Blockchain (e.g., Bitcoin and Ethereum) has drawn much attention and has been widely-deployed in recent years. However, blockchain scalability is emerging as a challenging issue. This paper outlines the existing solutions to blockchain scalability, which can be classified into two categories: first layer and second layer solutions. First layer solutions propose modifications to the blockchain (i.e., changing the blockchain structure, such as block size) while second layer solutions propose mechanisms that are implemented outside of the blockchain. In particular, we focus on sharding as a promising first layer solution to the scalability issue; the basic idea behind sharding is to divide the blockchain network into multiple committees, each processing a separate set of transactions. More specifically, (a) we propose a taxonomy based on committee formation and intra-committee consensus; and (b) we compare the main existing sharding-based blockchain protocols. We also present a performance-based comparative analysis (i.e., throughput and latency), of the advantages, and disadvantages in existing scalability solutions.
The term decentralized finance (DeFi) refers to an alternative financial infrastructure built on top of the Ethereum blockchain. DeFi uses smart contracts to create protocols that replicate existing financial services in a more open, interoperable, and transparent way. This article highlights opportunities and potential risks of the DeFi ecosystem. I propose a multi-layered framework to analyze the implicit architecture and the various DeFi building blocks, including token standards, decentralized exchanges, decentralized debt markets, blockchain derivatives, and on-chain asset management protocols.
Günümüzde kripto para birimlerinin önemi gittikçe artmaktadır. Kripto para birimleri sanal oyun platformlarında kullanılırken, şu an pek çok kurum ve kuruluş tarafından ödeme aracı olarak kullanılmaktadır. Güvenlik risklerine karşı blockchain (Blok Zinciri) adı verilen algoritması ile üretimi sağlanmaktadır. Kripto para fiyatlarının doğru olarak tahmin edilmesi yatırımcı ve karar vericiler açısından büyük önem taşımaktadır. Bu çalışma kapsamında en çok kullanılan dört kripto para birimine (Bitcoin, Ethereum, Ripple, Litecoin) ait fiyat değerleri tahmin edilmiştir. Çoklu kırılma testinden yararlanılarak her seriye ait kırılmalar belirlenerek analiz genişletilmiştir. Ele alınan sanal para değerlerini doğru bir şekilde tahmin etmek amacıyla hem klasik zaman serisi modellerinden hem de üç farklı tür yapay sinir ağı modelinden faydalanılmıştır. Ayrıca elde edilen tahminler üzerinde basit birleştirilme teknikleri uygulanmıştır. Rassal yürüyüşün egemen olduğu bu seriler arasından, özellikle işlem hacmi ve bilinilirliği en fazla olan Bitcoin sanal parasında rassal yürüyüş modelinden daha iyi sonuçlar elde edildiği gözlemlenmiştir.
With the advent of IoT, gadgets are now becoming more smart and independent. Truth is that the transformation towards the innovation is in progress yet there are still flaws, mainly in security areas like dependence on the data. Keeping in mind the advancement of IoT in the future, trusting in this vast approaching data source is of great importance. Blockchain is reached up to the position where it became the key innovation that will change the way we share data. Providing trust in conveyed situations, without using any advanced technical team is a development, which could change the way of working of numerous enterprises, the IoT amongst them. We can say with confidence that the concept of Blockchain, which is the technology behind crypto currency [3] Bitcoin [1], introduced a new era in the world of Internet and online services. In this paper, we will talk about develop a secure E-voting system using Blockchain technology where nobody can manipulate the votes and every user can vote only once. This is possible using the advantage of Ethereum smart contracts [2]. Smart contracts make it a powerful tool for the digitization of services in the Ethereum platform. Blockchain with smart contracts develops a safe, cheap, secure and transparent E-voting system. Ethereum and its network are suitable for it. Due to its consistency, large scale use and provision of smart contract logic. E-voting is an application that is possible using Blockchain technology with infused smart contracts. It needs to be digitalized over the Internet & that's what we will be working upon.
The aim of this study is to examine cryptocurrencies that use blockchain technology, reveal the current situation and discuss the future. In the study, cryptocurrencies are examined in detail with their definition, history, legal status, factors affecting their value, features and functions, advantages and disadvantages, and usage areas. As a result of the discussions in the study, five main conclusions were reached. (1) Cryptocurrencies cannot be defined as money, since they cannot fully fulfil the features and functions of money with their current status. (2) Although the values of cryptocurrencies are shaped depending on the supply and demand conditions, they are significantly affected by factors such as security, legal status, volume, and speculative and manipulative initiatives. (3) Cryptocurrencies do not yet have a widespread legal status worldwide. (4) Among the many advantages and disadvantages of cryptocurrencies, the most prominent advantage is security, and the most striking disadvantage is volatility. (5) Cryptocurrencies, with what they have demonstrated to date and promise for the future, will have the ability to be used wherever money is used, and even more.
