Authenticate Wallet

Authenticate Wallet is a community skill for verifying blockchain wallet ownership in web applications, covering signature requests, message verification, session management, and multi-chain wallet authentication patterns.

What Is This?

Overview

Authenticate Wallet provides patterns for implementing wallet-based authentication in decentralized applications. It covers wallet connection using provider APIs for MetaMask, WalletConnect, and Coinbase Wallet, message signing where users sign a challenge message to prove ownership of a wallet address, server-side signature verification using cryptographic recovery of the signer address, session management that maps verified wallet addresses to application sessions, and multi-chain support for Ethereum, Solana, and other blockchain networks. The skill enables developers to build passwordless authentication flows where wallet ownership serves as the identity credential.

Who Should Use This

This skill serves Web3 developers building decentralized applications with wallet login, teams adding blockchain-based authentication to existing platforms, and engineers implementing Sign-In with Ethereum or similar standards.

Why Use It?

Problems It Solves

Traditional username-password authentication does not apply to decentralized applications where users are identified by wallet addresses. Verifying wallet ownership requires cryptographic signature validation that differs across blockchain networks. Session management must map ephemeral wallet connections to persistent server sessions. Replay attacks can exploit signed messages without proper nonce and expiration handling.

Core Highlights

Wallet connection detects installed providers and requests account access. Message signing creates verifiable proof of address ownership without exposing private keys. Server verification recovers the signer address from the signature to confirm identity. Session binding links verified addresses to authenticated sessions with expiration.

How to Use It?

Basic Usage

import { ethers } from 'ethers';

// Client: request wallet signature
async function requestSignature() {
  const provider =
    new ethers.BrowserProvider(
      window.ethereum);
  const signer =
    await provider.getSigner();
  const address =
    await signer.getAddress();

  // Get challenge from server
  const res = await fetch(
    `/api/auth/challenge?`
    + `address=${address}`);
  const { message } =
    await res.json();

  // Sign the challenge
  const signature =
    await signer.signMessage(message);

  // Send signature to server
  const authRes = await fetch(
    '/api/auth/verify', {
      method: 'POST',
      headers: { 'Content-Type':
        'application/json' },
      body: JSON.stringify({
        address, message,
        signature }),
    });
  return authRes.json();
}

Real-World Examples

import { ethers } from 'ethers';
import jwt from 'jsonwebtoken';

// Server: generate challenge
const nonces = new Map<
  string, string>();

function generateChallenge(
  address: string
): string {
  const nonce =
    crypto.randomUUID();
  nonces.set(
    address.toLowerCase(), nonce);
  return [
    'Sign this message to',
    'authenticate with MyApp.',
    `Nonce: ${nonce}`,
    `Issued: ${new Date()
      .toISOString()}`,
  ].join('\n');
}

// Server: verify signature
function verifySignature(
  address: string,
  message: string,
  signature: string
): { token: string } | null {
  const recovered = ethers
    .verifyMessage(
      message, signature)
    .toLowerCase();

  if (recovered !==
      address.toLowerCase()) {
    return null;
  }

  const storedNonce = nonces.get(
    address.toLowerCase());
  if (!message.includes(
      storedNonce ?? '')) {
    return null;
  }

  nonces.delete(
    address.toLowerCase());

  const token = jwt.sign(
    { address: recovered },
    process.env.JWT_SECRET!,
    { expiresIn: '24h' });

  return { token };
}

Advanced Tips

Implement EIP-4361 Sign-In with Ethereum for a standardized message format that wallets can parse and display. Use nonces with short expiration times to prevent replay attacks where old signatures are reused. Support multiple wallet providers with a connector abstraction that normalizes the signing interface.

When to Use It?

Use Cases

Build a decentralized application login that authenticates users by wallet signature without passwords. Create a token-gated platform where access requires proof of NFT or token ownership. Implement a multi-chain authentication flow supporting both Ethereum and Solana wallets.

Related Topics

Blockchain authentication, digital signatures, Web3 login, EIP-4361, and session management.

Important Notes

Requirements

Ethers.js or a similar library for signature verification. A browser wallet extension such as MetaMask for client-side signing. Server-side JWT or session library for managing authenticated sessions.

Usage Recommendations

Do: generate unique nonces per authentication attempt to prevent signature replay. Verify signatures server-side rather than trusting client-reported addresses. Include timestamps in challenge messages to limit signature validity windows.

Don't: store signed messages as permanent credentials since they should be single-use. Skip nonce validation which opens the door to replay attacks. Assume all wallets support the same signing interface without provider detection.

Limitations

Wallet authentication requires users to have a browser wallet extension installed. Signature formats differ across blockchain networks requiring chain-specific verification logic. Users unfamiliar with wallet signing may find the authentication flow confusing compared to traditional login.