Today, the majority of the web’s content and user data is controlled by a few large tech companies. There is a growing movement to devolve this control evenly across the entire internet, representing the transition to Web3. In order for this movement to be successful, technologies and protocols must be developed to enable web users to use the web securely without trusting any other user. That is, today’s web is structured so that users must trust these companies, so trustless alternatives haven’t already been developed. Broadly, this movement emphasizes developing peer-to-peer networks, blockchains, and distributed storage systems. These systems make use of cryptographic primitives to guarantee security.
We present a decentralized online gaming platform implemented as a Decentralized Application (DApp) on the Ethereum blockchain. The gaming platform enables secure gaming, where the account balances and the stakes of the players are secured by a smart contract. Moreover, the fair enforcement of the game rules and the deposit of the winnings of the players and the gaming platform into their accounts are guaranteed by the smart contract. The gaming platform proposes lending functionalities that allow players to securely borrow tokens from the gaming platform in order to participate in the games.
Befekadu G. Gebraselase, Bjarne E. Helvik, Yuming Jiang
Bitcoin is the first and the most extensive decentralized electronic cryptocurrency system that uses blockchain technology. It uses a peer-to-peer (P2P) network to operate without a central authority and propagate system information such as transactions or blockchain updates. The communication between participating nodes is highly relying on the underlying network infrastructure to facilitate a platform. Understanding the impact of peer formation strategies, peer list, and delay is vital in understanding node to node communication and the system performance. Therefore, we performed an extensive study on the transaction characteristics of Bitcoin through a testbed. The analysis shows that peer selection strategies affect the transaction propagation and confirmation times. In particular, better performance, in terms of smaller transaction confirmation time and lower number of temporary forks, may be achieved by adjusting the default nearby-based peer selection strategy.
Matthias Grundmann, Max Baumstark, Hannes Hartenstein
A recent spam wave of IP addresses in the Bitcoin P2P network allowed us to estimate the degree distribution of reachable peers. The resulting distribution indicates that about half of the reachable peers run with Bitcoin Core’s default setting of a maximum of 125 concurrent connections and nearly all connection slots are taken. We validate this result empirically. We use our observations of the spam wave to group IP addresses that belong to the same peer. By doing this grouping, we improve on previous measurements of the number of reachable peers and show that simply counting IP addresses overestimates the number of reachable peers by 15 %. We revalidate previous work by using our observations to estimate the number of unreachable peers.
Due to the widespread use of smart contracts, Ethereum has become the second-largest blockchain platform after Bitcoin. Many different types of Ethereum accounts (ICO, Mining, Gambling, etc.) also have quite active trading activities on Ethereum. Studying the transaction records of these specific Ethereum accounts is very important for understanding their particular transaction characteristics, and further labeling the pseudonymous accounts. However, traditional methods are generally based on static and global transaction networks to conduct research, ignoring useful information about dynamic changes. Our work chooses six kinds of important account labels, and builds ego networks for each kind of Ethereum account. We focus on the interaction between the target node and neighbor nodes with temporal analysis. Experiments show that there is a significant difference between various types of accounts in terms of several network features, helping us better understand their transaction patterns. To the best of our knowledge, this is the first work to analyze the dynamic characteristics of Ethereum labeled accounts from the perspective of transaction ego networks.
Andrew Cullen, Lianna Zhao, Luigi Vigneri, Robert Shorten
An outstanding problem in the design of distributed ledgers concerns policies that govern the manner in which users interact with the network. Network usability is crucial to the mainstream adoption of distributed ledgers, particularly for enterprise applications in which most users do not wish to operate full node. For DAG-based ledgers such as IOTA, we propose a user-node interaction mechanism that is designed to ensure the risk of a user experiencing a poor quality of service is low. Our mechanism involves users selecting nodes to issue their transactions to the ledger based on quality of service indicators advertised by the nodes. Simulation results are presented to illustrate the efficacy of the proposed policies.
This paper examines the effects of inherent risks in the emerging technology of non-fungible tokens and proposes an actionable set of solutions for stakeholders in this ecosystem and observers. Web3 and NFTs are a fast-growing 300 billion dollar economy with some clear, highly publicized harms that came to light recently. We set out to explore the risks to understand their nature and scope, and if we could find ways to mitigate them. In due course of investigation, we recap the background of the evolution of the web from a client-server model to the rise of Web2.0 tech giants in the early 2000s. We contrast how the Web3 movement is trying to re-establish the independent style of the early web. In our research we discover a primary set of risks and harms relevant to the ecosystem, and classify them into a simple taxonomy while addressing their mitigations with solutions. We arrive at a set of solutions that are a combination of processes to be adopted, and technological changes or improvements to be incorporated into the ecosystem, to implement risk mitigations. By linking mitigations to individual risks, we are confident our recommendations will improve the security maturity of the growing Web3 ecosystem. We are not endorsing, or recommending specifically any particular product or service in our solution set. Nor are we compensated or influenced in any way by these companies to list these products in our research. The evaluations of products in our research have to simply be viewed as suggested improvements.
