The rise of programmable open distributed consensus platforms based on the blockchain technology has aroused a lot of interest in replicated stateful computations, aka smart contracts. As blockchains are used predominantly in financial applications, smart contracts frequently manage millions of dollars worth of virtual coins. Since smart contracts cannot be updated once deployed, the ability to reason about their correctness becomes a critical task. Yet, the de facto implementation standard, pioneered by the Ethereum platform, dictates smart contracts to be deployed in a low-level language, which renders independent audit and formal verification of deployed code infeasible in practice. We report an ongoing experiment held with an industrial blockchain vendor on designing, evaluating, and deploying Scilla, a new programming language for safe smart contracts. Scilla is positioned as an intermediate-level language, suitable to serve as a compilation target and also as an independent programming framework. Taking System F as a foundational calculus, Scilla offers strong safety guarantees by means of type soundness. It provides a clean separation between pure computational, state-manipulating, and communication aspects of smart contracts, avoiding many known pitfalls due to execution in a byzantine environment. We describe the motivation, design principles, and semantics of Scilla, and we report on Scilla use cases provided by the developer community. Finally, we present a framework for lightweight verification of Scilla programs, and showcase it with two domain-specific analyses on a suite of real-world use cases.
The microgrid trading market can effectively solve the problem of in-situ consumption of distributed energy and reduce the impact of distributed generation (DG) on the grid. However, the traditional microgrid trading model has some shortcomings, such as high operation cost and poor security. Therefore, in this paper, a microgrid market trading model was developed using consortium blockchain technology and Nash game equilibrium theory. Firstly, blockchain container is used to authenticate the users who want to participate in the transaction. Then, the pricing system collects and integrates transaction requests submitted by users, then formulates transaction pricing strategy of microgrid using Nash equilibrium theory. Finally, the price, trading volume, and user information are submitted to the blockchain container for transaction matching to achieve the transaction. After the transaction is completed, its related information is recorded in the hyperledger and the dispatch system is called. The scene simulation was implemented on Fabric 1.1 platform and the results analyzed. Results show that the trading model proposed in this paper greatly reduces the cost of electricity purchase and improves the benefits of electricity sales. Besides, the model is far more capable of handling transactions than the models based on Bitcoin and Ethereum.
This paper presents a system architecture to promote the development of smart transportation systems. Thanks to the use of distributed ledgers and related technologies, it is possible to create, store and share data generated by users through their sensors, while moving. In particular, IOTA and IPFS are used to store and certify data (and their related metadata) coming from sensors or by the users themselves. Ethereum is exploited as the smart contract platform that coordinates the data sharing and provisioning. The necessary privacy guarantees are provided by the usage of Zero Knowledge Proof. We show some results obtained from some use case scenarios that demonstrate how such technologies can be integrated to build novel smart services and to promote social good in user mobility.
The out-of-gas error occurs when smart contract programs are provided with inputs that cause excessive gas consumption, and would be easily exploited to make the DoS attack. Multiple approaches have been proposed to estimate the gas limit of a function in smart contracts to avoid such error. However, under estimation often happens when the contract is complicated. In this work, we propose V-Gas, which could automatically generate inputs that maximizes the gas cost and reduce the under estimation cases. V-Gas is designed based on feedback-directed mutational fuzz testing. First, V-Gas builds the gas weighted control flow graph (CFG) of functions in smart contracts. Then, V-Gas develops gas consumption guided selection and mutation strategies to generate the input that maximize the gas consumption. For evaluation, we implement V-Gas based on js-evm, a widely used ethereum virtual machine written in javascript, and conduct experiments on 736 real-world transactions recorded on Ethereum. 44.02\% of the transactions would have out-of-gas errors under the estimation results given by solc, means that the recorded real gas consumption for those recorded transactions is larger than the gas limit value estimated by solc. While V-Gas could reduce the under estimation ratio to 13.86\%. Furthermore, V-Gas has exposed 25 previously unknown out-of-gas vulnerabilities in those widely-used smart contracts, 5 of which have been assigned unique CVE identifiers in the US National Vulnerability Database.
