Blockchain Papers

Urban Vidovič, Vid Keršič, Muhamed Turkanović

No abstract is available for this record.

Martijn de Vos, Georgy Ishmaev, Johan Pouwelse

The popularity of blockchain technology has bootstrapped many “Web3” applications, e.g., Ethereum and IPFS, that apply distributed ledger technology to store transactions. The amount of transactions generated and stored in such Web3 applications is significant and, in its raw form, usually not searchable by users. Existing Web3 transaction indexing and search engines are predominantly centralized and, therefore, can manipulate search results or censor particular queries. With the proliferation of Web3 transactions and applications, a decentralized and censorship-resistant search primitive is becoming essential. We present DeScan, a decentralized and censorship-resistant indexing and search engine for Web3. Users index their local Web3 transactions using custom rules that output triplets. Generated triplets are bundled in a distributed transaction graph that is searchable by other users. To coordinate search and distribute the storage of the transaction graph over peers in the network, we build upon a Skip Graph (SG) data structure. Since the Skip Graph does not provide any resilience against adversarial peers that censor searches, we propose four modifications to improve its robustness. We implement DeScan and conduct experiments with up to 12 800 peers and 10 million Ethereum transactions. Our experiments show that DeScan with our modifications enabled can tolerate 20% adversarial peers and 35% unresponsive peers without disruption. Moreover, we find that searches in DeScan are usually completed well within a second, even when the network grows. Finally, we show that storage and network costs are evenly distributed amongst peers as the network grows.

Giulio Caldarelli

Before the advent of alternative blockchains such as Ethereum, the future of decentralization was all in the hands of Bitcoin. Together with Nakamoto itself, early developers were trying to leverage Bitcoin’s potential to decentralize traditionally centralized applications. However, because Bitcoin was a decentralized machine, the available non-trustless oracles were considered unsuitable. Therefore, strategies had to be elaborated to solve the so-called “oracle problem” in the newborn scenario. By interviewing early developers and crawling early forums and repositories, this paper aims to retrace and reconstruct the chain of events and contributions that gave birth to oracles on Bitcoin. The evolution of early protocols, along with the difficulties encountered in their development, are also outlined. Analyzing technical and social barriers to building oracles on Bitcoin, the transition to Ethereum will also be discussed.

Ayana T. Aspembitova, Michael A. Bentley

Decentralized finance (DeFi) is by far the most popular application of blockchain technology. Despite the wide acceptance of new financial instruments and services, there are still many unexplored areas in the field. We dedicate this research to the understanding of one of the most crucial limitations of decentralized finance-oracles. DeFi protocols, as well as other blockchain applications, function in a closed environment and regularly need to fetch real-world information (e.g., assets' prices)-the tool used for this purpose is called an oracle. We review the existing oracle types in DeFi applications and focus our research on the least explored one: when another protocol, typically a decentralized exchange, serves as a price oracle. After explaining the mechanisms behind the decentralized exchanges, we introduce an algorithmic model that allows one to safely design a decentralized oracle and adjust crucial parameters. We believe that understanding and implementing the logic presented in the model can help to reduce the chances of price manipulations attacks, which are the most frequent incident types in DeFi.

Keundug Park, Heung-Youl Youm

This paper proposes a solution to the transfer problem between blockchain-based heterogeneous cryptocurrencies and CBDCs, with research derived from an analysis of the existing literature. Interoperability between heterogeneous blockchains has been an obstacle to service diversity and user convenience. Many types of cryptocurrencies are currently trading on the market, and many countries are researching and testing central bank digital currencies (CBDCs). In this paper, existing interoperability studies and solutions between heterogeneous blockchains and differences from the proposed service model are described. To enhance digital financial services and improve user convenience, transfer between heterogeneous cryptocurrencies, transfer between heterogeneous CBDCs, and transfer between cryptocurrency and CBDC should be required. This paper proposes an interoperable architecture between heterogeneous blockchains, and a decentralized peer-to-peer (P2P) service model based on the interoperable architecture for transferring between blockchain-based heterogeneous cryptocurrencies and CBDCs. Security threats to the proposed service model are identified and security requirements to prevent the identified security threats are specified. The mentioned security threats and security requirements should be considered when implementing the proposed service model.