Smart contract-based development of decentralized applications is increasing with the development of blockchain technology. Although blockchainbased smart contracts are expected to revolutionize the digital economy, several security issues need to be addressed before this technology can be used reliably. The recent discovery of security weaknesses in Ethereum smart contracts questions the reliability of smart contracts. Therefore, there is a need to create and diagnose security weaknesses in Ethereum smart contracts to mitigate security risks. In this study, we assessed the potential security weaknesses of running smart contracts on Ethereum.
blockchain is decentralized immutable ledger technology maintaining integrity. So to conduct tamperproof election it’s one of the approach towards it. Smart contracts are Self executed code that is written on Ethereum platform in blockchain. An E-voting system should be completely secure and does not allow voting twice that is double spending in blockchain. So it should be completely transparent. In research work electronic voting application is implemented and tested using smart contract on Ethereum platform with the help of metamask wallet. The results of ballots and votes will be stored on Ethereum blockchain with the help of consensus algorithm proof of stake. This consensus is used in validating a transaction with concept of majority approval. Current electronic voting system requires a centralized authority to control the procedure from ballot input to result output and for monitoring of election. While blockchain technology provide decentralized system which is open across connected nodes. Blockchain assets provide increased level of system security from hacking and fraud. Every transaction in blockchain is time-stamped and signed digitally with the help of cryptographic algorithms, and it assigns unique hash value to every block so it can be trace easily. Blockchain technology is one of solutions because it embraces a decentralized system and the entire databases are owned by many users. The blockchain technology also has much vulnerability due to which many attacks like 51% attack, Double Spending attack, DDOS attack, Sybil attack, Eclipse attack and Routing attack can be performed on it.
Due to enormous increase in development of technology maintenance of user’s information has become major concern. However, user’s information has been effectively maintained by the third parties but the problems with the current system are cost has been increased for maintaining information, lack of transparency and fairness, overuse of power and nature of opaqueness in the current system. So distributed system/ledger i.e., Blockchain came into existence to solve the problems encountered with the current system. The advantages of the proposed distributed system are cost is negligible by eliminating the need of third parties, effectively enhancing the execution speed of transactions and facilitating its reconciliation, maintaining transparency thereby ensuring integrity of user’s information. In this paper, we introduce Ethereum based blockchain network for maintaining user’s information through smart contracts. Experimental results shows that how effectively user’s information has been maintained through blockchain based networks.
We present the main concepts, components, and usage of GASOL, a Gas AnalysiS and Optimization tooL for Ethereum smart contracts. GASOL offers a wide variety of cost models that allow inferring the gas consumption associated to selected types of EVM instructions and/or inferring the number of times that such types of bytecode instructions are executed. Among others, we have cost models to measure only storage opcodes, to measure a selected family of gas-consumption opcodes following the Ethereum's classification, to estimate the cost of a selected program line, etc. After choosing the desired cost model and the function of interest, GASOL returns to the user an upper bound of the cost for this function. As the gas consumption is often dominated by the instructions that access the storage, GASOL uses the gas analysis to detect under-optimized storage patterns, and includes an (optional) automatic optimization of the selected function. Our tool can be used within an Eclipse plugin for Solidity which displays the gas and instructions bounds and, when applicable, the gas-optimized Solidity function.
With Industry 4.0, IT infrastructure has started to be used more effectively in the manufacturing sector. Cyber physical systems, IoT, cloud manufacturing, big data are some of the technologies that make up the concept of Industry 4.0. These technologies have solved many problems in the manufacturing sector. One of these technologies, cloud manufacturing technology, has emerged with the idea of pay as you go. This technology has enabled manufacturing resources to be leased and shared on a global scale. However, it has problems arising from its central structure and the need for a reliable 3rd party. Reliability, security, continuity, scalability, data lock-in, single point failure, data manipulation are some of the main problems. Blockchain (BC) is a decentralized and distributed technology. The data stored on the BC network cannot be altered in any way. With these features, we believe that BC-supported cloud manufacturing systems can overcome the aforementioned problems and eliminates the need for a reliable 3rd party. Based on this belief, in this study the agreements and communication between the resource provider and the customer, which is one of the basic functions of cloud manufacturing platforms, are realized with a decentralized application using BC-based smart contracts (SCs). The designed application is called the decentralized cloud manufacturing application (DCMApp). DCMApp does not operate on a fully public BC network, it has a hybrid structure and uses the Ethereum network as a public BC network. These features make DCMApp different from other BC-based cloud manufacturing applications. DCMApp's hybrid structure has enabled more transparent, economic and safe manufacturing agreements. It is also possible to store agreements on the BC network at a low cost without installing any server infrastructure. The use of Ethereum network makes it almost impossible to manipulate agreements.