Out-of-gas errors occur when smart contract programs are provided with inputs that cause excessive gas consumption and which will be easily exploited to perform Denial-of-Service attacks. Various approaches have been proposed to estimate the gas limit of a function in smart contracts to avoid such error. However, underestimation often occurs when the contract is complex In this work, we propose V-Gas, which automatically generates inputs that maximize the gas cost and reduce underestimation. V-Gas is designed based on static analysis and feedback-directed mutational fuzz testing. First, V-Gas builds the gas weighted control flow graph of functions in smart contracts. Then, V-Gas develops gas consumption guided selection and mutation strategies to generate the input that maximize the gas consumption. For evaluation, we implement V-Gas based on js-evm, a widely used Ethereum virtual machine written in Javascript, and conduct experiments on 736 real-world transactions recorded on Ethereum. A total of 44.02% of the transactions would have out-of-gas errors based on the estimation results given by solc, meaning that the recorded real gas consumption for those transactions is larger than the gas limit estimated by solc. In comparison, V-Gas could reduce the underestimation ratio to 13.86%. To evaluate the performance of feedback-directed engine in V-Gas, we implemented other directed fuzzing engines and compared their performance with that of V-Gas. The results showed that V-Gas generates the same or higher gas estimation value on 97.8% of the transactions with less time, usually within 5 minutes. Furthermore, V-Gas has exposed 25 previously unknown out-of-gas vulnerabilities in widely used smart contracts, 6 of which have been assigned unique CVE identifiers in the U.S. National Vulnerability Database.
Ramiro Daniel Camino, Christof Ferreira Torres, Mathis Baden, Radu State
Ethereum smart contracts have recently drawn a considerable amount of attention from the media, the financial industry and academia. With the increase in popularity, malicious users found new opportunities to profit by deceiving newcomers. Consequently, attackers started luring other attackers into contracts that seem to have exploitable flaws, but that actually contain a complex hidden trap that in the end benefits the contract creator. In the blockchain community, these contracts are known as honeypots. A recent study presented a tool called HONEYBADGER that uses symbolic execution to detect honeypots by analyzing contract bytecode. In this paper, we present a data science detection approach based foremost on the contract transaction behavior. We create a partition of all the possible cases of fund movements between the contract creator, the contract, the transaction sender and other participants. To this end, we add transaction aggregated features, such as the number of transactions and the corresponding mean value and other contract features, for example compilation information and source code length. We find that all aforementioned categories of features contain useful information for the detection of honeypots. Moreover, our approach allows us to detect new, previously undetected honeypots of already known techniques. We furthermore employ our method to test the detection of unknown honeypot techniques by sequentially removing one technique from the training set. We show that our method is capable of discovering the removed honeypot techniques. Finally, we discovered two new techniques that were previously not known.
Tien Tuan Anh Dinh, Anwitaman Datta, Beng Chin Ooi
Research in blockchain systems has mainly focused on improving security and bridging the performance gaps between blockchains and databases. Despite many promising results, we observe a worrying trend that the blockchain landscape is fragmented in which many systems exist in silos. Apart from a handful of general-purpose blockchains, such as Ethereum or Hyperledger Fabric, there are hundreds of others designed for specific applications and typically do not talk to each other. In this paper, we describe our vision of interoperable blockchains. We argue that supporting interaction among different blockchains requires overcoming challenges that go beyond data standardization. The underlying problem is to allow smart contracts running in different blockchains to communicate. We discuss three open problems: access control, general cross-chain transactions, and cross-chain communication. We describe partial solutions to some of these problems in the literature. Finally, we propose a novel design to overcome these challenges.
Abstract Although the logistics management has been improving, the information management is still stagnant. The renewal mechanism of logistics information is the basic requirement of logistics system, but it is more important to solve the trust problem of logistics information. It is good for improving the logistics management to design a verifiable information management mechanism which can help relevant participants establish trust relationships. This paper analyzes the development status of block chain technology, then a decentralized and self-verifiable system management program model is designed. Finally, the application is implemented based on the intelligent contract design of Ethereum block chain.
