Smart contracts are pieces of code that reside inside the blockchains and can be triggered to execute any transaction when specifically predefined conditions are satisfied. Being commonly used for commercial transactions in blockchain makes the security of smart contracts particularly important. Over the last few years, we have seen a great deal of academic and practical interest in detecting and fixing the bugs in smart contracts written by Solidity. But little is known about the real bug fixes in Solidity smart contract projects. To understand the bug fixes and enrich the knowledge of bug fixes in real-world projects, we conduct an empirical study on historical bug fixes from 46 real-world Solidity smart contract projects in this paper. We provide a multi-faceted discussion and mainly explore the following four questions: File Type and Amount, Fix Complexity, Bug distribution, and Fix Patches. We distill four findings during the process to explore these four questions. Finally, based on these findings, we provide actionable implications to improve the current approaches to fixing bugs in Solidity smart contracts from three aspects: Automatic repair techniques, Analysis tools, and Solidity developers.
Leonhard Balduf, Martin Florian, Björn Scheuermann
We explore issues relating to the storage of digital art, based on an empirical investigation into the storage of audiovisual data referenced by non-fungible tokens (NFTs). We identify current trends in NFT data storage and highlight problems with implemented solutions. We particularly focus our investigation on the use of the Interplanetary Filesystem (IPFS), which emerges as a popular and versatile distributed storage solution for NFTs. Based on the analysis of discovered data storage techniques, we propose a set of best practices to ensure long-term storage survivability of NFT data. While helpful for forming the NFT art market into a legitimate long-term environment for digital art, our recommendations are also directly applicable for improving the availability and integrity of non-NFT digital art.
Open access
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Advanced Data Storage Technologies
Digital and Traditional Archives Management
Advanced Steganography and Watermarking Techniques
Blockchain is the technology to secure transaction by connected ledgers. Non Fungible Token (NFT) transactions are getting popular daily from 2021 and it generates new economy world. The transactions of NFTs are stored in the blockchain but the contents of NFTs are not stored if the contents are so big amount of volume, because of higher transaction gas fee. We propose long term storage node system architecture named Sustainable Generation Manager (SGM) which is using hash based file system on storage node on blockchain to maintain these contents of data of NFTs. This paper shows the architecture, parameters and implementation of SGM on our original voting blockchain.
The purpose of this paper is to present a prototype of a platform for data exchange that integrates blockchain and distributed file system technologies. The development phases are defined, an architecture and topology design is suggested, and the main functionalities of the prototype are implemented. Also presented are experiments and results on prototype’s performance and resource usage evaluation. The presented prototype’s functionalities enable upload/download files operations, a monetization protocol, digital rights management for some file formats, testing the performance with different file sizes, testing the decentralized operation mode, performance and resource usage evaluation and activity log reporting. Presented are results of 800 test experiments for the blockchain and distributed file system networks performance, the prototype functionality verification and the estimation of resource usage.
The growth in information and communication technology has led to phenomenons in the financial sector as well. This primarily alludes to the introduction of cryptocurrencies, a decentralised medium of exchange, which provides an alternative to the centuries-old idea of physical money. There is a visible relationship between the principles of behavioural finance and the value/returns that these cryptocurrencies have. These currencies are not dependent on the behaviour of the financial markets and economy but instead on the supply and demand of the currency along with its popularity which is dependent purely on the individuals.
Jongho Seol, Jinfu Ke, Shital Joshi, N. Park · 5 authors
This paper proposes a quantitative model to assess the performance of a NFT (Non-Fungible Token)-centered chain as referred to as a NFT Chain in this paper. NFT chain in general stores its data distributed across on chain (e.g. NFT registration data and an address pointing at the data located off chain such as meta data table and ultimate digital asset's data) due to the high cost to store the potentially high volume of data for digital assets. Therefore, it is expected that the overall performance of NFT chain is primarily to be dominated and bound by the off-chain performance. The proposed performance model employing an embedded Markovian queueing process model, tracks a bivariate state of the NFT chain such that$(i,j)$where$i$stochastically tracks the number of slots of the transactions executed on chain and$j$stochastically tracks the number of transactions off chain as well, and the states transition as determined by$\lambda_{on}, \lambda_{off}, \mu$, and the number of slots in the current block. Extensive numerical simulations are performed to validate the efficacy of the model. The primary set of variables used in the simulations consists of$\lambda_{on}, \lambda_{off}, \mu$and the average number of slots of the transactions during a block posting,$L$, is simulated based on both$L_{on}$and$L_{off}$; and the average waiting time$W$based on both$W_{on}$and$W_{off}$, in an intermingled manner in order to take into account of the nature of NFT transactions executed across on- and off-chain without loss of generality. The simulation results demonstrate a good agreement with the expected and intuitive trends and the proposed NFT chain performance model serves as a sound theoretical foundation for the design of an NFT chain from the system's perspective.