Morteza Alizadeh, Karl Andersson, Olov Schelén

User identification in decentralized systems is a demanding task. Identification systems should work resiliently and have efficient performance. Moreover, identification systems should protect the data that they must store against hackers and saboteurs. Keeping a system with decentralized identification without any intervention in the middle has attracted attention to improve earlier centralized identification systems. Decentralized Identifiers (DIDs) constitute a solution for identification divided into different modules. The verifiable data registry is one of the main parts of this technology, which is distributed storage of identity properties. We analyze the decentralized identification data registry and compare the performance of verifiable data registry based on blockchain and the Distributed Hash Table (DHT) on different scales of systems. Our evaluation results show that DHT has better performance. Furthermore, a model based on DHT shows that in addition to immutable storage and faster query time, it makes systems handle or search in data storage with lower searching time compared to Ethereum Blockchain as another immutable secure technology. Finally, our results show that DHT is a better solution than other models in different scenarios. Although blockchain has promising results on a small scale, it still has problems with storage and query time in large-scale systems.

J. D. Preece, Christopher J. Morris, John M. Easton

The System for Ticketing Ubiquity with Blockchains (STUB) is a novel solution to multi-modal transport ticketing. Introduced previously using Hyperledger Fabric, STUB utilises the distributed mechanics of blockchain technology right at the core of its architecture, allowing stakeholders from different transport modes to vend and validate tickets on a shared ledger. This open approach to ticketing data will benefit transport governing bodies, transport operators, and passengers alike by ensuring cross-party cooperation and presenting a fresh holistic approach to the ticketing sector. This paper addresses issues from STUB 1.0, concerning validating tickets for a multi-modal transport system. To overcome this, we propose creating a graph structure, known as the Transport Network Graph (TNG), to represent the transport network with all of the services provided by the Transport Service Providers (TSPs). This enables the implementation of an automated Revenue Allocation System (RAS), whilst retaining the benefits provided by blockchain technology.

Peiyun Zhang, Chenxi Li, MengChu Zhou, Wenjun Huang · 6 authors

No abstract is available for this record.

Mingyang Yuan, Yang Xu, Cheng Zhang, Yunlin Tan · 7 authors

The Internet of vehicles (IoV) has a substantial impact on traffic efficiency improvement and accidents avoidance. Due to restricted resources, vehicles must share observed data with RSUs and other vehicles to execute some time-tolerant computing tasks. However, data provided by vehicles cannot always be trusted due to the presence of attackers. Fake messages could have catastrophic ramifications, such as vehicle collisions. Furthermore, extensive data sharing might cause channel congestion, resulting in the loss of vital messages during delivery. To overcome the aforementioned issues, we propose TRUCON, a blockchain-based trusted data sharing mechanism with congestion control in IoV. Firstly, we propose a Kademlia algorithm-based traffic data forwarding method to control channel congestion state. By adjusting the bucket size and distance threshold, source vehicles can limit the number of reference vehicles forwarded. Secondly, we present a cuckoo filter-based traffic data deduplication and discrimination approach. To avoid repetitive sharing, vehicles and RSUs can check their local filters to verify if the current data report has been shared. Based on the foregoing, we propose a blockchain-based trust management mechanism with congestion control. RSUs serve as full nodes while vehicles are light nodes in the blockchain. Finally, we develop a trust management prototype system with congestion control that incorporates both on-chain and off-chain parts. It signifies that our scheme is both feasible and effective.

Pedro Ákos Costa, João Leitão, Yannis Psaras

Web3 aims at creating a decentralized platform that is competitive with modern cloud infrastructures that support today's Internet. However, Web3 is still limited, supporting only applications in the domains of content creation and sharing, decentralized financing, and decentralized communication. This is mainly due to the technologies supporting Web3: blockchain, IPFS, and libp2p, that although provide a good collection of tools to develop Web3 applications, are still limited in terms of design and performance. This motivates the need to better understand these technologies as to enable novel optimizations that can push Web3 to its full potential. Unfortunately, understanding the current behavior of a fully decentralized large-scale distributed system is a difficult task, as there is no centralized authority that has full knowledge of the system operation. To this end, in this paper we characterize the workload of IPFS, a key enabler of Web3. To achieve this, we have collected traces from accesses performed by users to one of the most popular IPFS gateways located in North America for a period of two weeks. Through the fine analysis of these traces, we gathered the amount of requests to the system, and found the providers of the requested content. With this data, we characterize both the popularity of requested and provided content, as well as their geo-location (by matching IP address with the MaxMind database). Our results show that most of the requests in IPFS are only to a few different content, that is provided by large portion of peers in the system. Furthermore, our analysis also shows that most requests are provided by the two largest portions of providers in the system, located in North America and Europe. With these insights, we conclude that the current IPFS architecture is sub-optimal and propose a research agenda for the future.