Οι υπηρεσίες ονοματοδοσίας παρέχουν τα απαραίτητα θεμέλια για την ανάπτυξη ποικίλων και σημαντικών εφαρμογών, όπως το ηλεκτρονικό εμπόριο και η ηλεκτρονική τραπεζική. Επί του παρόντος, αυτές οι υπηρεσίες ονοματοδοσίας βρίσκονται υπό τον έλεγχο κεντρικοποιημένων οντοτήτων, τις οποίες πρέπει να εμπιστευόμαστε ότι λειτουργούν σωστά. Δυστυχώς, η κεντρικοποίηση (εμπιστοσύνης) επιφέρει πολλά μειονεκτήματα όσον αφορά την ασφάλεια, τη διαθεσιμότητα και την ανοχή σφαλμάτων,όπως φαίνεται από μία πληθώρα περιστατικών ασφάλειας κατά τη διάρκεια των ετών όπου τέτοιες οντότητες έχουν παραβιαστεί. Η αποκέντρωση έχει προταθεί ως εναλλακτική λύση για την αντιμετώπιση αυτών των ζητημάτων. Παρ 'όλα αυτά,η αποκέντρωση εγείρει άλλα προβλήματα όπως, π.χ., η αντιμετώπιση της μη ανταποδοτικότητας και οι Σιβυλλικές επιθέσεις. Σε αυτή τη διατριβή, αξιοποιούμε την επεκτασιμότητα, την ασφάλεια, καθώς και τον ενσωματωμένο μηχανισμό παροχής κινήτρων των συστημάτων blockchain και προτείνουμε τον σχεδιασμό μιας αποκεντρωμένης υπηρεσίας ονοματοδοσίας βασισμένη σε έξυπνα συμβόλαια. Πιο συγκεκριμένα, είμαστε οι πρώτοι που παρουσιάζουμε τον πλήρη φορμαλισμό του προβλήματος σχεδιασμού υπηρεσιών ονοματοδοσίας στο πλαίσιο τoυ μοντέλου Γενικής Σύνθεσης και αποδεικνύουμε την ασφάλεια της κατασκευής μας υπό την ισχυρή υπόθεση RSA στο μοντέλο του Τυχαίου Μαντείου και την ύπαρξη μιας ιδεατής λειτουργικότητας έξυπνου συμβολαίου.Το κύριο εμπόδιο στην πραγματοποίηση μιας υπηρεσίας ονοματοδοσίας βασισμένη σε έξυπνα συμβόλαια είναι το μέγεθος της αποθηκευμένης πληροφορίας σε αυτά η οποία,όντας η πιο δαπανηρή πηγή πρόσβασης και τροποποίησης, θα πρέπει να ελαχιστοποιηθεί για να θεωρηθεί μια κατασκευή βιώσιμη. Επιλύουμε αυτό το ζήτημα ορίζοντας και χρησιμοποιώντας στην υπηρεσία ονοματοδοσίας μας έναν προσθετικό, παγκόσμιο κρυπτογραφικό συσσωρευτή δημόσιας κατάστασης σταθερού μεγέθους, ένα κρυπτογραφικό εργαλείο το οποίο μπορεί να είναι ανεξάρτητου ενδιαφέροντος στο πλαίσιο των πρωτοκόλλων blockchain. Αυτός ο συσσωρευτής προκαλεί αποθήκευση σταθερού μεγέθους πληροφορίας εις βάρος υπολογιστικής πολυπλοκότητας. Για να διερευνήσουμε το αντίκτυπο ανάμεσα σε αυτά τα δύο,προτείνουμε και υλοποιούμε μια δεύτερη κατασκευή, η οποία διατηρεί τις ιδιότητες ασφαλείας της πρώτης και, όπως απεικονίζεται μέσα από την αξιολόγησή μας, είναι η μόνη έκδοση με σταθερού μεγέθους αποθηκευμένη πληροφορία που μπορεί να αναπτυχθεί στη βασική αλυσίδα τουEthereum, της πιο αξιοσημείωτης δημόσιας πλατφόρμας έξυπνων συμβολαίων κατά τη στιγμή αυτής της γραφής. Συγκρίνουμε αυτές τις δύο κατασκευές με την απλή προσέγγιση των περισσότερων προηγούμενων υλοποιήσεων, π.