Best Practices for Developing Secure Web3 Applications: Building Trustworthy DApps

Written by: Salus

Develop trustworthy DApps For building user trust, ensuringSafetysex, provide a good user experience, and driveBlockchainThe application of technology is crucial.可信赖的 DApp 为用户提供了Safety, transparent and decentralized interactive environment forBlockchainThe sustainable development and widespread application of technology have laid a solid foundation. We mainly explain the technology stack for building DApps from the following five aspects:

1. intelligentcontractDevelopment: Ensure intelligencecontractdesigned to comply with best practices andSafetyprinciples, following a modular and extensible architecture to allow for future upgrades and modifications.

2. 智能合约测试：进行全面的单元测试、集成测试和系统测试，以确保合约的正确性和稳定性。同时，通过模拟各种场景和攻击，检查合约的鲁棒性和Safetysex.

3. Front-end development: Ensure user-friendly interface, ease of use, and secure interaction with smart contracts. Implement necessary verification and authorization mechanisms to protect user privacy and assets.

4. Middleware development: Ensure the security and reliability of middleware to protect user data and transactions through appropriate encryption and authentication mechanisms. At the same time, middleware also needs to provide efficient interfaces and functions to facilitate seamless communication between the front end and smart contracts.Xiaobai Navigationmutual.

5. Smart contract deployment: Ensure the correctness and integrity of the contract during the deployment process, and perform necessary data migration and transfer. Choose appropriate deployment tools and networks, and follow best practices and security guidelines.

1 Smart contract development

1.1 Characteristics of smart contracts

Smart contracts are the core components of DApps, and they define the logic and functionality of DApps. Smart contracts have unique programming languages, including Solidity, Vyper, Move and Rust, etc. Understanding the characteristics of smart contracts is very important for developing DApps. Here are some key features:

• Transactional: During the execution process, smart contracts must either all be executed successfully or all be rolled back to an unmodified state. This requires us to pay attention to the design of function APIs in the process of writing smart contracts, avoid overloading parameters, and handle errors carefully.

• Error handling: Common error handling methods include using the "require" statement to pass in error information or using the "revert" statement to customize the error type. These error handling methods will cause transaction failure and require custom error type capture on the front end.

• Running cost: The state storage of smart contracts will consume Gas fees. Therefore, when designing storage objects, you must make good use of the declared memory space to avoid excessive memory usage. At the same time, data structure declarations at different locations will incur different costs, and functions that change state will consume Gas.

• Immutability: Once a smart contract is deployed, it cannot be dynamically replaced or upgraded. Therefore, you need to consider whether to rely on an upgradeable architecture and ensure the upgradeability of the contract before deployment.

• Permissions and Visibility: The contract is transparent to everyone in the network, so sensitive data should not be stored in the contract and avoid relying on the state in the block as a basis for judgment of core business logic. It is recommended to use permission control mechanisms such as Ownable and AccessControl.

• Security: The security of the contract is very important and must follow security best practices, including contract code security guidelines and adequate test cases. Don’t trust untested contract code and subjectively expect it to work.

1.2 Safety Practices

In DApp development, it is crucial to ensure that smart contracts are secure and easy to audit.Here are some best practices and recommendations for keeping smart contracts secure:

• Standardized development framework: Using a standardized development framework can help improve the credibility of smart contracts. Standardized development frameworks are usually created and maintained by experienced developers and security experts, and contain some code and patterns that have been verified and optimized. By using these frameworks, developers can avoid common security issues and be able to use code that has been tested and audited to improve the security of their contracts. For example, OpenZeppelin is a widely used and proven smart contract development framework that provides some standard contract templates and libraries to help developers build safe and reliable contracts.

• Logging using events: By using events to record the execution of a smart contract, the functionality and operations of the contract can be better tracked. Events can be defined and triggered in the contract, recording the details of an operation, such as the caller's address, timestamp, and parameters passed to the function. This log information is extremely valuable for auditing contracts and identifying potential vulnerabilities. For example, in a crowdfunding contract, you can define an event to record the details of each donation, including the donor's address and donation amount. In this way, all operations and changes to the contract can be recorded, making it easier for auditors to inspect and analyze.

