Metamask: How can I safely check if a user has an address from Metamask? [copy]

Address Verification Protection with Metamask: A Step-by-Step Guide

As a web developer, you’ve probably faced the challenge of verifying the owner’s identity when a user shares their Ethereum wallet address on your website. That’s where Metamask comes in, a popular browser extension that securely manages and stores Ethereum accounts. In this article, we’ll explain how to use Metamask to verify that a user owns an address from your website.

What is Metamask?

Before we dive into the solution, let’s quickly talk about what Metamask does. It’s a secure wallet extension that allows users to import their Ethereum accounts directly into your website or mobile app. When a user imports their account, they can choose to share it with you or keep it private.

Step 1: Prepare your website for verification

To verify that a user owns an address from Metamask, you’ll need to create a simple endpoint on your server that accepts the imported address as input. For this example, let’s say your website uses Node.js as its main language.

Create a new file called “index.js” and add the following code:

const express = require('express');
const program = express();
app.post('/verify-address', (req, res) => {
const address = req.body.address;
// Integrate with Metamask API to verify ownership
import('metamask').then((api) => {
api.verifyAddress(address).then((result) => {
if (result.verified) {
res.json({ message: 'User owns this address' });
} else {
res.json({ message: 'User does not own this address' });
}
}).catch((error) => {
console.error(error);
res.status(500).json({ error: 'Failed to verify ownership' });
});
}).catch((error) => {
console.error(error);
res.status(400).json({ error: 'Invalid request data' });
});
});
});

This code imports the metamask API and uses it to check if the imported address is owned by Metamask. If ownership is confirmed, we will respond with a success message.

Step 2: Integrate Metamask with your website

To integrate Metamask with your website, you will need to add the metamask library as a dependency in your package.json file:

{
"name": "mysite",
"version": "1.0.0",
"dependencies": {
"@types/metamask": "^3.4.7",
"Express": "^4.17.1"
}
}

Then create a new file called “metamask.js” and add the following code:

import { ethers } from 'ethers';
import * as metamask from '@types/metamask';
const api = metamask;
export default async function verifyAddress(address) {
const account = await api.getAccount(address);
if (account) {
return true;
} else {
return false;
}
}

This code uses the metamask API to get the Ethereum account object associated with the imported address.

Step 3: Call the verification function

To verify user ownership, call the verifyAddress function on your website:

const address = '0x...user-addr...'; // Replace with the actual metamask address
fetch('/verify-address', {
method: "POST",
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify({address }),
})
.then((response) => response.json())
.then((result) => console.log(result))
.catch((error) => console.error(error));

Replace “…user-addr…” with the actual metamask address that you imported from your website.

By following these steps, you can securely verify that a user has an Ethereum address using Metamask. This method ensures that the verification process is encrypted and tamper-proof, thus protecting sensitive user data.