In the last decade, ICT infrastructures for smart cities have become a reality and the number of projects affecting citizens' lives is growing. In particular, the technology supporting civic participation is mature, although many systems do not reach the needed critical mass, as they are not able to capture the interest of their intended target. To overcome this difficulty, we describe a proposal for encouraging citizens' participation by a reward mechanism based on a civic currency, powered by blockchain tokens, used to recognize civic engagement.
This paper focuses on two of the key challenges a developer encounters when reusing smart contracts: finding actionable information about existing smart contracts (descriptors) and writing the necessary integration logic to invoke selected contracts and implement missing functions. As for the former issue, the paper proposes a smart contract description format that allows the developer to search for publicly available contracts, understand which features a contract exposes and how to invoke them, according to a service-oriented approach. For the latter, the paper implements a simple, model-driven development environment consisting in a visual programming editor that provides a set of modeling constructs encoding specific, reuse-oriented code patterns. The approach is implemented and demonstrated in the context of the blockchain platform Ethereum and its programming language Solidity. The results obtained show that the proposed approach can be beneficial in the development of composite smart contracts and generic blockchain applications.
Transaction privacy is a hard problem on an account-based blockchain such as Ethereum. While Ben-Sasson et al. presented the Zerocash protocol [BCG+14] as a decentralized anonymous payment (DAP) scheme standing on top of Bitcoin, no study about the integration of such DAP on top of a ledger defined in the account model was provided. In this paper we aim to fill this gap and propose ZETH, an adaptation of Zerocash that can be deployed on top of Ethereum without making any change to the base layer. Our study shows that not only ZETH could be used to transfer Ether, the base currency of Ethereum, but it could also be used to transfer other types of smart contract-based digital assets. We propose an analysis of ZETH's privacy promises and argue that information leakages intrinsic to the use of this protocol are controlled and well-defined, which makes it a viable solution to support private transactions in the context of public and permissioned chains.
Although a massive amount of bandwidth is available at mm-waves, physics dictates the use of legacy frequencies in the sub 6-GHz range. This necessitates dynamic spectrum access in the face of exponentially growing spectral demands. However, disorganized spectrum sharing causes interference, leads to a chaotic situation, and loss of capacity. Moreover, it is difficult to ensure that the primary users are compensated for sharing their licensed bands. We propose a Blockchain-based platform to address these limitations. A digital token, called spectral token, is introduced to validate and track the use of a licensed frequency band while enforcing sequential access to spectrum by secondary users to avoid interference. The proposed platform enables both advertising and sensing based spectrum sharing under different leasing policies. Such sharing and leasing policies are coded into smart contracts, which digitally enforce the contractual clauses of the leasing agreement. When a deal is made, the smart contract automatically transfers the spectral token between primary and secondary users within the agreed time frame while paying the primary user in cryptocurrency. We developed a proof of concept solution using the Ethereum Blockchain to demonstrate the utility of the proposed platform and its throughput and latency characteristics.
Crowdfunding has become a popular form of collective funding, in which small donations or investments, made by groups of people, support the development of new projects in exchange of free products or different types of recognition. Social network sites, on the other hand, promote user cooperation and currently are at the basis of any individuals cyber-interactions. In this paper, we present LikeStarter, a blockchain-based decentralized platform that combines social interactions with crowdfunding mechanisms, allowing any user to raise funds while becoming popular in the social network. Being built over the Ethereum blockchain, LikeStarter is structured as a Decentralized Autonomous Organization (DAO), that fosters crowdfunding without the intervention of any central authority, and recognizes the active role of donors, enabling them to support artists or projects, while making profits.
This paper contributes a shred of quantitative evidence to the embryonic literature as well as existing empirical evidence regarding spillover risks among cryptocurrency markets. By using VAR (Vector Autoregressive Model)-SVAR (Structural Vector Autoregressive Model) Granger causality and Student’s-t Copulas, we find that Ethereum is likely to be the independent coin in this market, while Bitcoin tends to be the spillover effect recipient. Our study sheds further light on investigating the contagion risks among cryptocurrencies by employing Student’s-t Copulas for joint distribution. This result suggests that all coins negatively change in terms of extreme value. The investors are advised to pay more attention to ‘bad news’ and moving patterns in order to make timely decisions on three types (buy, hold, and sell).