• Implement Access Control: Access control is a mechanism for controlling who can access certain resources or perform certain operations and authenticate them before accessing or performing them. In smart contracts, access control can be implemented using modifiers, which can be added to functions to check that specific conditions are met before executing the function. By implementing access controls, you can ensure that only authorized entities can perform specific operations or access sensitive data. For example, in a voting contract, a modifier can be defined to verify that only specific addresses can perform voting operations, ensuring that only authorized users can participate in the voting process.

• Follow the principle of least privilege: The principle of least privilege requires that each user be granted only the minimum access rights necessary to perform their job. In smart contracts, least privilege can be achieved through access control mechanisms. By implementing access controls and following the principle of least privilege, you can limit the permissions granted to each entity to ensure they can only perform necessary operations. For example, in a multi-user contract, different permission levels can be defined for each user, and only the necessary permissions are granted to the user based on their identity and needs to prevent abuse and unnecessary operations. Doing so reduces the risk of the contract being compromised because even if an account is compromised, the attacker can only perform restricted actions.

• Multi-signature: Using multi-signature for key transactions is an important measure in smart contract security practices. Multi-signature requires that multiple parties must sign before a key transaction can be executed to complete the transaction. This mechanism can provide additional security and mitigate some potential attack risks, such as replay attacks and transaction malleability.

• 说明定时器和超时：由于Blockchain网络中的交易执行时间是不确定的，智能合约容易受到利用时间问题的攻击，比如预测随机数攻击、前运行攻击、三明治攻击等。为了减轻这些时间问题的攻击，使用定时器和超时机制是一种有效的方法。定时器可以用于安排合约中的功能在特定时间执行，从而避免依赖于区块链网络的执行时间。超时机制可以限制合约中某些函数的执行时间，确保它们不会无限期地执行下去。

1.3 Smart contracts can be upgraded

Smart contract upgrade refers to the process of updating or modifying smart contracts that have been deployed on the blockchain.Smart contract upgrades involve changing the business logic of a smart contract while preserving the state of the contract. Smart contract upgrades allow developers to improve the logic, functionality, or security of the contract to adapt to new needs or fix problems in existing contracts. Upgrading smart contracts is a complex activity that requires a high degree of caution to prevent the introduction of vulnerabilities.

Smart contract upgrades typically require the following steps:

• Write new contract code: Developers write new contract code as needed, including improvements to the original contract. New code should undergo rigorous testing to ensure its correctness and security.

• Deploying a new contract: The new contract code needs to be deployed through a different contract address from the original contract. Before deploying a new contract, developers need to ensure that data migration or transfer is properly handled during the upgrade process.

• Migration or transfer of data: If the smart contract upgrade involves the migration or transfer of data, developers need to design corresponding mechanisms to ensure that the data is correctly migrated or transferred in the new contract. This usually involves the process of data interaction and conversion with the old contract.

• Update the contract address or interface: Once the new contract is successfully deployed, developers need to update the applications or user interfaces that interact with the contract to ensure that they adapt to the address or interface of the new contract.

2 Smart contract testing

Smart contract testing refers to the application of various testing methods and technologies to smart contracts to verify the function, security, performance and correctness of the contract.Smart contract testing aims to uncover potential issues, vulnerabilities, and errors in the contract and ensure that the contract behaves as expected under various circumstances.

2.1 Why test

Testing smart contracts is an important practice in smart contract development for several important reasons:

• Verify contract functions: Smart contracts are codes used to perform specific functions, such as transfers, status updates, etc. By conducting unit tests, you can verify that the various functions of the contract work as expected. This helps find and fix potential bugs, ensuring correct behavior and logic of the contract.

• Ensure contract security: Smart contracts typically involve processing and managing assets, such ascryptocurrency. Therefore, the security of the contract is crucial. By conducting unit tests, you can check whether the contract is threatened by common vulnerabilities and attacks, such as reentrancy attacks, integer overflows, etc. This helps to find and fix potential security vulnerabilities and ensure the security of the contract.

