[feature]: Ability to prove the existence of a Taproot Assets channel

[jcbrand]

Is your feature request related to a problem? Please describe.

We have a liquidity market place where we facilitate the opening of channels between nodes that aren't under our control.

As the 3rd party, we would like to be able to prove the existence of a Taproot Assets channel, to confirm that no fraud took place before we release the funds for the sale.

We have a way to prove the existence of public channels. We ingest the funding tx ID and then wait for the gossip message announcing the channel.

The problem is that currently all Taproot channels are private and cannot be made public due to limitations with the gossip protocol.

AFAIK, the funding transaction on its own is also not enough to prove the existence of a channel, since it could just be a 2-of-2 multisig not tied to channel creation (or made to spoof channel creation).

Describe the solution you'd like

One solution would be updating the gossip protocol so that Taproot channels can be made public.

@GeorgeTsagk mentioned the following in Slack, hinting at another possible solution:

In theory the protocol would allow for such a use case where you have, say, a 3rd party that you need to prove to that the channel is open. If you point them to the outpoint and provide them with the proofs they'll be able to verify that the outpoint corresponds to a private TA channel

Although to me it reads like having the tx outpoint and proofs will allow you to prove the existence of Taproot Assets in a 2-of-2 multisig transaction that could be a channel funding transaction but which has not been definitively proven to be one.

But perhaps there is a way to prove that an onchain transaction together with TA proofs was for the creation of a Taproot Assets channel?

[Roasbeef]

You can export a proof, then verify it.

I think that addresses your use case? In which case we can close this issue.

[jcbrand]

My understanding is that this lets us prove that a particular onchain transaction contains a specific Taproot asset, but it doesn't actually prove that the transaction was used to open a channel.