χ., του EthereumName Service, όπου όλα τα αρχεία ταυτότητας αποθηκεύονται πάνω στο έξυπνο συμβόλαιο, για να καταδείξουμε αρκετές ελλείψεις του Ethereumκαι του μοντέλου κοστολόγησής του. Για την αντιμετώπιση αυτών των ζητημάτων, καθώς και άλλων,εισαγάγουμε ένα εναλλακτικό παράδειγμα για την ανάπτυξη εφαρμογών βασισμένες σε έξυπνα συμβόλαια στις οποίες το μέθεγος της αποθηκευμένης πληροφορίας σε αυτά είναι σταθερή και διευκολύνει την επαλήθευση των δεδομένων των εφαρμογών, τα οποία αποθηκεύονται σε και αναζητούνται από ένα εξωτερικό, δυνητικά αναξιόπιστο, δίκτυο αποθήκευσης. Αυτή η προσέγγιση είναι σχετική για ένα ευρύ φάσμα εφαρμογών, όπως κάθε σύστημα αποθήκευσης κλειδιών και τιμών.Δείχνουμε την αποτελεσματικότητα της προσέγγιση μας με την παρουσίαση μιας μελέτης όπου προσαρμόζουμε το πιο ευρέως αναπτυγμένο πρότυπο για ανταλλάξιμα νομίσματα, δηλ., το πρότυπο νομισμάτων ERC20.Αντιμετωπίζουμε τη μονοτονικά αυξανόμενη αποθηκευμένη πληροφορία του Ethereum η οποία, αν δεν ελεγχθεί, θα έχει άμεσο αντίκτυπο στην ασφάλεια του Ethereum και, τελικά, στη μακροζωία του. Εισαγάγουμε επαναλαμβανόμενα τέλη που είναι ανάλογα με την αποθηκευμένη πληροφορία στα έξυπνα συμβόλαια και ρυθμιζόμενα από τους κόμβους που διατηρούν το δίκτυο. Προτείνουμε ένα μοντέλο όπου το κόστος των λειτουργιών αποθήκευσης αντικατοπτρίζει την προσπάθεια που πρέπει να καταβάλουν οι κόμβοι για να τις εκτελέσουν. Δείχνουμε ότι κάτω από ένα τέτοιο σύστημα τιμολόγησης που ενθαρρύνει οικονομία στην αποθηκευμένη πληροφορία στα έξυπνα συμβόλαια, οι κατασκευές που παρουσιάζονται σε αυτή τη διατριβή μειώνουν τα τέλη συναλλαγών κατά μία τάξη μεγέθους. Υποστηρίζουμε ότι αυτές οι βελτιώσεις είναι λογικές για κάθε πλατφόρμα έξυπνων συμβολαίων που επιθυμεί να υποστηρίζει την ανάπτυξη αυθαίρετων κατανεμημένων εφαρμογών από τους χρήστες της.
Denis Rangelov, Nikolay Tcholtchev, Philipp Lämmel, Ina Schieferdecker
In recent years the emergence of the Ethereum Blockchain has introduced a new alternative perspective on how web applications can be build. More precisely, the Ethereum Blockchain allows the development of applications, where programming code can be executed in a decentralized manner with no restrictions imposed by a central authority. However, as it is the case with many emerging technologies, there is a fair amount of trade-offs that have to be considered when this technology is used as a platform for implementing decentralized applications. In this work we present two architectural designs for building decentralized applications (DApps) based on the Ethereum Blockchain technology. Within this context, we discuss the inherent strengths and weaknesses of each of the architectural designs as well as the set of challenges that we faced during the development process.