• Improve code quality: Unit testing can help developers write high-quality code. By writing test cases and assertions, developers can verify the correctness of their code and ensure that it works properly under various circumstances. This helps improve the robustness, reliability, and maintainability of your code and reduces the cost of ongoing maintenance.

• Supports reconstruction and expansion: During the development process of smart contracts, as requirements change, the contract may need to be reconstructed or expanded. By having a complete suite of unit tests, you can ensure that existing functionality and logic are not broken during refactoring or expansion. This helps maintain code stability and simplifies subsequent development and maintenance.

• Continuous integration and deployment: In a development environment of continuous integration and deployment, unit testing is an important link. By automatically running unit tests, problems in the code can be discovered and solved in time to ensure the quality and reliability of the code. This helps make development teams more productive and releases products faster.

2.2 What is tested

When testing smart contracts, we mainly test the following aspects:

• Contract functionality and behavior: Our main goal in testing smart contracts is to verify that the functionality and behavior of the contract work as expected. This includes testing that the various functions and methods of the contract execute correctly and are consistent with expected results. For example, if the contract is a transfer contract, we can test whether it can correctly implement the transfer function of funds.

• Edge cases of the contract: We also need to test the behavior of the contract in various edge cases. This includes testing the boundary values of input parameters, such as minimum values, maximum values, null values, etc., as well as testing the contract's ability to handle abnormal situations, such as processing invalid inputs, processing unauthorized operations, etc. By testing edge cases, we can discover potential problems and vulnerabilities that may exist in the contract.

• Contract security: Security is an important aspect in smart contract testing.We need to test the contract for potential security vulnerabilities, such as reentrancy attacks, integer overflow, unauthorized access, etc.Through security audits and testing for specific vulnerability types, we can discover and fix security issues in contracts to ensure the security of user assets.

• Contract performance and scalability: Smart contracts need to have good performance and scalability to handle a large number of transactions and users. Therefore, we need to conduct performance testing and stress testing to verify the performance and stability of the contract under high load and concurrent users. By testing the performance and scalability of a contract, we can optimize the design and implementation of the contract to improve its throughput and response time.

• Contract integration and compatibility: If the smart contract needs to be integrated with other components or services, we need to conduct integration tests to verify whether the contract cooperates properly with other components. This includes integration of front-end applications, interaction with other contracts, etc. At the same time, we also need to test the compatibility of the contract in different Ethereum clients and network environments to ensure the consistency and reliability of the contract in different environments.

2.3 What are the testing methods?

• Unit testing: Unit testing is a method of testing various functions and methods in smart contracts. Verify that the contract behaves as expected by writing test scripts, simulating the input and environment of the contract, and making assertions on the output of the contract.

• Integration testing: Integration testing is a method of testing whether the interactions between different components are working properly. In smart contract development, integration tests can be written to test the integration of the contract with front-end applications or other services such as blockchain nodes or databases. Integration testing ensures that the contract works properly with other components and verifies the functionality and performance of the overall system.

• Property-based testing: Property-based testing focuses on whether the behavior of the contract satisfies predefined properties. These properties are assertions about the behavior of the contract that should always remain true under different scenarios. Static analysis and dynamic analysis are two common techniques used to perform property-based testing. The static analyzer accepts the source code of a smart contract as input and outputs a result stating whether the contract satisfies a certain property. Dynamic analysis generates symbolic or concrete inputs to smart contract functions to see if any execution traces violate specific properties.

• Security Audit: Security audit is also manual testing.By carefully reviewing the code and logic of the contract, and using professional auditing tools and techniques, potential vulnerabilities and security risks can be discovered. Security audits are critical to protecting the assets in the contract and the security of users.If you have smart contract audit needs, please contactSalus, we will provide you with high-quality services.

2.4 What are the testing tools?

Foundry and Hardhat are both popular development tools for testing smart contracts.

Foundry is a smart contract development framework based on TypeScript that provides a powerful set of tools and libraries for creating and testing Ethereum smart contracts.

• Foundry uses Mocha and Chai, two popular JavaScript testing frameworks, to write and execute a variety of test cases.

• Foundry provides some built-in assertion functions for verifying the expected behavior of smart contracts.

• Foundry also supports testing with an emulator to avoid consuming resources and fees on the actual Ethereum network.

