Web3 authentication replaces the traditional username-password model with cryptographic wallet signatures. Users prove ownership of their blockchain address by signing a message with their private key, eliminating the need for password storage, email verification, and centralised identity providers. This model is fundamental to decentralised applications and is increasingly relevant for any platform interacting with blockchain users.
Sign-In with Ethereum (SIWE)
EIP-4361, known as Sign-In with Ethereum, standardises the wallet authentication flow. The process works as follows: the dApp generates a structured message containing the domain, wallet address, statement, nonce, and expiration time. The user signs this message using their wallet (MetaMask, WalletConnect, or similar). The server verifies the signature against the claimed address using ecrecover, validates the nonce to prevent replay attacks, and creates a session. The SIWE standard ensures the message is human-readable so users understand exactly what they are signing. Libraries like siwe and viem handle message creation, parsing, and verification on both client and server.
Session Management
After wallet verification, the server needs to maintain a session. Common approaches include:
- JWT tokens: Issue a signed JWT containing the wallet address and expiration. The token is sent with subsequent requests. Stateless and scalable, but tokens cannot be revoked before expiration without a blocklist.
- Server-side sessions: Store session data in Redis or a database, referenced by a session cookie. Allows immediate revocation and richer session data, at the cost of server-side state.
- Hybrid approach: Use short-lived JWTs for API authentication combined with refresh tokens stored server-side. This balances performance with security.
Multi-Wallet and Multi-Chain Support
Modern dApps need to support multiple wallet providers and blockchain networks. Libraries like wagmi, RainbowKit, and Web3Modal abstract wallet connection handling, providing a unified interface across MetaMask, Coinbase Wallet, WalletConnect-compatible wallets, and hardware wallets. For multi-chain support, the authentication flow must handle chain switching and validate signatures according to each chain's standards. Solana uses a different signing scheme (Ed25519) than Ethereum (secp256k1), so multi-chain auth requires chain-specific verification logic.
UX Considerations
Wallet-based authentication has significant UX challenges. Not every user has a crypto wallet, and the concept of signing a message is unfamiliar to mainstream users. Provide clear onboarding for users without wallets, offer social login as a fallback with optional wallet linking, and explain what the signature request means in plain language. Consider progressive Web3 integration — start with traditional authentication and allow users to connect wallets later for blockchain-specific features. At Born Digital, we design authentication flows that bridge the gap between Web2 familiarity and Web3 capability, ensuring both crypto-native users and newcomers have a smooth experience.