lightning-dev

Waiting SIGHASH_ANYPREVOUT and Packing Packages

Waiting SIGHASH_ANYPREVOUT and Packing Packages

Original Postby Antoine Riard

Posted on: June 24, 2021 13:03 UTC

Antoine Riard and Michael Folkson recently discussed the challenges of roadmaps in decentralized ecosystems like Bitcoin.

They agreed that it is important to discuss changes, but putting specific future version numbers on changes is speculative at best and misleading at worst. The conversation also touched on the challenge of coordinating across different Bitcoin layers, and the concern of layer-monoculture cropping up in the ecosystem.In an email thread on the Lightning-dev mailing list, Antoine Riard proposed two potential solutions to the pre-signed feerate problem: package-relay or SIGHASH_ANYPREVOUT. The discussion included considerations related to fee-bumping algorithms, mempool policies, and L2 protocols. Riard emphasized the importance of addressing safety holes and the potential harm of inaction, as well as the importance of an open exchange of ideas and a hacker ethos. Links to related discussions and issues on GitHub were provided throughout the thread.The Lightning Network is exploring solutions to the pre-signed feerate issue, with package-relay and SIGHASH_ANYPREVOUT being potential options. While the latter has been discussed during LN meetings, there isn't a clear understanding of how it can solve pinnings beyond those logs. One concern is that if Bitcoin Core rewrites the blind CPFP fee bump transaction to refer to any prevout, other miners could do the same and incentivize rewriting to the oldest state. This could lead to an attacker reusing their attack at no cost and forcing the honest user to pay another anyprevout bounty to miners. However, package-relay is seen as a reasonable temporary patch and a clear improvement for low feerate transactions received from external parties.Regarding deployment timelines, creating them without consulting the large number of contributors working on the project seems inappropriate. This sentiment was expressed in a post on the Bitcoin-dev mailing list. Ultimately, things will get done when they get done. The conversation between Riard and Folkson highlighted the need for ongoing discussion and collaboration across various contributors to make progress in decentralized ecosystems like Bitcoin.