Sina Rafati Niya, Sebastian Allemann, Arik Gabay, Burkhard Stiller
Data leaks and privacy scandals have been a growing concern of the last decade. While most traditional, i.e., centralized, online platforms require users to register with their personal data, they potentially expose the user's identity and data to be used for unintended purposes. This work proposes TradeMap as an integrated architecture, designing and enabling an online end-to-end (e2e) trading market place, while supporting anonymous management features. TradeMap addresses the Swiss Financial Market Supervisory Authority (FINMA) regulations by designing a FINMA-complaint Know Your Customer (KYC) platform. Additionally, TradeMap is based on blockchains and employs Ethereum Smart Contracts (SC). Thus, trust and anonymity between the market place and the KYC system relies on zero knowledge proof-based SCs used for user identification processes. With this management approach proposed, the user authentication is only verified within the KYC platform, providing a legally valid and fully anonymous online trading platform.
Electronic Health Records (EHRs) have improved many aspects of healthcare and allowed for easier patient management for medical providers. Blockchains have been proposed as a promising solution for supporting Electronic Health Records (EHRs), but have also been linked to scalability concerns about supporting real-world healthcare systems. This paper quantifies the scalability issues and bottlenecks related to current blockchains and puts into perspective the limitations blockchains have with supporting healthcare systems. Particularly we show that well known blockchains such as Bitcoin, Ethereum, and IOTA cannot support transactions of a large scale hospital system such as the University of Kentucky HealthCare system and leave over 7.5M unsealed transactions per day. We then discuss how bottlenecks of blockchains can be relieved with sidechains, enabling well-known blockchains to support even larger hospital systems of over 30M transactions per day. We then introduce the Patient-Healthchain architecture to provide future direction on how scaling blockchains for EHR systems with sidechains can be achieved.
Eder J. Scheid, Timo Hegnauer, Bruno Rodrigues, Burkhard Stiller
The blockchain (BC) world is rapidly becoming a universe of several ledgers designed for a specific purpose, holding data previously stored (i.e., siloed) in centralized databases. The use of different BCs for the same purpose could hamper the frictionless exchange of data or value. On one hand, it is natural that there are competing implementations exploring the benefits of BC. On the other hand, the problem of siloed data re-emerges, with respect to isolated chains. In this regard, BC interoperability is necessary to connect different BCs, exchanging information and assets. Moreover, to foster BC employment, developers must be able to interact with such different BCs without knowing the details of each implementation. This paper presents a novel solution, called Bifröst, to store and retrieve data on different BCs. Bifröst employs a notary scheme, which allows for connectivity to different BCs. The presented prototype is highly modular and currently implements seven adapters to popular BC implementations, including Bitcoin, Ethereum, and Stellar. The developed prototype was evaluated concerning performance, security, and data size to verify the feasibility of such an implementation and assess design decisions taken during its development.
The widespread recognition of the smart contracts has established their importance in the landscape of next generation blockchain technology. However, writing a correct smart contract is notoriously difficult. Moreover, once a state-changing transaction is confirmed by the network, the result is immutable. For this reason, it is crucial to perform a thorough testing of a smart contract application before its deployment. This paper's focus is on the test coverage criteria for smart contracts, which are objective rules that measure test quality. We analyze the unique characteristics of the Ethereum smart contract program model as compared to the conventional program model. To capture essential control flow behaviors of smart contracts, we propose the notions of whole transaction basis path set and bounded transaction interaction. The former is a limited set of linearly independent inter-procedural paths from which the potentially infinite paths of Ethereum transactions can be constructed by linear combination, while the latter is the permutations of transactions within a certain bound. Based on these two notions, we define a family of path-based test coverage criteria. Algorithms are given to the generation of coverage requirements. A case study is conducted to compare the effectiveness of the proposed test coverage criteria with random testing and statement coverage testing.
