Date: Fri, 11 Aug 2023 07:38:13 +0000
To: Tobin Harding <me@tobin.cc>, "bitcoin-dev@lists.linuxfoundation.org"
 <bitcoin-dev@lists.linuxfoundation.org>
From: symphonicbtc <symphonicbtc@proton.me>
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Subject: Re: [bitcoin-dev] segwit naming ambiguity
Precedence: list

Transactions should be considered segwit if they match the witness program =
structure of "A scriptPubKey (or redeemScript as defined in BIP16/P2SH) tha=
t consists of a 1-byte push opcode (for 0 to 16) followed by a data push be=
tween 2 and 40 bytes" as defined in [BIP141](https://github.com/bitcoin/bip=
s/blob/master/bip-0141.mediawiki#witness-program). This would return true f=
or version 0 segwit outputs as well as version 1 taproot outputs.

I would propose a different function for differentiating v0 vs taproot scri=
pts. Bitcoin core uses an [enum](https://github.com/bitcoin/bitcoin/blob/ma=
ster/src/script/standard.h#L51), of which you can use something similar. Co=
re also uses a different [enum](https://github.com/bitcoin/bitcoin/blob/mas=
ter/src/outputtype.h) for wallet logic, but it has a highly confusing namin=
g scheme which imo should be avoided.

Additionally, witness programs nested inside P2SH need to be considered. Th=
e context in which these are interpreted depends on whether or not they sho=
uld be differentiated from other P2SH, as is shown with the 2 separate enum=
s from core. It is possible that this would cause some ambiguity, and it sh=
ould be explicitly documented how such functions would return for different=
 types of programs. These nested programs should technically also be consid=
ered segwit for a simple `is_segwit`, as they have segregated witness data.

v0 is the most common way of referring to version 0 segwit.

Symphonic


------- Original Message -------
On Friday, August 11th, 2023 at 4:45 AM, Tobin Harding via bitcoin-dev bitc=
oin-dev@lists.linuxfoundation.org wrote:

> Question for OG bitcoin API designers please.
>
> If you were to see the following function
>
> `is_segwit()`
>
> would you assume it returns `true` or `false` for a p2tr transaction?
>
> Currently we (rust-bitcoin) are being liberal with the use of `v0` but
> its a pretty ugly. Is there an official, or widely used, name for segwit =
v0?
>
> Thanks,
> Tobin.
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev