Collaborative learning techniques allow numerous clients conjointly to improve artificial intelligence models using their private datasets. The clients carry out the training locally and periodically exchanging gradient values through devices. Unlike conventional training approaches, the training data in the collaborative techniques are not revealed publicly. Regardless of privacy merits, clients are often less motivated to improve the model due to inadequate incentives procedural. In short, the resources owned are not maximally utilized. To tackle the issue, we design a collaborative learning model with a secure, fair, and immutable incentive mechanism by leveraging blockchain technology. Incentives are distributed proportionately to clients according to their respective contributions. We implement our incentive schemes on Ethereum. We also evaluate the performance of collaborative learning in a different setting. The results indicate that the design objectives are met.
Sangwon Hong, Yoongdoo Noh, Jeyoung Hwang, Chanik Park
Business is innovating with the advent of blockchain that tokenizes digital assets. To expand the blockchain's potential, Ethereum, a representative permissionless blockchain platform, supports the fungible token (FT) standard ERC-20 and the nonfungible token (NFT) standard ERC-721. Hyperledger Fabric (Fabric), a representative permissioned blockchain platform, proposed FabToken to support tokens in version 2.0.0 alpha. But FabToken contains only FTs, not NFTs. Given the market share in the enterprise blockchains, Fabric needs to support NFTs as soon as possible. This paper presents a unique digital asset management system called FabAsset so that Fabric can run decentralized applications that require NFTs. This paper describes the design of FabAsset, consisting of chaincode and SDK (Software Development Kit), and the prototype of a decentralized signature service leveraging FabAsset to validate its usefulness.
Blockchain is a service operated by a peer-to-peer type distributed network, and protocol control such as JSON-RPC is implemented as the interface for flexibility and operability. However, attacks that use protocol control against vulnerable and unmanaged interfaces have been reported. One of the methods to track cyber attacks on such a malicious user's network service is a honeypot that imitates the service and acquires attacker's behavior information. In this research, focusing on the Ethereum network, the behavior of malicious users is clarified using malicious communication history sent to simple honeypots installed in nine countries, Ethereum network information and darknet arrival packets. By analyzing these, the behavior of attackers and the tendency of requests were elucidated, and primary safety measures were established.
Abstract The purpose of this research is to identify how effective the determinants of the improved price changes in cryptocurrencies are and if they are predictable. The study addresses several independent variables that are in our consideration which may impact the prices the most. To obtain the results, panel data has been used to run fixed effects models. Then we treated them as time series data to run dynamic trend indicator and first-differencing volatility regression model. Important political shocks and instabilities have been analyzed and interpreted in this paper. In the light of our findings we were able to comment on the complex relation between cryptocurrency prices and socio-political situations throughout the time range. The results address that cryptocurrency price changes are predictable. It is easy to say that major stakeholders (Apple, Amazon, Facebook, Google, Tesla) affect the most prices. Internet search trends seem to have an impact but at the end it has been found that the correlation is strong. We have evaluated all the major cryptocurrency prices with exact accuracy of 95.38% using the volatility regression model effectively. All the cryptocurrencies are evaluated against US dollars in regard of different cryptocurrency like Bitcoin, Ethereum, Litecoin and Ripple digital currency. Cryptocurrencies shouldn’t be seen as a gambling medium and should be taken more seriously like an investment medium. In some specific occasions investing in cryptocurrencies may lead lucrative income.
