rich1.0Matt Corallo [ARCHIVE] (npub1e4…jxmcu)https://yabu.me/npub1e46n428mcyfwznl7nlsf6d3s7rhlwm9x3cmkuqzt3emmdpadmkaqqjxmcunjumphttps://yabu.me📅 Original date posted:2021-03-15 📝 Original message:There have been many threads on this before, I'm not sure anything new has been brought up here. Matt On 3/15/21 17:48, Luke Dashjr via bitcoin-dev wrote: > I do not personally see this as a reason to NACK Taproot, but it has become > clear to me over the past week or so that many others are unaware of this > tradeoff, so I am sharing it here to ensure the wider community is aware of > it and can make their own judgements. Note that this is most definitely *not* news to this list, eg, Anthony brought it up in "Schnorr and taproot (etc) upgrade" and there was a whole thread on it in "Taproot: Privacy preserving switchable scripting". This issue has been beaten to death, I'm not sure why we need to keep hitting the poor horse corpse. > > In short, Taproot loses an important safety protection against quantum. > Note that in all circumstances, Bitcoin is endangered when QC becomes a > reality, but pre-Taproot, it is possible for the network to "pause" while a > full quantum-safe fix is developed, and then resume transacting. With Taproot > as-is, it could very well become an unrecoverable situation if QC go online > prior to having a full quantum-safe solution. This has been discussed ad nauseam, and it all seems to fall apart once its noted just how much Bitcoin could be stolen by any QC-wielding attacker due to address reuse. Ultimately, no "pause" can solve this issue, and, if we learned about a QC attacker overnight (instead of slowly over time), there isn't anything that a non-Taproot Bitcoin could do that a Taproot Bitcoin couldn't. > Also, what I didn't know myself until today, is that we do not actually gain > anything from this: the features proposed to make use of the raw keys being > public prior to spending can be implemented with hashed keys as well. > It would use significantly more CPU time and bandwidth (between private > parties, not on-chain), but there should be no shortage of that for anyone > running a full node (indeed, CPU time is freed up by Taproot!); at worst, it > would create an incentive for more people to use their own full node, which > is a good thing! This is untrue. The storage space required for Taproot transactions is materially reduced by avoiding the hash indirection. > Despite this, I still don't think it's a reason to NACK Taproot: it should be > fairly trivial to add a hash on top in an additional softfork and fix this. For the reason stated above, i think such a fork is unlikely. > In addition to the points made by Mark, I also want to add two more, in > response to Pieter's "you can't claim much security if 37% of the supply is > at risk" argument. This argument is based in part on the fact that many > people reuse Bitcoin invoice addresses. > > First, so long as we have hash-based addresses as a best practice, we can > continue to shrink the percentage of bitcoins affected through social efforts > discouraging address use. If the standard loses the hash, the situation > cannot be improved, and will indeed only get worse. I truly wish this were the case, but we've been beating that drum for at least nine years and still haven't solved it. Worse, there's a lot of old coins that are unlikely to move any time soon that are exposed whether we like it or not. > Second, when/if quantum does compromise these coins, so long as they are > neglected or abandoned/lost coins (inherent in the current model), it can be > seen as equivalent to Bitcoin mining. At the end of the day, 37% of supply > minable by QCs is really no different than 37% minable by ASICs. (We've seen > far higher %s available for mining obviously.) Except its not? One entity would be able to steal that entire block of supply rather quickly (presumably over the course of a few days, at maximum), instead of a slow process with significant upfront real-world cost in the form of electricity.