The concerns held on the scalability of permissionless Blockchain platforms are a significant hindrance to their wider adoption. To address this issue rigorously, we consider it opportune to assess the current implementation and the associated improvement proposals, within a single coherent evaluation framework. This work addresses this specific question in the particular context of Ethereum, a prominent implementation of Blockchain, using a threefold approach. First, it maps the internal constituents of Ethereum onto a layered architecture inspired in the ISO/OSI model, so that its provisioning organization can be better understood. Second, it employs the AKF Scale Cube to analyze the pros and cons of the present specification of Ethereum, as well as of the current improvement proposals, so that the scalability challenges can be reasoned about in an orderly fashion. Finally, it uses an extensible test environment with synthetic benchmarks so that the transaction throughput of the current implementation of Ethereum can be evaluated in a private scenario, when no smart contract is to run. Our conclusions suggest that Ethereum respects the scalability trilemma being versed on security and decentralization renouncing scalability. These limits can be mitigated by adopting novel solutions such as Plasma and Sharding which enable a significant increment of performance by partitioning the data, and, ultimately, unlocking parallel execution of the transactions.
Smart contracts are at the heart of many decentralized applications, encapsulating core parts of the business logic. They handle the exchange of valuable assets like crypto-currencies or tokens in a transparent, decentralized manner. Being computer programs, they are also prone to programming errors, which have already lead to spectacular losses. Therefore, methods and tools have emerged to support the development of secure smart contracts and to aid the analysis of deployed ones. Assessing the quality of such tools turns out to be difficult. There are academic tools, tools developed by companies, and community tools in open repositories, but no comprehensive survey that may serve as a guide. Most discussions of related work in research papers are not helpful either, as they concentrate on methods rather than tools, base their review on publications about the tools rather than the tools themselves, or disregard tools outside of academia. Our survey aims at filling this gap by considering tools regardless of their provenance and by installing and testing them. It is meant as a guide for those who intend to analyze already deployed code, want to develop secure smart contracts, or plan to teach a related subject. We investigate 27 tools for analyzing Ethereum smart contracts regarding availability, maturity level, methods employed, and detection of security issues.
Popular blockchain such as Ethereum and several others execute complex transactions in blocks through user defined scripts known as smart contracts. Normally, a block of the chain consists of multiple transactions of smart contracts which are added by a miner. To append a correct block into blockchain, miners execute these smart contract transactions (SCT) sequentially. Later the validators serially re-execute the SCT of the block. In the current era of multi-core processors, by employing serial execution of the transactions, the miners and validators fail to utilize the cores properly and as a result have poor throughput. By adding concurrency using object semantics to smart contracts execution, we can achieve the better efficiency and higher throughput. Some authors have used read-write STMs (RWSTMs) for the concurrent execution of SCT. Working with higher level operations provide greater concurrency, better throughput and reduces the number of aborts than RWSTMs. In this paper, we develop an efficient framework to execute the SCT concurrently by miner using optimistic Object-Based Software Transactional Memory systems (OSTMs) and Multi-Version OSTMs (MV-OSTM). A proposed block includes SCT, final states of the shared data-items, hash of the previous block and a block graph (BG). BG captures the conflicting relations among the transactions. Later, the validators re-execute the same SCT concurrently and deterministically with the help of BG given by miner to verify the final state. If the validation is successful then proposed block appended into the blockchain and miner gets incentive otherwise discard the proposed block. MV-OSTM and OSTM miner performs 4.5x and 3.86x average speedups over serial miner. Along with, MV-OSTM and OSTM validator outperforms average 32.81x and 29.76x than serial validator.
As an append-only distributed database, blockchain is utilized in a vast variety of applications including the cryptocurrency and Internet-of-Things (IoT). The existing blockchain solutions have downsides in communication and storage efficiency, convergence to centralization, and consistency problems. In this paper, we propose LightChain, which is the first blockchain architecture that operates over a Distributed Hash Table (DHT) of participating peers. LightChain is a permissionless blockchain that provides addressable blocks and transactions within the network, which makes them efficiently accessible by all the peers. Each block and transaction is replicated within the DHT of peers and is retrieved in an on-demand manner. Hence, peers in LightChain are not required to retrieve or keep the entire blockchain. LightChain is fair as all of the participating peers have a uniform chance of being involved in the consensus regardless of their influence such as hashing power or stake. LightChain provides a deterministic fork-resolving strategy as well as a blacklisting mechanism, and it is secure against colluding adversarial peers attacking the availability and integrity of the system. We provide mathematical analysis and experimental results on scenarios involving 10K nodes to demonstrate the security and fairness of LightChain. As we experimentally show in this paper, compared to the mainstream blockchains like Bitcoin and Ethereum, LightChain requires around 66 times less per node storage, and is around 380 times faster on bootstrapping a new node to the system, while each LightChain node is rewarded equally likely for participating in the protocol.
