Smart Contract in the Loop

A smart contract is a program running on a blockchain platform. Smart devices send data to smart contracts or change their own status based on smart contracts. Businesses want to use smart devices and smart contracts to streamline workflow because smart contracts reduce the need in trusted intermediators and cut down enforcement costs. However, developing smart contract applications is challenging due to different memory models, different interaction models, and a dearth of supporting tools and libraries. When developers are asked to reimplement conventional applications to smart contracts, it is thus ideal to automatically transform them, avoiding manual labor, as well as ensuring reliability and security. This paper contributes a set of rules to transform conventional applications in the Model-View-Controller (MVC) pattern into smart contracts running on Hyperledger Fabric, a blockchain platform preferred by businesses. Major transformations are performed in the model, while in the controller, model calls are replaced by smart contract calls. The source application and the target smart contract are all written in Java. Our rules add read-your-writes consistency that Hyperledger Fabric does not natively support. Runtime pre- and post-condition checking in the original application is supported in the transformed smart contract. We evaluated our rules on CoCoME and other MVC applications, and all code ran correctly and passed unit tests.

The popularity of blockchain is on the rise as the technology is touted to become an enabler of many existing and futuristic applications. These applications range from cryptocurrency-based financial applications to secure supply chain management, privacy-protected medical data handling, secure yet transparent e-voting, decentralized Internet of Things (IoT), and fault-tolerant Unmanned Aerial Vehicles (UAVs) towards future 6G communication networks. There are numerous inherent features of blockchain that drive these applications, such as transparency, decentralization, non-repudiation, immutability, pseudonymity, provenance, and lower operational costs. Moreover, the smart contracts further enhance the capabilities of blockchain. Thus, this chapter aims to provide an in-depth understanding of blockchain and smart contracts. In particular, the chapter begins by introducing blockchain as one of the most popular types of Distributed Ledger Technology (DLT). Subsequently, the block structure, transaction process flow, salient features, and the different types of blockchain are presented. Next, the concept of smart contract is discussed along with its salient features and the different blockchain platforms that support smart contracts. Furthermore, the chapter introduces various growing applications of blockchain. Finally, the security aspects of blockchain and smart contracts are briefly discussed since it is an evolving technology.

Because of sophisticated question paper fraud and leaks, educational institutions face significant challenges in maintaining the integrity of examinations. Conventional security techniques that concentrate on centralized systems have shown themselves susceptible to internal threats and illegal access. This paper presents a blockchain-based system that transforms examination security through smart contracts and distributed ledger technology. Our approach builds a private permissioned blockchain with multi-signature authentication, time-locked releases, and quantum-resistant encryption using Hyperledger Fabric. Our approach builds a private permissioned blockchain with multi-signature authentication, time-locked releases, and quantum-resistant encryption using Hyperledger Fabric. Real-time audit logging, geographic access restrictions, and fragment-based storage are some of the major innovations. Unauthorized access attempts have decreased by 99.9% and administrative overhead has decreased by 60% in pilot installations. The framework provides educational institutions with a safe and scalable solution, with the potential to integrate AI and enhance evaluation capabilities. This study significantly advances educational technology by addressing significant security concerns and enabling efficient exam administration.

Smart Derivative Contracts (Presentation Slides of the 14th Quant Finance Conference)