Distributed ledger technology (DLT) offers new and unique advantages for information systems, but some of its features are not a good fit for many applications. We review the properties of DLT and propose a new type of architecture for DLT based on main-sub ledger. Our scheme pays more attention to data privacy, effectively relieves the pressure of data storage for nodes, thereby improves data handling capability.
This paper proposes a solution for validating an End-to-End service chain built by multiple actors that may not trust each other. We notably introduce a “data layer” powered by a Distributed Ledger (DL, a.k.a “Blockchain”) using a Directed Acyclic Graph (DAG). This component will enable all players involved in a network service chain to share trusted and secure performance data, whilst avoiding the participation of trusted third parties. We consider as a driving use case a scenario where resource providers and resource consumers (a.k.a “prosumers”) interact together to build on-demand network services. We thus focus on a Cloud-based Radio Access Network scenario and anticipate network disaggregation, allowing the infrastructure to be shared between multiple providers. We show through simulation that the usage of a DAG-based ledger will make the proposed data layer scalable despite the amount of performance data required for monitoring.
Abstract : People’s lives have been profoundly impacted by the headway of innovation which has worked on their lives from each viewpoint. Clearly, innovation assumes a significant part in each circle of life and information stockpiling and sharing is a significant part of it. Current information sharing and storage devices depend on trusted third parties (TTP) and because of the contribution of third parties, such frameworks need straightforwardness, security, trust and strength. To solve these issues, this paper proposes a blockchain-based secure information sharing application by consolidating the highlights of IPFS and Ethereum. In this proposed scheme ethereum blockchain, decentralized storage, encryption and IPFS are combined to build an application that maximizes the tech<em>nological resources and provide</em> with an effective storage website ,Ethereum blockchain, decentralized capacity, encryption, and InterPlanetary File System are consolidated to assemble an application that boosts the innovative assets and gives a viable storage site. To carry out the proposed situation, smart contracts are written in solidity and sent on the nearby Ethereum test network. The proposed plot accomplishes security, transparency, legitimacy of owner, access control and nature of information.
Light clients for distributed ledger networks can verify blockchain integrity by downloading and analyzing blockchain headers. They are designed to circumvent the high resource requirements, i.e., the large bandwidth and memory requirements that full nodes must meet, which are unsuitable for consumer-grade hardware and resource-constrained devices. Light clients rely on full nodes and trust them implicitly. This leaves them vulnerable to various types of attacks, ranging from accepting maliciously forged data to Eclipse attacks. We introduce Aurora-Trinity, a novel version of light clients that addresses the above-mentioned vulnerability by relying on our original Aurora module, which extends the Ethereum Trinity client. The Aurora module efficiently discovers the presence of malicious or Byzantine nodes in distributed ledger networks with a predefined and acceptable error rate and identifies at least one honest node for persistent or ephemeral communication. The identified honest node is used to detect the latest canonical chain head or to infer the state of an entry in the ledger without downloading the header chain, making the Aurora-Trinity client extremely efficient. It can run on consumer-grade hardware and resource-constrained devices, as the Aurora module consumes about 0.31 MB of RAM and 1 MB of storage at runtime.
In this study, we proposed an architecture for Web 3.0, which is based on the hashed interactions among user nodes that can transform bilateral trusts into collective time order, which is the major achievement of blockchain technology, without the expensive Proof of Work or the questionable Proof of Stake.
Blockchain is one of the IT industry's fastestgrowing technology niches. We chose to use blockchain technology to develop a web application for our project. We'll create a fully functional crypto-currency with full stack functionality and blockchain logic. We are proposing a new improvement in which we will not use any database server at the backend. Instead, we'll use Redis to create a publisher/subscriber network that will enable us to broadcast various messages and chain them across the network. Every node in the network will have a wallet, and they will make various transactions, which will then be added to the blockchain to block, and then broadcasted to the rest of the chain This eliminates the need for a database infrastructure to be created and maintained. We will create a mining algorithm (proof of work algorithm) for selecting blocks (collection of transactions) that will change its difficulty rate based on the computational power present in the node to node network, and for each block mined and successfully added to the chain will be rewarded with a reward in the form of our Cryptocurrency.
