Threshold signing
Threshold signing is how SQRL Enterprise enforces multi-party control. It works the same way for every movement, every asset deployment and every enforcement action.
When an action is submitted from a vault, each of the vault's signers is notified. Each signer reviews the action and signs with their software key, Trezor or HSM. When the number of signatures reaches the vault's threshold, the transaction is finalised and broadcast automatically.
The final signature is the point of no return
There is no confirmation step after the threshold is met. The transaction is broadcast immediately and cannot be cancelled. Review every detail before you sign.
If a vault is 2-of-3, two signatures are enough. A third is not needed.
#What enforces the threshold
- Bitcoin. The vault's script requires M valid signatures from its listed keys. A transaction that falls short is rejected by the network.
- The asset contract. For the assets a vault administers, the contract accepts admin calls only from a transaction that spends the vault's coins, so asset control has the same quorum.
- Maker-checker. The operator who proposed the action cannot count as one of its approvers.
Key takeaway
The threshold is enforced by Bitcoin's script, not just by SQRL's policy. No single signer can move a vault's value, and SQRL cannot move it for them.