Multi-signature (Multisig)
Wallet requiring multiple private keys to approve a transaction.
Multisig (multi-signature) is a security model where a transaction requires signatures from multiple private keys before it can be executed — eliminating "single point of failure".
Format: M of N
•2 of 3: requires 2 of 3 keys (most commonly used)
•3 of 5: requires 3 of 5 keys (corporate level)
Usage:
•Joint funds — prevents one team member from spending everything
•Personal backup — 3 keys at 3 physical locations, 2 needed for transaction
•Exchange custody — institutions keep 2 of 3 keys offline
Implementations:
•Bitcoin native multisig (P2SH, P2WSH)
•Safe (Gnosis Safe) — most widespread on Ethereum, $100+ billion TVL
•Casa, Unchained Capital — multisig services for private users
Downside: more complicated to set up and use than standard wallet.