In this paper, we present a methodology for quantifying the decentralization degree of a blockchain network. To accomplish this, we use two well-known graph models of Erdös-Rény and Barabási–Albert in order to study the blockchain network topology. We then quantify the decentralization degree using the clustering coefficient of our network models. We validate our approach through extensive simulations and analyze the decentralization degree with respect to network parameters such as the number of connections per node and the peer selection algorithm. Our results expose the trade-off between the average shortest path and the decentralization degree. Furthermore, we observe the impact of the average shortest path on the network speed and traffic overhead. Finally, we demonstrate that the presence of hub-like nodes such as relay gateways negatively impacts the decentralization degree of blockchain networks.
Kadir Korkmaz, Joachim Bruneau‐Queyreix, Sonia Ben Mokhtar, Laurent Réveillère
Most of today's online services (e.g., social networks, search engines, market places) are centralized, which is recognized as unsatisfactory by a majority of users for various reasons (e.g., centralized governance, censorship, loss of control over personal data). Blockchain technologies promise a new Web revolution (Web 3.0) through the decentralization of online services. However, one of the key limitations for this revolution to happen at a planetary scale is the poor performance of today's blockchains. We propose in this paper ALDER, a solution for unlocking the performance of off-the-shelf leader-based blockchains by multiplexing their consensus protocol. Our solution leverages the existence of multiple potential leaders to alleviate the bottleneck that exists at different levels of consensus protocols. To illustrate the benefits it brings to Blockchain performance, we apply ALDER to three representative blockchains, namely Algorand (Proof-of-Stake), RapidChain (Sharding-based) and Bitcoin (Proof-of-Work). Our evaluation, involving up to 10,000 nodes deployed on 100 physical machines, shows that using ALDER can provide up to a 300% improvement in both throughput and latency reduction.
Peter Lone, Kumar Nagarajan, Trish Supples, Paul T. P. Wong
Although distributed ledgers frequently are viewed as a revolutionary technology that could transform many markets, the technology has not yet received wide-scale business adoption. This may be due in part to a lack of use cases for which the decentralized and distributed features of distributed ledger technology (DLT) are optimal. But payment directories (known in certain markets as registries), which facilitate the lookup of payments-related information, may be a use case that has specific challenges that take better advantage of these features than other use cases explored by businesses to date. Directories that support routing of information to support payments like aliases for peer-to-peer payments and business-to-business e-invoices may benefit from the use of DLT. DLT allows market participants to maintain and to protect localized information without the competitive, operational, and technical challenges of a centralized database.
<div>Abstract—Despite the various advantages inherent in the use of blockchain technology, blockchain application platforms are characterized by bottlenecks, latency, energy inefficiency, time inefficiency, low transaction throughput, vulnerability to 51% attacks, and a lack of fairness in the sharing of mining proceeds. These challenges are currently affecting the performance of this technology, hindering its rapid development and adoption for real-time applications such as Electronic Voting Applications (EVAs). It is well known that the consensus mechanism responsible for the security and consistency features of a blockchain, is also responsible for most of the above challenges.</div><div>In this paper, a new consensus mechanism, Proof of Vote (PoV) is proposed, a lightweight consensus mechanism specifically adapted for EVA, as a replacement for the heavyweight Proof of Work (PoW) consensus algorithm. We use the Ethereum blockchain as a decentralized application platform, in which we develop a decentralized electronic voting application (ADEVA), replacing the Ethereum PoW consensus algorithm with the proposed PoV consensus algorithm. Thus we implemented ADEVA with PoV and compared it to the two major consensus mechanisms: Proof of work (PoW) and Proof of Stake (PoS). We found that PoV enhanced the performance of ADEVA over and above that achieved using PoW and PoS. The low resource utilization and high transaction throughput of ADEVA with PoV makes it a scalable solution for real-world EVAs.</div>
Mehrdad Kiamari, Bhaskar Krishnamachari, Muhammad Naveed, Seokgu Yun
We present Blizzard, a Byzantine fault tolerant (BFT) distributed ledger protocol that is aimed at making mobile devices first-class citizens in the consensus process. Blizzard introduces a novel two-tier architecture by having the mobile nodes communicate through online brokers, and includes a decentralized matching scheme to ensure each node connects to a certain number of random brokers. Through mathematical analysis, we derive a guaranteed safety region (i.e., the set of ratios of malicious nodes and malicious brokers for which the safety is assured) for the Blizzard protocol. Liveness is shown as well. We analyze the performance of Blizzard in terms of its throughput, latency, and message complexity. Through experiments based on a software implementation, we show that Blizzard is capable of throughput on the order of several thousand transactions per second per shard and sub-second confirmation latency.
