In the emerging world of IoT applications, machines are going to be at the endpoints of the Internet engaging in complex Machine to Machine (M2M) communications. Be it a personal assistant (softbot)making an appointment with a doctor or an autonomous car filling fuel or charging at a refueling station, in the future, it is going to be M2M communications without human intervention. In such a scenario, robust and secure technology is essential to record every M2M transactions. This paper makes use of blockchain, a distributed ledger technology for intelligent transportation systems. It is proposed that blockchain networks such as Ethereum have the foundations to record and satisfy the transaction that has happened between the machines. A permissioned Ethereum blockchain the smart contract is used for recording each every transaction that come off between the car and electric station. An algorithm is proposed to recharge the autonomous electric vehicles as a case study.
Blockchain technology allows the formation of a distributed record of a digital event in a decentralized manner where no third-party controls data and related transactions. This technology was used early for value transfer but now it has a wide range of applications in various fields such as healthcare, banking, the internet of things and many more. In the education sector, it gives numerous chances for decentralized management of records in educational institutions. Certificates distributed in colleges or universities are mostly hard copy. Students submit these certificates while applying for jobs at public or private sectors, where all these certificates are needed to be verified manually, it is very time-consuming process. There can be incidents where students may produce the fake certificate and it is difficult to identify them. This problem of fake academic certificates has been a longstanding issue in the academic community. There are chances that some may have produce the certificate which is not legit and that may get unnoticed by the verifier during the verification process. Because of the above situation, ineligible candidate will get a chance illegally. The key issues in Certificate verification for Workplace, banks and other businesses are in storage, retrieval and access to data with security. Blockchain technology can be enforced to solve these troubles in storing and accessing of data. This technology provides a common shared platform from where to store, retrieve and access documents securely. The very nature of the technology is in the distributed, shared, open ledgers, verifiable by all. This problem can be solved by storing the digital certificates on the Blockchain.
With the evolving complexity of software systems, interest in software performance analysis has increasingly grown in recent years. Its main objective is to optimize software applications by analyzing its structure, behavior and dependencies, from design to code. Blockchain technologies, also known as distributed ledger technologies, have gained a lot of popularity in the recent years. Particularly the Ethereum blockchain, which apart from having its own cryptocurrency, is programmable. Meaning that developers can use it to create new decentralized applications which rely on smart contracts. Smart contracts are immutable computer programs that run deterministically in the context of the Ethereum Virtual Machine. The main purpose of this report is to explain the process of development of a tool to assist Ethereum developers to visually analyze static and dynamic behaviour of their smart contracts to improve their performance through optimizing gas usage.
The increasing role of renewables, together with the escalation of digital technologies and the pressure for a more active role of consumers and prosumers, are the natural basis for the development of Local Electricity Markets (LEM). The goal of this paper is to contribute to the current debate on LEM, drafting several proposals about key issues to be considered in outlining the LEM business model and market design. We take advantage of the ongoing project "NEMoGrid", which aims at defining and validating a prototype of LEM by integrating local PVs generation into the grid and with a peer-to-peer trading scheme. Transactions are settled on the Ethereum blockchain and the LEM is validated through onsite tests in Switzerland. Such tests are still running, therefore we use preliminary findings to make our suggestions, also highlighting several caveats and policy complexities. Keywords: local energy markets, peer-to-peer, renewable energy sources, electricity market design, electricity business models.
