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From: Pieter Wuille <bitcoin-dev@wuille.net>
To: Ali Sherief <ali@notatether.com>,
	Bitcoin Protocol Discussion
	<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 15:27:05 +0000	[thread overview]
Message-ID: <BQZI2zpZwzJcXi_Gxr0f1wg9ZD6U5nb0HTOfIu4i50nM6FqFNqFjfm4DbOIxg94IwZQ4pHAthUNeGUkwHENJwAhap-bIkuKRN8ErZyFeR-o=@wuille.net> (raw)
In-Reply-To: <bG2Fk0bM_4lbwijBwZRiGgCAmktVOFSY5vR5k1D7QSc8imn9NWXxfOLPgMl5p22vfAPDHeuEA_p6TDhU7qGFoVmZok57RzA9rEV1LJzHpsM=@notatether.com>

------- 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



  reply	other threads:[~2022-07-28 15:36 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-28  7:27 [bitcoin-dev] Zero-knowledge proofs e.g. Schnorr are incompatible with address signing without compromise Ali Sherief
2022-07-28 15:27 ` Pieter Wuille [this message]
2022-07-28 15:51   ` Ali Sherief
2022-07-28 15:58     ` Pieter Wuille

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