Chitturi Prasad, Gummuluri Udaya Chandrika, Vani Venkata Sai Sindhu Garapati, Ganga Rama Koteswara Rao · 6 authors
Immutability is a term used a lot in blockchain and cryptocurrency development when attemptingto analyze the economic interpretation of a network. Designs like the 21 million Bitcoin supply in BTC or incidents like the DAO fork bailout that split the Ethereum community into ETH and ETC are major examples of immutability values determining the ethos of a chain. This research sets out tocategorize different features of blockchain immutability and analyze them in three different networks: Bitcoin (BTC), Ethereum (ETH), and Ethereum Classic (ETC). Further in the paper, the Finney Ratio is introduced to help understand how blockchain immutability can be measured over time. The paper then visualizes overall blockchain immutability over time using radar charts as an immutability map. The Szabo Score is then introduced as a tool to score overall mutability over time for each blockchain.
In this paper, we present a plugin for visualising vote based consensus\nmechanisms primarily aimed to help engineers understand and debug blockchain\nand distributed ledger protocols. Both tools are built as Grafana plugins and\nmake no assumptions on the data storage implementation. The plugins can be\nconfigured via Grafana plugin configuration interface to fit the specifics of\nthe protocol implementation.\n
Current work in the field of smart contracts is primarily aimed at developers and directly connected to an underlying cryptocurrency. Those self-enforcing contracts are suitable for financial applications, but often disregard regular agreements that do not rely on digital money or are difficult to specify in the form of program code. In order to promote social interaction and self-organization for all types of users, we present Fides, a framework for creating contracts based on natural language that focuses on security and privacy. The use of natural language, detached from the actual payment process, allows everyone to create digital contracts inside a decentralized peer-to-peer network without relying on an inefficient Blockchain solution. These agreements are not only intended for interactions between humans, but can also be established between devices by automation.
Non-Fungible Token (NFT) has garnered remarkable attention to decentralized digital asset management. Permissionless blockchains store NFT content data leveraging P2P storage networks, in which data resource flows subject to financial incentives. For permissioned blockchains, without incentives, the placement of content data to the storage network requires a sound strategy, including the placement process and the replica location strategy, to avoid problems such as communication cost excess and storage unfairness, which greatly limit the service efficiency and sustainability of the storage network. Therefore, in this paper, we propose a new collaboration model between blockchain and the P2P storage network for issuing a new NFT, in which blockchain can complete the placement process and promote rational data distribution in the P2P storage network. Our proposed replica location strategy mainly considers three factors: storage fairness, service efficiency, and business load. Through theoretical analysis and experiments, it is proved that our replica location strategy has a better performance in both fairness and efficiency.
Bitcoin builds upon an unstructured peer-to-peer overlay network to disseminate transactions and blocks. Broadcast in such a network is slow and brings inconsistencies, i.e., peers have different views of the system state. Due to the delayed block propagation and the competition of mining, forking, i.e., the blockchain temporarily diverges into two or more branches, occurs frequently, which wastes computation power and causes security issues. This paper proposes an autonomous and distributed topology optimization mechanism to reduce block propagation delay and hence reduce the occurrence of blockchain forks. In the proposed mechanism, a node can autonomously update his neighbor set using the information provided by his current neighbors, since each neighbor will recommend a peer from his own neighbor set, i.e., a neighbor's neighbor, to this node. Each recommendation is based on a peer's propagation ability, which is characterized as a criteria function obtained through a combination of empirical analysis and machine learning. We further propose some metrics to evaluate a Bitcoin network topology. Experiment results reflect the effectiveness of the proposed mechanism and also indicate the correlation between block propagation time and fork rate.
