I’m sorry you couldn’t find anyone to debate Sztorc. Listening now.

What BIP300 boils down to, as Sztorc said in the interview, is a peg-in/peg-out mechanism. My main problem is with the peg-out. Sztorc repeatedly says, and said in the interview, that there’s no downside. I disagree. The downside is increased incentives for miner centralization and politicization.

Let me back up this claim. I’m sorry, but it’ll take a few paragraphs. First I’ll explain how the BIP300 peg-out mechanism works, then how it incentivizes centralization.

From the BIP300 abstract:

> In Bip300, txns are not signed via cryptographic key. Instead, they are "signed" by hashpower, over time. Like a big multisig, 13150-of-26300, where each block is a new "signature".

This is the crux of BIP300. Traditional Bitcoin outputs are locked by secrets and unlocked by signed transactions (proof-of-key). For the peg-out process to be decentralized, Drivechain needed a different unlocking mechanism.

Under BIP300, block producers vote with hashrate on which withdrawal requests they support. Bundles with sufficient votes succeed. Bundles with insufficient votes are dropped.

The capabilities of a 51% attacker on mainchain are well known. They can rewrite history, but they can’t steal coins other than writing history all the way back to when those coins were received. They can censor transactions, but this would incentivize competing miners to ramp up as fees increase, etc.

Under BIP300, a 51% attacker gains a new ability. Such an attacker can sweep sidechain escrow. That is, they can propose and then cast all the 13151 votes to withdraw the mainchain locked BTC supporting the peg.

In this scheme, the attacker’s blocks are otherwise normal, valid blocks, taking fees and earning subsidy. That is, the attacker is earning mainchain coin and rolling history forward. No rewriting necessary.

A cohort of mining pools could collaborate to carry out such an attack, without even bringing all the hash together under one controller. To do this: have the withdrawal bundle pay out proportionally to the participating pools. Any block creator can propose such a heist, and everyone’s interest is to play along. Individual miners who want in on the action can then switch their hash to any of the participating pools.

One final note on politicization. Miners today choose pools based on various criteria like fee rate, pool size, payout schedule, payout mechanism (Lightning/on-chain), customer support, privacy, ease-of-use etc. But for the most part, miners are profit-maximizing businesses that choose pools based on profitability.

Under BIP300, there will be a new criterion for choosing pools: how the pool votes. Choosing where to point your hash will become a political choice in addition to an economic one.

I have other concerns about BIP300, but the pressure to centralize and politicize mining is my main one. Thanks for reading. 🙏