Guangsheng Yu, Qin Wang, Tingting Bi, Shiping Chen · 5 authors

Architectural design contexts contain a set of factors that greatly influence software application development. Among them, organizational design contexts consist of high-level company concerns and how it is structured, for example, stakeholders and development schedules heavily impacting design considerations. The Decentralized Autonomous Organization (DAO), as a vital concept in the Web3 space, represents an organization constructed by automatically executed rules, such as via smart contracts, holding features of the permissionless committee, transparent proposals, and fair contribution by participated stakeholders. In this work, we conduct a systematic literature review of existing DAO literature to summarize its structural features, benefits and challenges, and potential development directions in the context of Web3 applications.

Manoj Kamber, Prof. Divya Kumar Shah

Internet Banking offers clients the availability of dealing with one's assets whenever, anyplace. In any case, any web-based exchanges will be inclined to security dangers. Existing framework utilizes two way validation factors(OTP) that are handily broken by digital assailants prompting clients having their record subtleties compromised while not having the arrangement of aggressor's recognizable proof. Thus in this paper we propose a versatile SIM sequential based check framework to protect portable exchanges on cell phones with Blockchain based waiter side secure framework. The supporter character module(sim) chronic number is enlisted with the client's record and in the event that a gatecrasher attempts to start an exchange from some other sim, there emerges a befuddle of the login certifications then framework sends area data of the interloper to the bank. The bank then cautions the enrolled client via mailing them the interloper's subtleties. Since the versatile sim chronic number is remarkable to the sim and isn't physically rather separated, there is no chance of gatecrasher starting the exchange from another gadget, subsequently defeating the worries connected with OTP. The Ethereum Blockchain innovation gives server side information base security by checking the advanced marks during the exchange and agreement calculation for exchange affirmation. Blockchain based security is numerically demonstrated for secure financial exchange.

Fengyang Guo, Xun Xiao, Artur Hecker, Schahram Dustdar

IOTA blockchain is a new type of distributed ledger systems that is lightweight without mining and feeless-of-using. Rather than using a chain structure as in traditional blockchains, IOTA organizes ledger records with a directed acyclic graph (DAG), called Tangle. When message entries are committed into the ledger, the ledger tangle grows in a special way where multiple messages could be attached by different processing nodes in parallel. Such a unique evolution process motivates us to study the ledger tangle dynamics, which is unexplored so far. In this paper, we present the first generative modeling for IOTA tangle based on stochastic analysis. A key finding is that IOTA tangle renders a double Pareto Lognormal (dPLN) distribution, rather not typical network models (e.g., Power-Law and Exponential distributions). Quantitative comparisons show that the fitting quality of our model outperforms existing popular models on official real world datasets published by IOTA Foundation. Estimated model parameters are provided, which is immediately instrumental for a more realistic IOTA network generator design. The proposed generative model also provides a deeper understanding of the internal mechanics of IOTA network.

Soosan Naderi Mighan, Jelena Mišić, Vojislav B. Mišić

We provide a comprehensive analytical model for block distribution in the Ethereum distribution network. We begin with a model for node connectivity based on reported measurements' and model the distribution of blocks using a Jackson network together with a priority M/G/1 queuing system. Our results show that the probability distribution of block response time is close to exponential distribution, while block delivery time exhibits a hypo-exponential distribution. Both distributions exhibit a thicker tail than the exponential distribution due to the peculiarities of the gossip-like protocol used to propagate blocks and transactions in Ethereum.

Viet-Bang Pham, Tuan-Dat Trinh

Decentralized Finance (DeFi) – an ecosystem of financial applications built on top of blockchain technology – has kept powering ahead and attracted a large amount of capital in just a few years. As the core part of the DeFi ecosystem, decentralized lending protocols allow users to become lenders or borrowers in a completely decentralized fashion, such that an individual has complete control over their funds at all times. Collecting, analyzing, and visualizing lending data are crucial as these lending protocols are growing steadily. This paper presents an analysis model for decentralized lending protocols. Our main contributions are as follows. (i) We analyze and compare the top lending protocols; (ii) We present a general model to collect and process a large amount of data from multiple lending protocols in an exact and efficient manner; (iii) We design and implement a lending visualization system with various charts divided into three categories, i.e., lending market overview, token analysis, and user analysis.

Authors unavailable

Buyers have a lot of options these days with the rapid advent of modern centralized marketplaces which harness the internet as their main infrastructure. While convenience is provided in abundance, some major concerns with these platforms are the lack of data privacy, its power to obstruct vendors/merchants and the expenses for arbitrary reasons related with posting and selling of the items. In this work, the framework for an application is put forward by us, which benefits off of the Ethereum blockchain to address these issues. After the abstract is read by the user through the medium of a web interface, their input is sent to the Ethereum network using the web3.js API. Resolution of these security issues can be attempted by leveraging the blockchain technology and executing a DApp(Decentralized application) which will act as a virtual commercial centre wherein consumers will actually be able to trade digital resources or NFT's utilizing crypto tokens.

Raul Cristian Bag, Bruno Spilak, Julian Winkel, Wolfgang Karl Härdle

Living in the Information Age, the power of data and correct statistical analysis has never been more prevalent. Academics and practitioners require nowadays an accurate application of quantitative methods. Yet many branches are subject to a crisis of integrity, which is shown in an improper use of statistical models, $p$-hacking, HARKing, or failure to replicate results. We propose the use of a Peer-to-Peer (P2P) ecosystem based on a blockchain network, Quantinar (quantinar.com), to support quantitative analytics knowledge paired with code in the form of Quantlets (quantlet.com) or software snippets. The integration of blockchain technology makes Quantinar a decentralized autonomous organization (DAO) that ensures fully transparent and reproducible scientific research.

Alexander Kudzin, Kentaroh Toyoda, Satoshi Takayama, Atsushi Ishigame

(1) Background: To solve the blockchain scaling issue, sharding has been proposed; however, this approach has its own scaling issue: the cross-shard communication method. To resolve the cross-shard communication scaling issue, rollups have been proposed and are being investigated. However, they also have their own scaling limitations, in particular, the degree of compression they can apply to transactions (TXs) affecting how many TXs can be included in one block. (2) Methods: In this paper, we propose a series of novel data structures for the compiling of cross-shard TXs sent using rollups for both public and private Ethereum. Our proposal removes redundant fields, consolidates repeated fields, and compresses any remaining fields in the rollup, modifying its data structure to compress the address, gas, and value fields. (3) Results: We have shown that our proposals can accommodate more cross-shard TXs in a block by reducing the TX size by up to 65% and 97.6% compared to the state-of-the-art in public and private Ethereum, respectively. This compression in TX size results in an over 2× increase in transactions per block (TPB) for our proposals targeting both types of Ethereum. (4) Conclusions: Our proposals will mitigate the scaling issue in a sharded blockchain that utilizes rollups for cross-shard communication. In particular, it will enable such sharded Ethereum networks to be deployed for large-scale decentralized systems.

Łukasz Opioła, Kamil Jarosz, Łukasz Dutka, Renata Słota · 5 authors

Scientific and commercial endeavors could benefit from cross-organizational, decentralized collaboration, which becomes the key to innovation. This work addresses one of its challenges, namely efficient access control to assets for distributed data processing among autonomous data centers. We propose a group membership management framework dedicated for realizing access control in decentralized environments. Its novelty lies in a synergy of two concepts: a decentralized knowledge base and an incremental indexing scheme, both assuming a P2P architecture, where each peer retains autonomy and has full control over the choice of peers it cooperates with. The extent of exchanged information is reduced to the minimum required for user collaboration and assumes limited trust between peers. The indexing scheme is optimized for read-intensive scenarios by offering fast queries -- look-ups in precomputed indices. The index precomputation increases the complexity of update operations, but their performance is arguably sufficient for large organizations, as shown by conducted tests. We believe that our framework is a major contribution towards decentralized, cross-organizational collaboration.