Rui Torres de Oliveira, Marta Indulska, Tatiana Zalan
In the past two decades, digital technologies have substantially changed the ways in which individuals and firms communicate and transfer knowledge, with wide-ranging implications for organisations and institutions. From an organisational perspective, the emergence of digital technologies has enhanced the materialisation of new business models (Foss and Saebi, 2017; Rachinger et al., 2019), the personalisation of products and services (Cenamor et al., 2017), the relation of trust between market agents and asymmetries of information (Urena et al., 2019), new products and services (Matt et al., 2015) and the pace of product life-cycles (Seetharaman et al., 2018), to name a few. This digital transformation has far-reaching implications for organisations but is particularly important to multinational enterprises (MNEs) as it allows them to reduce the liability of foreignness (Johanson and Vahlne, 2009), enhance knowledge creation and improve knowledge transfer and learning (Gaur et al., 2019), augment trust-building (Monaghan et al., 2020), build agile global value chains (GVCs) (Kano et al., 2020) and improve the speed of internationalisation (Oviatt and McDougall, 1994). All this results in a reduction of uncertainties and thus lowers the risk perception (Clarke and Liesch, 2017), which impels international commitment decisions. An important new technology with potential for significant and wide-ranging impacts is blockchain. With this technology it is now possible to, for example, transfer the ownership of physical assets, such as cars and real estate, stocks, bonds and money over the internet through digital contracts (Andreesen, 2014). The changes that blockchain technology brings about leave academics, businesses and governments grappling with the consequences. Academic research has focussed on the economics of blockchains (Evans, 2014; Davidson et al., 2016) and blockchain use cases, especially in the financial, information and communications technology, and public sectors (Bohme et al., 2015; Friedlmaier et al., 2017; Tapscott and Tapscott, 2016). Because blockchain has multiple barriers to widespread adoption (Iansiti and Lakhani, 2017), researchers have explored regulatory barriers to the adoption of cryptocurrencies and smart contracts (Caytas, 2017; Werbach and Cornell, 2017) as well as technical barriers, such as scalability, interoperability, performance and data privacy (Hileman and Rauchs, 2017; Yli-Huumo et al., 2016). Tapscott and Tapscott (2016) argue that blockchain constitutes an institutional innovation, the “cryptoeconomy” – an economic system not defined by geographic location, political structure or legal system, but which uses cryptographic techniques to incentivise appropriate behaviour of participants in place of using trusted third parties (Pilkington, 2016). From this perspective, blockchains are platforms for building economic coordination using distributed ledgers augmented with computational features, such as money (cryptocurrencies), programmable contracts (e.g. smart contracts) and organisations made of software (DAOs, or distributed autonomous organisations). Thus, blockchain technology is not only innovative but also is a building block for new forms of economic governance and socio-political order (Davidson et al., 2016). Despite the critical importance of digital technologies, such as blockchain and organisations’ digital transformations, the international business (IB) literature has been slow to unpack the implications for organisations’ internationalisation motivations and processes. Furthermore, and more recently, the emergence of fully digital organisations, such as digital platforms (Uber or Airbnb), social media (Facebook or Twitter), e-commerce (Taobao) or financial services (TransferWise), are still very much a black box to IB literature. With this special issue, we aimed to uncover a small part of the necessary embracement that the IB field needs to achieve to be prepared to perform their societal role of informing managers, entrepreneurs, officials and other agents of change. To do so, we look specifically at the implications of blockchain technology in the IB field. While IB literature is lagging behind in the study of blockchain, MNEs are – and have been for some time – actively exploring blockchain’s potential, particularly in the financial (Bohme et al., 2015), compliance (Anjum et al., 2017), healthcare (Mettler, 2016), data protection (Finck, 2018) and logistics (Hackius and Petersen, 2017) contexts. In China alone, by the end of March 2020, a total of 35 MNEs (including Microsoft, Oracle, Mastercard, Sony, Intel and Walmart) applied for 212 blockchain-related patents (Global Times, 2020). As explained elsewhere (Finextra, 2017), banking and finance now account for some 30% of blockchain use cases, and nearly 70% of central banks are experimenting with blockchain technology. Entrepreneurial start-ups and initial coin offerings – a form of crowd funding made possible because of blockchain (Kastelein, 2017) – have been the drivers behind an unprecedented surge of innovation, ranging from new, competing protocols (e.g. Tezos and EOS) to smart contracts on Ethereum, decentralised applications (e.g. Telegram), and new currencies with unique features (e.g. monero and zcash) (Vereckey, 2018). Thus, and more than ever, we need to push the blockchain agenda and investigate its implications for IB. In the following sub-sections, we outline the key implications of blockchain technology in the context of IB.
Abstract Blockchain technology and Internet of Things technology are two new technologies formed in the current transmission of information technology. In the implementation of its technical control, it can scientifically control the information sharing work and realize the artificial adjustment of the transmission control of the Internet of Things technology. In this paper, research on the Internet of Things data sharing model based on block chain with a view to provide guidance to the security of Things data sharing technology under the block chain. In this paper, Hyperledger Fabric block chain platform-based platform, proposed a block-based chain of IOT data sharing model, security and data privacy is an enhancement, obtained by the performance of the test model. Throughput is maximized when the write transaction sending frequency is 100 TPS and the query transaction sending frequency is 250 TPS. The maximum write throughput is 60 TPS, which is better than Bitcoin and Ethereum on the public chain, which proves the feasibility of the model implementation. This model can achieve storage and sharing without the help of a third-party centralized organization, and directly establish trust between participants, which can ensure the safe sharing of data.
