Brollup emulates covenants through a Musig-nested-NOIST protocol, relying on pre-signed signatures produced during highly interactive signing sessions.

A major drawback of interactive signing sessions is the vulnerability to denial of service (DoS) attacks. Protocols like Coinjoins, Ark, and Brollup (as an Ark variant) require participants to commit to signing transactions. If a participant fails to uphold their commitment, they are blacklisted, and the entire signing session must be restarted.