User Activated Soft Fork Split Protection

Summary:

James Hilliard, a Bitcoin developer, has proposed a new option called "splitprotection" that miners can use to prevent a chain split ahead of the BIP148 activation date. The soft fork would be essentially BIP91 but using BIP8 instead of BIP9 with a lower activation threshold and immediate mandatory signalling lock-in. Miners would be able to respond to market forces quickly ahead of BIP148 activation by signalling for split protection.Any miners already running BIP148 should be encouraged to use splitprotection. This BIP provides a way for a simple majority of miners to coordinate activation of the existing segwit deployment with less than 95% hashpower before BIP148 activation. Due to time constraints unless immediately deployed BIP91 will likely not be able to enforce mandatory signaling of segwit before the Aug 1st activation of BIP148.Jared Lee Richardson has raised concerns that this BIP represents a gamble, which may not be a good one. The biggest risk of BIP148 is an extended chain split, this BIP provides a way for a simple majority of miners to eliminate that risk. There are two primary factors involved here, economic support and hash power, either of which is enough to make a permanent chain split unlikely. Miners will mine whichever chain is most profitable. However, there may be lag time immediately after the split if there is an economic majority but not a hash power majority initially. This is risk mitigation that only requires miners support however. The main issue is just one of activation timelines, BIP91 as is takes too long to activate unless started ahead of the existing segwit2x schedule. The splitprotection BIP allows miners to signal their intention to run BIP148 in order to prevent a chain split. Rather than encourage it, it may strengthen an extreme minority chainsplit that may wind up on the wrong side of two segwit-activated chains. If Core had taken a strong stance to include BIP148 into the client, and if BIP148 support were much much broader, it would be a more dangerous attempt to compromise with a small but vocal group that are the ones creating the threat to begin with.Jared Lee Richardson has suggested an optional flag for risk mitigation measures which could signal on a different bit than bit4 so that miners can have a more standard approach to activation that requires stronger consensus and may be more forgiving than BIP148. The split-protection soft fork is a method to lower the signaling threshold of a soft fork, while it is in the process of being deployed in a backwards-compatible way. The technique is used to activate the existing "segwit" deployment without needing to release a new deployment by orphaning non-signalling blocks during the BIP9 bit 1 "segwit" deployment. The deployment is compatible with the existing "segwit" bit 1 deployment scheduled between midnight November 15th, 2016 and midnight November 15th, 2017, and also with the existing BIP148 deployment. However, miners will need to upgrade their nodes to support split-protection; otherwise, they may build on top of an invalid block.During the deployment, if a relayed block does not signal for segwit, it must upgrade or risk rejection as an invalid block. Users should either upgrade to split-protection or wait for additional confirmations when accepting payments. A majority of miners may find it desirable to have a method that ensures there is no chain split as we approach BIP148 activation. The split-protection soft fork is compatible with BIP91 only if BIP91 activates before it and before BIP148. The deployment uses a BIP8 style timeout to ensure that the BIP is compatible with BIP148 and that BIP148 compatible mandatory signalling activates regardless of miner signalling levels.This document is dual licensed as BSD 3-clause, and Creative Commons CC0 1.0 Universal. References for this deployment include mailing list discussions, P2SH flag day activation, BIP9 version bits with timeout and delay, BIP16 Pay to Script Hash, BIP91 Reduced threshold Segwit MASF, BIP141 Segregated Witness (Consensus layer), BIP143 Transaction Signature Verification for Version 0 Witness Program, BIP147 Dealing with dummy stack element malleability, BIP148 Mandatory activation of segwit deployment, and BIP149 Segregated Witness (second deployment). The benefits of segwit are also highlighted in this document.

Updated on: 2023-06-12T01:50:48.830796+00:00