G Pazhev, Gr. Spasov, Mitko Shopov, Galidiya Petrova
Abstract The paper presents an implementation of a smart home architecture with two gateways based on collaboration of blockchain technology and Internet of Things (IoT) Message oriented middleware (MOM) architecture for management of internal home appliances. A basic overview of IoT MOM, MQTT (Message Queue Telemetry Transfer) protocol and blockchain architectures is made and the key characteristics and consensus algorithms are presented. Some challenges and the Ethereum smart contracts concept of the blockchain technology are discussed.
Open access
Blockchain Technology Applications and Security
IoT and Edge/Fog Computing
Advanced Steganography and Watermarking Techniques
Today, the online review system cannot fully support the business since there are fraudulent activities inside. The companies that get low score reviews are induced to raise their score for the market competition capability by paying to the platform for deleting or editing the posted reviews. Moreover, the automatic filtration system of a platform removes some reviews without the awareness of the users. The low transparency platform causes low credibility toward the reviews. Blockchain technology provides exceptionally high transparency since every action can be traced publicly. However, there are some tradeoffs that need to be considered, such as cost and response time. This work tends to find the potential of using Blockchain technology in the online review system by testing four implementation approaches of the Ethereum Smart Contract. The result illustrates that using IPFS to store the data is a practical way of reducing transaction costs. Besides, preventing using Smart Contract states can significantly reduce costs too. The response time for using the Blockchain and IPFS system is slower than the centralized system. However, posting a review does not need a fast response. Thus, it is worthy of trading response time with transparency and cost. In the business view, the review posting with cost causes more difficulty to generate fake reviews. Moreover, there are other advantages over the centralized system, such as the reward system, bogus review voting, and global database. Thus, credibility improvement for a consumer online review system is a potential application of Blockchain technology.
In isolated network domains, global trustworthiness (e.g., consistent network view) is critical to the multiple-domain business partners who aim to perform the trusted corporations depending on each isolated network view. However, to achieve such global trustworthiness across distributed network domains is a challenge. This is because when multiple-domain partners are required to exchange their local domain views with each other, it is difficult to ensure the data trustworthiness among them. In addition, the isolated domain view in each partner is prone to be destroyed by malicious falsification attacks. To this end, we propose a blockchain-based approach that can ensure the trustworthiness among multiple-party domains. In this paper, we mainly present the design and implementation of the proposed trustworthiness-protection system. A cloud-based prototype and a local testbed are developed based on Ethereum. Finally, experimental results demonstrate the effectiveness of the proposed prototype and testbed.
Spyros Voulgaris, Nikos Fotiou, Vasilios A. Siris, George C. Polyzos · 6 authors
The use of blockchains to improve product quality and safety control in food supply chains through transparent, trusted, and secure end-to-end traceability frameworks, has received increased attention in the last few years. The use of blockchains, though, does not come at no cost. Poor design of blockchain-based applications can lead to prohibitive costs, intolerable delays, and nonscalable systems. In this work we explore different architectures for blockchain-based traceability and quality control of produce, proposing, evaluating, and comparing four different scenarios. Our evaluation uses public and private Ethereum instances, and assesses the considered architectures in terms of cost and overall throughput.
In most cities, the availability of parking is a major concern. The misuse of parking spots as drivers park for longer than permitted periods cause more delays, inconvenience to others, and even parking tickets. Moreover, the payment systems at many locations are still not electronic and rely on hard currency. The search for a parking space also contributes to congestion, pollution, and other safety issues. This paper introduces an end-to-end system that enables automatic car payments in a safe, private, secure, and efficient manner using Blockchain technology. The proposed solution utilizes Ethereum to prototype a solution which can facilitate the parking payments. In addition, Android auto and application modules that automate the payment process have also been developed. Moreover, a validation technique for enhancing the quality and correctness of the proposed solution, namely Model-Based Testing Techniques, has been discussed. The latter consists of deriving test suites from an adopted formal model, performing them, and assessing the correctness. The used formal model may combine both functional and load aspects. A list of techniques for improving the formal testing approach was identified. Besides, the authors explained how to manage dynamic adaptations of the system under test and how to use isolation strategies for avoiding interference between testing and business behaviors. Finally, an optimization phase for testers placement inspired by fog computing is proposed as well.