The new frame of Blockchain and other Distributed Ledger Technologies (DLT), has empowered smart contract applications and has expanded research represented considerable authority in brilliant agreement. Smart Contracts are computerized securities that are dispersed, decentralized and require no outsider. Smart Contracts fill in as an extraordinary option for conventional securities/marks. With the utilization of customary SDLC models and the idea of square permanence these agreements are presented. With these qualities of permanence, decentralized nature, cost-time adequacy, there is no necessity of outsider as we are attempting to make this smart contract as an option in contrast to conventional money contracts. The offering system is by and large utilized by state run administrations and organizations to get labor and products from assembling adventures along with specialist co-ops. In any case, e-offering being the most utilized procurement usual methodology, there are different security suggestions present. Blockchain innovation can be utilized to address these security insinuation as it intensely centers around the decentralization of data and is secured by encryption, unsegregated with undeniable square based design for exchanging the board. Here we have examined on how smart contract gets that dependence on ethereum blockchain and how they can be utilized to plan a circulated e-offering framework. We have isolated the task in four areas which are as per the following (i)Tender creation and distributing process, (ii)Bidding process on the delicate, (iii)Evaluation and arranging the bid, (iv)Selecting the Winning bid. Different calculations are utilized to help through each cycle. The security challenges connected with security and realness are assessed then they are placed into correlation with the ongoing offering process. The chief target of this paper is to incorporate an unprejudiced, straightforward and open offering plan. Keywords: Blockchain, Impartial and Open Tendering Scheme, ethereum, e-tender.

Blockchain is a peer-to-peer distributed ledger technology, nowadays widely used and a hot topic in the industries. A Smart Contract is a virtual contract based on Blockchain technology which executes and operates between two parties (especially a buyer and a dealer) when a certain condition of the contract is met. The objective of this research is to present a decentralized transaction system based on Blockchain technology implemented using Smart Contract. Blockchain based cryptocurrencies are an evidence for a secure implementation of any currency-based centralized systems put forth in use in a decentralized way. Current transaction systems and payment gateways are centralized systems that need monitoring and verification from a central agency like a bank or a third party organization which are not completely automated as some of the processes are human controlled. Also deposition and withdrawal of money sometimes take a long procedural time. Still these systems are neither completely error free nor secure and time to time certain issues may arise. Even nowadays some payment methods charges transaction fee which is like paying for the money you are paying for. In this research paper we are proposing an automated Ethereum blockchain technology based transactionsystem which will eliminate the bank and third party verification.Each block of the Ethereum blockchain in the system will store the transaction details also linked with all the previous transaction details in the form of a chain. A Smart Contract is used to define the terms and conditions of the transaction which include account creation, ether deposition and withdrawal. This system enables users to carry out transaction without any fraud and losses from anywhere around the globe within split seconds. Keywords: Transaction system ,Blockchain, Smart Contract, decentralized,crypto-currency

Blockchain and Distributed Ledger Technology (DLT) have emerged at once to transform various industries through revolutionary innovations that secure transactions and develop smart contracts as well as detect and prevent fraud. Blockchain technology serves the purpose of this study to better secure digital transactions and render them more transparent while also achieving greater efficiency. Blockchain protects records from tampering because of its decentralized structure and unalterable properties so organizations achieve reduced risk of fraud and unauthorized changes. Smart contracts act as automated self-executing agreements which perform predefined rules to minimize transaction needs of intermediaries thus reducing operational costs The research addresses implementation barriers of blockchain adoption including the challenges related to scalability and regulatory challenges in addition to energy consumption issues. This paper presents investigative research about blockchain and DLT using case examples to show their capability for generating economic innovation while promoting digital integrity in modern digital markets