Hardhat is a powerful Ethereum development environment for writing, deploying and testing smart contracts.

• Hardhat integrates with the Mocha and Chai testing frameworks, as well as other useful tools such as Ethers.js and Waffle.

• Hardhat provides some built-in assertion functions for verifying the behavior and status of smart contracts.

• Hardhat also supports the use of virtual machines for testing to avoid operating on the actual Ethereum network.

When using Foundry or Hardhat for smart contract testing, you can test the following:

• Whether the functionality and logic of the smart contract works as expected.

• Whether the contract interacts correctly with other contracts.

• Whether the contract's exception handling in various situations is correct.

• Whether the status change of the contract is correct.

• Whether the contract is deployed and used correctly in different network environments.

These tools also provide additional features such as code coverage analysis and performance testing to help developers better evaluate and improve the quality and performance of their smart contracts.

3 Front-end development

3.1 Choose a front-end framework

In DApp development, choosing an appropriate front-end framework is very important for developing secure and trustworthy front-end applications.

3.1.1 ethers.js

ethers.js is a JavaScript library for building DApp front-ends. ethers.js is the first choice for many developers to build DApp front-ends. Many well-known DApp projects use ethers.js to interact with the Ethereum network and operate smart contracts.

It provides the following main functions:

• Ethereum account management: ethers.js allows you to generate and manage public keys, private keys and addresses for Ethereum accounts. You can use these accounts to conduct transactions, call smart contract methods, and more.

• Smart contract interaction: ethers.js provides a simple set of APIs for interacting with smart contracts on Ethereum. You can use ethers.js to deploy smart contracts, call contract methods, obtain contract status, etc. ethers.js also provides type-enhanced smart contract encoding and decoding capabilities, making interacting with smart contracts easier and more reliable.

• Transaction creation and signing: With ethers.js, you can create and send Ethereum transactions. ethers.js provides a simple interface to build transaction objects and supports signing transactions. This allows you to send ether and perform contract operations in a secure manner.

• Ether unit conversion, handling Ethereum events, subscribing to blockchain events, and other functions: ethers.js provides many other useful functions, such as Ethereum unit conversion (conversion from Wei to Ether, etc.), handling Ethereum events ( Such as monitoring contract events) and subscribing to blockchain events, etc. These features make building DApp front-ends more convenient and efficient.

For DApp front-end construction, ethers.js has the following advantages:

• Simple and easy to use: ethers.js provides an intuitive API that makes interacting with the Ethereum blockchain simple and easy.

• Security: ethers.js provides secure methods to handle private keys and signed transactions to ensure the safety of users' assets.

• Feature-rich: ethers.js provides many useful functions, such as Ether unit conversion, handling Ethereum events, etc., simplifying the development process.

For DApp front-end building, ethers.js has the following disadvantages:

• Learning Curve: For beginners, it may take some time and effort to learn and understand the concepts and workings of Ethereum.

• Dependence on the Ethereum network: The functionality of ethers.js relies on the availability and stability of the Ethereum network. If there is a problem with the network, it may affect the normal operation of the DApp.

3.1.2 React

React is a popular front-end framework for building user interfaces. Although React itself does not directly provide the functionality to interact with the blockchain, you can integrate React with the blockchain in the following ways to implement the functionality to interact with the blockchain:

• Using Web3.js: Web3.js is a JavaScript library for interacting with the Ethereum network. You can introduce Web3.js into your React project and use it to connect to the Ethereum network, deploy and call smart contracts, send transactions, and more. Through Web3.js, you can communicate with Ethereum nodes and perform operations related to interacting with the blockchain.

• Using ethers.js: ethers.js is another popular JavaScript library for interacting with the Ethereum network. It provides a concise set of APIs for handling Ethereum accounts, deploying and calling smart contracts, sending transactions, and more. You can use ethers.js in your React project to implement the function of interacting with the blockchain.

• Using blockchain explorer APIs: Some blockchain explorers (such as Etherscan or Infura) provide APIs that allow developers to interact with the Ethereum network through RESTful interfaces. You can use these APIs in React projects to obtain blockchain data, query transactions, obtain contract information, etc.

