> To be clear, are you talking about anchor channels or non-anchor channels?
> Because in anchor channels, all outputs other than the anchor outputs provided
> for fee bumping can't be spent until the commitment transaction is mined, which
> means RBF/CPFP isn't relevant.

I think the distinction is irrelevant here as pre-anchor channel if I have one spendable HTLC output spend and I gain knowledge of my counterparty commitment transaction from networks mempools, the spend is malleable and can be used as a CPFP. If you assume anchor channels, you have 2 anchor outputs as long both parties have balance outputs or pending HTLCs.

Though pre-anchor, legacy channels the counterparty commitment transaction will have to be attached with a fee under min mempool fee for the replacement cycling to happen, and let network congestion happen.

I think the more interesting case is a future world with package relay deployed at the p2p level and anchor output on the lightning-side. Here the most advanced replacement as illustrated in the test can happen (where commitment has an anchor output - see L125).

Best,
Antoine

Le jeu. 2 nov. 2023 à 06:26, Peter Todd <pete@petertodd.org> a écrit :
On Thu, Nov 02, 2023 at 05:24:36AM +0000, Antoine Riard wrote:
> Hi Peter,
>
> > So, why can't we make the HTLC-preimage path expire? Traditionally, we've
> tried
> > to ensure that transactions - once valid - remain valid forever. We do
> this
> > because we don't want transactions to become impossible to mine in the
> event of
> > a large reorganization.
>
> I don't know if reverse time-lock where a lightning spending path becomes
> invalid after a block height or epoch point solves the more advanced
> replacement cycling attacks, where a malicious commitment transaction
> itself replaces out a honest commitment transaction, and the
> child-pay-for-parent of this malicious transaction is itself replaced out
> by the attacker, leading to the automatic trimming of the malicious
> commitment transaction.

To be clear, are you talking about anchor channels or non-anchor channels?
Because in anchor channels, all outputs other than the anchor outputs provided
for fee bumping can't be spent until the commitment transaction is mined, which
means RBF/CPFP isn't relevant.

--
https://petertodd.org 'peter'[:-1]@petertodd.org