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

As a web developer, you’ve likely encountered the challenge of verifying an owner’s identity when a user shares their Ethereum wallet address on your website. This is where Metamask comes in – a popular browser extension that securely manages and stores Ethereum accounts. In this article, we’ll walk through how to use Metamask to verify if a user owns an address from within your website.

What is Metamask?

Before diving into the solution, let’s quickly cover 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 whether to share it with you or keep it private.

Step 1: Prepare Your Website for Verification

To verify if 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 assume your website uses Node.js as its backend language.

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

const express = require('express');

const app = 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 verify if the imported address is owned by Metamask. If ownership is verified, we respond with a success message.

Step 2: Integrate Metamask with Your Website

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

{

  "name": "my-website",

  "version": "1.0.0",

  "dependencies": {

    "@types/metamask": "^3.4.7",

    "express": "^4.17.1"

  }

}

Next, 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 retrieve an Ethereum account object associated with the imported address.

Step 3: Call the Verification Function

To verify a user’s ownership, call the verifyAddress function from 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 you imported from your website.

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

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