From: Rusty Russell <rusty@rustcorp.com.au>
To: Johnson Lau <jl2012@xbt.hk>,
	bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org>
In-Reply-To: <F8C553EE-9AF5-4348-90B7-3EC55FC46B4C@xbt.hk>
References: <87po25lmzs.fsf@rustcorp.com.au>
	<F8C553EE-9AF5-4348-90B7-3EC55FC46B4C@xbt.hk>
Date: Thu, 10 May 2018 11:36:41 +0930
Message-ID: <87bmdoe026.fsf@rustcorp.com.au>
MIME-Version: 1.0
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Subject: Re: [bitcoin-dev] Making OP_TRUE standard?
Precedence: list

Johnson Lau <jl2012@xbt.hk> writes:
> You should make a =E2=80=9C0 fee tx with exactly one OP_TRUE output=E2=80=
=9D standard, but nothing else. This makes sure CPFP will always be needed,=
 so the OP_TRUE output won=E2=80=99t pollute the UTXO set

That won't propagate :(

> Instead, would you consider to use ANYONECANPAY to sign the tx, so it
> is possible add more inputs for fees? The total tx size is bigger than
> the OP_TRUE approach, but you don=E2=80=99t need to ask for any protocol
> change.

No, that would change the TXID, which we rely on for HTLC transactions.

> In long-term, I think the right way is to have a more flexible SIGHASH sy=
stem to allow people to add more inputs and outputs easily.

Agreed:
https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2018-April/015862.h=
tml

But in the long term we'll have Eltoo and SIGHASH_NOINPUT which both
allow different solutions.

Cheers,
Rusty.