Olaoluwa Osuntokun [ARCHIVE] on Nostr: 📅 Original date posted:2017-08-07 📝 Original message: > I think it does ...

📅 Original date posted:2017-08-07
📝 Original message:
> I think it does already:

Yep! An oversight on my part.

> So, you're suggesting SIGHASH_SINGLE|SIGHASH_ANYONECANPAY?

Precisely. The code modifications required to switch to this signing mode
are
trivial.

> though it's a pretty obscure case where we want to close out many HTLCs at
> once; this is more for fee bumping I think.

Well it's for both. In the case of a commitment transaction broadcast (for
what
ever reason) each party is able to group together HTLC's expiring around the
same height (in the case that the pre-image for a bunch was never revealed.
This leads to less transactions on-chain, and lower fees cumulative for
either
side to sweep all funds back into their primary wallet.

The fee bumping use case is also a bonus!


On Sat, Jul 29, 2017 at 10:36 PM Rusty Russell <rusty at rustcorp.com.au>
wrote:

> Rusty Russell <rusty at rustcorp.com.au> writes:
>
> >
> https://docs.google.com/document/d/1ng6FaOLGS7ZQEsv3kn6W-t2GzQShhD7eFPz-1yFQZm0/edit?usp=sharing
>
> Some feedback, since I missed what seems like a very productive
> discussion!
>
> > HTLC floor created by second-level HTLC transactions
> > Pierre points out that should choose HTLC min high enough that don’t run
> into issues.
> > Laolu points out this means that unable to send and claim small-ish
> amounts chain.
> > Laolu points out that would basically CREATE a dust output in the
> process.
> > LAOLU SUGGESTS THAT TRIM OUTPUT SPEC PORTION SHOULD ALSO SAY DON’T
> CREATE DUST OUTPUT ON SECOND LEVEL TX
>
> I think it does already:
>
> For every offered HTLC, if the HTLC amount minus the HTLC-timeout fee
> would be less than `dust_limit_satoshis` set by the transaction owner,
> the commitment transaction MUST NOT contain that output
>
> (Similarly for received HTLCs)
>
> ie. don't create HTLC outputs which would need an HTLC tx with a dust
> output.
>
> > Don’t use sighash-all on the second-level HTLC transactions
> > Laolu points out that this would allow us to coalesce many HTLC
> > transactions into a single one. Saves on-chain foot print, and also
> > allows to add more fees. Basically like “Lighthouse” (by hearn).
>
> So, you're suggesting SIGHASH_SINGLE|SIGHASH_ANYONECANPAY?
>
> I *think* this would work, though it's a pretty obscure case where we
> want to close out many HTLCs at once; this is more for fee bumping I
> think.
>
> There are two other cases where we don't rely on the TXID, and such an
> approach would be possible:
>
> 1. Commitment tx with no HTLC outputs.
> 2. The closing transaction.
>
> Cheers,
> Rusty.
>
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