This thesis work is aimed at developing understanding of the hash functions and algorithms being used in blockchain technologies Bitcoin in comparison to Ethereum and private blockchain hash functions. This study attempts to answer one fundamental research question: “What considerations are important in assessing blockchain cryptographic security, with an emphasis on hash functions”. \n \nThe study was carried out qualitatively using a desk research approach and combining this approach with using two public blockchains-based cryptocurrencies; Ethereum and Bitcoin as case studies. The research aims to provide a holistic view of blockchain cryptographic security comparing Bitcoin and Ethereum as use cases, and thus providing a consolidated document which students studying cryptography can access to obtain a better understanding of what is involved in blockchain security. From an academic perspective, the research aims at providing a model which can be used in assessing what is important to consider in the cryptographic security of blockchains. \n \nThree main categories of factors considered were presented in the proposed model which were strategical factors, complexity attributes and technical drivers. This results in a base crucial metrics such as absence of secret seeds, efficiency of verification, preimage collision resistance, fixed output size, low collision probability, and even distribution of preimages in output.
Having set out in the last chapter some of the basics that underlie the Blockchain, this chapter will further develop some of the concepts described previously. In particular, the concept of the Blockchain will be expanded upon to encompass different versions of the Blockchain currently in operation. The reader will be introduced to some of the technical refinements in the Ethereum Blockchain that have given rise to what has been termed ‘smart contracts’ that allow the automatic execution of code to ensure that certain actions take place once a stipulated set of conditions is found to exist. From here, the discussion will move to consider how Blockchain proponents seek to resolve some of the conventional consumer protection issues that tend to emerge from a doctrinal perspective in consumer sales contracts.
Internet of Things (IoT) and blockchain are two technologies which are pioneer nowadays and in the future. IoT become pioneer because our goverment sets Industrial Revolution 4.0 which signifies the IoT technology. For blockchain, it is a technology which has a significant development. These two technologies have a good future. The innovation in this design is combining these two technologies. IoT has a problem in securitization, but blockchain has an advantage in security. So, by combining these technologies, the problem could be resolved. This design used microcontroller ESP32. It will collect three data sets, i.e. altitude, pressure and temperature. The data will be sent through Internet to Ethereum blockchain network in Ropsten TestNet. The Data will store in state variables. Twenty data have been sent and tested. The data has been verified to be stored in Ethereum Virtual Machine because the data could be verified through etherscan.io. So, the conclusion is this design could prove that blockchain could be used to data securitization in IoT. Internet of Things (IoT) dan blockchain merupakan dua teknologi yang akan menjadi pioneer saat ini dan di masa mendatang. Pioneer saat ini karena pemerintah menetapkan Revolusi Industri 4.0 yang salah satu titik beratnya adalah IoT. Untuk blockchain, saat ini merupakan teknologi yang mengalami perkembangan signifikan. Kedua teknologi ini menjanjikan. Salah satu hal yang dapat menjadi inovasi adalah menggabungkan keduanya. IoT memiliki permasalahan pada sekuriti, sedangkan blockchain memiliki keunggulan dalam hal sekuriti. Dengan demikian, menggunakan teknologi blockchain untuk aplikasi IoT akan menjadi solusi. Alat yang dirancang menggunakan mikrokontroler ESP32. Alat ini akan mengakuisis data dari tiga buah sensor, yaitu sensor ketinggian, tekanan dan suhu. Data-data ini dikirim melalui Internet ke jaringan blockchain Ethereum di TestNet Ropsten. Data tersebut akan disimpan di state variables. Dua puluh data dikirim dan berhasil disimpan di Ethereum Virtual Machine. Ini terbukti dengan setiap data yang dikirim dapat divalidasi dan terekam di etherscan.io. Dengan demikian, perancangan alat ini berhasil membuktikan bahwa IoT dapat menggunakan blockchain untuk sekuritisasi data.