Abstract Ability to perform fast analysis on massive public blockchain transaction data is needed in various applications such as tracing fraudulent financial transactions. The blockchain data is continuously growing and is organized as a sequence of blocks containing transactions. This organization, however, cannot be used for parallel graph algorithms which need efficient distributed graph data structures. Using message passing libraries (MPI), we develop a scalable cluster-based system that constructs a distributed transaction graph in parallel and implement various transaction analysis algorithms. We report performance results from our system operating on roughly 5 years of 10.2 million block Ethereum Mainnet blockchain data. We report timings obtained from tests involving distributed transaction graph construction, partitioning, page ranking of addresses, degree distribution, token transaction counting, connected components finding and our new parallel blacklisted address trace forest computation algorithm on a 16 node economical cluster set up on the Amazon cloud. Our system is able to construct a distributed graph of 766 million transactions in 218 s and compute the forest of blacklisted address traces in 32 s.
David Richter, David Kretzler, Pascal Weisenburger, Guido Salvaneschi · 6 authors
Decentralized applications (dApps) consist of smart contracts that run on blockchains and clients that model collaborating parties. dApps are used to model financial and legal business functionality. Today, contracts and clients are written as separate programs - in different programming languages - communicating via send and receive operations. This makes distributed program flow awkward to express and reason about, increasing the potential for mismatches in the client-contract interface, which can be exploited by malicious clients, potentially leading to huge financial losses. In this paper, we present Prisma, a language for tierless decentralized applications, where the contract and its clients are defined in one unit. Pairs of send and receive actions that "belong together" are encapsulated into a single direct-style operation, which is executed differently by sending and receiving parties. This enables expressing distributed program flow via standard control flow and renders mismatching communication impossible. We prove formally that our compiler preserves program behavior in presence of an attacker controlling the client code. We systematically compare Prisma with mainstream and advanced programming models for dApps and provide empirical evidence for its expressiveness and performance. The design space of dApp programming and other multi-party languages depends on one major choice: a local model versus a global model. In a local model, parties are defined in separate programs and their interactions are encoded via send and receive effects. In a global language, parties are defined within one shared program and interactions are encoded via combined send-and-receive operations with no effects visible to the outside world. The global model is followed by tierless [Christian Queinnec, 2000; Cooper et al., 2007; Choi and Chang, 2019; Fowler et al., 2019; Serrano et al., 2006; Serrano and Prunet, 2016; Radanne et al., 2016; Weisenburger et al., 2018] and choreographic [Kohei Honda et al., 2011; Fabrizio Montesi et al., 2014; Saverio Giallorenzo et al., 2020] languages. However, known approaches to dApp programming follow the local model, thus rely on explicitly specifying the client-contract interaction protocol. Moreover, the contract and clients are implemented in different languages, hence, developers have to master two technology stacks. The dominating approach in industry is Solidity [Mix, 2019] for the contract and JavaScript for clients. Solidity relies on expressing the protocol using assertions in the contract code, which are checked at run time [Solidity documentation - common patterns, 2020]. Failing to insert the correct assertions may give parties illegal access to monetary values to the detriment of others [Nikolić et al., 2018; Luu et al., 2016]. In research, contract languages [Ankush Das et al., 2019; Michael J. Coblenz, 2017; Franklin Schrans et al., 2018; Franklin Schrans et al., 2019; Michael J. Coblenz et al., 2019; Michael J. Coblenz et al., 2019; Reed Oei et al., 2020; Sam Blackshear et al., 2019] have been proposed that rely on advanced type systems such as session types, type states, and linear types. The global model has not been explored for dApp programming. This is unfortunate given the potential to get by with a standard typing discipline and to avoid intricacies and potential mismatches of a two-language stack. Our work fills this gap by proposing Prisma - the first language that features a global programming model for Ethereum dApps. While we focus on the Ethereum blockchain, we believe our techniques to be applicable to other smart contract platforms. Prisma enables interleaving contract and client logic within the same program and adopts a direct style (DS) notation for encoding send-and-receive operations (with our awaitCl language construct) akin to languages with async/await [Gavin M. Bierman et al., 2012; Scala async rfc]. DS addresses shortcomings with the currently dominant encoding of the protocol’s finite state machines (FSM) [Mix, 2019; Michael J. Coblenz, 2017; Franklin Schrans et al., 2018; Franklin Schrans et al., 2019; Michael J. Coblenz et al., 2019; Michael J. Coblenz et al., 2019]. We argue writing FSM style corresponds to a control-flow graph of basic blocks, which is low-level and