A fundamental issue in blockchain systems is their scalability in terms of data storage, computation, communication, and security. To resolve this issue, a promising research direction is coding theory, which is widely used for distributed storage, recovery from erasures or channel errors and/or to reduce communication cost. To this end, this article provides the first comprehensive survey of approaches that employ coding theory to scale blockchain systems. It shows how the use of coded symbols or shards allow participants to only store a fraction of the total blockchain, protect against malicious nodes or erasures, ensure data availability in order to promote transparency, and scale the security of sharded blockchains. Further, coded symbols help reduce communication cost when disseminating blocks, which help bootstrap new nodes and speed up consensus of blocks. For each category of solutions, we highlight problems and issues that motivated their designs and use of coding. Moreover, we provide a qualitative analysis of their storage, communication, and computation costs.
Recent years have witnessed growing consolidation of web operations. For example, the majority of web traffic now originates from a few organizations, and even micro-websites often choose to host on large pre-existing cloud infrastructures. In response to this, the "Decentralized Web" attempts to distribute ownership and operation of web services more evenly. This paper describes the design and implementation of the largest and most widely used Decentralized Web platform --- the InterPlanetary File System (IPFS) --- an open-source, content-addressable peer-to-peer network that provides distributed data storage and delivery. IPFS has millions of daily content retrievals and already underpins dozens of third-party applications. This paper evaluates the performance of IPFS by introducing a set of measurement methodologies that allow us to uncover the characteristics of peers in the IPFS network. We reveal presence in more than 2700 Autonomous Systems and 152 countries, the majority of which operate outside large central cloud providers like Amazon or Azure. We further evaluate IPFS performance, showing that both publication and retrieval delays are acceptable for a wide range of use cases. Finally, we share our datasets, experiences and lessons learned.
I’m going to talk from an artist’s perspective about “Art and NFTs—Past and Future.” There are a lot of surprising details in the short history of non-fungible tokens (NFTs) and some pretty interesting ideas that are ready to unfold in the future. As an artist, the work I’ve done has always been media-based, including video, software, and related forms. Not so long ago, I was making video artworks, akin to short, experimental, independent films. Along with my partner, Jennifer McCoy, I have produced “net art”—art made for viewing and audience participation on the Internet. Since all of the work that I—along with my friends and other artists in the community—made was digital and intangible, there was very little way to participate in the art market. There were no tangible works that could be made and sold. A digital media-based artwork could circulate in non-commercial contexts such as art or film festivals or museum curations, but rarely could it participate in the traditional art market like a painting could. For example, in 2001, the Whitney Museum of American Art acquired a JavaScript-based project of ours called 201—A Text Algorithm. A code-based piece can enter the museum, but it is usually through donations and commissions rather than sales. That was the experience for my friends and me for a long time. Working with an intangible form are always on the sidelines of the greater visual arts community. As a result, I—along with many other artists—adopted a strategy of physicalization: you make your work sculptural and turn your media ideas into objects. We made physical media sculptures that were met with success. In 2001, the Metropolitan Museum of Art purchased an early work of ours Every Shot, Every Episode, which was recently part of the exhibition Pictures Revisited. Although Every Shot, Every Episode is a media art piece, it is exhibited sculpturally in the form of a small, wall-mounted suitcase. In other projects, we created sculptures that included video and kinetics, such as miniature film sets made with small cameras. One of these is in the Museum of Modern Art (MoMA) collection and another was purchased by the Grand Duke Jean Museum of Modern Art (MUDAM) in Luxembourg. Although the projects contain software and media, their embodiment as physical objects allows them to be displayed and collected in traditional ways. This was the course of my practice in the early 2000s. To be sure, I used the transition from digital to physical not only as a way to participate in the art market but also for artistic and aesthetic reasons. This choice certainly allowed my works to be collected and, as a result, a broader conversation about who was buying and supporting new media art began. It was an exciting time. But there lingered a real question about how one might make and sell work that is natively digital.
