Roadmap › Blockchain & Web3 Fundamentals › Module: Building dApps
Lessons in this course (15)
14. Wallets, custody and Web3 authentication
Intermediate★ Must knowLesson 14 of 15
- Custodial wallets (exchange holds keys — e.g. centralised exchanges) vs non-custodial (user holds keys — MetaMask, hardware wallets). "Not your keys, not your coins."
- Hot (online) vs cold (offline, hardware/air-gapped) storage; multisig (Safe: M-of-N signatures) for treasuries; MPC wallets split keys across parties.
- Sign-In with Ethereum (SIWE, ERC-4361): backend issues a nonce → user signs a structured message → backend verifies the signature recovers the address → issues a session/JWT. No passwords; protects against replay with nonce, domain and expiry.
- EIP-712 typed structured data signing — human-readable signatures for permits/orders.