more suited to be written by a compiler than by a human. With FSM style, the contract is a passive entity whose execution is driven by clients. whereas the DS encoding allows the contract to actively ask clients for input, fitting dApp execution where a dominant contract controls execution and diverts control to other parties when their input is needed. In the following Prisma snippet, the payout function is a function invoked by the contract when it is time to pay money to a client. In Prisma, variables, methods and classes are separated into two namespaces, one for the contract and one for the clients. The payout method is located on the contract via the annotation @co. The body of the method diverts the control to the client using awaitCl(...) { ... }, hence the contained readLine call is executed on the client. Note that no explicit send/receive operations are needed but the communication protocol is expressed through the program control flow. Only after the check client == toBePayed that the correct client replied, the current contact balance balance() is transferred to the client via transfer. @co def payout(toBePayed: Arr[Address]): Unit = { awaitCl(client => client == toBePayed) { readLine("Press enter for payout") } toBePayed.transfer(balance()) } Overall, Prisma relieves the developer from the responsibility of correctly managing distributed, asynchronous program flows and the heterogeneous technology stack. Instead, the burden is put on the compiler, which distributes the program flow by means of selective continuation-passing-style (CPS) translation and defunctionalisation and inserts guards against malicious client interactions. We needed to develop a CPS translation for the code that runs on the Ethereum Virtual Machine (EVM) since the EVM has no built-in support for concurrency primitives which could be used for asynchronous communication. While CPS translations are well-known, we cannot use them out-of-the-box because the control flow is interwoven with distribution in our case. A CPS translation that does not take distribution into account would allow malicious clients to force the contract to deviate from the intended control flow by sending a spoofed continuation. Thus, it was imperative to prove correctness of our distributed CPS translation to ensure control-flow integrity of the contract.
Леонід Куперштейн, Mykhailo Krentsin, A. V. Dudatyev, Vladyslav Kaplun
The basic concepts of peer-to-peer networks are analyzed. The current areas of their use are indicated, namely file-sharing services, teleconferencing systems, gaming and trade services, etc. The types of structural organization are considered, and their advantages and disadvantages are determined. According to the degree of centralization, pure, hybrid and federal architectures are distinguished. The classification of peer-to-peer peer networks by connection method and function is also given. Analysis of the prevalence of peer-to-peer networks in the modern world has proved the demand and relevance of the use of decentralized network technology, especially in the field of finance. Possible types of attacks on peer-to-peer networks are analyzed. Both general and specific attacks are highlighted. Specific attacks are oriented on user, application or network. Methods and mechanisms of protection for each of the studied types of attacks are given. The results of the analysis are systematized, namely for each attack the impact on the data, the degree of danger and the level of protection is determined. It also indicates the direction of violation of information security of each attack, namely the integrity, accessibility, confidentiality. It turned out to be no less interesting for malefactors, as evidenced by the significant number of hacks. The research of attacks on P2P networks showed a wide range of both general and specialized. At the same time, attacks are differentiated according to the degree of danger and the aspect of security breach. The most dangerous were attacks that could violate the confidentiality and integrity of data. These include the following attacks: distributed denial of service, index poisoning, sibyl attack, eclipse attack, botnets, masquerade. The research is the basis for further study of the shortcomings of the protection of peer-to-peer networks and the development of new secure mechanisms for data exchange in decentralized structures.
Jonathan Heiss, Robert Muth, Frank Pallas, Stefan Tai
Many service systems rely on verifiable identity-related information of their users. Manipulation and unwanted exposure of this privacy-relevant information, however, must at the same time be prevented and avoided. Peer-to-peer blockchain-based decentralization with a smart contract-based execution model and verifiable off-chain computations leveraging zero-knowledge proofs promise to provide the basis for next-generation, non-disclosing credential management solutions. In this paper, we propose a novel credential on-chaining system that ensures blockchain-based transparency while preserving pseudonymity. We present a general model compliant to the W3C verifiable credential recommendation and demonstrate how it can be applied to solve existing problems that require computational identity-related attribute verification. Our zkSNARKs-based reference implementation and evaluation show that, compared to related approaches based on, e.g., CL-signatures, our approach provides significant performance advantages and more flexible proof mechanisms, underpinning our vision of increasingly decentralized, transparent, and trustworthy service systems.