Aisyah Ismail, Mark Toohey, Young Choon Lee, Zhongli Dong · 5 authors
Blockchain technology is an immutable append-only decentralized ledger that theoretically makes it an ideal data storage system. The nature of blockchain design ensures stored data is reliable, trustworthy, and transparent. However, the blockchain's full-replication feature makes it ineffective to store a large volume of data directly on-chain. This paper provides a systematic review and analysis of existing decentralized file systems. Our focus was on systems that can support large, high-frequency data writing while still providing swift and easy data retrieval for blockchain-based applications. The challenge, in our view, is to find ways to achieve those efficiency outcomes while still retaining the key decentralized features of blockchain design. With that in mind, we assessed the costs involved in using nine state-of-the-art decentralized file systems and we also considered their latency performance.
Jesper Kristensen, Juan P. Madrigal-Cianci, Giorgos Felekis, Maria Liatsikou
In the scientific and commercial worlds, predicting cryptocurrency prices over time has gotten a lot of interest. Most related studies use variations of Recurrent Neural Networks to forecast the next value of a single coin due to the temporal nature of the challenge. As a result, determining how effectively such a model would perform across various tasks (cryptocurrencies), several future timesteps, and forecasting horizons will be difficult. This paper proposes a multi-task and multi-step sequence-to-sequence model that is trained jointly on 22 cryptocurrencies' time series. Our findings show the value of sequence-to-sequence modeling for future predictions, as well as the significant improvements in accuracy and training time that can be achieved by using a single multi-task model rather than numerous distinct models for each task.
Blockchain received a vast amount of attention in recent years and is still growing. The second generation of blockchain, such as Ethereum, allows execution of almost any program in Ethereum Virtual Machine (EVM), making it a global protocol for distributed applications. The code deployment and each operation performed in EVM cost the network fee called gas, which price varies and can be significant. That is why code optimization and well-chosen algorithms are crucial in programming on the blockchain. This paper evaluates the gas usage of several exact pattern matching algorithms on the Ethereum Virtual Machine. We also propose an efficient implementation of the algorithms in the Solidity/YUL language. We evaluate the gas fees of all the algorithms for different parameters (such as pattern length, alphabet size, and text size). We show a significant gas fee and execution time reduction with up to 22-fold lower gas usage and 55-fold speed-up comparing to StringUtils (a popular Solidity string library).
Haoxian Chen, Gerald Whitters, Mohammad Javad Amiri, Yuepeng Wang · 5 authors
This paper presents DeCon, a declarative programming language for implementing smart contracts and specifying contract-level properties. Driven by the observation that smart contract operations and contract-level properties can be naturally expressed as relational constraints, DeCon models each smart contract as a set of relational tables that store transaction records. This relational representation of smart contracts enables convenient specification of contract properties, facilitates run-time monitoring of potential property violations, and brings clarity to contract debugging via data provenance. Specifically, a DeCon program consists of a set of declarative rules and violation query rules over the relational representation, describing the smart contract implementation and contract-level properties, respectively. We have developed a tool that can compile DeCon programs into executable Solidity programs, with instrumentation for run-time property monitoring. Our case studies demonstrate that DeCon can implement realistic smart contracts such as ERC20 and ERC721 digital tokens. Our evaluation results reveal the marginal overhead of DeCon compared to the open-source reference implementation, incurring 14% median gas overhead for execution, and another 16% median gas overhead for run-time verification.