In recent years, blockchain-based cryptocurren-cies have attracted much attention. Attacks targeting cryptocurrencies and related services directly profit an attacker if successful. Related studies have reported attacks targeting configuration-vulnerable nodes in Ethereum using a method called honeypots to observe malicious user attacks. They have analyzed 380 million observed requests and showed that attacks had to that point taken at least 4193 Ether. However, long-term observations using honeypots are difficult because the cost of maintaining honeypots is high. In this study, we analyze the behavior of malicious users using our honeypot system. More precisely, we clarify the pre-investigation that a malicious user performs before attacks. We show that the cost of maintaining a honeypot can be reduced. For example, honeypots need to belong in Ethereum's P2P network but not to the mainnet. Further, if they belong to the testnet, the cost of storage space can be reduced.
Blockchain technology provides a “tamper-proof distributed ledger” for its users. Typically, to ensure the integrity and immutability of the transaction data, each node in a blockchain network retains a full copy of the ledger; however, this characteristic imposes an increasing storage burden upon each node with the accumulation of data. In this paper, an off-chain solution is introduced to relieve the storage burden of blockchain nodes while ensuring the integrity of the off-chain data. In our solution, an off-chain remote DB server stores the fully replicated data while the nodes only store the commitments of the data to verify whether the off-chain data are tampered with. To minimize the influence on performance, the nodes will store data locally at first and transfer it to the remote DB server when otherwise idle. Our solution also supports accessing all historical data for newly joined nodes through a snapshot mechanism. The solution is implemented based on the Hyperledger Fabric (HLF). Experiments show that our solution reduces the block data for blockchain nodes by 93.3% compared to the original HLF and that our advanced solution enhances the TPS by 9.6% compared to our primary solution.
Blockchain-based IoT systems can manage IoT devices and achieve a high level of data integrity, security, and provenance. However, incorporating the existing consensus protocols in many IoT systems limits scalability and leads to high computational cost and network latency. We propose a hierar-chical and location-aware consensus protocol for IoI-blockchain applications inspired by the original Raft protocol to address these limitations. The proposed consensus protocol generates the consensus candidate groups based on nodes' individual reputation and distance information to elect the leader in each sub-layer blockchain and uses our threshold signature scheme to reach global consensus. Experimental results show that the proposed consensus protocol is scalable for large IoT applications and significantly reduces the communication cost, network latency, and agreement time by more than 50% compared with the Raft protocol for consensus processing.
The progressive decentralization of web services brought a need for new instruments to support the development of P2P protocols and applications. The only tools available are network or event simulators, which help the development in artificial or extremely controlled environments. They usually provide low-level support with completely unstructured networks. LibP2P is a library that tries to solve all such problems, letting the users easily deploy nodes on the Internet. It also comes with a set of functionalities, to solve the most important problems of P2P networks, such as NAT traversal, peer and content discovery and routing, and much more. In this paper, we employ LibP2P to implement min-bitcoin, a minimal version of the protocol used by the Bitcoin network to exchange the blocks. We evaluate our implementation to assess the applicability of LibP2P in a real-life blockchain scenario. The evaluation uncovers that setting up communication channels is time-consuming, but data transfers are fast. Additionally, LibP2P efficiently manages cases in which nodes are behind a NAT, under VPN, or in geographically distant places.
The existing Bitcoin security research has mainly followed the security models in [22, 35], which stipulate that an adversary controls some mining power in order to violate the blockchain consistency property (i.e., through a double-spend attack). These models, however, largely overlooked the impact of the realistic network synchronization, which can be manipulated given the permissionless nature of the network. In this paper, we revisit the security of Bitcoin blockchain by incorporating the network synchronization into the security model and evaluating that in practice. Towards this goal, we propose the ideal functionality for the Bitcoin network synchronization and specify bounds on the network outdegree and the block propagation delay in order to preserve the consistency property. By contrasting the ideal functionality against measurements, we find deteriorating network synchronization reported by Bitnodes and a notable churn rate with 10% of the nodes arriving and departing from the network daily.
