Create a Basic Smart Wallet Using the ERC4337 Standard

The ERC-4337 standard introduces a new account abstraction layer for Ethereum, enabling a more flexible and user-friendly approach to account management, especially for smart contract wallets. It makes it possible for smart contracts to send transactions on behalf of users, creating new opportunities for sophisticated account recovery procedures, specifying transaction parameters, and paying transaction fees with currencies other than ETH. For more information, visit Smart Contract Development Services.

Creating a Smart Wallet using ERC4337 Token Standard

Prerequisites:

Node.js and npm: Ensure that you have Node.js and npm installed on your machine.

Hardhat: Development framework for Ethereum, allowing for smart contract compilation, testing, and deployment.

Code Editor: Choose a code editor of your preference to code the smart contract. Example — VS Code.

Below is a simplified example of a smart contract that follows the ERC-4337 standard. This contract acts as a basic smart wallet that can hold funds and execute transactions on behalf of its owner.

Define the interface for ERC-20 tokens

interface IERC20 {
    //Transfer function
    function transfer(address to, uint amt) external returns (bool);
    //Approve function
    function approve(address spender, uint amt) external returns (bool);
    //Transfer from function
    function transferFrom(address from, address to, uint amt) external returns (bool);
    //Balance function
    function balanceOf(address _account) external view returns (uint);
}

Deposit and Withdrawal:

Functions are provided to deposit ETH into the wallet (deposit) and withdraw ERC20 tokens (withdrawToken). The contract can also receive ETH directly thanks to the receive function.

// Deposit funds into the wallet
    function deposit() external payable {}
// Withdraw ERC20 tokens from the wallet
    function withdrawERC20Token(IERC20 token, address to, uint256 amount) external onlyOwner {
        require(token.transfer(to, amount), "Token transfer failed");
    }
// Allow wallet to receive ETH
    receive() external payable {}

Transaction Execution:

The executeTransaction function allows the owner to execute arbitrary transactions, sending ETH and data to other contracts or addresses

// Execute a transaction from the wallet
    function executeTransaction(address payable to, uint256 value, bytes calldata data) external onlyOwner {
        (bool success, ) = to.call{value: value}(data);
        require(success, "Transaction failed");
    }

Modifiers and Safety Checks

The onlyOwner modifier ensures that only the wallet owner can execute certain functions, adding a layer of security.

modifier onlyOwner() {
        require(msg.sender == owner, "Not the owner");
        _;
    }

This example is a basic illustration and can be extended with more features like multi-signature control, transaction limits, and recovery options to create a more robust and user-friendly smart wallet that leverages the ERC-4337 standard. You can find the whole code for the example below:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

interface IERC20 {
    //Transfer function
    function transfer(address to, uint amt) external returns (bool);
    //Approve function
    function approve(address spender, uint amt) external returns (bool);
    //Transfer from function
    function transferFrom(address from, address to, uint amt) external returns (bool);
    //Balance function
    function balanceOf(address _account) external view returns (uint);
}contract BasicSmartWallet {
    address public owner;    modifier onlyOwner() {
        require(msg.sender == owner, "Not the owner");
        _;
    }    constructor(address _owner) {
        owner = _owner;
    }    // Deposit funds into the wallet
    function deposit() external payable {}    // Execute a transaction from the wallet
    function executeTransaction(address payable to, uint256 value, bytes calldata data) external onlyOwner {
        (bool success, ) = to.call{value: value}(data);
        require(success, "Transaction failed");
    }    // Allow wallet to receive ETH
    receive() external payable {}    // Withdraw ERC20 tokens from the wallet
    function withdrawERC20Token(IERC20 token, address to, uint256 amount) external onlyOwner {
        require(token.transfer(to, amount), "Token transfer failed");
    }    // Approve an allowance for an ERC20 token
    function approveToken(IERC20 token, address spender, uint256 amount) external onlyOwner {
        require(token.approve(spender, amount), "Token approve failed");
    }
}

If you are interested in developing similar or more complex blockchain-based solutions, like crypto wallets, smart contracts, or DeFi solutions, connect with our skilled smart contract developers to get started.