• usewalletIntegrated libraries: somewallet集成库（如 MetaMask 或 WalletConnect）提供了与以太坊网络进行交互的功能，并提供了方便的用户界面和身份验证。您可以在 React 项目中使用这些库来实现用户wallet的集成，以便用户可以进行交易和与智能合约进行交互。

The method of integrating React with blockchain interaction can be combined with React's component development model. You can create specialized components to handle the logic and user interface for interacting with the blockchain. By interacting with the blockchain network, you can implement functions such as querying account balances, executing contract methods, and monitoring blockchain events.

It is important to note that security and privacy are very important when interacting with the blockchain. Ensure proper handling of private keys, signing transactions, and limiting user permissions for sensitive operations during interactions. Use the latest security best practices and follow the specifications and recommendations of blockchain networks to ensure the security and reliability of your applications.

Compared with ethers.js, React has the following advantages when interacting with the blockchain:

• Strong ecosystem: React has a huge developer baseCommunityand rich third-party library support. This means you can easily find libraries and tools that integrate with React to support interaction with the blockchain. The broad support of the React ecosystem can provide you with more solutions and resources.

• Component development: React’s component development model makes building functions that interact with the blockchain more modular and maintainable. You can encapsulate the logic and user interface for interacting with the blockchain into independent components, making code organization and reuse clearer and more convenient.

• Virtual DOM: React uses virtual DOM technology to minimize DOM operations and improve performance and rendering efficiency by comparing the difference between the two states before and after. This is very helpful for handling large amounts of blockchain data and frequently updating interfaces.

Compared with ethers.js, React has the following disadvantages when interacting with the blockchain:

• Requires additional learning costs: If you have not been exposed to React before, mastering the basic concepts and working methods of React may require some learning costs. This may extend the time it takes for you to implement functionality to interact with the blockchain.

• Integration complexity: React’s flexibility and freedom make integration of interacting with blockchains potentially relatively complex. You need extra work to ensure compatibility between React and the blockchain library and handle integration issues that may arise.

In contrast, ethers.js is a JavaScript library designed specifically for interacting with the Ethereum network. It provides a concise set of APIs that make interacting with Ethereum more direct and simple. Compared to React, ethers.js may be more focused on interacting with Ethereum, providing more blockchain-related features and tools.

However, the advantages of using React to interact with the blockchain lie in its powerful ecosystem, the advantages of component-based development, and the performance advantages brought by virtual DOM technology. This makes React a flexible, scalable and efficient choice, especially suitable for the development of large and complex applications.

3.2 Scaffolding project

When developing DApp, after choosing a suitable front-end framework, you usually need to build a scaffolding project. A scaffold is a starting point or base template that provides a default project structure, configuration, sample code, and tools. By using scaffolding, developers can avoid the tedious work of building an application from scratch and instead develop quickly based on existing default settings and sample code. Scaffolding can also provide some best practices and implementation of common functions to assist developers in following the best development process.

3.2.1 What are the main components of scaffolding?

Scaffolding in DApps usually includes the following main components:

• Smart Contracts: The scaffolding provides one or more sample smart contracts that handle the business logic of the application. These contracts define the functionality and behavior of the DApp.

• Front-end interface: Scaffolding usually contains a basic front-end interface for interacting with users and demonstrating the functionality of the DApp. These interfaces can be built using technologies such as HTML, CSS, and JavaScript.

• Test scripts: The scaffolding provides some sample test scripts for verifying the correctness and reliability of smart contracts. These test scripts can help developers write and run automated tests to ensure that DApps run correctly under different circumstances.

• Configuration files: Scaffolding usually contains some configuration files for configuring the development environment, deploying smart contracts, connecting to the Ethereum network, etc. These configuration files can be customized according to the developer's needs.

3.2.2 What should you pay attention to when building scaffolding?

When building a DApp scaffolding project, you need to consider blockchain network connections, the introduction of Web3 libraries, security, integration of front-end frameworks and libraries, testing, documentation, etc.

• Choose the right scaffolding tool: It is very important to choose a scaffolding tool that is suitable for your DApp development. There are some commonly used scaffolding tools such as Create React App, Vue CLI, etc. They all provide some default configurations and commands to quickly create and run a basic DApp project.