Abstract Bitcoin is a popular decentralized cryptocurrency, and the Bitcoin network is essentially an unstructured peer-to-peer (P2P) network that can synchronize distributed database of replicated ledgers through message broadcasting. In the Bitcoin network, the average clustering coefficient of nodes is very high, resulting in low message propagation efficiency. In addition, average node degree in the Bitcoin network is also considerably large, causing high message redundancy when nodes use the gossip protocol to broadcast messages. These may affect message propagation speed, hindering Bitcoin from being applied to scenarios of high transactional throughputs. To illustrate, we have collected single-hop propagation data of transactions of 366 blocks from Bitcoin Core. The analysis results show that transaction verification and network delay are two major causes of low transaction propagation efficiency. In this paper, we propose a novel P2P network structure, called local clique network (LCN), for message broadcasting in the Bitcoin network. Specifically, to reduce transaction validation latency and message redundancy, in LCN local nodes (logically) form cliques, and only a few nodes in a clique broadcast messages to the other cliques, instead of each node sending messages to its neighboring nodes. We have conducted extensive experiments, and the results show that message redundancy is low in LCN, and message propagation speed increases significantly. Meanwhile, LCN exhibits excellent robustness when average node degree remains high in the Bitcoin network.
Pedro Casas, Matteo Romiti, Peter Holzer, Sami Ben Mariem · 6 authors
Proposed in 2016 and launched in 2018, the Bitcoin (BTC) Lightning Network (LN) can scale-up the capacity of the BTC blockchain network to process a significantly higher amount of transactions, in a faster, cheaper, and more privacy preserving manner. The number of LN nodes has been significantly increasing since 2018, and today there are more than twelve thousand nodes actively participating of so-called LN payment channels. The upcoming Taproot upgrade to the Bitcoin protocol would further boost the development and adoption of the LN. Taproot is the most significant upgrade to the Bitcoin network since the block size increase of 2017, and it will make LN transactions cheaper, more flexible, and more private. We focus on the characterization of the LN network topology, using network active measurements. By crawling the underlying P2P network supporting the Bitcoin LN over a span of 10-months, we unveil the LN in terms of size and location of its nodes as well as connectivity protocols, comparing it to the P2P IP network supporting the BTC blockchain. Among our findings, we show that IP addresses exposed by LN nodes correspond mainly to customer networks, even if most BTC nodes are actually deployed at major cloud providers, and that LN nodes significantly rely on anonymized networks and protocols such as Onion, with more than 40% of LN nodes connect through Tor.
Summary In the Bitcoin system, transactions and their collections (i.e., blocks) are distributed over a peer‐to‐peer (P2P) network (i.e., Bitcoin network) constructed by participating nodes. Each node maintains a distributed ledger (i.e., blockchain) consisting of retrieved blocks. Therefore, speedy block distribution over the Bitcoin network is essential for all nodes to reach a global consensus on the blockchain. On the other hand, Bitcoin clients are developed as open source software, and thus they can be modified by malicious users. Existing work has pointed out that an attacker can delay the block propagation between neighboring nodes by exploiting the regular timeout mechanism for unexpected slow block transfer caused by temporal network trouble. In this paper, we focus on block diffusion delay attacks, where multiple attackers collude with a specific miner (i.e., a special node that creates new blocks and broadcasts these blocks to the other miners) to disturb the propagation of blocks generated by competing miners. Through simulation experiments, we first reveal that about 30% of honest nodes cannot normally retrieve a block when there are only 1% of the nodes in the system are high‐degree adversary nodes in the system. This indicates that the malicious miner colluding with the attackers can intentionally delay the diffusion of the block mined by the competing miner, so as to win the competitive block diffusion even if it loses at the competitive block mining. To alleviate the block diffusion delay attack, we propose two kinds of countermeasures: a proactive approach that is a speedy recovery method from the interruption by adjusting the timeout value and a reactive approach that is a block retrieval node selection method based on the past download rate from each neighbor. Through simulation experiments, we show the countermeasures can effectively alleviate the risk.
In this paper, we focus on the video streaming as a concrete application of the Peer-to-Peer (P2P) technology, and consider the problem of properly recording contributions made by each peer to make a fair differentiation of provided services. More specifically, we propose a simple implementation of distributed reward system for P2P video streaming by combining WebTorrent API and Ethereum-based smart contracts. We also conduct experiments to confirm that the prototype system certainly realizes a service differentiation.