Wuhui Chen, Xiaoyu Qiu, Zicong Hong, Zibin Zheng · 6 authors

Blockchain technology has gained popularity owing to the success of cryptocurrencies such as Bitcoin and Ethereum. Nonetheless, the scalability challenge largely limits its applications in many real-world scenarios. Off-chain payment channel networks (PCNs) have recently emerged as a promising solution by conducting payments through off-chain channels. However, the throughput of current PCNs does not yet meet the growing demands of large-scale systems because: 1) most PCN systems only focus on maximizing the instantaneous throughput while failing to consider network dynamics in a long-term perspective; 2) transactions are re-actively routed in PCNs, in which intermediate nodes only passively forward every incoming transaction. These limitations of existing PCNs inevitably lead to channel imbalance and the failure of routing subsequent transactions. To address these challenges, we propose a novel proactive look-ahead algorithm (PLAC) that controls transaction flows from a long-term perspective and proactively prevents channel imbalance. In particular, we first conduct a measurement study on two real-world PCNs to explore their characteristics in terms of transaction distribution and topology. On that basis, we propose PLAC based on deep reinforcement learning (DRL), which directly learns the system dynamics from historical interactions of PCNs and aims at maximizing the long-term throughput. Furthermore, we develop a novel graph convolutional network-based model for PLAC, which extracts the inter-dependency between PCN nodes to consequently boost the performance. Extensive evaluations on real-world datasets show that PLAC improves state-of-the-art PCN routing schemes w.r.t the long-term throughput from 6.6% to 34.9%.

Donald J. Patterson, Bill Tomlinson

The Proof-of-Work algorithm that underlies Bitcoin and many other cryptocurrencies is well known for its energy-intensive requirements. The Proof-of-Stake algorithm that underlies Ethereum2 and various other cryptocurrencies is less impactful environmentally, but it has a second, looming issue: the problem of wealth inequality. We have developed an alternative to Proof-of-Work and Proof-of-Stake, called Proof-by-Location, that has the potential to address both of these issues. This paper describes Proof-by-Location and a financial platform called Xylem that is based on it. This platform seeks to distribute transaction fees to billions of cryptocurrency "Notaries" around the world (essentially, anyone with a smartphone), who work together to establish a distributed consensus about financial transactions. Using Xylem as a global financial infrastructure could lead to significantly better social and environmental outcomes than existing financial platforms.

Matheus Leal, Flávia Pisani, Markus Endler

Movement tracking information can reveal much about the daily operation of companies. Several applications can benefit from recording the physical places a mobile entity visits and how long it stays at each position. This paper discusses the need for an Available, Reliable, Transparent, Immutable, and Irrevocable service for Mobility Records (ARTIIMoR). We present an approach to recording spatio-temporal presence information in a reliable, immutable, and scalable way using a multilayer Distributed Ledger Technology (DLT) architecture for storing location information in variable levels of abstraction and aggregation. We implemented this multilayer solution as a middleware service that uses Complex Event Processing on smartphones to efficiently record nearby place-specific beacons in a DLT. We compare the performance of inserting data in the IOTA, Ethereum, and Hyperledger DLTs, the impact that different data aggregation techniques have on insertion performance, and the effect of the multilayer approach on data query performance.

Barbara Guidi, Andrea Michienzi, Laura Ricci

Web3 is progressively decentralising Internet services with the introduction of the blockchain, from social networks to online trading. Filecoin is a Web3 storage marketplace implemented on top of the Interplanetary File System that aims at decentralising storage by rewarding users who pledge storage to the system. Clients form deals with storage miners, who store deals on the Filecoin blockchain for transparency and auditability. Storage miners can also obtain extra rewards when they mine a block. In this paper, we show that although Filecoin aims at complete decentralisation, the rewarding system acts as the opposite. We download a dataset composed of 47.5M messages and expose that most of the blocks are created by the same storage miners, who are also the ones that pledge more storage. An analysis of their identity shows that they belong to cloud companies, that have a lot of extra storage resources. The effect observed is due to the fact that storage miners are able to commit all extra storage to the system, even when there are no deals in them. Additionally, this effect is further intensified by recent updates to Filecoin, which let storage miners update committed storage to deal-containing storage effortlessly.

Kim Aksel Tahuil Borgen

Web3 represents an evolution of the centralized and siloed topology of Web2 by focusing on more connected, decentralized, and open technology to democratize data and services between databases, tools, devices, people, teams and organizations to provide secure single sources of truth on decentralized trust lay-ers. However, sensitive data, such as intellectual property, classified information, personal data, or medical records, cannot be distributed to those without explicit access. A standard solution is to encrypt the data before uploading and then distribute the decryption key to select persons. This solution does not sufficiently protect against data leakage. In addition, legal, contractual, and GDPR requirements are not met in current Web3 systems. This study suggests critical requirements for any Web3 system that targets sensitive data, private and permissioned needs, and enterprise and governmental applications. A preliminary framework is then introduced for building compliant Web3 systems to the suggested requirements. The study proposes changes to the Inter Planetary File System (IPFS) protocol, with the main change being that each request checks against a ledger if the requestor has access to the data. Two novel Ethereum smart contracts, Enterprise Architecture and Smart Legal Contract, are presented to meet the suggested requirements.