• Configure blockchain network connection: Depending on the blockchain network used by your DApp, you need to configure the network nodes connected to it. Normally, you need to provide the URL, port number, and other necessary authentication information of the network node. In this way, your DApp project can interact with the blockchain network.

• Introducing appropriate Web3 libraries: In DApp development, Web3 libraries need to be used to interact with the blockchain. According to the blockchain platform you choose, select the corresponding Web3 library and introduce it into the project. For example, if you use Ethereum as the underlying blockchain, you can use Web3.js or ethers.js to communicate with Ethereum.

• Security considerations: Security is very important in DApp development.Make sure your scaffolding project includes some common security measures, such as preventing cross-site scripting attacks (XSS), preventing replay attacks, etc.You can use some security-related libraries or frameworks, such as the security libraries provided by OpenZeppelin.

• Integrate front-end frameworks and libraries: Choose the front-end frameworks and libraries suitable for your DApp project and integrate them in the scaffolding project. Common choices include React, Vue, etc. Make sure these frameworks and libraries are preconfigured in your scaffolding project and running smoothly.

• Adding tests: It is very important to add tests in your scaffolding project. You can choose a suitable testing framework, such as Jest, Mocha, etc., and write unit tests and integration tests to ensure the quality and stability of the code.

• Documentation and sample code: Detailed documentation and sample code can be very helpful in scaffolding projects. This helps other developers better understand the structure and functionality of the project and get started quickly.

3.2.3 What kind of scaffolding is there?

When it comes to scaffolding Ethereum-based web applications, there are a few popular options. The following is an introduction to the three main scaffolding, including a comparison of their main functions, features, and advantages and disadvantages.

Truffle

• Main functions: Truffle is a complete Ethereum development framework that provides smart contract compilation, deployment and testing tools, as well as the function of interacting with the Ethereum network. It also includes a powerful development environment for rapid development and testing of DApps.

• Features: Truffle provides a powerful set of command line tools and development environment to help you manage smart contracts, test and deploy DApps. It also supports Solidity and JavaScript and has a rich plugin ecosystem.

Embark

• Main functions: Embark is an Ethereum development framework for building decentralized applications. It provides an easy-to-use set of tools and command line interface for developing, testing and deploying Ethereum smart contracts and DApps.

• Features: Embark integrates some popular front-end frameworks and libraries, such as React, Vue, etc., making it easier to develop DApps. It also provides a powerful plug-in system to extend its functionality.

scaffold-eth

• Main functions: scaffold-eth is an Ethereum-based web application scaffolding designed to help developers quickly build Ethereum DApps. It provides a complete set of tools and templates, including front-end interfaces, smart contracts, test scripts, etc.

• Features: scaffold-eth uses Hardhat as a smart contract development framework, supports Solidity and TypeScript, and integrates some useful tools and libraries. It provides sample code and tutorials to help developers quickly get started with Ethereum development.

3.3 Front-end dependencies

In DApp front-end development, it is recommended to use some excellent front-end libraries to reduce workload and improve code delivery quality. The following are some commonly used front-end library recommendations:

• wagmi: wagmi provides a wealth of React hooks to complete the process of interaction between the DApp front-end and the contract. It simplifies the interaction process with contracts, making it easier for developers to handle operations such as transactions and contract calls.

• useDApp: useDApp is a complex React hooks library that supports multicall.js. It provides some convenient functions, such as handling multiple contract calls, handling Ethereum transfers, handling EIP-712 signatures, etc.

• Siwe: Siwe is a library for implementing the wallet login process. It provides a simple and secure way to implement wallet login and authentication, and integrates with other libraries and tools.

• i18next and react-i18next: If you plan to provide multi-language versions and detection, you can use libraries such as i18next and react-i18next. They provide a convenient way to implement multi-language support and allow developers to easily switch and manage different languages in the front-end interface.

4 Middleware development

In DApp development, middleware usually sits between the front-end application and the blockchain network. It acts as a middle layer between front-end applications and the underlying blockchain, handling and managing interactions with the blockchain.

