rich1.0Lloyd Fournier [ARCHIVE] (npub1kh…y05yp)https://yabu.me/npub1khlhcuz0jrjwa0ayznq2q9agg4zvxfvx5x7jljrvwnpfzngrcf0q7y05ypnjumphttps://yabu.me📅 Original date posted:2020-12-15 📝 Original message: > It seems difficult to recommend YOLO commitment transactions becoming the standard way to recover funds. It could be preferable to the current system but even that is up for debate I guess. > I feel like I can recommend oblivious settlements because (i) it's covert (like YOLO commitments txs unlike current system) and (ii) it's "what you see is what you get" -- you are guaranteed to recover the funds that you are presented with once you finally trigger the recovery Off list Dave correctly pointed out to me that this wasn't a very clear picture of the situation. After some thought, I came up with these claims that I think I can make strongly: 1. Before you reveal that you are doing recovery you are guaranteed to have a tx in hand that: i. You can broadcast first ii. You can choose the fee to be as high as you like iii. Is not replaceable. 2. If the malicious party is *not* willing to risk broadcasting a revoked tx then you are guaranteed to recover the face value of the transaction(s) you have in hand. 3. An honest party is never at risk of broadcasting a revoked commitment tx. 4. You never have to reveal that you were doing a recovery i.e. the channel can continue (strictly preferable to 1) Current system has: 3 Oblivious mutual close has: 1,2,3 YOLO commitments has: 1,5 So I think the question of YOLO commitments vs oblivious mutual close is whether paying the price of losing (2,3) is worth the upgrade from (1) to (5). The concern with (1) is that once you broadcast to the network the obliviously transferred "mutual close" transaction, the malicious party then has a hint that you have lost data and they can try and broadcast a favourable revoked transaction. This should be very hard since in (1) you broadcast first, can choose as large a fee as you like and the tx does not signal replaceability whereas the revoked tx *will* signal replaceability. I'm also personally trying to avoid losing (3) because to keep [1] applicable. As a side note: in YOLO commitment transactions you have to recover some additional metadata from the other party -- in particular the compressed revocation keys that you *should* know otherwise the channel cannot continue to operate. So a signature on the compressed revocation keys must be given to the other party before you lose data and returned to you when you are given the commitment transaction upon reconnection. This should be easy enough to do though. [1] https://github.com/LLFourn/witness-asymmetric-channel#scorched-earth-punishments On Tue, Dec 15, 2020 at 12:13 AM David A. Harding <dave at dtrt.org> wrote: > > The idea I'm working with in revocable signature based channels [1] is > > to make the node lose its static secret key if it posts a revoked > > commitment tx. This means they could lose ALL funds from ALL their > > channels with ALL their peers if they ever broadcast a single revoked > > commitment transaction. This would be a very bad thing to happen while > > you're trying to recover funds. > > Yikes! A very bad thing indeed. I'll have to re-read about witness > asymmetric channels; I don't think I realized that was a consequence of > using them. > It's an optional feature -- see link[1] above where I just added an explanation of it. I actually see no reason why you couldn't apply revocable signatures to transaction asymmetric channels (LN as it is today) you just have to overhaul the revocation mechanism. In general I agree with your points that side-channels may be effective tools to reveal whether a node has had data loss or not. I think in both YOLO commitments and oblivious mutual close it is easy enough to simulate data-loss up to a point to try and catch malicious peers using side channels. At least you don't have to ask the peer to broadcast a tx to find out! Cheers, LL -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.linuxfoundation.org/pipermail/lightning-dev/attachments/20201215/7b1e9210/attachment.html>