In the traditional approach to a digital asset management system, the data processing mechanism is not transparent or visible to the data owners since the data is managed solely by the service provider. With the rapid development of blockchain technology, the above issues can be resolved by leveraging the tamper-resistance and decentralization characteristics of blockchain. However, post the implementation of the EU General Data Protection Rules (GDPR) in 2018, the protection of data owners has taken center stage. This has led to several principles of personal data deletion, such as Storage Limit and the Right to Be Forgotten to conflict with the blockchain. It is also observed that, out of the various smart contracts deployed to manage digital assets, often only specific smart contracts are invoked, while the rest of the deployed smart contracts are rarely invoked, leading to smart contract designs exhibiting similar patterns with very little creativity. This current scenario has motivated us to propose SPChain, a smarter and private GDPR-compliant digital asset management framework enabled by blockchain. In this approach, a decentralized InterPlanetary File System has been adopted to solve the problem of SPOF. In addition, the combination of digital assets with artificial intelligence models has been proposed so as to make digital assets accessible to a larger number of applications and to enable better creativity. In this design, artificial intelligence models have been run in independent, virtualized containers and invoked through smart contracts. The proposed SPChain can be applied to the field of digital art management to provide a complete implementation based on the Hyperledger Fabric. Using this proposed framework, model developers, digital art creators, collectors, service providers, as well as third parties can not only benefit from securely managing digital assets and combining them with AI models, but also from simultaneously complying with the rights stipulated in the GDPR. During the course of the experiments conducted, the latency, throughput, and resource consumption of different functions in the smart contracts have been measured. After adjusting the batch timeout of the block and the maximum number of transactions in a block, the throughputs were observed to be about 500 TPS, with 10 to 15 TPS for reading and writing operations, respectively. The latency ranges were found to range from 0 to 7 seconds, with 2.5 to 5 seconds for reading and writing operations, respectively.

As a computer programmer, a smart contract encapsulates the contractual features of the parties’ transactions through code. Some blockchain technology platforms, such as Hyperledger Fabric, IBM Blockchain and Ethereum, currently allow smart contracts. Smart contracts on these platforms are kept on the blockchain and are not under the control of any party involved. They can’t be tampered with after they’ve been digitally signed and placed on the blockchain. The use of smart contracts in blockchains is critical. It is the authors’ primary goal with this research to provide an alternative to standard contracts by allowing users to modify data stored in the chain. Methodology for designing smart contracts is presented in this article, along with an example of how it has used modifications to the data stored in the chain. In this article, we present a methodology for the design of smart contracts and we also illustrate its application with a case study.

A phenomenon-based approach is used to learn more about how blockchain technology could improve Ghana’s economic sectors in terms of cost savings, efficiency, and reliability with reduced risks. With our proposed blockchain-enabled frameworks, we describe how blockchains’ Internet-of-Things (IoTs) and Distributed Ledger Technologies (DLTs) might reduce transaction, contract, and monitoring-related costs in the Agriculture & Agro-processing sector’s supply chains. We also demonstrate how Smart Contracts (SMCs) and Distributed Ledger Technologies (DLTs) can improve time and cost-based efficiencies in local procurements, logistic contract execution, and supply chains across the Mining & Minerals processing sector. With the help of IoTs, DLTs, and SMCs, information asymmetries in the finance sector can be reduced to improve the financing for Small and Medium-sized Enterprises (SMEs). The Technological-Organizational-Environmental (TOE) elements remain crucial in the adoption of blockchain technology. As a result, it’s critical to provide adequate frameworks for blockchain adoption.

Solidity smart contract allow developers to formalize financial agreements between users. Due to their monetary nature, smart contracts have been the target of many high-profile attacks. Brute-force verification of smart contracts that maintain data for up to \(2^{160}\) users is intractable. In this paper, we present SmartACE, an automated framework for smart contract verification. To ameliorate the state explosion induced by large numbers of users, SmartACE implements local bundle abstractions that reduce verification from arbitrarily many users to a few representative users. To uncover deep bugs spanning multiple transactions, SmartACE employs a variety of techniques such as model checking, fuzzing, and symbolic execution. To illustrate the effectiveness of SmartACE, we verify several contracts from the popular OpenZeppelin library: an access-control policy and an escrow service. For each contract, we provide specifications in the Scribble language and apply fault injection to validate each specification. We report on our experience integrating Scribble with SmartACE, and describe the performance of SmartACE on each specification.