Blaž Podgorelec, Muhamed Turkanović, Sašo Karakatič
The basis of blockchain-related data, stored in distributed ledgers, are digitally signed transactions. Data can be stored on the blockchain ledger only after a digital signing process is performed by a user with a blockchain-based digital identity. However, this process is time-consuming and not user-friendly, which is one of the reasons blockchain technology is not fully accepted. In this paper, we propose a machine learning-based method, which introduces automated signing of blockchain transactions, while including also a personalized identification of anomalous transactions. In order to evaluate the proposed method, an experiment and analysis were performed on data from the Ethereum public main network. The analysis shows promising results and paves the road for a possible future integration of such a method in dedicated digital signing software for blockchain transactions.
In this study, we attempted to develop and implement a blockchain Corda-based record sharing system for traditional agricultural (agri-) researchers, workers, and their managers. Corda differs from other domain and practical blockchain techniques (e.g., Bitcoin, Ethereum) with respect to its main aims and structural features. Corda-based network systems can transmit and share basic data concerning ledgers at banks or other financial societies and can be handled on common web browsers (e.g., Google Chrome or Microsoft Internet Explorer). This study consists of three phases: (1) designing and confirming the validity of the entire system, (2) constructing and tuning various minor system settings (e.g., programs or networking specifications), and (3) conducting experiments in indoor settings using hoe acceleration data obtained from previous research projects. The integrated system performed with an acceptable level of accuracy. However, it was extremely difficult to quantitatively present the accuracy data. We were unable to concretely show the success and error rates for the data transmitting and receiving, nor the examination operation time. We thus present the specific error content. Overall, the main error trends were (1) errors concerning the rather small transaction time-delay, (2) mistakes concerning the transaction data in the system, and (3) broken transaction data in the system. In particular, we could determine the transaction time delay according to the JavaScript operations and features by observing. We present experimental ranges for these time delays and other error types. Noting concerns concerning previous trials, we suggest practical applications of the proposed system. In short, we believe that our results are novel achievements in the fusion of agricultural informatics, statistics, and human dynamics. We believe that combining this data and other kinds of timeline data with blockchain-based technology and multiple sensors will improve not only agri-business and management, but also agri-skill and security.
Guntur Dharma Putra, Volkan Dedeoglu, Salil S. Kanhere, Raja Jurdak
Heterogeneous and dynamic IoT environments require a lightweight, scalable, and trustworthy access control system for protection from unauthorized access and for automated detection of compromised nodes. Recent proposals in IoT access control systems have incorporated blockchain to overcome inherent issues in conventional access control schemes. However, the dynamic interaction of IoT networks remains uncaptured. Here, we develop a blockchain based Trust and Reputation System (TRS) for IoT access control, which progressively evaluates and calculates the trust and reputation score of each participating node to achieve a self-adaptive and trustworthy access control system. Trust and reputation are explicitly incorporated in the attribute-based access control policy, so that different nodes can be assigned to different access right levels, resulting in dynamic access control policies. We implement our proposed architecture in a private Ethereum blockchain comprised of a Docker container network. We benchmark our solution using various performance metrics to highlight its applicability for IoT contexts.
Data analytics has captured attention of both researchers as well as business organizations, since a long time now, as the knowledge or information getting analyzed and evolved is priceless in upbringing the business. Blockchain is the latest technology which is getting adopted at a faster rate due to its unique properties. This paper focuses mainly on data models, and some tools used for data analytics being used in blockchain environment. Public blockchain is an open ledger platform which allows to perform data analytics.