In blockchain applications, transaction latency is crucial for determining the quality of service (QoS). Transaction latency is measured as the time between its issuance and its inclusion in a block in the chain. When different applications use the same blockchain network, a block proposer often prioritizes its own application transactions over other applications transactions to minimize its own latency. To maintain fairness, a block proposer is typically supposed to select the included transactions randomly providing each transaction similar chances to be included. The random selection might cause some transactions to experience high latency since this selection implies a high variance in the time a transaction waits until it is selected. We suggest an alternative, age-aware approach towards fairness so that transaction priority is increased upon observing a large waiting time. The challenge with this approach is that the age of a transaction is not absolute due to transaction propagation. Moreover, a node might present its transactions as older to obtain priority. We consider three network restrictions on transaction propagation and explain how to enhance fairness in each one of them. We describe three declaration schemes in which a node declares its pending transactions providing the ability to validate transaction age. We demonstrate the advantages of the solutions on Ethereum and synthetic data in reducing tail latency.
Crowdsourcing is a promising computing paradigm that utilizes collective intelligence to solve complex tasks. While it is valuable, traditional crowdsourcing systems lock computation resources inside each individual system where tasks cannot reach numerous potential workers among the other systems. Therefore, there is a great need to build a federated platform for different crowdsourcing systems to share resources. However, the security issue lies in the center of constructing the federated crowdsourcing platform. Although many studies are focusing on privacy-preserving crowdsourcing, existing solutions require a trusted third party to perform the key management, which is not applicable in our federated platform. The reason is that it is difficult for a third party to be trusted by various systems. In this paper, we present a secure crowdsourcing framework as our initial effort toward this direction, which bridges together the recent advancements of blockchain and cryptographic techniques. Our proposed design, named PFcrowd, allows different crowdsourcing systems to perform encrypted task-worker matching over the blockchain platform without involving any third-party authority. The core idea is to utilize the blockchain to assist the federated crowdsourcing by moving the task recommendation algorithm to the trusted smart contract. To avoid third-party involvement, we first leverage the re-writable deterministic hashing (RDH) technique to convert the problem of federated task-worker matching into the secure query authorization. We then devise a secure scheme based on RDH and searchable encryption (SE) to support privacy-preserving task-worker matching via the smart contract. We formally analyze the security of our proposed scheme and implement the system prototype on Ethereum. Extensive evaluations of real-world datasets demonstrate the efficiency of our design.
Blockchain Technology is used to develop applications more easily and maintain the information as safe and secure. This work is aimed towards developing a recruitment process supported by blockchain technology. Currently, a manual system is used to recruit employees; Manual recruitment is a time consuming, costlier non-secure process. Selection and recruiting the candidates is a vital process for an organization. The proposed method uses blockchain technology for the recruitment process. The entered candidate details are verified by the college, organization for the last workplaces, and law enforcement. Based on the approval, the candidate data is stored in a block with its transaction hash value. The transaction hash consists of the unique predefined fixed-length text of the block and it secures the data from tampering. SHA-256 is one of the hashing algorithms to develop a transaction hash. Once the candidate information is stored in the blockchain, the recruiters read the candidate data from the blockchain and select the validated candidate for the recruitment process. It ensures that they are retrieving the valid details of candidates and can proceed for the further recruitment process. The technology uses a Smart contract under the Ethereum platform to provide security for the recruitment application and tested using the Ganache tool.
Zakaria Abou El Houda, Abdelhakim Hafid, Lyes Khoukhi
Smart grids (SGs) and advanced metering infrastructures (AMIs) are considered as the new evolution of classical electrical grids. The recent emergence of smart meters is paving the way for the proliferation of smart grids, where billions of smart meters are interconnected to provide novel pervasive services (e.g., real time pricing application and real time energy consumption), and automate diagnostic and daily energy metering (i.e., gas, electric) tasks (e.g., billing, monitoring, planning and predicting of energy usage). The recent explosion in the number of insecure smart meters is changing the view towards SG from enabler of smart homes into a powerful amplifying tool that creates new vectors for cyberattacks (i.e., smart-homes Distributed Denial-of-Service (DDoS) attacks) at large scale. This motivated us to design a new flexible, secure, efficient and trustworthy access control scheme based on blockchain and smart contract. Although access control exists in AMI, it is based on a centralized model (i.e., router/gateway, firewall) which introduces a bottleneck (i.e., single point of failure) and causes the collapse of the system. In this paper, we propose a new decentralized-based access control architecture for SG based on blockchain; it uses smart contracts (i.e., Ethereum's smart contracts) in order to manage permissions in a fully distributed and trustworthy manner. The architecture is implemented, tested and deployed on the Ethereum official test network Ropsten [1]. The results confirm that the proposed blockchain based access control scheme achieves security, flexibility, efficiency, and cost effectiveness making it a promising solution to mitigate DDoS attacks in SGs.
