Liquidity griefing in multi-party transaction protocols

[instagibbs]

@morehouse

There was also some discussion at the last Lightning spec meeting about p2tr being a viable input type if a proof is provided that only key-path spends are possible. Unfortunately, I think key-path spends can still have their witnesses inflated via the annex

There is no annex relay that is considered standard, by any implementation of bitcoin I know of, for exactly this reason. If it becomes standard we need to ensure it cannot be used for witness inflation.

@t-bast

fortunately package relay, v3 transactions, ephemeral anchors and cluster mempool are seeing a lot of active research!

For the first iteration it’s going to target the commitment transaction style use-case exclusively. I can see two futures:

1. v3 sees a big uptake. We can’t think of anything better than ah-hoc rules with bits, and we add another bit that specifically helps in scenarios such as dual funding/splicing/hltlcs
2. Post-cluster mempool we figure out a more general opt-in method, and “relax” v3 into this. Could relax tx topology, make it safe for usage in dual-funding/splicing, and previous users of the bit continue on as usual.