Roben Castagna Lunardi, Henry Cabral Nunes, Vinicius da Silva Branco, Bruno Hugentobler Lipper · 6 authors
Blockchain emerged as a solution for data integrity, non-repudiation, and availability in different applications. Data sensitive scenarios, such as Health Care, can also benefit from these blockchain properties. Consequently, different research proposed the adoption of blockchain in Health Care applications. However, few are discussed about incentive methods to attract new users, as well as to motivate the system or application usage by existing end-users. Also, little is discussed about performance during code execution in blockchains. In order to tackle these issues, this work presents the preliminary evaluation of TokenHealth, an application for collaborative health practice monitoring with gamification and token-based incentives. The proposed solution is implemented through smart contracts using Solidity in the Ethereum blockchain. We evaluated the performance of both in Ropsten test network and in a Private instance. The preliminary results show that the execution of smart contracts takes less than a minute for a full cycle of different smart contracts. Also, we present a discussion about costs for using a Private instance and the public Ethereum main network.
Yi Zhong, Anmin Zhou, Lei Zhang, Jing Fan · 5 authors
As the root cause of illegal cyber activities, botnets are evolving continuously over the last two decades. Current researches on botnet command and control mechanism based on blockchain network suffer from high economic cost, single point of failure, and limited scalability. In this paper, we present DUSTBot, a novel P2P botnet model based on Bitcoin transactions to prepare for new cyber threats. Specifically, a covert, duplex, and low-cost command and control (C&C) channel in the Bitcoin network is presented in our work. DUSTBot uses the Bitcoin main network as the downstream channel while using the Bitcoin testnet as the upstream channel. Furthermore, the peer list exchange algorithm based on the Ethereum block hash proposed in this paper is effective against routing table poisoning attack and P2P botnet crawling. The robustness of DUSTBot against node removal is studied through constructing the botnet with a P2P simulator. We deploy the implementation of DUSTBot on cloud platforms to test its feasibility and performance. Moreover, the stealthiness of DUSTBot and the effectiveness of the proposed peer list exchange algorithm are evaluated. The results demonstrate the feasibility, performance, stealthiness, and robustness of DUSTBot. In the end, possible countermeasures are discussed to mitigate similar threats in the future.
Blockchain software development is becoming more and more important for any modern software developer and IT startup. Nonetheless, blockchain software production still lacks a disciplined, organized and mature development process, as demonstrated by the many and (in)famous failures and frauds occurred in recent years. In this paper we present ABCDE, a complete method addressing blockchain software development. The method considers the software integration among the blockchain components—smart contracts, libraries, data structures—and the out-of-chain components, such as web or mobile applications, which all together constitute a complete DApp system. We advocate for ABCDE the use of agile practices, because these are suited to develop systems whose requirements are not completely understood since the beginning, or tend to change, as it is the case of most blockchain-based applications. ABCDE is based on Scrum, and is therefore iterative and incremental. From Scrum, we kept the requirement gathering with user stories, the iterative-incremental approach, the key roles, and the meetings. The main difference with Scrum is the separation of development activities in two flows—one for smart contracts and the other for out-of-chain software interacting with the blockchain—each performed iteratively, with integration activities every 2–3 iterations. ABCDE makes explicit the activities that must be performed to design, develop, test and integrate smart contracts and out-of-chain software, and documents the smart contracts using formal diagrams to help development, security assessment, and maintenance. A diagram derived from UML class diagram helps to effectively model the data structure of smart contracts, whereas the exchange of messages between the entities of the system is modeled using a modified UML sequence diagram. The proposed method has also specific activities for security assessment and gas optimization, through systematic use of patterns and checklists. ABCDE focuses on Ethereum blockchain and its Solidity language, but preserves generality and with proper modifications might be applied to any blockchain software project. ABCDE method is described in detail, and an example is given to show how to concretely implement the various development steps.
Since the world’s first virtual currency was issued on the Bitcoin blockchain network in 2009, there has been a proliferation of various other private digital token offerings on blockchain networks—in particular, on the Ethereum blockchain. Milkau and Bott (2018) report that several governments are considering implementing digital currencies as a “complement to cash.” Blockchain technology holds great promise for innovative applications capable of facilitating any number of business operations, and several large companies including IBM, American Express, Toyota, JP Morgan Chase, Goldman Sachs, Walt Disney, Oracle, and Facebook have already invested heavily in the emerging technology. Crowdfunding is also a popular application of blockchain technology. Tech entrepreneurs have issued digital tokens for virtual currency as a means of circumventing the tedious regulations of the SEC governing the raising of capital. The regulatory status of these digital tokens and their associated trading platforms has been approached with a certain degree of ambiguity and controversy. This paper explores and explains the regulatory issues of fintech regarding digital tokens, making a valuable addition to the scarce literature on this topic.