Mobile crowdsensing (MCS) is an efficient approach for large-scale sensing data collection by leveraging the mobility and capability of mobile devices. To avoid the weaknesses of traditional centralized crowdsensing systems, blockchain has been introduced to secure the process of MCS. This paper studies a location-aware scenario, where privacy of users are protected in a blockchain- based MCS system, and formulates an optimization problem to maximize the coverage given a budget based on reverse auction. An incentive mechanism named MMCB is further proposed and implemented as smart contracts in blockchain to solve the problem. We demonstrate that the mechanism achieves a set of desirable properties, including computation efficiency, individual rationality, truthfulness, budget feasibility, approximation, and privacy preservation. To protect the identity privacy of workers and obtain anonymity, a linkable ring signature is employed in smart contracts. In addition, a Pedersen commitment is utilized for protecting workers’ bid profile and the submitted sensing data is encrypted and only accessible to the requester. We implement a prototype system based on the Hyperledger Fabric platform, and the evaluation results show that our privacy-preserving incentive mechanism architecture improves 36.2% coverage and reduces 53.1% payment with better security level compared to the state-of-the-art schemes.

Smart contracts are agreements between parties which, not only describe the ideal behaviour expected from those parties, but also automates such ideal performance. Blockchain, and similar distributed ledger technologies have enabled the realisation of smart contracts without the need of trusted parties—typically using computer programs which have access to digital assets to describe smart contracts, storing and executing them in a transparent and immutable manner on a blockchain. Many approaches have adopted fully fledged programming languages to describe smart contract, thus inheriting from software the challenge of correctness and verification—just as in software systems, in smart contracts mistakes happen easily, leading to unintended and undesirable behaviour. Such wrong behaviour may show accidentally, but as the contract code is public, malicious users can seek for vulnerabilities to exploit, causing severe damage. This is witnessed by the increasing number of real world incidents, many leading to huge financial losses. As in critical software, the formal verification of smart contracts is thus paramount. In this paper we argue for the use of deductive software verification as a way to increase confidence in the correctness of smart contracts. We describe challenges and opportunities, and a concrete research program, for deductive source code level verification, focussing on the most widely used smart contract platform and language, Ethereum and Solidity.

Blockchain technology appears to be the ideal solution for storing data in a transparent and decentralized manner. It also allows open access to data and enhances its immutable nature. This technology has helped prove its usefulness in several industries so far, however, distributed ledger technology does not work as a pure database. Therefore, some problems occur in accessing data. Querying data in the blockchain leads to performance and bandwidth problems. This primarily occurs because the blockchain does not have a primary query language, unlike regular databases. The distributed nature of the blockchain is in this case an obstacle. In this paper, a safe and fast method will be proposed to retrieve consistent data from the blockchain-based on the smart contract that will be opened after completing the transaction procedures. All nodes will sign the proposed transaction (by adding a special hash to each node resulting from the transaction information and node data). Upon completion of Transaction procedures, A smart contract will be opened (in which a QR is placed) resulting from converting the signatures in the transaction to QR When the smart contract data is retrieved, the QR for each transaction will be used All node signatures and transaction data will be extracted. The data will be retrieved by the QR generated for each transaction after it is stored in all nodes servers participating in the system. A new method was proposed to generate a hash for each node present in the system. The proposed method was tested in terms of time and complexity, and the algorithm was statistically analyzed, and all the results proved successful.

The Internet of Things (IOT) is integrated with supply chain management process to track the product. To track the product smart tags is used. The smart tags like QR code and NFC is used. But with the technology enhancement the block chain is introduced into the supply chain management process. The block chain is the great revolution that data in the centralized form is transformed in to a decentralized manner. The distributed Ledger Technology (DLT) is one of the method used in ethereum block chain. The main advantage of using DLT is, it offers decentralized, privacy-preserving and verifiable process in the smart tags. In existing system only single server was used to maintain all the process like supplier, manufacturer and distributor. In this application we are using different server which was more secure than existing system. The proposed solution in this paper is it checks the product evidence during the entire lifecycle of the product by using the smart contract. The data can be immutable by using smart contract with ethereum block chain. The duplication is manipulated by the block chainserver.