Disasters are getting more frequent and unpredictable due to climate change and other factors. The tasks of first responders and community volunteers are getting more challenging as the frequency and intensity of disasters increase. This study explores how blockchain technologies using Ethereum can assist in increasing speed and level of availability of needed materials and services that may be required during or in the aftermath of disasters for rescue and recovery. The federated blockchain model also provides financial transactions securely and transparently by incorporating a donation mechanism for fund payment, monetary compensation or incentivization through the use of tokens and other digital assets to the materials and service providers. Inter-government agencies and co-operation and collaboration during disaster response and recovery events can also be achieved by solving the financial budget issue.
Ethereum is the most popular blockchain. It has become really well-known in the last few years because it lets users deploy their smart contracts on top of it. Gas is used to measure the computational effort when executing a transaction and to reward miners. Users set the gas limit when proposing a transaction, and if the miner runs out of gas before performing it, an out-of-gas exception is raised, reverting to the previous state before execution. Thus, inferring gas consumption is really important for not losing resources.
Besides, some exploits have been found that have led to major economic losses, due to subtle bugs in the code. An example of it is the famous DAO attack.
In order to tackle the efficiency and soundness problems mentioned above, we have to rely on formal methods that guarantee the soundness and accuracy of possible analysis. Research has been done previously in this topic, and it has led to the creation of tolos that analyze different features on Ethereum Virtual Machine(EVM) code. Among them, Gastap is one of the few tools based on static analysis that manages to infer gas upper bounds for transactions. Gastap is one of the most accurate tools in the field, having a great success rate. It generates a Control-Flow-Graph (CFG) as an intermediate representation of the analysis. However, the current algorithm used by Gastap is not precise. Therefore, a considerable number of smart contracts cannot be analyzed.
This dissertation proposes a new algorithm for generating a Complete CFG from an EVM smart contract. We will prove that this algorithm is sound, and prove completeness is lost only in certain cases.
It greatly improves the performance from the previous version. Experiments corroborate this fact: we have analyzed a total of 10,736 files, generating a CFG from roughly 90%, in contrast with the 80% of the contracts that could be analyzed before. From the 10% remaining, only less than 1% of the contracts still fail due to our analysis. Besides, we achieve a great efficiency: CFG generation time takes less than 0,01% of the total time for the analysis.
Another key feature of the proposed algorithm is that it can be easily implemented and adapted to other stack-based programs.
Mahmudul Hassan Ashik, Mirza Mohd Shahriar Maswood, Abdullah G. Alharbi
Ethereum is a blockchain-based distributed network and has been a successful platform to host decentralized applications. On the other hand, fog computing has emerged as one of the most demanding field for research as it brings the services of cloud to the edge of the network, i.e. closer to the IoT devices. To satisfy the QoS requirement of latency sensitive applications, the concept of fog computing is introduced in order to implement the idea of smart home, city etc. Though the fog nodes can support latency sensitive applications, but their computational capacity is low which leads to more vulnerability against known attacks. But Ethereum has paved the way to develop smart contracts to implement any logic written in it upon calling. The usage of smart contracts in securing the fog node can be effective as it runs in a blockchain enabled network which makes the smart contract immutable and secured against modification. This creates a scope of using smart contract's logic to ensure the security of fog nodes and IoT devices which they earnestly require. This also eliminates the necessity of public-private key pair and other authentication systems used in fog-cloud architecture. In our work, we modified the conventional fog-cloud architecture by introducing blockchain-based fog layer to ensure better security and privacy for both fog layer and IoT devices.
Recently the blockchain technology has been actively studied due to its great potentiality. The smart contract is a key mechanism of the blockchain system. Due to the short history of the smart contract, many issues have not been solved yet. One main issue is vulnerability and another main issue is cost optimization. While the vulnerability of smart contract has been actively studied, the cost optimization has been rarely studied. In this paper, we propose two cost optimization methods for smart contracts running on the blockchain system. Triggering a function in a smart contract program code may require costs and it is repeated continuously. So the minimization of costs required to trigger a function of smart contract while maintaining the performance equally is very important. The proposed two methods minimize the usage of expensive permanent variables deployed on the blockchain system. We apply the proposed two methods to three prevalent blockchain platforms: Ethereum, Klaytn and Tron. Evaluation experiments verify that the proposed scheme significantly reduces the costs of functions in the smart contract written with Solidity.