This paper proposes SilentDelivery, a secure, scalable and cost-efficient protocol for implementing timed information delivery service in a decentralized blockchain network. SilentDelivery employs a novel combination of threshold secret sharing and decentralized smart contracts. The protocol maintains shares of the decryption key of the private information of an information sender using a group of mailmen recruited in a blockchain network before the specified future time-frame and restores the information to the information recipient at the required time-frame. To tackle the key challenges that limit the security and scalability of the protocol, SilentDelivery incorporates two novel countermeasure strategies. The first strategy, namely silent recruitment, enables a mailman to get recruited by a sender silently without the knowledge of any third party. The second strategy, namely dual-mode execution, makes the protocol run in a lightweight mode by default, where the cost of running smart contracts is significantly reduced. We rigorously analyze the security of SilentDelivery and implement the protocol over the Ethereum official test network. The results demonstrate that SilentDelivery is more secure and scalable compared to the state of the art and reduces the cost of running smart contracts by 85%.
Abstract Background With the advent of precision medicine, pharmacogenomics data is becoming increasingly critical to patient care. These data describe the relationship between a particular variant in the genome and the response to a drug by the patient. As utilizing this kind of data becomes more integral to medical treatment decisions, appropriate storage and sharing of this data will be critical. A potential way of securely storing and sharing pharmacogenomics data is a smart contract with the Ethereum blockchain. This is an open-source blockchain platform for decentralized applications. A transaction-based, state machine, the “world” of Ethereum maintains user accounts and storage in a network state. Immutable pieces of code called “smart contracts” may be deployed to the Ethereum network and run on the Ethereum Virtual Machine when called by a user or other contract. The 2019 iDASH (Integrating Data for Analysis, Anonymization, and Sharing) competition for Secure Genome Analysis challenged participants to develop time- and space-efficient smart contracts to log and query gene-drug relationship data on the Ethereum blockchain. Methods We designed a smart contract to store and query pharmacogenomics data (gene-drug interaction data) in Ethereum using an index-based, multi-mapping approach allowing for time and space efficient storage and query. Our solution to the IDASH competition ranked in the top three at a workshop held in Bloomington, IN in October 2019. Although our solution performed well in the challenge, we wanted to improve its scalability and query efficiency. To that end, we developed an alternate “fastQuery” solution that stores pooled rather than raw data, allowing for significantly improved query time for 0-AND queries, and constant query time for 1- and 2-AND queries. Results We tested the performance of both of our solutions in Truffle (v5.0.31) using datasets ranging from 100 to 1000 entries, and inserting data at 25, 50, 100, and 200 observations at a time. On a private, proof-of-authority test network, our challenge solution requires approximately 70 seconds, 500 MB of memory, and 80 MB of disk space to insert 1000 entries (200 at a time); and 400 ms and 5 MB of memory to query a two-AND query from 1000 entries. This solution exhibits constant memory for insertion and querying, and linear query time. Our alternate fastQuery solution requires approximately 60 seconds, 500 MB of memory, and 80 MB of disk space to insert 1000 entries (200 at a time); and 83 ms and 5 MB of memory to query a two-AND query from 1000 entries. This solution exhibits constant memory for insertion and querying, linear query time for 0-AND queries, and constant query time for 1- and 2-AND queries in a database of up to 1000 entries. Conclusion In this study we showed that pharmacogenomics data can be stored and queried efficiently on the Ethereum blockchain. Our approach has the potential to be useful for a wide range of datasets in biomedical research; while we focused on gene-drug interaction data, our solution designs could be used to store a range of clinical trial data. Moreover, our solutions could be adapted to store and query data in any field where high-integrity data storage and efficient access is required.
