Subject: Re: [bitcoin-dev] Speedy Trial

From: "Russell O'Connor" <[email-masked]>
Date: Fri, 11 Mar 2022 08:47:14 -0500

On Fri, Mar 11, 2022 at 7:18 AM Jorge Timón <[email-masked]> wrote:

> I talked about this. But the "no-divergent-rules" faction doesn't like it,
> so we can pretend we have listened to this "faction" and addressed all its
> concerns, I guess.
> Or perhaps it's just "prosectution complex", but, hey, what do I know
> about psychology?
>

Your accusations of bad faith on the part of myself and pretty much
everyone else makes me disinclined to continue this discussion with you.
I'll reply, but if you want me to continue beyond this, then you need to
knock it off with the accusations.

> A major contender to the Speedy Trial design at the time was to mandate
>> eventual forced signalling, championed by luke-jr.  It turns out that, at
>> the time of that proposal, a large amount of hash power simply did not have
>> the firmware required to support signalling.  That activation proposal
>> never got broad consensus, and rightly so, because in retrospect we see
>> that the design might have risked knocking a significant fraction of mining
>> power offline if it had been deployed.  Imagine if the firmware couldn't be
>> quickly updated or imagine if the problem had been hardware related.
>>
>
> Yes, I like this solution too, with a little caveat: an easy mechanism for
> users to actively oppose a proposal.
> Luke alao talked about this.
> If users oppose, they should use activation as a trigger to fork out of
> the network by invalidating the block that produces activation.
> The bad scenario here is that miners want to deploy something but users
> don't want to.
> "But that may lead to a fork". Yeah, I know.
> I hope imagining a scenario in which developers propose something that
> most miners accept but some users reject is not taboo.
>

This topic is not taboo.

There are a couple of ways of opting out of taproot.  Firstly, users can
just not use taproot.  Secondly, users can choose to not enforce taproot
either by running an older version of Bitcoin Core or otherwise forking the
source code.  Thirdly, if some users insist on a chain where taproot is
"not activated", they can always softk-fork in their own rule that
disallows the version bits that complete the Speedy Trial activation
sequence, or alternatively soft-fork in a rule to make spending from (or
to) taproot addresses illegal.

As for mark, he wasn't talking about activation, but quantum computing
> concerns. Perhaps those have been "addressed"?
> I just don't know where.
>

Quantum concerns were discussed.  Working from memory, the arguments were
(1) If you are worried about your funds not being secured by taproot, then
don't use taproot addresses, and (2) If you are worried about everyone
else's funds not being quantum secure by other people choosing to use
taproot, well it is already too late because over 5M BTC is currently
quantum insecure due to pubkey reuse <
https://nitter.net/pwuille/status/1108091924404027392>.  I think it is
unlikely that a quantum breakthrough will sneak up on us without time to
address the issue and, at the very least, warn people to move their funds
off of taproot and other reused addresses, if not forking in some quantum
secure alternative.  A recent paper <
https://www.sussex.ac.uk/physics/iqt/wp-content/uploads/2022/01/Webber-2022.pdf>
suggest that millions physical qubits will be needed to break EC in a day
with current error correction technology.  But even if taproot were to be
very suddenly banned, there is still a small possibility for recovery
because one can prove ownership of HD pubkeys by providing a zero-knowledge
proof of the chaincode used to derive them.