multisig

An m-of-n multisig in ~120 lines of Solidity: owners submit, confirm, and execute transactions once the threshold is reached.

A multisig replaces "one private key holds the treasury" with "m of n keys must agree". This is the minimal useful version, written to be readable rather than feature-complete.

Model

• submit(target, value, data) records a transaction and auto-confirms it for the proposer, returning a txId.
• confirm(txId) / revoke(txId) add or remove an owner's confirmation.
• execute(txId) runs the call once confirmations >= threshold. It is callable by anyone, which is normal: the value has already been authorised.
• addOwner / removeOwner manage the owner set; removal is blocked if it would leave fewer owners than the threshold.

One owner has at most one live confirmation per transaction, enforced by the confirmedBy mapping rather than by convention.

What it deliberately does not do

• No off-chain signature collection. Every confirmation is an on-chain transaction. Real deployments usually add EIP-712 signatures so approvals can be gathered for free and submitted in one go.
• No reentrancy guard. The transaction is marked executed before the external call, and there is no callback into the multisig's own state, but if you add features that re-enter, add a guard.
• No daily limits, no guardian, no upgrade path. Those are policy decisions and belong in the layer above this contract.

Development

forge install foundry-rs/forge-std
forge test -vvv

License

MIT