Subject: Re: [bitcoin-dev] BIP proposal: Inhibiting a covert attack on the Bitcoin POW function

From: David Vorick <[email-masked]>
Date: Wed, 5 Apr 2017 23:23:22 -0400

I have a practical concern related to the amount of activation energy
required to get something like this through. We are talking about
implementing something that would remove tens to hundreds of millions of
dollars of mining revenue for miners who have already gambled that this
income would be available to them.

That's not something they are going to let go of without a fight, and we've
already seen this with the segwit resistance. Further, my understanding is
that this makes a UASF a lot more difficult. Mining hardware that has
unique optimizations on one chain only can resist a UASF beyond a simple
economic majority, because they can do more hashes on the same amount of
revenue. Threshold for success is no longer 51%, especially if you are
expecting the miners to struggle (and this is a case where they have a very
good reason to struggle). Any resistance from the hashrate during the early
days of a UASF will inevitably cause large reorgs for older nodes, and is
not much better than a hardfork.

I don't know what the right answer is. But I know that we are not going to
get segwit without a fight. We are not going to invalidate covert asicboost
without a fight. And we are working with a system that actively (and is
demonstrably very effective at doing it) resists changes which are
contentious. This is definitely a contentious change, because an important
part of the community (the miners) is going to be actively resisting it.

I urge everybody to realize how difficult something like this is going to
be to pull off. We are literally talking about invalidating hardware (or at
least the optimized bits). It's only going to succeed if everybody is
conclusively on board. As you consider proposals, realize that anything
which is not the simplest and least contentious is already dead.