Abstract Coin selection method refers to the process undergone when selecting a set of unspent transaction outputs (UTXOs) from a cryptocurrency wallet or account to use as inputs in each transaction. The most applied coin selection method that UTXO-based cryptocurrencies currently employ is an algorithm that decides on a certain set of UTXOs that matches the target amount and limits the transaction fee. However this approach trades off favourable maintenance overhead of the entire network for low transaction fees, as many low-value UTXOs known as “dust” is produced. Over time, this will impact the scalability and management of the cryptocurrency network as the global set of UTXOs become larger. Therefore, there is an urgency to find a higher-performing coin selection method suitable for UTXO-based cryptocurrencies. This paper proposes a method based on the greedy and genetic algorithm for effectively choosing sets of UTXOs in Bitcoin. The main objective of this coin selection strategy is to get as close as possible to the target while also maintaining and possibly reducing the number of UTXO inputs.
This perspective highlights some recent progress on the research of Byzantine fault tolerant (BFT) consensus protocol in the era of blockchains, including both partially synchronous BFT and asynchronous BFT protocols, their fundamental building blocks, and their variants.
Under the current national network environment, anyone can participate in publishing. As an important information resource, knowledge files reflect the workload of publishers. Moreover, high-quality knowledge files can promote the progress of society. However, pirated inferior files have the opposite effect. At present, most organizations use centralized servers to centrally manage the knowledge files released by users. In addition, it is necessary to introduce an untrusted third party to examine and encrypt the contents of files, which leads to an opaque process of file storage transactions, tampering with intellectual copyright, and the inability to have consistent systems of file management among institutions due to the lack of uniform standards for the same intellectual files. The purpose of this paper is to ensure the safe storage of knowledge files on the one hand and to realize efficient sharing of copyrighted files on the other hand. Therefore, this paper combines NDN (Named Data Network) technology with a distributed blockchain and an Interplanetary File System (IPFS) and proposes a blockchain knowledge file storage and sharing method based on an NDN. The method uses the NDN itself for the file content signature and encryption, thereby separating the file security and transmission process. At the same time, the method uses a flexible NDN reverse path forwarding and routing strategy, combining an IPFS private storage network to improve the safety of the encrypted data storage security. Finally, the method takes advantage of all participating nodes consensus and shares files in the synchronized blockchain to ensure traceability. This paper introduces the structure and principles of the method and describes the process of file upload and transfer. Finally, the performance of the method is compared and evaluated, and the advantages and disadvantages of the method and the future research direction are summarized.
Ilya Grishkov, Roland Kromes, Thanassis Giannetsos, Kaitai Liang
This paper offers a prototype of a Hyperledger Fabric-IPFS based network architecture including a smart contract based encryption scheme that meant to improve the security of user's data that is being uploaded to the distributed ledger. A new extension to the self-encryption scheme was deployed by integrating data owner's identity into the encryption process. Such integration allows to permanently preserve ownership of the original file and link it to the person/entity who originally uploaded it. Moreover, self-encryption provides strong security guarantees that decryption of a file is computationally not feasible under the condition that the encrypted file and the key are safely stored.
With the development of blockchain applications, the requirements for file storage in blockchain are increasing rapidly. Many protocols, including Filecoin, Arweave, and Sia, have been proposed to provide scalable decentralized file storage for blockchain applications. However, the reliability is not well promised by existing protocols. Inspired by the idea of insurance, we innovatively propose a decentralized file storage protocol in blockchain, named as FileInsurer, to achieve both scalability and reliability. While ensuring scalability by distributed storage, FileInsurer guarantees reliability by enhancing robustness and fully compensating for the file loss. Specifically, under mild conditions, we prove that no more than 0.1\% value of all files should be compensated even if half of the storage collapses. Therefore, only a relatively small deposit needs to be pledged by storage providers to cover the potential file loss. Because of lower burdens of deposit, storage providers have more incentives to participate in the storage network. FileInsurer can run in the top layer of the InterPlanetary File System (IPFS), and thus it can be directly applied in Web 3.0, Non-Fungible Tokens, and Metaverse.
