Chapter 22: Crypto Custody, Privacy Cryptography & Web3 Security

Web3 security combines controls across private keys, proofs, smart contracts, oracles, and interoperability. This chapter explains how those trust boundaries execute, where they fail, and how a multi-tenant financial platform contains the resulting risk.

• 22.1 Key Management: HSMs, MPC Wallets, HD Wallet Derivation, Hot/Cold/Warm Architecture, Hardware Wallet Integration
• 22.2 Zero-Knowledge Proofs & Privacy Computation: zk-SNARKs/STARKs, ZK-Rollups, Privacy-Preserving KYC, Private Set Intersection (PSI), and Garbled Circuits
• 22.3 Smart Contract Security: Reentrancy, Formal Verification, Audits, Proxy/Upgrade Patterns
• 22.4 Cross-Chain Infrastructure: Bridges, Oracle Networks, Interoperability Protocols
• Chapter 22 References