Block-chain is rapidly evolving. There are continuous enhancements. In order to validate transactions algorithm is used. The traditional approach of Proof of Work (POW) is where miners are incentivized to compete with each other to complete transactions. Alternate system is proof of stake (POS) where in the validators lock up some of their tokens and thus replace the role of miners. Generation three block chain, which are the latest and fastest ones are mostly Proof of Stake (POS). Hence the POW systems seek to leverage the POS properties in order to attain higher speed and scalability. The paper discusses the approach with Ethereum has taken to migrate from the current POW protocol to POS protocol. The concept of Caster is focused as implementation. Casper further has two subtypes of approaches know as Friendly Finality Gadget (FFG) and Correct by Construction (CBC). The paper discusses on safety guard over these algorithms.
We have created a demonstration permissioned Distributed Ledger Technology (DLT) datastore for the UF<sub>6</sub> cylinder tracking safeguards use-case utilizing the Ethereum DLT framework and using Solidity for smart contract code. Our demonstration creates a simulated dataset representing tracking of 75,000 UF<sub>6</sub> cylinders across 11 example nuclear facilities worldwide. Our DLT system allows for easy input and reading of shipping and receiving data, including a Graphical User Interface (GUI). Sandia’s Emulytics capability was leveraged to help create the DLT node network and assess performance. We find that our DLT prototype can easily handle to ~150,000 UF<sub>6</sub> cylinder shipments per year worldwide, without any excessive computational or storage burden on the IAEA or Member States. Next steps could include a demonstration to the IAEA and potentially demonstrating integration with TradeLens, a DLT in use by a consortium of international shipping companies representing over half of world shipping trade.
William Zhang, Sebastian Banescu, Leonardo Pasos, Steven Stewart · 5 authors
Smart contracts are executable programs that enable the building of a programmable trust mechanism between multiple entities without the need of a trusted third-party. At the time of this writing, there were over 10 million smart contracts deployed on the Ethereum networks and this number continues to grow at a rapid pace. Smart contracts are often written in a Turing-complete programming language called Solidity, which is not easy to audit for subtle errors. Further, since smart contracts are immutable, errors have led to attacks resulting in losses of cryptocurrency worth 100s of millions of USD and reputational damage. Unfortunately, manual security analyses do not scale with size and number of smart contracts. Automated and scalable mechanisms are essential if smart contracts are to gain mainstream acceptance. Researchers have developed several security scanners in the past couple of years. However, many of these analyzer either do not scale well, or if they do, produce many false positives. This issue is exacerbated when bugs are triggered only after a series of interactions with the functions of the contract-under-test. A depth-n vulnerability, refers to a vulnerability that requires invoking a specific sequence of n functions to trigger. Depth-n vulnerabilities are time-consuming to detect by existing automated analyzers, because of the combinatorial explosion of sequences of functions that could be executed on smart contracts. In this paper, we present a technique to analyze depth-n vulnerabilities in an efficient and scalable way by combining symbolic execution and data dependency analysis. A significant advantage of combining symbolic with static analysis is that it scales much better than symbolic alone and does not have the problem of false positive that static analysis tools typically have. We have implemented our technique in a tool called MPro, a scalable and automated smart contract analyzer based on the existing symbolic analysis tool Mythril-Classic and the static analysis tool Slither. We analyzed 100 randomly chosen smart contracts on MPro and our evaluation shows that MPro is about n-times faster than Mythril-Classic for detecting depth-n vulnerabilities, while preserving all the detection capabilities of Mythril-Classic.
