RE BIP 300: 26% censoring attack

The security dynamics of Bitcoin Improvement Proposal (BIP) 300 are currently facing potential risks due to the ability for attackers to manipulate bundle scores through ALARM messages. An attacker possessing a 26% stake can indefinitely censor BIP 300 bundles by reducing their score in each block where an ALARM message is sent. This manipulation makes it challenging for a bundle to achieve the necessary score of 13,150 within the 26,300 block window, given that the expected score increase per block is only 0.48, resulting in an anticipated total score of 12,624.

To address this vulnerability, it's proposed that ALARM messages or any form of downvoting should be prohibited. This change would support reverting to the honest majority security assumption where a proposal with at least 51% backing is almost guaranteed to succeed, while one with less than 49% support will likely fail. The current scenario deviates significantly from Bitcoin's standard security model, which traditionally operates under the 50% honest majority assumption. A modification to align with a 75% honest majority assumption could be considered if the intention is to enhance security against attackers with less than 75% of the hashrate attempting fund theft.

These suggested changes aim to fortify the integrity of the drivechain process and ensure fair and secure transaction verifications in line with Bitcoin's overarching security principles.