Alexander Pfeiffer, Natalie Denk, Thomas Wernbacher, Stephen Bezzina · 6 authors
Non-Fungible Tokens (NFTa) can either represent an original digital artwork, or act as a digital reference to the actual work. In both as digital references to the actual work. In both cases the record in the distributed ledger, mostly a blockchain-based database, intends to serve as a proof of ownership or transfer of rights. NFTs might also add a further purpose, which in blockchain terms is referred to as “a utility", such as access to special websites, chats or clubs in emerging metaverse platforms. This use-case paper presents a first introduction of two early stage demonstrators, set outside the common use of art images or images of historical events as NFTs. The first case shows how educational credentials can be created, in which different teachers contribute to assessment achievements. We elaborate how these partial achievements are verified separately within the actual credentials. In the second case study, we build on previous research in regard to NFTs in the music industry and show the combination of physical vinyl record special editions, in our case vinyls signed by the band, and the ownership certificate as NFT. For both demonstrators we used, in different settings, the crypto art platform NFTmagic and the blockchain-token wallet Sigbro. We developed and tested the results within the setting of a roleplay as a group and show how blockchain technologies and especially NFTs can be made useful in new ways, inspired by the ongoing process of discovering risks and opportunities in ‘crypto art’, thus initiating discussion on the topic and effectively bridging the cybersecurity and (digital) art communities.
The embrace of cryptocurrencies by institutional investors is well underway. The futures market has already had a significant impact on this industry. Digital asset exposure may go up while the risk of loss is reduced by using derivatives. Decentralized finance and crypto-derivative trading are the focus of this article. We analyzed the function of a central clearing house (C.C.P.) and Exchange for Derivatives, especially Cryptocurrency derivatives. We mapped some critical attributes of DeFi (Decentralized Finance) to the concept of decentralized Exchange. In the light of this analysis, we reviewed an existing Cryptocurrency derivatives exchange that is trying to become a decentralized exchange. We studied dYdX, a major decentralized crypto-derivative exchange. We assessed its core purpose as a crypto-derivative exchange to investigate the positive aspects of the D.C.E. (Decentralized Crypto-derivative exchange). Decentralized crypto-derivative exchanges have considerable problems in terms of liquidity and market-making, and we determined that different incentive schemes by these exchanges have successfully overcome these issues. By linking additional trading nodes and boosting the trust of traders and investors, we believe these exchanges may be made more efficient.
Non-fungible tokens (NFTs) are transferrable rights to digital assets, such as images, videos, or music. The phenomenon and its markets have grown significantly since early 2021. The number of NFT marketplaces has been rising continuously since a couple of years. Majority of them employ centralized systems for storage of digital assets (files). This is contradictory to the notion of decentralized systems. In this project we propose a secure platform for trading digital assets in the form of Non-Fungible tokens. It will enable the users to create new digital assets and trade them in exchange of Ethereum-based cryptocurrency. Along with this, we aim to explore technical feasibility of a decentralized file system (using IPFS protocol) for storing the digital assets in a more secured way. In this way, we attempt to address the issue of file storage. Also, this project is an attempt to advocate the use of block chain technology.
One of the biggest challenges for decarbonizing the grid is allowing those parties with access to distributed energy resources to provide necessary energy and market participant information in a secure manner to support grid and market operations. Multiple entities, protocols, communication networks, and devices present significant challenges for market operators responsible for data governance such as confidentiality and data integrity. One approach is managing parties within and across networked microgrids with a Distribution System Operator (DSO) responsible for facilitating a transactive energy marketplace for their customers. An identity-based cybersecurity mesh fabric using a distributed ledger for delivering edge services was recently demonstrated to ensure data from two networked microgrids and a DSO could be shared across the various systems. A system that included a private blockchain for data governance and access control services needed for these secure interactions was designed and demonstrated. This paper highlights the overall microgrid data flows and data transactions along with the implementation considerations of cybersecurity controls across already installed assets, simulated microgrids, and smart buildings.
Jemin Andrew Choi, Sidi Mohamed Beillahi, Peilun Li, Andreas Veneris · 5 authors
We present the Layered Merkle Patricia Trie (LMPT), a performant storage data structure for processing transactions in high-throughput systems when com-pared to traditional Merkle Patricia Tries used in Ethereum clients. LMPTs keep smaller intermediary tries in memory to alleviate read and write amplification from high-latency disk storage. As an additional feat, they also allow for the I/O and transaction verifier threads to be scheduled in parallel and independently. LMPTs can ultimately reduce significant I/O traffic that happens on the critical path of transaction processing. Empirical results presented here confirm that LMPTs can process up to × 6 more transactions per second on real-life workloads when compared to existing Ethereum clients.