Mohamed Ridda Laouar, Zaineb Touati Hamad, Sean B. Eom
The potential of urban planning to solve environmental problems in general and manage waste, in particular, is important because the illegal dumping of solid waste is one of the events related to illegal waste treatment activities. The waste management process is very poor, especially when it comes to confirming the correct destination for the delivery of waste. In this work, we are proposing a chain-based approach to waste tracking to enable waste data reporting in a single system. The blockchain is a technology that has already proven itself in the financial sector. It securely records transactions in a large, time-stamped ledger using the proof of work algorithm (PoW), and allows us to write smart contracts on the ethereum network. The application of this technology to the waste sector will enable reliable, transparent and secure recording of all waste movements, thus enabling waste to be traced from source to treatment and disposal. Users will be able to import and export data through a user interface offering different levels of functionality and access. It will also identify and act on illegal wasteful crimes.
The paper presents the use of states of explosionproof method for analyzing the behavior of systems that provide smart contract technology. The selected example system is ShadowEth, whose main task is to ensure sufficient confidentiality of information stored in the Ethereum blockchain currency. The Petri network model for the ShadowEth system has been presented. The system
Ethereum Virtual Machine (EVM) is the run-time environment for smart contracts and its vulnerabilities may lead to serious problems to the Ethereum ecology. With lots of techniques being developed for the validation of smart contracts, the security problems of EVM have not been well-studied. In this paper, we propose EVMFuzz, aiming to detect vulnerabilities of EVMs with differential fuzz testing. The core idea of EVMFuzz is to continuously generate seed contracts for different EVMs' execution, so as to find as many inconsistencies among execution results as possible, eventually discover vulnerabilities with output cross-referencing. First, we present the evaluation metric for the internal inconsistency indicator, such as the opcode sequence executed and gas used. Then, we construct seed contracts via a set of predefined mutators and employ dynamic priority scheduling algorithm to guide seed contracts selection and maximize the inconsistency. Finally, we leverage different EVMs as crossreferencing oracles to avoid manual checking of the execution output. For evaluation, we conducted large-scale mutation on 36,295 real-world smart contracts and generated 253,153 smart contracts. Among them, 66.2% showed differential performance, including 1,596 variant contracts triggered inconsistent output among EVMs. Accompanied by manual root cause analysis, we found 5 previously unknown security bugs in four widely used EVMs, and all had been included in Common Vulnerabilities and Exposures (CVE) database.
Damiano Di Francesco Maesa, Paolo Mori, Laura Ricci
This work proposes to exploit blockchain technology to define Access Control systems that guarantee the auditability of access control policies evaluation. The key idea of our proposal is to codify attribute-based Access Control policies as smart contracts and deploy them on a blockchain, hence transforming the policy evaluation process into a completely distributed smart contract execution. Not only the policies, but also the attributes required for their evaluation are managed by smart contracts deployed on the blockchain. The auditability property derives from the immutability and transparency properties of blockchain technology. This paper not only presents the proposed Access Control system in general, but also its application to the innovative reference scenario where the resources to be protected are themselves smart contracts. To prove the feasibility of our approach, we present a reference implementation exploiting XACML policies and Solidity written smart contracts deployed on the Ethereum blockchain. Finally, we evaluate the system performances through a set of experimental results, and we discuss the advantages and drawbacks of our proposal.
This paper evaluates the current cybersecurity vulnerability of the prolific use of Elliptical Curve Digital Signature Algorithm (**ECDSA**) cryptography in use by the Bitcoin Core, Ethereum, Bitcoin Cash, and enterprise blockchains such as Multi-Chain and Hyperledger projects Fabric, and Sawtooth Lake. These blockchains are being used in media, health, finance, transportation and government with little understanding, acknowledgment of the risk and no known plans for mitigation and migration to safer public-key cryptography. The second aim is to evaluate ECDSA against the threat of **Quantum Computing** and propose the most practical National Institute of Standards and Technology (NIST) Post-Quantum Cryptography candidate algorithm lattice-based cryptography countermeasure that can be implemented near-term and provide a basis for a coordinated industry-wide lattice-based public-key implementation. Commercial quantum computing research and development is rapid and unpredictable, and it is difficult to predict the arrival of fault-tolerant quantum computing. The current state of covert and classified quantum computing research and advancement is unknown and therefore, it would be a significant risk to blockchain and Internet technologies to delay or wait for the publication of draft standards. Since there are many hurdles Post-Quantum Cryptography (PQC) must overcome for standardisation, coordinated large-scale testing and evaluation should commence promptly.