Over the last years, research activities on blockchain technologies have fairly increased. Firstly introduced with Bitcoin, some projects have since emerged to create or improve blockchain features like privacy while others propose to overcome technical limitations such as scalability and energy consumption. New proposals are often evaluated with ad hoc tools and experimental environments. Reproducibility and comparison of these new contributions with the state of the art of the blockchain technologies are therefore complicated. To the best of our knowledge, only a few tools partially address the design of a generic benchmarking of blockchain technologies (e.g., load generation). In this paper, we introduce BCTMark, a generic framework for benchmarking blockchain technologies on an emulated network in a reproducible way. To illustrate the portability of experiments using BCTMark, we have conducted some experiments on two different testbeds: a cluster of Dell PowerEdge R630 servers (Grid'5000) and one of Raspberry Pi 3+. Experiments have been conducted on three different blockchain systems (Ethereum Clique/Ethash and Hyperledger Fabric) to measure their CPU consumption and energy footprint for different numbers of clients.
As one of the leading blockchain systems in operation, Ethereum has numerous smart contracts deployed to implement a variety of functions. Unfortunately, speculators introduce scams such as Ponzi scheme in the traditional financial sector into some of these smart contracts, causing millions of dollars of losses to investors. At present, there are a few of quantitative identification methods for new fraud modes under the background of Internet finance, and detection methods for the Ponzi scheme contracts on Ethereum are even less. In this paper, we propose an improved convolutional neural network as a detection model for Ponzi schemes in smart contracts. We use real smart contracts to evaluate the feasibility and usefulness of our mode. Results show that our improved convolutional neural network can overcome difficulties in training caused by different length of smart contracts' bytecodes. Compared with the state-of-the-art methods, the precision and recall rate of our model for Ponzi scheme detection are improved by 3.2% and 24.8% respectively.
Abstract Electronic payments is something that is currently in high demand by investors today, but transactions are often constrained due to various problems, especially from third parties. For this reason, cryptocurrency emerged, which is one of the solutions for conducting electronic payment transactions. Some types of cryptocurrency that are most in demand by investors are bitcoin, ethereum, and ripple. The fluctuation value of cryptocurrency is very difficult to predict so that investors often experience losses when making transactions. This study aims to predict cryptocurrency prices such as bitcoin, ethereum and ripple using data mining algorithms. The data mining algorithm used in this prediction process is K-NN, Neural Network, SVM, Linear Regression, Random Forest and Decision Tree. Data mining modeling is done by dividing the dataset into each type of commodity and then analyzed using each algorithm. The results of this study indicate that the accuracy value obtained from some data mining algorithms is good enough to predict cryptocurrency prices
Christos Profentzas, Magnus Almgren, Olaf Landsiedel
With the rise of the Internet of Things (IoT), billions of devices ranging from simple sensors to smart-phones will participate in billions of micropayments. However, current centralized solutions are unable to handle a massive number of micropayments from untrusted devices. Blockchains are promising technologies suitable for solving some of these challenges. Particularly, permissionless blockchains such as Ethereum and Bitcoin have drawn the attention of the research community. However, the increasingly large-scale deployments of blockchain reveal some of their scalability limitations. Prominent proposals to scale the payment system include off-chain protocols such as payment channels. However, the leading proposals assume powerful nodes with an always-on connection and frequent synchronization. These assumptions require in practice significant communication, memory, and computation capacity, whereas IoT devices face substantial constraints in these areas. Existing approaches also do not capture the logic and process of IoT, where applications need to process locally collected sensor data to allow for full use of IoT micro-payments. In this paper, we present TinyEVM, a novel system to generate and execute off-chain smart contracts based on sensor data. TinyEVM's goal is to enable IoT devices to perform micro-payments and, at the same time, address the device constraints. We investigate the trade-offs of executing smart contracts on low-power IoT devices using TinyEVM. We test our system with 7,000 publicly verified smart contracts, where TinyEVM achieves to deploy 93% of them without any modification. Finally, we evaluate the execution of off-chain smart contracts in terms of run-time performance, energy, and memory requirements on IoT devices. Notably, we find that low-power devices can deploy a smart contract in 215 ms on average, and they can complete an off-chain payment in 584 ms on average.
