Pieter Wuille [ARCHIVE] on Nostr: 📅 Original date posted:2020-12-21 📝 Original message:On Sunday, December 20, ...
📅 Original date posted:2020-12-21
📝 Original message:On Sunday, December 20, 2020 9:37 PM, Karl-Johan Alm via bitcoin-dev <bitcoin-dev at lists.linuxfoundation.org> wrote:
> Thanks a lot for taking the time to brush up the BIP. For what it's
> worth, I am all for these changes, and I see them as clear
> improvements all around.
>
> IIRC Pieter was the one who originally suggested the two-checks
> approach (invalid, inconclusive, valid) which is being modified here,
> so would be good if you chimed in (or not -- which I'll assume means
> you don't mind).
I agree with the idea of permitting incomplete validators to return inconclusive as well. That doesn't really reduce the functionality (given that "inconclusive" was already a potential result), and it obviously makes it much more accessible to a variety of software.
This suggestion breaks the original use of inconclusive though: the ability to detect that future features are used in the signature. The idea was to use divergence between "consensus valid" and "standardness valid" as a proxy for future extensions to be detected (e.g. OP_NOPn, future witness versions, ...). I think it's undesirable that these things now become unconditionally invalid (until the BIP is updated, but once that happens old validators will give a different result than new ones).
Since the BIP no longer relies on a nebulous concept of standardness, and instead specifically defines which standardness features are to be considered, this seems easy to fix: whenever validation fails due to any of those, require reporting inconclusive instead of invalid (unless of course something actually invalid also happens). In practice I guess you'd implement that (in capable validators) by still doing validation twice, once with all features enabled that distinguish between valid/invalid, and if valid, again but now with the features enabled that distinguish between valid and (invalid or inconclusive).
Cheers,
--
Pieter
📝 Original message:On Sunday, December 20, 2020 9:37 PM, Karl-Johan Alm via bitcoin-dev <bitcoin-dev at lists.linuxfoundation.org> wrote:
> Thanks a lot for taking the time to brush up the BIP. For what it's
> worth, I am all for these changes, and I see them as clear
> improvements all around.
>
> IIRC Pieter was the one who originally suggested the two-checks
> approach (invalid, inconclusive, valid) which is being modified here,
> so would be good if you chimed in (or not -- which I'll assume means
> you don't mind).
I agree with the idea of permitting incomplete validators to return inconclusive as well. That doesn't really reduce the functionality (given that "inconclusive" was already a potential result), and it obviously makes it much more accessible to a variety of software.
This suggestion breaks the original use of inconclusive though: the ability to detect that future features are used in the signature. The idea was to use divergence between "consensus valid" and "standardness valid" as a proxy for future extensions to be detected (e.g. OP_NOPn, future witness versions, ...). I think it's undesirable that these things now become unconditionally invalid (until the BIP is updated, but once that happens old validators will give a different result than new ones).
Since the BIP no longer relies on a nebulous concept of standardness, and instead specifically defines which standardness features are to be considered, this seems easy to fix: whenever validation fails due to any of those, require reporting inconclusive instead of invalid (unless of course something actually invalid also happens). In practice I guess you'd implement that (in capable validators) by still doing validation twice, once with all features enabled that distinguish between valid/invalid, and if valid, again but now with the features enabled that distinguish between valid and (invalid or inconclusive).
Cheers,
--
Pieter