4.1 What functions does middleware have?

Middleware can perform the following functions:

• Wallet connection and authorization management: The middleware can provide wallet connection functions, communicate with the user's wallet and manage the user's authorization status. It handles operations such as wallet connection, login and logout, and manages user authentication and permissions.

• Transaction processing and signing: Middleware can handle the interaction with the contract and is responsible for constructing transactions, signing them, and sending transactions to the blockchain network. It can handle the life cycle of transactions, including constructing transactions, processing transaction status, and event monitoring.

• Data caching and querying: Middleware can cache and query contract data to improve application performance and response speed. It caches the results of a contract's view function calls, updating and refreshing the cache as needed.

• Event listening and processing: Middleware can monitor contract events on the blockchain and perform corresponding operations when the events are triggered. It handles subscribing, parsing, and responding to events, and updates the state and interface of the front-end application.

• Error handling and logging: Middleware can handle errors and exceptions during interaction with the blockchain and provide appropriate error handling and logging mechanisms. It can catch and handle errors and provide useful error information and feedback to front-end applications.

4.2 What are the middleware tools?

In DApp development, you may use the following middleware tools to achieve the required functions. These middleware tools can help you simplify the DApp development process and provide functions such as interaction with the blockchain, wallet connection and authorization management, and data management. Which tools to use depends on your needs and technology stack.

• Web3.js: Web3.js is a JavaScript library for interacting with the Ethereum network. It provides a series of APIs for connecting to the Ethereum network, instantiating contracts, sending transactions, reading contract data and other operations.

• ethers.js: ethers.js is another popular JavaScript library for interacting with Ethereum. It provides functions similar to Web3.js, including connecting to the Ethereum network, instantiating contracts, signing transactions, etc.

• Metamask: Metamask is a commonly used Ethereum wallet plug-in. It can be integrated with Web3.js or ethers.js to provide user wallet connection and transaction signature functions. Through Metamask, users can authorize DApps to access their wallet addresses and perform transaction operations.

• Drizzle: Drizzle is a state management library based on Web3.js, specially designed for DApp development. It can help you manage the status of DApp, interact with smart contracts, and provides some convenient functions, such as automatic subscription to events, automatic status update, etc.

• Truffle Suite: Truffle Suite is a development suite for Ethereum DApp development, which includes tools such as the Truffle framework, Ganache private chain, and Drizzle. The Truffle framework can be used to compile, deploy and test smart contracts, the Ganache private chain can be used for local development and debugging, and Drizzle can be used for state management and interaction with smart contracts.

• Infura: Infura is a platform that provides Ethereum node hosting services. It helps you easily connect to the Ethereum network and interact with the blockchain through APIs without having to run and maintain nodes yourself.

• IPFS: If your DApp needs to store and retrieve large amounts of files or data, you may consider using IPFS (InterPlanetary File System). IPFS is a peer-to-peer distributed file system that provides high availability and decentralized storage.

4.3 Safety precautions

Security needs to always be top priority when DApps interact with wallets and contracts.Ensure you use trusted connectors, verify wallet addresses and transaction status, perform input validation and data encryption, and perform regular security reviews and vulnerability fixes.

Connect wallet security:

• Use a trusted wallet connector: Make sure the wallet connector you use is verified and trusted. Use well-known connectors such as MetaMask, WalletConnect or Portis.

• User authorization restrictions: When a user authorizes a wallet connection, make sure the user understands the wallet they are connecting to and only authorizes permissions relevant to your application. Avoid requesting unnecessary permissions.

• Wallet address verification: Before using the wallet address, its correctness should be verified. You can use the API provided by the wallet connector to verify that the address provided by the user matches the address of the connected wallet.

Security of write operations with contracts:

• Transaction Confirmation and Signing: Before writing to the contract, make sure to use the wallet connector to confirm and sign the transaction. This ensures that transactions are authorized and signed by the user, providing additional security.

• Input validation: Input validation is always performed before user-supplied data is passed to the contract for write operations. Ensure that input data is in the expected format and range to prevent problems caused by malicious input.

• Transaction status monitoring: After submitting a transaction, monitor the transaction status to ensure that the transaction is successfully confirmed and written to the blockchain. This allows timely updates on the front-end status and provides feedback to users.

