Setting up Crypto Wallets for Web3 Authentication

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Integrating cryptocurrency wallets into your application is a powerful way to embrace the future of decentralized identity and user authentication. With growing interest in blockchain-based login systems, developers are increasingly turning to solutions that support Web3 authentication using popular crypto wallets like MetaMask. This guide walks you through a seamless integration process using Ethereum-compatible wallets, enabling secure, self-sovereign identity for your users.

Whether you're building a decentralized app (dApp), NFT marketplace, or blockchain gaming platform, allowing users to log in with their crypto wallets enhances both security and user experience. No more forgotten passwords—just one-click access powered by public-key cryptography.

Understanding Web3 Authentication

Web3 authentication shifts control of digital identity from centralized providers to end users. Instead of relying on email and password combinations stored on servers, users authenticate using their cryptocurrency wallets, which act as identity anchors on the blockchain.

This method leverages cryptographic signing: the server sends a challenge message, the user signs it with their private key (via their wallet), and the server verifies the signature against the known public address. Since only the rightful owner can sign messages with their private key, this process ensures strong, phishing-resistant authentication.

👉 Discover how easy it is to enable secure crypto wallet logins today.

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Step 1: Retrieve the User’s Ethereum Address

The first step in enabling wallet-based login is obtaining the user's Ethereum address. Most modern crypto wallets inject a global window.ethereum object into the browser environment, allowing dApps to interact with them directly.

To request access to the user’s MetaMask wallet and retrieve their address:

const [address] = await window.ethereum.request({ method: 'eth_requestAccounts' });

This prompts MetaMask to display a permission window asking the user to share their account. If window.ethereum is undefined, the user doesn’t have a compatible wallet installed—consider showing a helpful message or redirecting them to install one.

Always handle errors gracefully. For example:

try {
  const [address] = await window.ethereum.request({ method: 'eth_requestAccounts' });
  console.log("Connected:", address);
} catch (error) {
  console.error("User rejected connection request", error);
}

Step 2: Initiate Authentication via API

Once you have the Ethereum address, initiate the authentication flow by calling /v1/crypto_wallets/authenticate/start. This endpoint generates a unique challenge message that the user must sign.

Here’s an example request using the Stytch SDK:

const stytch = require("stytch");
const client = new stytch.Client({
  project_id: "PROJECT_ID",
  secret: "SECRET",
  env: stytch.envs.test,
});

const params = {
  crypto_wallet_address: "0x6df2dB4Fb3DA35d241901Bd53367770BF03123f1",
  crypto_wallet_type: "ethereum",
  user_id: "user-test-16d9ba61-97a1-4ba4-9720-b03761dc50c6", // optional
  siwe_params: {
    domain: "example.com",
    uri: "https://example.com",
  },
};

client.cryptoWallets.authenticateStart(params)
  .then(resp => { console.log(resp); })
  .catch(err => { console.log(err); });

Using Sign in with Ethereum (SIWE) is highly recommended. It adds an extra layer of security by embedding contextual information (like domain and URI) into the signable message, preventing phishing attacks where malicious sites try to trick users into signing unauthorized requests.

👉 Learn how SIWE strengthens security in decentralized logins.

Step 3: Request Message Signature

After receiving the challenge from the API response, prompt the user to sign it using their wallet. This step triggers a MetaMask popup asking for explicit approval.

const signature = await window.ethereum.request({
  "method": "personal_sign",
  "params": [challenge, address]
});

Ensure you handle cases where users decline to sign. A well-designed UX should provide feedback and allow retry attempts without friction.

Step 4: Complete Authentication

With the signed message in hand, finalize the authentication by sending the signature back to your backend, which then calls /v1/crypto_wallets/authenticate.

const params = {
  crypto_wallet_address: "0x6df2dB4Fb3DA35d241901Bd53367770BF03123f1",
  crypto_wallet_type: "ethereum",
  signature: "0x0c4f82edc3c818b6beff4b89e0682994e5878074609903cecdfb843241728be32f75949e2fbae63dcccdef97c0e3789a26441f7e11456cc1f2ef79b3a436010f1b"
};

client.cryptoWallets.authenticate(params)
  .then(resp => { console.log(resp); })
  .catch(err => { console.log(err); });

Stytch validates the signature against the original challenge and address. On success, it returns a session token—your signal that the user is authenticated and ready to proceed.

You can also pass session_duration_minutes to control session length or reuse an existing session_token for continuity across sessions.

Step 5: You’re Done!

Congratulations—you’ve successfully implemented a secure, modern login system using Ethereum-based crypto wallets. Users can now access your app with just a few clicks, all while maintaining full control over their digital identity.

But don’t stop here. Consider extending this functionality:

Frequently Asked Questions (FAQ)

Q: Can I use this method with wallets other than MetaMask?
A: Yes! Any Ethereum-compatible wallet that exposes the window.ethereum provider (like Coinbase Wallet or Trust Wallet) can be used. The same principles apply across platforms.

Q: What is Sign in with Ethereum (SIWE), and why should I use it?
A: SIWE is a standardized protocol that binds authentication messages to specific domains and URIs. It helps prevent phishing by ensuring users only sign messages intended for your legitimate domain.

Q: Is Web3 authentication secure?
A: Yes—when implemented correctly. Unlike traditional passwords, private keys never leave the user’s device. Combined with SIWE and proper backend validation, it offers superior protection against common threats.

Q: Do users need ETH in their wallet to log in?
A: No. Authentication via signing does not require gas fees or any on-chain transactions—it’s purely off-chain verification.

Q: How do I manage user sessions after login?
A: After successful authentication, use the returned session token to establish and maintain user state securely on your backend.

Q: Can I link multiple wallets to one user account?
A: Yes. By passing the same user_id during authentication, you can associate multiple crypto addresses with a single user profile.

👉 Start building your own secure, wallet-powered login system now.