This is a best effort cancellation, and might not prevent solvers from settling the orders (if the order is part of an in-flight settlement transaction for example). Authentication must be provided by an EIP-712 signature of an OrderCancellations(bytes[] orderUids) message.
Signed OrderCancellations.
EIP-712 signature of struct OrderCancellations { orderUid: bytes[] } from the order's owner.
OrderCancellation signed by the owner.
"0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
How was the order signed?
eip712, ethsign Up to 128 UIDs of orders to cancel.
Unique identifier for the order: 56 bytes encoded as hex with 0x
prefix.
Bytes 0..32 are the order digest, bytes 30..52 the owner address and
bytes 52..56 the expiry (validTo) as a uint32 unix epoch timestamp.
Order(s) are cancelled.