Smart contracts on the Ethereum blockchain are notoriously known as vulnerable to external attacks. Many of their issues led to a considerably large financial loss as they resulted from broken payments by digital assets, e.g., cryptocurrency. Existing research focused on specific patterns to find such problems, e.g., reentrancy bug, nondeterministic recipient etc., yet may lead to false alarms or miss important issues. To mitigate these limitations, we designed the SafePay analysis framework to find unfair payments in Ethereum smart contracts. Compared to existing analyzers, SafePay can detect potential blockchain transactions with feasible exploits thus effectively avoid false reports. Specifically, the detection is driven by a systematic search for violations on fair value exchange (FVE), i.e., a new security invariant introduced in SafePay to indicate that each party “fairly” pays to others. The preliminary evaluation validated the efficacy of SafePay by reporting previously unknown issues and decreasing the number of false alarms.
Smart contracts on the Ethereum blockchain can be utilized as secure places to store cryptocurrency if they are designed carefully. However, while cryptocurrency is kept in smart contracts, such as being paid to a blockchain service, no extra profit is generated. The time value of cryptocurrency serves only as collateral, which is an issue of capital inefficiency. Therefore, we propose to maximize the time value of cryptocurrency in smart contracts by supplying it to decentralized money markets of Compound to earn supply interest. Furthermore, by utilizing the interest generated, we can mitigate the liquidity risk of Compound and thus do not diminish the flexibility of the original service much. Experiments are conducted to testify the proposed method, and the implementation cost is estimated to be 2.1 US dollars. We also discuss the potential systemic risk in the decentralized finance system.
Biometric authentication is the preferred authentication scheme in modern computing systems. While it offers enhanced usability, it also requires cautious handling of sensitive users' biometric templates. In this paper, a distributed scheme that eliminates the requirement for a central node that holds users' biometric templates is presented. This is replaced by an Ethereum/IPFS combination to which the templates of the users are stored in a homomorphically encrypted form. The scheme enables the biometric authentication of the users by any third party service, while the actual biometric templates of the user never leave his device in non encrypted form. Secure authentication of users in enabled, while sensitive biometric data are not exposed to anyone. Experiments show that the scheme can be applied as an authentication mechanism with minimal time overhead.
2 source records
User Authentication and Security Systems
Biometric Identification and Security
Advanced Steganography and Watermarking Techniques
The traditional loyalty systems usually offer people benefits in a specific sector. The users usually need to stay within the loyalty system for a long time and accumulate points in order to win rewards which may not be very interesting for them most of the time. Additionally, users usually do not prefer to share their personal information to join these loyalty systems due to privacy concerns. It has, therefore, been observed that the number of customers in the loyalty systems is decreasing day by day. To reduce these drawbacks a loyalty program which complies with ERC20 standards was proposed in this study using tokens based on the Ethereum blockchain. Using this new generation loyalty system, users can convert their earned tokens to Ether in the market and they can receive services or products with the accumulated tokens according to their interests from any supplier that has been contracted by the manufacturer. Additionally, users in the designed system do not need to carry many different cards, it is adequate to have only one Ethereum wallet. Furthermore, users do not need to share any personal data to join the loyalty system. Suppliers can also request Ether from the manufacturer for the tokens they have accumulated from the members of the loyalty system. The proposed loyalty system has been implemented and presented in this study.
Yuichiro Chinen, Naoto Yanai, Jason Paul Cruz, Shingo Okamura
Ethereum smart contracts are programs that are deployed and executed in a consensus-based blockchain managed by a peer-to-peer network. Several re-entrancy attacks that aim to steal Ether, the cryptocurrency used in Ethereum, stored in deployed smart contracts were found in the recent years. A countermeasure to such attacks is based on dynamic analysis that executes the smart contracts themselves, but it requires the spending of Ether and knowledge of attack patterns for analysis in advance. In this paper, we present a static analysis tool named RA (Re-entrancy Analyzer), a combination of symbolic execution and equivalence checking by a satisfiability modulo theories solver to analyze smart contract vulnerabilities against re-entrancy attacks. In contrast to existing tools, RA supports analysis of inter-contract behaviors by using only the Ethereum Virtual Machine bytecodes of target smart contracts, i.e., even without prior knowledge of attack patterns and without spending Ether. Furthermore, RA can verify existence of vulnerabilities against re-entrancy attacks without execution of smart contracts and it does not provide false positives and false negatives. We also present an implementation of RA to evaluate its performance in analyzing the vulnerability of deployed smart contracts against re-entrancy attacks and show that RA can precisely determine which smart contracts are vulnerable.
