Author: Antoine Riard 2021-12-19 18:55:01
Published on: 2021-12-19T18:55:01+00:00
In a Bitcoin Core developer mailing list, Antoine Riard proposes the deprecation of opt-in Replace-by-Fee (RBF) in favor of full-RBF as the default replacement policy. The rationale for this proposal is to mitigate the risk of denial-of-service (DoS) attacks on multi-party funded transactions enabled by RBF opt-out. A malicious counterparty can broadcast its low-feerate, opt-out spending of its own collateral input far before engaging in cooperative funding, leading to a DoS. Opt-in RBF doesn't suit deployment of robust second-layer protocols; as those issues are still early, they deserve more research. The current state of discussion is to introduce a `fullrbf` config-knob turned to false. Jeremy Rubin suggests easing into getting rid of full-RBF by keeping the flag working but making enforcement of non-replaceability something that happens n seconds after first seen, reducing the ability to partition mempools by broadcasting irreplaceable conflicts all at once. This approach introduces an overhead cost in the funding of multi-party transactions as collateral inputs have to be sanitized by sending them first to a replaceable nVersion output.Opt-in RBF is also a low-cost partitioning tool, and its existence nullifies most potential progress to mitigate malicious partitioning. To enhance the security of 0-confs, Bitcoin services could react after detecting successful double-spend attempts by attaching a CPFP to the merchant transaction or slash the service account if the sender is already known to the service provider. Other approaches include "side-trust" models and economic reputation-based compensations. Overall, the conversation highlights how a transaction relay/mempool acceptance policy might be beneficial to some class of deployed Bitcoin applications while being detrimental to newer ones, and preserving the interests of 0-confs users while enabling upcoming interests of fancy L2s to flourish is a good conversation to have.
Updated on: 2023-06-14T22:36:13.761915+00:00