in the network. The Ethers library provides functionalities to engage the Ethereum framework. This way an OSN (Online Social Network) service based on blockchain is created and its decentralized operations are performed. Due to a decentralized autonomous organization that is designed for user autonomy, users can democratically self-manage the OSN.
Consensus mechanisms play a critical role in blockchain networks, ensuring that all participants agree on the state of the distributed ledger. However, existing consensus mechanisms have limitations in terms of efficiency, security, and decentralization. In this research paper, we propose a Hybrid Consensus Mechanism (HCM) that combines the advantages of Delegated Proof of Stake (DPoS), Practical Byzantine Fault Tolerance (PBFT), and Proof of Elapsed Time (PoET) to address these limitations. HCM uses a set of trusted validators (delegates) similar to DPoS, who participate in a PBFT-like consensus protocol to reach agreement on the state of the ledger. PoET is used to randomly select the leader for each consensus round, preventing the concentration of power. HCM also introduces a dynamic delegation mechanism and sharding technique to enhance fairness, resilience, and scalability in blockchain networks. We provide detailed technical insights, backed by underlying data, to illustrate the effectiveness of HCM in achieving efficient and secure consensus.
The peer-to-peer energy trading on the decentralized platform among microgrids requires new approaches to be developed. The heterogeneous microgrids may be surplus or deficit power due to uncertainty in power generation and electric power demand. This paper proposes the blockchain-based adaptive non-cooperative game strategy among the owners of microgrids. The power token-based smart contracts have been created for energy trading among the networked microgrids. The smart contracts are made secure, reliable, and trustworthy with blockchain technology. The distributed identity-based microgrid (DIBM) scheme is designed to avoid the distributed denial of service (DDoS) attack. For the smart power contracts, the hash key has been obtained with python programming and other simulation work has been done in MATLAB.
Miguel Pincheira, Elena Donini, Massimo Vecchio, Raffaele Giaffreda
Blockchain is currently a core technology for developing new types of decentralized applications. With the unique properties of blockchain, unique challenges and characteristics are introduced to the system. Among these characteristics, the infrastructure costs and benefits of the system are critical to evaluate the feasibility of any system and have yet to be addressed in the current literature. This work presents a framework for evaluating blockchain applications’ infrastructure costs and benefits. The framework includes a taxonomy to classify the related transactions, a model to evaluate the infrastructure costs and benefits in applications using public or private blockchains, and a methodology to guide the use of the model. The model is based on simple parameters that describe the systems, and the methodology helps to identify and estimate these parameters at any stage of the application life cycle. We quantitatively analyze three real use cases to demonstrate the framework’s merit. The analyses highlight the model’s accuracy by achieving the same results presented in the use cases. Furthermore, the use-case analyses emphasize the framework’s potential to evaluate different scenarios across the entire life cycle of blockchain-based applications.
Heterogeneous blockchains are expected to be increasingly deployed in real-world applications, making cross-chain transaction confirmations essential. Currently, confirmations for cross-chain transactions are usually accomplished through an intermediary, such as a relay chain, which may well become a performance bottleneck. Sharding has been widely used to improve the blockchain throughput through parallel transaction validations by distributing transactions into multiple sub-communities, Yet, when sharding technique is directly applied over a relay chain, it results in an excessive number of cross-shard transactions, offsetting the throughput improvement.In this paper, we propose Sliver, a novel transaction distribution mechanism specifically designed for improving the relay chain throughput for the first time. We first capture and leverage the unique characterization of transaction dependency on the relay chain, and place those transactions with dependency into one shard. Consequently, this completely eliminates cross-shard transactions. However, due to the varying nature of transaction dependency, such a transaction placement can lead to a highly skewed distribution in terms of the number of transactions (i.e., shard size) to be validated in different shards, which negatively affects the relay chain throughput. We proceed to formulate the transaction distribution as an integer optimization problem with a lexicographical minimization objective for achieving a balanced shard size. While such a problem is proved to be NP-hard, we are able to mathematically transform it to a linear programming (LP) formulation by incorporating several unique properties in the integer optimization formulation, which can then be efficiently solved using off-the-shelf LP solvers. Theoretical and experimental analyses show that Sliver is extremely efficient in solving the assignment problem and the throughput can be 5 × that of the state-of-the-art under various configurations.