Philipp Frauenthaler, Marten Sigwart, Christof Spanring, Michael Sober · 5 authors
Current blockchain relay schemes require the immediate validation of each relayed block header by the destination blockchain. This leads to high operating cost when deploying these relays between Ethereum-based blockchains where validating block headers on-chain is computationally expensive.To overcome these limitations, we introduce a novel relay scheme that employs a validation-on-demand pattern combined with economic incentives to reduce the cost of operating a relay between Ethereum-based blockchains by up to 92%. With this relay scheme, decentralized interoperability between blockchains like Ethereum and Ethereum Classic becomes feasible.
Kevin Wittek, Dominik Krakau, Neslihan Wittek, James H. Lawton · 5 authors
Proof of Existence as a blockchain service has first been published in 2013 as a public notary service on the Bitcoin network and can be used to verify the existence of a particular file in a specific point of time without sharing the file or its content itself. This service is also available on the Ethereum based bloxberg network, a decentralized research infrastructure that is governed, operated and developed by an international consortium of research facilities. Since it is desirable to integrate the creation of this proof tightly into the research workflow, namely the acquisition and processing of research data, we show a simple to integrate MATLAB extension based solution with the concept being applicable to other programming languages and environments as well.
Di Huang, Chenyu Zhang, Qiang Li, Huachun Han · 7 authors
As a new data structure, blockchain has the characteristics of decentralization, high security and information disclosure, which integrates and innovates a variety of computer technologies. Virtual power plant (VPP) is able to increase the operational flexibility of the energy resources and plays an important role in the aggregation of distributed generation resources. For the problem of scheduling difficulty and low transaction efficiency of VPP, this paper proposes a VPP transaction mechanism based on blockchain, which considers the stability on matching supply and demand and priority of renewables. The consortium blockchain is used to allow qualified users to participate in the energy transaction. A market trading platform for VPP based on peer-to-peer (P2P) network in the environment of Ethereum is designed. The incentive mechanism is added to improve the transaction efficiency and the transaction process of VPPis simulated. It shows that the blockchain-based VPP trading mechanism has excellent economy and traceability.
Land Registration is a use case which involves lot of middlemen and central authorities in the process which then puts trust in the system. Keeping traces of who owns which part of land is challenging when there are hundreds or thousands of land records to maintain. Using Blockchain will remove the middlemen in the system and also will reduce corruption and increase speed of the process. Land Registration is a simple decentralized application which is build using the Ethereum Blockchain principals. We can use this registration procedure as an substitute to bypass the existing system flaws. Here the user who owns the land registers his land details and also enters market value of the land by providing all the necessary proofs. A government authority who traditionally looks into land registry is assigned as a super admin can do the registration process. Lands coming under a particular village can be registered to the system only through the super admin who is assigned to that village. The smart contract used here is written in such a way that the owner has to transfer his property completely to the buyer and no transaction of the land can be partial. Even we allow a government authority is involved in registration process, the entire process is transparent and the transaction happens only between the two clients.