Digital evidence handling and preservation are one stage of digital forensic process. This part is very crucial because digital evidence is the basis of digital forensic process. The credibility of digital evidence must be maintaned for law and court process. Process of preservation of digital evidence known as chain of custody (CoC). CoC is a document that used to ensure that digital evidence remains and does not change. Both during the investigation process until the completion of the forensic process. Electronic evidence documentation is different from digital evidence documentatation. The different are character and the metadata. Some adjustments need to be accomodated on system for digital evidence. Digital evidence is easy to change as well as its CoC document. It needs to be protected. A new technology is needed that can ensure integrity of digital evidence and CoC Document like the blockchain. In this study, digital evidence management will be built on the CoC concept with blockchain technology. More precisely, this design combines the framework of the Digital Evidence Bag (DEC) with blockchain technology. This prototype is known as the Blockchain Digital Evidence Bag (B-DEC). B-DEC utilizes the data storage integrity to accommodate digital evidence management that refers to DEC. In this case, the prototype will build on a smart contract based on Ethereum. The development of the DEC framework also will be adjusted to accommodate DEC applications in the blockchain.
Open access
Artificial Intelligence in Healthcare and Education
Tang Nguyen, Long Vuong, Son Nguyen, Cam Pham · 5 authors
TomoChain1 is a blockchain based on Ethereum framework with the following advantages points: low transaction fee, fast confirmation time, double validation and randomization for security guarantees. In our previous technical white paper, we proposed Proof-of-Stake Voting (PoSV) consensus protocol, a Proof-of-Stake (PoS)-based blockchain protocol with a fair voting mechanism, rigorous security guarantees and fast finality. One of the key parts of PoSV is the double validation process, which requires randomization to generate the list of block verifiers (with uniform distribution and unpredictability) for each epoch. In other words, randomization of block verifiers in double validation is the key factor of reducing risks coming from paired hand-shaking attackers trying to commit malicious blocks.
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
With the process of the population aging, the problem of the aged in the urban is becoming increasingly prominent in China, especially the shortage of pension resources. In order to solve this problem, we proposed Volunteer time bank (VOLTimebank) based on blockchain, a novel distributed ledger that allows transactions without any third party organization. VOLTimebank is a record management system to handle volunteer service records. The system provides a channel for volunteers to serve the elderly and gives volunteers a way to exchange the services they can offer today with the services that they hope to get in the future. And a Delegated Proof of Stake (DPOS) consensus mechanism is used to select auditors, whose main task is to audit volunteers' services. Each holder of the (volunteer medals (VOLMedals) has the right to vote for auditors and be voted to be an auditor. As a proof of concept, we present a prototype implementation of VOLTimebank via smart contracts based on Ethereum. VOLTimebank is a true realization of "Serve today, enjoy tomorrow", encouraging more people to take part in the volunteer services, for the elderly and for themselves. This paper is intended to illustrate the ideas and methods of VOLTimebank.
Attribute-based access control makes access control decisions based on the assigned attributes of subjects and the access policies to protect objects by mediating operations from the subjects. Authority, which validates attributes of subjects, is one key component to facilitate attribute-based access control. In an increasingly decentralized society, multiple attributes possessed by subjects may need to be validated by multiple different authorities. This paper proposes a multi-authority attribute-based access control scheme by using Ethereum's smart contracts. In the proposed scheme, Ethereum smart contracts are created to define the interactions between data owner, data user, and multiple attribute authorities. A data user presents its attributes to different attribute authorities, and after successful validation of attributes, obtains attribute tokens from respective attribute authorities. After collecting enough attribute tokens, a smart contract will be executed to issue secret key to the data user to access the requested object. The smart contracts for multi-authority attribute-based access control have been prototyped in Solidity, and their performance has been evaluated on the Rinkeby Ethereum Testnet.
D. Nagarajan, M. Lathamaheswari, Said Broumi, J. Kavikumar
Blockchain Technology (BCT) is a growing and reliable technology in various fields such as developing business<br> deals, economic environments, social and politics as well. Without having a trusted central party this technology, gives the<br> guarantee for safe and reliable transactions using Bitcoin or Ethereum. In this paper BCT has been considered using Bitcoins.<br> Also Blockchain Single and Interval Valued Neutrosophic Graphs have been proposed and applied in transaction of Bitcoins.<br> Also degree, total degree, minimum and maximum degree have been found for the proposed graphs. Further, comparative<br> analysis is done with advantages and limitations of different types of Blockchain graphs.