Cryptocurrency, without exaggeration, can be called one of the most popular and demanded digital assets. The use of electronic means guarantees anonymity for users. Blockchain technology allows you to trace transactions, but does not provide an opportunity to determine the owner of the wallet. However, the issue of exchanging digital assets for traditional money remains open for many users.\n\nWhat do you need to work with digital currency?\nTo buy cryptocurrency and start working with digital assets, you need a virtual wallet and a Visa or MasterCard bank card. There are the following types of wallets:\n\nLocal. Also called desktop. A local wallet is a program that is installed on a computer.\n\n\nMobile. Application for installation on a mobile device. Programs should be downloaded from the official stores AppStore and Play Market.\n\n\nOnline wallet. It is available from any device, but it is not the safest option, so it is not recommended to use it for storing large amounts. An online wallet is perfect for those who are just getting started with digital assets.\n\n\nHardware. It is a USB device. Suitable for storing large amounts.\n\n\nWhen choosing a wallet, you need to focus on your needs. The most convenient way to pay is from a mobile phone. If you plan to make frequent financial transactions, it is better to use an online wallet. The registration procedure will differ depending on the platform you choose.\n\nOnline exchangers\nExchange services offer the fastest and easiest way to exchange cryptocurrencies. Such sites allow you to withdraw money by various methods, including to a bank card. As a rule, such services operate according to a similar algorithm.\n\nTo exchange funds, you must:\n\n - choose the currency of interest;\n - indicate the method of receiving funds;\n - enter the required information;\n - pass verification.\nThen the exchange service will send the number of the virtual account to which the transaction is made in the specified amount. After the money is transferred, you need to confirm the action. As a rule, the exchange takes no more than 15 minutes, but there are times when the application is processed for more than 2 hours. This is usually due to DDoS attacks on the blockchain platform or digital asset renewal. In this case, it is better to contact the technical support of the service. If the operation does not go through because of your mistake, most likely, the money will be lost.\n\nDepending on the service, the commission can range from 1-2% to 10% and higher. It is necessary to choose a site taking into account the needs and parameters of interest. For this, you can use special aggregators. This will allow you to quickly find the option you are interested in. It is better to choose from services that have been operating for at least three years.\n\nCompany Alligator offers to exchange Bitcoins and other cryptocurrencies on favorable terms. The service has been offering its services since 2015 and is one of the most reliable in Russia, Ukraine and the CIS countries. Millions of users work with Alligator every month. The latest software and servers ensure maximum security for user assets. All user data is securely protected.\n\nThe service offers favorable conditions, a good rate and a small commission. Thanks to qualified technical support, any issues are resolved before they become problems. Transactions usually take several minutes to complete. All transactions are performed quickly, and in total, the exchanger supports more than 150 digital currencies.\n\nP2P sites and their features\nYou can withdraw funds from a cryptocurrency wallet to an electronic or bank account through the P2P platform. There are a lot of such systems, so you can choose the option that will meet your exact requirements. On such platforms, digital assets are exchanged between two users. The P2P platform acts as a guarantor. The commission is set by the service, and in some cases it may be absent altogether.\nThe P2P platform acts as a guarantor of the transaction. The seller is guaranteed to receive money before his digital currency reaches the stranger's account. However, there is one point here: there is no guarantee that the user who buys your digital currency will not use a stolen bank card to transfer funds. To minimize risks, it is recommended to conclude deals with users who have a good reputation. On P2P sites, as a rule, there is a user rating, which determines the percentage of success.\n\nHow to exchange money on the exchange\nMany trading platforms provide for the possibility of withdrawing money to a bank card. This is a convenient and safe way. But many exchanges charge a high commission for direct withdrawals, as trading platforms usually cooperate with counterparties. When transferring funds, the platform first transfers the currency to a third-party service. The exchange partner transfers money to the client, after which the operation can be considered completed.\n\nIn this case, the costs are quite high, but this option is the most transparent and popular. It should be borne in mind that not all exchanges are equally safe. The vulnerability of such services is one of the main problems. Trading platforms attract the attention of hackers, and in the event of a hacked wallet, the probability of a refund is minimal.\n\nIf you decide to make money on digital assets, we recommend that you study several cryptocurrency reviews in order to understand which one is the most promising and which one should work with. It is most profitable to make money on the course races, but for this you need to regularly monitor any fluctuations.