The term “smart contracts” has become ubiquitous to describe an enormous number of programs uploaded to the popular Ethereum blockchain system. Despite rapid growth of the smart contract ecosystem, errors and exploitations have been constantly reported from online contract systems, which has put financial stability at risk with losses totaling millions of US dollars. Most existing research focuses on pinpointing specific types of vulnerabilities using known patterns. However, due to the lack of awareness of the inherent nondeterminism in the Ethereum blockchain system and how it affects the funds transfer of smart contracts, there can be unknown vulnerabilities that may be exploited by attackers to access numerous online smart contracts. \n \nIn this paper, we introduce a methodical approach to understanding the inherent nondeterminism in the Ethereum blockchain system and its (unwanted) influence on contract payments. We show that our new focus on nondeterminism-related smart contract payment bugs captures the root causes of many common vulnerabilities without relying on any known patterns and also encompasses recently disclosed issues that are not handled by existing research. To do so, we introduce techniques to systematically model components in the contract execution context and to expose various nondeterministic factors that are not yet fully understood. We further study how these nondeterministic factors impact contract funds transfer using information flow tracking. The technical challenge of detecting nondeterministic payments lies in discovering the contract global variables subtly affected by read-write hazards because of unpredictable transaction scheduling and external callee behavior. We show how to augment and instrument a contract program into a representation that simulates the execution of a large subset of the contract behavior. The instrumented code is then analyzed to flag nondeterministic global variables using off-the-shelf model checkers. \n \nWe implement the proposed techniques as a practical tool named NPChecker (Nondeterministic Payment Checker) and evaluate it on 30K online contracts (3,075 distinct) collected from the Ethereum mainnet. NPChecker has successfully detected nondeterministic payments in 1,111 online contracts with reasonable cost. Further investigation reports high precision of NPChecker (only four false positives in a manual study of 50 contracts). We also show that NPChecker unveils contracts vulnerable to recently-disclosed attack vectors. NPChecker can identify all six new vulnerabilities or variants of common smart contract vulnerabilities that are missed by existing research relying on a “contract vulnerability checklist.”
The fake certificate is a special global problem in today's digital age. Thousands of universities and educational institutions around the world do not exist but can release hundreds of millions of fake degrees. Verifying the integrity of qualifications is a real challenge for today's employers. Applying the anti-data modifying properties of blockchain technology, this study proposes a solution issuing and verifying digital certificates called EUniCert to solve this problem. By changing the design and integrating new consensus algorithm used in Ethereum platform into the Unicoin network that was used to verify and store the information related to the issued digital certificate, the EUniCert improves the latency to validate transactions as well as the number of verified blocks in the blockchain network compared to the previous solution that we have proposed. We implement a simple blockchain system to illustrate the management operation of the digital certificates on the ethereum platform. Besides, we conduct a simulation to evaluate the performance of our proposal compared with the previous system. The result is that the average latency decreases by 3.27 times as well as the number of verified blocks increases by 11% compared with the previous system.
With the advancement of digitization, digital ecosystems are playing an increasingly important role in value creation. The mechanism by which digital ecosystems create value, however, has been generally deemed to be a mixed effect due to various factors. On the basis of signaling theory, this paper explores the effect of information transmission on the value creation capability of a digital ecosystem from two dimensions: the scale and sustainability of value creation. Taking a sample of weekly transaction data from Ethereum during August 2015–August 2018, our research proposes an integrated framework of information transmission in value creating, and discusses the diffusion process of the network effect within the digital ecosystem. As a generally accepted exchange medium, digital currency traffic acts as an observable proxy of information flow in a crypto-digital ecosystem, where the effects of heterogeneity in transaction attributes are filtered. Empirical results show that information transmission positively influences the scale and sustainability of value creation activities in a digital ecosystem by affecting user number and transaction frequency. Further research reveals that user number is the initial driving force of the network effect and a critical factor for the overall ecosystem market capitalization. This research provides a new insight into the design of sustainable value creation mechanisms under digital circumstances.
Daniel Cerecedo Hernández, Carlos Armando Franco Ruiz, Mario Iván Contreras-Valdez, Jovan Axel Franco Ruiz
El objetivo de esta investigación es analizar la presencia de burbujas financieras o un comportamiento explosivo en cuatro criptomonedas: Ethereum, Ripple, Bitcoin Cash y EOS. La selección de los activos se basó en la capitalización de mercado. La metodología implementada fue una prueba simple y generalizada (SADF y GSADF) de una variación de la prueba aumentada de Dickey-Fuller propuesta por Phillips et al. (2011, 2015). Encontramos diez, siete, seis y siete comportamientos exuberantes en los activos mencionados, respectivamente. Esta metodología ha sido en gran parte inexplorada y podría emplearse de manera estándar en el sector financiero para cualquier otro activo. Esta es la primera investigación que detecta este tipo de comportamiento para un grupo de criptomonedas con frecuencia diaria. Con el presente trabajo y el artículo de Li et al. (2018), el 68,47% del mercado ha sido analizado bajo la metodología. En consecuencia, este comportamiento podría estar disperso en todo el sector.
