Crypto Wallet Engineering

A crypto wallet is software or hardware that manages private keys (cryptographic secrets) and enables signing transactions (approving transfers of coins). When you send Bitcoin, the wallet signs with your private key to prove you own those coins. Wallet types: custodial (Coinbase holds your keys), non-custodial (you hold your keys), hardware (offline device), hot (connected to internet), cold (offline storage). Each has tradeoffs: convenience vs security.