Brollup v2, Now Without The Trusted Setup

Brollup v2 introduces a new state channel design and eliminates the need for a trusted setup by making the global state statechannel-aware. The core idea is to execute payable conditions based on state updates rather than creating new VTXOs. This decouples finality from block production and ties it directly to state updates.

This is similar to the Lightning Network; however, Lightning operates in a 2-of-2 setting, where only the involved parties are aware of the channel’s state. The channel state remains private, with outsiders gaining limited information only in the event of a force closure.

The strategy involves making channel states publicly accessible to everyone at all times. By publicly exposing channel content and ensuring accessibility at the DA layer, the global state becomes aware of individual channel states. Implementing this for all channels enables our Bitcoin Virtual Machine to verify payments between specific channels and execute payable conditions accordingly.

While one might expect storing channel content in the DA to consume a significant number of bytes, this isn’t the case! Brollup v2 employs an efficient approach where the only overhead comes from an 8 vByte signature commitment s by the operator. All other channel content can be derived from the calldata field outlined in my earlier announcement.