Public blockchains like Ethereum use Merkle trees to verify transactions received from untrusted servers before applying them to the blockchain. We empirically show that the low throughput of such blockchains is due to the I/O bottleneck associated with using Merkle trees for processing transactions. We present RAINBLOCK, a new architecture for public blockchains that increases throughput without affecting security. RAINBLOCK achieves this by tackling the I/O bottleneck on two fronts: first, decoupling transaction processing from I/O, and removing I/O from the critical path; second, reducing I/O amplification by customizing storage for blockchains. RAINBLOCK uses a novel variant of the Merkle tree, the Distributed Sharded Merkle tree (DSM-TREE) to store system state. We evaluate RAINBLOCK using workloads based on public Ethereum traces (including smart contracts) and show that RAINBLOCK processes 20K transactions per second in a geo-distributed setting with four regions spread across three continents.
Ethereum is a blockchain platform that hosts and executes general-purpose computer programs known as smart contracts. Users execute smart contracts by sending transactions to one of the functions of the contract. The execution of smart contracts in Ethereum has a cost that is measured in Gas unit. Executing a function of a smart contract burns a certain amount of gas units (a.k.a., gas usage). The total gas usage depends on how much computing power is necessary to carry out the execution of the function. Ethereum follows a free-market policy for deciding the transaction fee for executing a transaction. More specifically, users choose how much they are willing to pay in cryptocurrency for each unit of gas (a.k.a., gas price). Miners process transactions to gain mining rewards, which come directly from the paid transaction fees by users. However, neither the user nor the miner know, beforehand, the gas usage of a transaction. In this thesis, we analyze the Ethereum transaction data spanning between Oct. 2017 and Feb. 2019 (the Byzantium period) to conduct two studies that examine how gas usage and price impact the transaction processing dynamics of the Ethereum blockchain platform. \n \nIn our first study, we examine the strategies that are adopted by miners to prioritize transactions, the stability of the gas usage of contract functions, and whether the gas usage of a contract transaction can be predicted within a reasonable margin. We observe that most miners follow the default strategy for prioritizing transactions (which solely relies on gas price), a significant amount of contract functions have a very stable gas usage history, and it is possible to provide a real-time estimation of the gas usage of a transaction for these contracts with a median Adjusted RSquared of 0.86. \n \nIn the second study, we focus on understanding gas prices. We analyze how users commonly set gas prices and whether the contracts that are involved in user-to-contract transactions influence gas prices. Subsequently, we build a regression model to discover the factors that are strongly associated with the gas price of transactions. We observe that the gas prices set by users assume a wide range of values, vary considerably over time, and change based on the user. We also observe that the gas price of user-to-contract transactions differ significantly across contracts and functions. Lastly, we observe that different factors are more strongly associated with gas prices at different times. \n \nOur findings can help researchers to focus on the vulnerabilities of the current gas mechanism in their future work, provide developers insights on how to improve their decentralized applications (DApps) regarding transactions, motivate users to make an informed decision when issuing a transaction, and help miners to adopt optimized mining strategy.
Distributed Ledger Technology (DLT) is a shared, synchronized and replicated data spread spatially and temporally with no centralized administration and/or storage. Each node has a complete and identical set of records. All participants contribute to building and maintaining the distributed ledger. Current DLT technologies fall into two broad categories. Those that use block-chains such as in Bitcoin or Ethereum, and newer approaches which reduce computational loads for verification. All current approaches though difficult to crack can be vulnerable to quantum algorithms using Quantum Information Technologies (QIT). This effort joins the 2 technologies, constructing a Quantum Distributed Ledger (QDL) which provides a higher level of security using QIT and a decentralized data depository using DLT. This enhanced security prevents middleman attacks with quantum computers yet retains the advantages of a decentralized ledger of data.