Currently, digital certificate systems based on blockchain have been extensively developed and adopted. However, most of them do not take into account the certificate quality. To evaluate the credibility of certificates issued by educational institutions, we propose a novel blockchain-based system with credit self-adjustment (BC-CS). In BC-CS, employers can provide feedback according to the performances of their employees (i.e., students) holding different certificates. Based on the feedback, BC-CS automatically adjusts the certificate credits by using our proposed credit self-adjustment algorithm. To verify the feasibility of our proposed system, a decentralized application prototype has been developed on an Ethereum network. Experimental results demonstrate that the proposed system can fully support multi-step accreditation and automatic adjustment for certificate credit.
Giancarlo Fortino, Fabrizio Messina, Domenico Rosaci, Giuseppe M. L. Sarnè
The blockchain (BC) paradigm is currently modifying all the major Internet of Things (IoT) application domains, giving the opportunity of constructing decentralized environments in which trustful and anonymous activities can be efficiently performed. BC proposes an approach which assures data saved on a distributed ledger (DL) would be continuously synchronized and in such a way the ledger will remain consistent. The DL has the responsibility to maintain a higher level of consistency. Given a connected network, the optimum neighbor selection (ONS) of paths can be obtained by finding the minimum spanning tree of the network. However, none of past approaches proposed in the literature to construct ONS considered the problem of having nodes with low levels of reliability in the network and even malicious or fraudulent nodes, that is a situation very common in an IoT environment. In this article, we propose an optimized BC ONS algorithm, called trust-based ONS (TONS), which allows the miners to communicate with a globally optimized selection of neighbors. The algorithm can also guarantee that these nodes are the most reliable miners. We also describe an experimental simulation campaign we have performed to evaluate the effectiveness and the efficiency of our approach.
Michael G. Xevgenis, Dimitrios G. Kogias, Panagiotis Karkazis, Helen C. Leligou
Undoubtedly, we are witnessing a new era of computer networks that aspire to support modern demanding applications by providing the highest Quality of Experience (QoE) to the end user. Next Generations Networks (NGNs) ensure that characteristics such as ultra-low latency, high availability and wide service coverage can be met across the network regardless of the network infrastructure ownership. To accomplish that, beyond the necessary improvements in the radio propagation field, changes have been made in the core network functions which are now characterized as programmable, and software defined. Software Defined Networks (SDNs) and Network Function Virtualization (NFV) are the keystones of the NGNs flexibility. The high expectations of NGNs’ performance and the continuous changes in the network conditions lead to the development of new network management frameworks that add elasticity and dynamicity and minimize human intervention. ETSI (the European Standards Organization) presents the Zero-touch Service Management (ZSM) framework that uses hyped technologies such as Artificial Intelligence (AI) and Machine Learning (ML) to achieve full end-to-end automation of the network services’ management across one or many different domains. Focusing on multi-domain network service management, there are several security issues identified by the standardization team which mostly derive from the lack of trust among network providers. In the present research, we explore the suitability of blockchain technology adoption for facing these security issues. Blockchain technology inherently addresses security in trustless environments such as the infrastructures defined by the ZSM team. Our contribution is three-fold: (a) we define the architecture of a multi-domain network infrastructure that adopts the ZSM approach and integrates blockchain functionality, (b) we explore the adoption of different blockchain and distributed ledger technologies (DLT) approaches to address ZSM security needs and (c) we provide guidelines to prospective solution designers/implementers on the detailed requirements that this solution has to meet to maximize the offered value.
Di Zhang, Junqing Le, Xinyu Lei, Tao Xiang · 5 authors
Blockchain is extensively applied to many fields as an immutable distributed ledger. However, the immutability contradicts regulations such as the GDPR ruling “the right to be forgotten” of data. Besides, numerous emerging blockchain-based applications call for elastic data management. To erase some data, redactable blockchains are proposed for breaking the immutability in a controlled way. Unfortunately, the prior solutions may suffer from poor security and centralized control of the redaction privilege. They cannot support dynamic nodes, where the departure of participators will result in a single point of failure. This paper proposes a noveldynamic and decentralizedattribute-basedchameleonhash (DACH) to make blockchain history mutable, achieving asecurely anddynamicallyredactable blockchain (SDR-chain) in a decentralized setting. We first propose the formal definition, security models, and concrete construction of our DACH. Meanwhile, we design a delegation algorithm of DACH to support a dynamically changing committee, where participators can freely and securely leave and join the network. Then, the transactions of the SDR-chain are redacted by computing DACH collisions. The security is analyzed in the random oracle model. Finally, theoretical analysis and experimental evaluation demonstrate that our SDR-chain is superior to the prior solutions in terms of security and functionality.