From: Ali Sherief <ali@notatether•com>
To: Pieter Wuille <bitcoin-dev@wuille•net>
Cc: "bitcoin-dev@lists•linuxfoundation.org"
<bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] Zero-knowledge proofs e.g. Schnorr are incompatible with address signing without compromise
Date: Thu, 28 Jul 2022 15:51:18 +0000 [thread overview]
Message-ID: <ltMy8y1N-J_DQ0rQiKcb1fkiBkd9PcLX6B4W_TZ6i7bdmNWQMXJ0h2fet6DFKvllyH0QNzzVnqMpxT3vMgxdwJKOfsUKf8lS5P5sTC4-3j8=@notatether.com> (raw)
In-Reply-To: <BQZI2zpZwzJcXi_Gxr0f1wg9ZD6U5nb0HTOfIu4i50nM6FqFNqFjfm4DbOIxg94IwZQ4pHAthUNeGUkwHENJwAhap-bIkuKRN8ErZyFeR-o=@wuille.net>
> Yes, that's an intentional design choice in BIP340, see note 5: https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki#cite_ref-5-0. The choice is either batch verifiability or public key recovery.
The way I understood the BIP, was that a user can do batch recovery or single-key recovery. Can you explain how it is possible to recover a public key from a single-key signature, because a few days earlier on the BIP-notatether-messageverify thread I was told (I think it was achow) that Schnorr doesn't allow for public key recovery.
At any case, I was already planning on just concatenating the public key after the signature (the other option I was thinking of, appending it after the Taproot address, is quite unruly in my opinion).
> I think it would be much better if people would cooperate to get BIP322 to move forward than to keep inventing other formats. It's the obvious solution in my opinion: not restricted to single-key policies, compatible with every script type, and trivially extensible to future schemes.
This is why I especially tried to avoid making a new format - My BIP is strictly an Informational one. That strategy worked pretty well up to now, but now I find myself forced to make a small concession in the design to support the verification of Taproot address. But I'm glad it's quite trivial as appending a single variable. So at least this BIP won't be an obstacle to any such effort.
[Besides, since I'm also planning on detecting BIP137 in the verification methods, I can assume the Signature field contains arbitrary data.]
> > , just like BIP340).
>
>
> How so? Every taproot compatible wallet has a BIP340 implementation.
I guess I made an assumption, since almost all of the wallets I have seen did not have a sign message feature, not even for legacy addresses.
- Ali
------- Original Message -------
On Thursday, July 28th, 2022 at 3:27 PM, Pieter Wuille <bitcoin-dev@wuille•net> wrote:
> ------- Original Message -------
> On Thursday, July 28th, 2022 at 3:27 AM, Ali Sherief via bitcoin-dev bitcoin-dev@lists•linuxfoundation.org wrote:
>
> > Essentially, zero-knowledge proofs such as Schnorr are not compatible with address message signing - the public key cannot be retrieved from the address or the signature, so the address does not actually prove the authenticity of a Schnorr signature. That's why the public key is required as an input in the first place.
>
>
> Yes, that's an intentional design choice in BIP340, see note 5: https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki#cite_ref-5-0. The choice is either batch verifiability or public key recovery.
>
> I regret ever using public key recovery when introducing the old legacy message signing scheme. It should just have used script signatures like BIP322 proposes.
>
> > In order to make it compatible with the address signing mechanism, the zero-knowledge part would have to be sacrificed in my BIP, or else a completely separate message signing format just for Taproot would be required
>
>
> You can avoid relying on public key recovery, and include the public key + BIP340 signature in the encoded signature.
>
> > (which, in my view, is redundant - there is already the draft BIP322 which can verify anything and everything, but nobody is implementing that
>
>
> I think it would be much better if people would cooperate to get BIP322 to move forward than to keep inventing other formats. It's the obvious solution in my opinion: not restricted to single-key policies, compatible with every script type, and trivially extensible to future schemes.
>
> > , just like BIP340).
>
>
> How so? Every taproot compatible wallet has a BIP340 implementation.
>
> Cheers,
>
> --
> Pieter
next prev parent reply other threads:[~2022-07-28 15:51 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-28 7:27 Ali Sherief
2022-07-28 15:27 ` Pieter Wuille
2022-07-28 15:51 ` Ali Sherief [this message]
2022-07-28 15:58 ` Pieter Wuille
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