Wallet login and signature operation security:

• Use the signature function provided by the wallet: For operations that require a signature (such as login or other sensitive operations), use the signature function provided by the wallet instead of passing sensitive data to the contract for processing. This ensures that data is signed and encrypted locally, protecting users’ private keys and sensitive information.

• Data Encryption: Ensure data is properly encrypted when performing wallet logins or other sensitive operations. Encryption algorithms and security protocols can be used to protect the confidentiality of data.

Security review and bug fixes:

• Security Review: For applications involving wallet and contract interaction, regular security reviews are necessary. Make sure your code and application architecture adhere to security best practices and evaluate and fix potential vulnerabilities.

• Vulnerability fixes: If a security vulnerability or vulnerability report is discovered, promptly fix and update your application. Prompt response and remediation of possible vulnerabilities are important steps in ensuring application security.

5 Smart contract deployment

Deploying a contract refers to deploying smart contracts onto the blockchain network for execution and use on the blockchain.

5.1 Precautions

• Smart contract bytecode: Contract bytecode is machine code generated by compiling smart contract source code. It is the actual execution code of the smart contract and is used to deploy the contract on the blockchain. Bytecode is a hexadecimal string that represents the logic and functionality of a contract and is the core part of executing contract operations on the blockchain.

• Gas: On the Ethereum network, each transaction requires a certain amount of Gas to execute. Deploying smart contracts is no exception. You need to provide enough gas to pay for the computing and storage resources required for contract deployment. The amount of gas depends on the complexity and size of the contract, as well as the congestion level of the network. You need to set a gas limit, which is the maximum amount of gas allowed to be used, to ensure successful contract deployment.

• A deployment script or plugin: A deployment script or plugin is a tool used to automate and simplify the contract deployment process. It can be a script file that contains the steps and instructions required to deploy the contract; or it can be a plug-in that is integrated into a development tool or framework to provide convenient deployment functions. This way, you can automate contract deployment by running scripts or using plugins, reducing the complexity of manual operations.

5.2 What to use to deploy smart contracts

You can deploy smart contracts to the blockchain platform through the following tools:

Remix: Remix is an integrated development environment that can be used to develop, deploy and manage Ethereum smart contracts. You can use Remix to compile and debug smart contracts, and deploy contracts using its user interface. You can find Remix’s official website and related documentation at the following link:

• Remix official website

• Remix related documents

Tenderly: Tenderly is a Web3 development platform that provides debugging, observability, and infrastructure building blocks for developing, testing, monitoring, and operating smart contracts. You can use Tenderly to debug and monitor smart contracts. The following is Tenderly’s official website and related resource links:

• Tenderly official website

• Tenderly related documents

Hardhat: Hardhat is a development environment for compiling, deploying, testing, and debugging Ethereum software. You can use Hardhat to write deployment scripts and perform deployment operations. The following is Hardhat’s official website and related resource links:

• Hardhat official website

• Hardhat's documentation on deploying contracts

Truffle: Truffle is a development environment, testing framework, deployment channel and other tools for developing Ethereum smart contracts. You can use Truffle to write deployment scripts and perform deployment operations. The following is Truffle’s official website and related resource links:

• Truffle official website

• Truffle documentation on network and application deployment

Thirdweb: Thirdweb is a tool that makes it easy to deploy any contract to any EVM-compatible blockchain using a single command. You can find more information about Thirdweb at the following links:

• Thirdweb related documents

You need to rigorously test and audit smart contracts before deploying them on the blockchain.If you are interested in smart contract auditing, pleasecontact us, we will work with you to provide you with professional audit services to ensure that your contract is safe and reliable. If the smart contract deployed to the blockchain still has problems, you need to upgrade it.

6 Summary

Building a trustworthy DApp requires focusing on security, stability and user experience in five aspects: smart contract development, smart contract testing, front-end development, middleware development and smart contract deployment. Through comprehensive design, testing and implementation, the reliability and trustworthiness of DApp in the blockchain environment can be ensured.

The article comes from the Internet:Best Practices for Developing Secure Web3 Applications: Building Trustworthy DApps

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