Multi-signature, or multisig, is a wallet control that requires two or more independent approvals before funds can be moved. Instead of one private key authorizing a transfer, several keys held by different people or systems must sign the transaction. A common setup is 2-of-3, where any two of three approved signers can complete the payment.
In cyber security, multisig reduces the impact of a stolen key, a compromised admin account, or a rushed insider action. Attackers who breach one machine or one credential still cannot spend funds alone. Defenders use multisig in exchange custody, treasury management, and high-value approval workflows to slow down unauthorized transfers and create audit trails. It is strongest when signer keys are separated across devices, locations, and roles, and when signing requests are monitored for unusual timing, amounts, or destinations.