A security-focused smart contract that enables users to whitelist trusted wallet addresses, block unknown interactions, and pause wallet activity when threats are detected.
- constructor(): Sets the contract deployer as the owner.
- register(string _firstName, string _lastName, address _userAddress): Registers a user (only once).
- whitelistAddress(address _safeAddress): Stores a trusted address for the user.
- updateWhitelistedAddress(uint256 _index, address _newSafeAddress): Allows users to update their safe address.
- getMyWhitelistedAddress(): View the list of safe addresses.
- sendETHToWhitelisted(address _userAddress): Owner-only function to send ETH to a user's whitelisted address.
- activateContract(): Turns on all core features.
- deactivateContract(): Turns off all core features.
- receive() / fallback(): Emits an event when ETH is sent directly or with unknown calldata.
🔐 Contract must be activated before usage.
- Custom Errors: Efficient gas-friendly error handling.
- Mappings & Structs: Secure data storage per user.
- Modifiers: Restrict access and control contract state.
- Access Control: Only owner can activate/deactivate or send ETH.
- Event Emissions: For tracking suspicious and valid ETH flows.
- ETH Transfer Handling: Uses .call() with full failure check.
- WalletGuard.sol
In a Web3 world full of wallet hacks, phishing, and malicious smart contract calls, building a protective layer over user interactions is essential. This teaches how to:
- Track and store user info securely.
- Create allowlists (whitelists).
- Block interactions and flag suspicious ETH behavior.
- Design for pause/resume security.
🗓 Posted on: July 14, 2025
🛠 Built on: July 12, 2025
- Language: Solidity ^0.8.18
- IDE: Remix + Visual Studio Code
- Version Control: Git + GitHub (SSH)
MIT License – feel free to learn, remix, and build with it.
Built with 🔥 by @BuildsWithKing
Part of the 30 Days of Solidity Challenge
🙏 Kindly give credit if this inspired your learning journey.