Software Engineering Applications enabled by Blockchain Technology: A Systematic Mapping Study

The novel, yet disruptive blockchain technology has witnessed growing attention, due to its intrinsic potential. Besides the conventional domains that benefit from such potential, such as finance, supply chain and healthcare, blockchain use cases in software engineering have emerged recently. In this study, we aim to contribute to the body of knowledge of blockchain-oriented software engineering by providing an adequate overview of the software engineering applications enabled by blockchain technology. To do so, we carried out a systematic mapping study and identified 22 primary studies. Then, we extracted data within the research type, research topic and contribution type facets. Findings suggest an increasing trend of studies since 2018. Additionally, findings reveal the potential of using blockchain technologies as an alternative to centralized systems, such as GitHub, Travis CI, and cloud-based package managers, and also to establish trust between parties in collaborative software development. We also found out that smart contracts can enable the automation of a variety of software engineering activities that usually require human reasoning, such as the acceptance phase, payments to software engineers, and compliance adherence. In spite of the fact that the field is not yet mature, we believe that this systematic mapping study provides a holistic overview that may benefit researchers interested in bringing blockchain to the software industry, and practitioners willing to understand how blockchain can transform the software development industry.publishedVersio

ItyFuzz: Snapshot-Based Fuzzer for Smart Contract

Smart contracts are critical financial instruments, and their security is of utmost importance. However, smart contract programs are difficult to fuzz due to the persistent blockchain state behind all transactions. Mutating sequences of transactions are complex and often lead to a suboptimal exploration for both input and program spaces. In this paper, we introduce a novel snapshot-based fuzzer ItyFuzz for testing smart contracts. In ItyFuzz, instead of storing sequences of transactions and mutating from them, we snapshot states and singleton transactions. To explore interesting states, ItyFuzz introduces a dataflow waypoint mechanism to identify states with more potential momentum. ItyFuzz also incorporates comparison waypoints to prune the space of states. By maintaining snapshots of the states, ItyFuzz can synthesize concrete exploits like reentrancy attacks quickly. Because ItyFuzz has second-level response time to test a smart contract, it can be used for on-chain testing, which has many benefits compared to local development testing. Finally, we evaluate ItyFuzz on real-world smart contracts and some hacked on-chain DeFi projects. ItyFuzz outperforms existing fuzzers in terms of instructional coverage and can find and generate realistic exploits for on-chain projects quickly.Comment: ISSTA 202

End-to-End Formal Verification of Ethereum 2.0 Deposit Smart Contract

We report our experience in the formal verification of the deposit smart contract, whose correctness is critical for the security of Ethereum 2.0, a new Proof-of-Stake protocol for the Ethereum blockchain. The deposit contract implements an incremental Merkle tree algorithm whose correctness is highly nontrivial, and had not been proved before. We have verified the correctness of the compiled bytecode of the deposit contract to avoid the need to trust the underlying compiler. We found several critical issues of the deposit contract during the verification process, some of which were due to subtle hidden bugs of the compiler.Ope

On-Chain Smart Contract Verification over Tendermint

Smart contracts are computer code that runs in blockchain and expresses the rules of an agreement among parties. A bug in their code has major consequences, such as rule violations and security attacks. Smart contracts are immutable and cannot be easily replaced to patch a bug. To overcome these problems, there exist automatic static analyzers that find bugs before smart contracts are installed in blockchain. However, this off-chain verification is optional: programmers are not forced to use it. This paper defines on-chain verification instead, that occurs inside the same blockchain nodes, when the code of smart contracts is installed. It acts as a mandatory entry filter that bans code that does not abide to the verification rules, that are consequently part of the consensus rules of the blockchain. Thus, an improvement in on-chain verification entails a consensus update of the network. This paper provides an implementation of on-chain verification for smart contracts written in the Takamaka subset of Java, running as a Tendermint application. It shows that on-chain verification works, reporting actual experiments

Assessing Smart Contracts Security Technical Debts

Smart contracts are self-enforcing agreements that are employed to exchange assets without the approval of trusted third parties. This feature has encouraged various sectors to make use of smart contracts when transacting. Experience shows that many deployed contracts are vulnerable to exploitation due to their poor design, which allows attackers to steal valuable assets from the involved parties. Therefore, an assessment approach that allows developers to recognise the consequences of deploying vulnerable contracts is needed. In this paper, we propose a debt-aware approach for assessing security design vulnerabilities in smart contracts. Our assessment approach involves two main steps: (i) identification of design vulnerabilities using security analysis techniques and (ii) an estimation of the ramifications of the identified vulnerabilities leveraging the technical debt metaphor, its principal and interest. We use examples of vulnerable contracts to demonstrate the applicability of our approach. The results show that our assessment approach increases the visibility of security design issues. It also allows developers to concentrate on resolving smart contract vulnerabilities through technical debt impact analysis and prioritisation. Developers can use our approach to inform the design of more secure contracts and for reducing unintentional debts caused by a lack of awareness of security issues

An Automated Analyzer for Financial Security of Ethereum Smart Contracts

At present, millions of Ethereum smart contracts are created per year and attract financially motivated attackers. However, existing analyzers do not meet the need to precisely analyze the financial security of large numbers of contracts. In this paper, we propose and implement FASVERIF, an automated analyzer for fine-grained analysis of smart contracts' financial security. On the one hand, FASVERIF automatically generates models to be verified against security properties of smart contracts. On the other hand, our analyzer automatically generates the security properties, which is different from existing formal verifiers for smart contracts. As a result, FASVERIF can automatically process source code of smart contracts, and uses formal methods whenever possible to simultaneously maximize its accuracy. We evaluate FASVERIF on a vulnerabilities dataset by comparing it with other automatic tools. Our evaluation shows that FASVERIF greatly outperforms the representative tools using different technologies, with respect to accuracy and coverage of types of vulnerabilities

Fundamental Approaches to Software Engineering

This open access book constitutes the proceedings of the 23rd International Conference on Fundamental Approaches to Software Engineering, FASE 2020, which took place in Dublin, Ireland, in April 2020, and was held as Part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2020. The 23 full papers, 1 tool paper and 6 testing competition papers presented in this volume were carefully reviewed and selected from 81 submissions. The papers cover topics such as requirements engineering, software architectures, specification, software quality, validation, verification of functional and non-functional properties, model-driven development and model transformation, software processes, security and software evolution

Smart Contract Analysis Through Communication Abstractions

Smart contracts are programs that manage interactions between many users. Recently, Solidity smart contract have become a popular way to enforce financial agreements between untrusting users. However, such agreements do not eliminate trust, but rather redirects trust into the correctness of the smart contract. This means that each user must verify that a smart contract behaves correctly, regardless of how other users interact with it. Verifying a smart contract relative to all possible users is intractable due to state explosion. This thesis studies how local symmetry can be used to analyze smart contracts from a few representative users. This thesis builds on the novel notion of participation, that gives explicit semantics to user interactions. From participation, a topology is obtained for how users interact during each transaction of a smart contract. Local symmetry analysis shows that most users are interchangeable within a topology, and therefore, most users are locally symmetric. This motivates local bundle abstractions that reduce contracts with arbitrarily many users to sequential programs with a few representative users. It is shown that local bundle abstractions can be used to ameliorate state explosion in smart contract verification, and to accelerate counterexample search in bounded analysis (e.g., fuzzing and bounded model checking). We implement local bundle abstraction in SmartACE, and show order-of-magnitude improvements in time when compared to a state-of-the-art smart contract verification tool