Οι τεχνολογικές εξελίξεις μεταμορφώνονται και συνεχώς αναπτύσσονται με τόσο γρήγορο ρυθμό, ώστε όλοι να πρέπει να παραμείνουν σε εγρήγορση για να μπορούν να τις παρακολουθήσουν. Το Blockchain είναι το νέο κύμα καινοτομίας που έχει ήδη αρχίσει να επανασχεδιάζει τον τρόπο εργασίας, τις κοινωνικές και πολιτικές αλληλεπιδράσεις και τους παραδοσιακούς τρόπους ανταλλαγής. Ωστόσο δεν είναι μόνο μια απλή αλλαγή, αλλά ένα ραγδαίως αναπτυσσόμενο φαινόμενο που ήδη βρίσκεται σε εξέλιξη. Κατά τη συγγραφή αυτή, περισσότερα από 40 κορυφαία χρηματοπιστωτικά ιδρύματα και πολλές διαφορετικές επιχειρήσεις σε διάφορες βιομηχανίες, άρχισαν να διερευνούν τις δυνατότητες του blockchain με σκοπό να μειώσουν το κόστος των συναλλαγών, να επιταχύνουν το χρόνο περάτωσής τους, να μειώσουν τον κίνδυνο απάτης και να εξαλείψουν τους μεσάζοντες ή τις υπηρεσίες διαμεσολάβησης. Η τεχνολογική ιδέα πίσω από το Blockchain είναι πολύ πανομοιότυπη με αυτή μιας βάσης δεδομένων και μέσα από αυτήν την προσέγγιση, γίνεται η χρήση του στην ανάπτυξη της voting εφαρμογής, αποδεικνύοντας με ρεαλιστικό τρόπο ότι η αλυσίδα του Ethereum μπορεί να αναλάβει ηγετικό ρόλο στη νέα εποχή, που σκοπό έχει τη δημιουργία αποκεντρωμένων εφαρμογών.
Anton Hasselgren, Katina Kralevska, Danilo Gligoroski, Sindre Andre Pedersen · 5 authors
BACKGROUND: Blockchain can be described as an immutable ledger, logging data entries in a decentralized manner. This new technology has been suggested to disrupt a wide range of data-driven domains, including the health domain. OBJECTIVE: The purpose of this study was to systematically review, assess and synthesize peer-reviewed publications utilizing/proposing to utilize blockchain to improve processes and services in healthcare, health sciences and health education. METHOD: A structured literature search on the topic was conducted in October 2018 relevant bibliographic databases. RESULT: 39 publications fulfilled the inclusion criteria. The result indicates that Electronic Health Records and Personal Health Records are the most targeted areas using blockchain technology. Access control, interoperability, provenance and data integrity are all issues that are meant to be improved by blockchain technology in this field. Ethereum and Hyperledger fabric seem to be the most used platforms/frameworks in this domain. CONCLUSION: This study shows that the endeavors of using blockchain technology in the health domain are increasing exponentially. There are areas within the health domain that potentially could be highly impacted by blockchain technology.
Smart contracts are immutable, verifiable, and autonomous pieces of code that can be deployed and ran on blockchain networks like Ethereum. Due to the immutability nature of blockchain, no change is possible on a deployed smart contract or a verified transaction. On the other hand, there are millions of dollars carried by smart contracts in Ethereum blockchain, and hence, a faulty smart contract can lead to a huge monetary loss. Therefore, it is important for smart contract developers to fully test and check the correctness of their code before deploying it on the blockchain. In this paper, we propose a testing mechanism for smart contracts in Solidity language, based on mutation testing. We analyzed a comprehensive list of known bugs in Solidity smart contracts, and designed 10 classes of mutation operators inspired by the real faults. Our experimental results show that our proposed mutation operators can regenerate 10 of 15 famous faulty smart contracts, which have resulted in millions of dollars loss. The results show the effectiveness of our proposed mutation operators in detecting real faults in Solidity smart contracts. We have also extended {\em Universal Mutator } tool with our mutation operators, so that it can automatically generate mutants for smart contracts written in Solidity.
Jiaming Ye, Mingliang Ma, Yun Lin, Lei Ma · 6 authors
Recent years have seen smart contracts are getting increasingly popular in building trustworthy decentralized applications. Previous research has proposed static and dynamic techniques to detect vulnerabilities in smart contracts. These tools check vulnerable contracts against several predefined rules. However, the emerging new vulnerable types and programming skills to prevent possible vulnerabilities emerging lead to a large number of false positive and false negative reports of tools. To address this, we propose Vulpedia, which mines expressive vulnerability signatures from contracts. Vulpedia is based on the relaxed assumption that the owner of contract is not malicious. Specifically, we extract structural program features from vulnerable and benign contracts as vulnerability signatures, and construct a systematic detection method based on detection rules composed of vulnerability signatures. Compared with the rules defined by state-of-the-arts, our approach can extract more expressive rules to achieve better completeness (i.e., detection recall) and soundness (i.e., precision). We further evaluate Vulpedia with four baselines (i.e., Slither, Securify, SmartCheck and Oyente) on the testing dataset consisting of 17,770 contracts. The experiment results show that Vulpedia achieves best performance of precision on 4 types of vulnerabilities and leading recall on 3 types of vulnerabilities meanwhile exhibiting the great efficiency performance.