Traditional distributed ledger technology has the disadvantages of low throughput, high resource consumption and poor scalability, which make it difficult to be applied in the field of Internet of things. As a new distributed ledger technology based on directed acyclic graph, IOTA aims to be applied in the field of Internet of things. However, IOTA suffers from the problem of fairness. In IOTA,a large number of honest transactions may not be approved, and the system has the risk of parasitic chain attack and splitting attack. In this paper we proposes a new tip selection algorithm, which can dynamically change the tip selection strategy. Interestingly, the concept of sharpness is proposed firstly to describe the extreme degree of a tangle-fragment in this paper.Experimental results show that our algorithm can make most honest transactions be verified, while always keeping the security of the tangle in an acceptable range.
Oct 10, 2021·Proceedings of the ... Annual Hawaii International Conference on System Sciences/Proceedings of the Annual Hawaii International Conference on System Sciences
Johannes Sedlmeir, Tim Wagner, Emil Djerekarov, Ryan Green · 6 authors
Enterprises have been attracted by the capability of blockchains to provide a single source of truth for workloads that span companies, geographies, and clouds while retaining the independence of each party's IT operations. However, so far production applications have remained rare, stymied by technical limitations of existing blockchain technologies and challenges with their integration into enterprises' IT systems. In this paper, we collect enterprises' requirements on distributed ledgers for data sharing and integration from a technical perspective, argue that they are not sufficiently addressed by available blockchain frameworks, and propose a novel distributed ledger design that is "serverless", i.e., built on cloud-native resources. We evaluate its qualitative and quantitative properties and give evidence that enterprises already heavily reliant on cloud service providers would consider such an approach acceptable, particularly if it offers ease of deployment, low transactional cost structure, and a combination of latency and scalability aligned with real-time IT application needs.
Felipe K. Shiraishi, Vitor H. Perles, Hector K. Yassuda, Leonardo T. Kimura · 6 authors
We propose Torrente, a distributed file-sharing solution with economic incentives. Its implementation is built as an extension of BitTorrent protocol, in such a manner that user access to file-sharing swarms is controlled by peers that verify micropayments receipts in a blockchain-based ledger. In addition, by using payment commitments, Torrente facilitates off-chain transactions for faster content sharing. The solution is created as a tool to enhance Amazon Biobank application security, but can be used isolated in cases such as file sharing with monetary incentives.
Lucian Trestioreanu, Cristina Nita-Rotaru, Aanchal Malhotra, Radu State
Payment systems are a critical component of everyday life in our society. While in many situations payments are still slow, opaque, siloed, expensive or even fail, users expect them to be fast, transparent, cheap, reliable and global. Recent technologies such as distributed ledgers create opportunities for near-real-time, cheaper and more transparent payments. However, in order to achieve a global payment system, payments should be possible not only within one ledger, but also across different ledgers and geographies. In this paper we propose Secure Payments with Overlay Networks (SPON), a service that enables global payments across multiple ledgers by combining the transaction exchange provided by the Interledger protocol with an intrusion-tolerant overlay of relay nodes to achieve (1) improved payment latency, (2) fault tolerance to benign failures such as node failures and network partitions, and (3) resilience to BGP hijacking attacks. We discuss the design goals and present an implementation based on the Interledger protocol and Spines overlay network. We analyze the resilience of SPON and demonstrate through experimental evaluation that it is able to improve payment latency, recover from path outages, withstand network partition attacks, and disseminate payments fairly across multiple ledgers. We also show how SPON can be deployed to make the communication between different ledgers resilient to BGP hijacking attacks.