Dynamic Symmetric Searchable Encryption (SSE) is a practical cryptographic primitive that enables data owners to search and update encrypted data hosted on untrusted servers. Recently, there is a growing interest to design dynamic SSE schemes with forward security. That is, the server cannot learn the association between the updated data and any query made in the past. However, due to the complexity of update operations, this security property introduces a great challenge of designing verifiable SSE schemes. It is difficult to verify the correctness of updated search results while preserving forward privacy. In this work, we explore how blockchain techniques can help us achieve a verifiable and dynamic SSE construction with forward security. First, we propose a new dynamic SSE scheme based on blockchain techniques, and apply it as the underlying building blocks to preserve forward-secure updates. Second, we resort to the emerging smart contract technique to customize a verification scheme, making updated results easily verifiable. Based on this new primitive, the robustness of the encrypted search service is ensured and forward security is preserved for update operations. Finally, we implement the prototype in Python and Solidity, and conduct performance evaluations on Ethereum. The extensive security analysis and performance evaluations on the real-world dataset demonstrate that our blockchain-assisted SSE scheme is secure and feasible.
The global usage and acceptability of bitcoin and other forms of cryptocurrencies as another \nmeans of payment have attracted the attention of financial and economic experts in recent times, but \nresearch on these means of payment and their relationship with economic and financial variables are \nscanty in Nigeria. This study, therefore, examined the nexus between the two key economic and \nfinancial variables (exchange rate and stock market price) and the most traded cryptocurrency (Bitcoin \nand Etherum) in Nigeria. The study used monthly data between August 2015 and December 2019 and \nemployed the Generalized Autoregressive Conditional Heteroscedasticity (GARCH 1,1), Exponential \nGeneralized Autoregressive Conditional Heteroscedasticity (EGARCH 1,1), and Granger causality \ntechnique to estimate the reaction of the volatility of exchange rates and stock market prices to volatility \nin cryptocurrency prices. The result shows that the stock market price is more influenced by the \ninstability of bitcoin and ethereum prices than the exchange rate in Nigeria. Further, there is evidence \nof a one-way causality from bitcoin and ethereum to all share index. Given these findings, there is a \nneed for the stock market investors in Nigeria to pay rapped attention to the movement of \ncryptocurrency prices.
Smart contracts in the blockchain systems such as Ethereum are usually executed or verified by all nodes, and thus inefficient for heavy-duty computation. This paper addresses the limitation by proposing, implementing, and evaluating a practical and efficient solution based on a game theoretic approach. The solution defines a template of heavy-duty smart contract (HDSC); recruits only a small number of executors to execute heavy-duty tasks; employs a game theoretic scheme to enforce economically-rational executors to individually or collectively perform the execution correctly. Extensive game theoretic analysis has been conducted to show the security and computational efficiency of the solution even in face of collusion among the executors. As a proof of concept, the proposed solution has been implemented and experimented to demonstrate its practicality and compatibility with Ethereum.
As the basis of the most existing blockchain networks, Proof of Work (PoW) consensus protocol highly relies on the computational resources, and thus causing a huge waste of energy. Proof of Stake (PoS) is the alternative to relieve the PoW dilemma. However, it is also under threat, i.e., discouragement attack, which is a way to bring down the blockchain networks without any effective defense against it. To prevent the discouragement attack, the founders of Ethereum argue that the system should set a withdraw delay instead of allowing the validators entry/exit quickly. But how to determine the delay is still an open question. In this paper, we adopt the cyber insurance idea and propose the insurance contract to help determine the withdraw delay, as well as the insurance claim to relieve the loss of victims. Specifically, instead of requiring the insurance premium from the validators, the cyber insurer first signs the contract with the blockchain representative (e.g., beacon chain). Then the blockchain representative would sign a series of contracts with the validators. By such design, the validators can obtain the insurance claim without paying the premium, while the blockchain networks can keep the validators staying online to resist the discouragement attack. Finally, through the simulations, we demonstrate that the proposed model is capable of providing adaptive insurance contracts for the different validators and keeping the profits of the blockchain network and the cyber insurer.