A popular method in practice offloads computation and storage in blockchains by relying on committing only hashes of off-chain data into the blockchain. This mechanism is acknowledged to be vulnerable to a stalling attack: the blocks corresponding to the committed hashes may be unavailable at any honest node. The straightforward solution of broadcasting all blocks to the entire network sidesteps this data availability attack, but it is not scalable. In this paper, we propose ACeD, a scalable solution to this data availability problem with $O(1)$ communication efficiency, the first to the best of our knowledge. The key innovation is a new protocol that requires each of the $N$ nodes to receive only $O(1/N)$ of the block, such that the data is guaranteed to be available in a distributed manner in the network. Our solution creatively integrates coding-theoretic designs inside of Merkle tree commitments to guarantee efficient and tamper-proof reconstruction; this solution is distinct from Asynchronous Verifiable Information Dispersal (in guaranteeing efficient proofs of malformed coding) and Coded Merkle Tree (which only provides guarantees for random corruption as opposed to our guarantees for worst-case corruption). We implement ACeD with full functionality in 6000 lines of Rust code, integrate the functionality as a smart contract into Ethereum via a high-performance implementation demonstrating up to 10,000 transactions per second in throughput and 6000x reduction in gas cost on the Ethereum testnet Kovan.
In this paper, we discuss the behavior of stock market returns in Tunisia during the COVID-19 outbreak. Using the OLS regression, we find that Bitcoin act as a hedge and Ethereum as a diversifier for Tunisia’s stock market before the COVID-19 outbreak; however, Bitcoin and Ethereum cannot generate benefits from portfolio diversification and hedging strategies for financial investors during the COVID-19. Moreover, Dash, Monero, and Ripple act as hedges before the COVID-19 outbreak and as diversifiers during this pandemic. Our results reveal that gold acts as a hedge and diversifier before the pandemic, but it's neither hedge nor a haven during the COVID-19 pandemic. Besides, the results indicated that the expected volatility of the US stock market has an impact on the Tunisian stock market. Finally, our results indicate that the growth rate of the COVID-19 confirmed cases and deaths harms Tunisia's stock market.
Karl Wüst, Siniša Matetić, Silvan Egli, Kari Kostiainen · 5 authors
Smart contracts are programmable, decentralized and transparent financial applications. Because smart contract platforms typically support Turing-complete programming languages, such systems are often said to enable arbitrary applications. However, the current permissionless smart contract systems impose heavy restrictions on the types of computations that can be implemented. For example, the globally-replicated and sequential execution model of Ethereum requires low gas limits that make many computations infeasible.
Suhani Jattan, Vineeth Kumar, R Akhilesh, Rachith R Naik · 5 authors
In today's world, more importance is given on the availability of the applications and various websites available in the digital market. People will manage their daily work on time, precisely, very fast, and with satisfaction. So various technologies are used to fulfil daily work. In India, there is no direct and efficient way of communication between the government and the public, for solving a problem i.e for getting a problem solved at any place, people may have to wait for three months, but it can probably be solved sooner. Nowadays, the scenario has changed. Many applications are available, which allow users to register their complaints. But there are some problems related to its transparency. This paper proposes an Ethereum blockchain application that will help people to register their complaints and get updates about the complaint. Adoption of blockchain technology makes the application more secure, transparent and immutable.
Pooja Sancheti, Meeradevi Meeradevi, Monica R. Mundada
The current agricultural supply chain is a centralized system that has many issues related to integrity, tracking, organizing the transactions. There is lack of trust and transparency in the supply chain. There are many irregularities in the implementation of schemes. The consumers doubt the quality of the food supplied to them. The farmers, wholesalers are affected from the payment frauds by the middlemen. Blockchain helps us solve these issues by keeping track of all the different stages of food. The public blockchain being transparent, open, immutable, trackable helps in reducing the irregularities, frauds. This paper proposes the agricultural supply chain system model that uses the Ethereum platform. The smart contracts are developed for different stages of the supply chain. These contracts ensure that all the pre-decided conditions are satisfied before proceeding with the transactions. This system ensures security, reliability, trust, openness. It eases the transactions, administrative processes. It gives a fair chance to farmers to quote a price using smart contracts.