Abstract This study investigates the information flow and social organization in a Bitcoin discussion network on Twitter (BDN), using social network analysis to examine user‐user interactions. Results suggest that BDN presents a heterogenous degree distribution, where most users have few interactions. A myriad of weakly defined but well‐connected subcommunities enables efficient information flow in the network. BDN emanates a small‐world effect, without the dominance of a few influential users. “Star‐power agents,” such as Elon Musk, are popular references among users, but the network is driven bottom‐up by smaller “two‐sided” users. This explorative study demonstrates how the classification of different users can be used in analyzing online communities. Future research could compare the network structure of BDN with other networks and utilize sentiment analysis to analyze the quality of information.
Blockchain brings many added values to modern business systems. However, Blockchain-based applications with massive IoT devices experience some limitations. The limitations are due to the linear structure and the consensus algorithms used in Blockchain that consume the participating nodes' considerable resources. In addition, IoT devices are generally with limited resources and have limited bandwidth connections. IOTA, based on Directed Acyclic Graph (DAG), is a new distributed ledger technology (DLT) for IoT devices. It proves its high scalability by providing parallel data processing. However, DAG is still not mature enough to fully replace Blockchain. In previous work, we proposed combining Blockchain and IOTA technologies to allow scalable transactions where Blockchain is employed in the backend, and Tangle is used in the frontend. This paper considers the proposed solution, focusing mainly on the connector part that intermediates both DLT technologies. The connector is a decentralized software component that supports the interaction between the DLT implicitly. The experiments' results show the flexibility to merge both DLTs using a message queuing protocol that enables smart contracts to run on the Tangle nodes and enriches the new platform with reliability and working offline features.
Kai Li, Yuzhe Tang, Jiaqi Chen, Yibo Wang · 5 authors
Ethereum relies on a peer-to-peer overlay network to propagate information. The knowledge of Ethereum network topology holds the key to understanding Ethereum's security, availability, and user anonymity. From a measurement perspective, an Ethereum network's topology is routing-table information hidden inside individual Ethereum nodes, measuring which poses challenges and remains an open research problem in the existing literature. This paper presents TopoShot, a new method uniquely repurposing Ethereum's transaction replacement/eviction policies for topology measurement. TopoShot can be configured to support Geth, Parity, and other major Ethereum clients. As validated on local nodes, TopoShot achieves 100% measurement precision and high recall 88% - 97%. To efficiently measure the large Ethereum networks in the wild, we propose a non-trivial schedule to run pair-wise measurements in parallel. To enable ethical measurement on Ethereum mainnet, we propose workload-adaptive configurations of TopoShot to minimize the service interruption to target nodes/network. We systematically measure a variety of Ethereum networks and obtain new knowledge including the full-network topology in major testnets (Ropsten, Rinkeby and Goerli) and critical sub-network topology in the mainnet. The results on testnets show interesting graph-theoretic properties, such as all testnets exhibit graph modularity significantly lower than random graphs, implying resilience to network partitions. The mainnet results show biased neighbor selection strategies adopted by critical Ethereum services such as mining pools and transaction relays, implying a degree of centralization in real Ethereum networks.
Bitcoin first proposed the Nakamoto consensus that applies proof of work into the blockchain structure to build a trustless append-only ledger. The Nakamoto consensus solves the distributed consistency problem in the public network but wastes too much computing power. Instead of consuming computing resources, many improved consensus schemes address this problem by leveraging miners’ storage resources. However, these schemes fail to let miners store data constantly and usually rely on a dealer to assign data, which is hard to build a reliable decentralized storage system. In this article, we first design a variant consensus algorithm named Proof of Continuous Work (PoCW) with a storage-related incentive mechanism. Miners can accumulate mining advantage by continuously submitting proofs of storage. Then, we present a hash ring-based data allocation algorithm using the blockchain’s state. Combined with both of them, we build a reliable blockchain-based storage system without relying on any third parties. The theoretical analysis and simulation results demonstrate that the proposed system has higher reliability than those existing systems, and we also give practical suggestions about system parameters. Finally, we discuss additional benefits that our system brings.