Willow's sync protocols require a tree hash (Bab), so each chunk is verified on arrival and a partial payload is a verified partial.

It removes the attack of sending garbage until the end, and it makes relaying partial data safe.

A payload can be large. The entry holds its digest, so you can check it when it arrives.

With an ordinary hash, you check only at the end. A bad peer could send gigabytes of garbage first.

Willow's sync protocols require a tree hash, called Bab. The payload is cut into chunks, and the digest covers the tree.

Each chunk is checked as it arrives, against the digest you already hold. Bad data is caught early, not at the end.

A half received payload is a verified half. You can pass it on, or stop, and lose nothing.

Check yourself. At which chunk is garbage detected?