Action: Spend

The Spend action allows a user to spend a note, adding to the transactions-value balance. The action contains the following fields.

• body — the body of the spend, containing the balance commitment, nullifier, and randomized verification key

• auth_sig — the signature to be verified by the randomized verification key

• proof — a zero-knowledge proof to verify that the supplied balance commitment, nullifier, verification key, and transactions anchor are valid

Spend::check_stateless verifies the spend auth signature and that the supplied proof matches the public inputs.

Spend::check_stateful checks that the nullifier has not been used before (also see ref↗).

Spend::execute will add the supplied note payload into the state commitment tree and emit an event.