From rusty at rustcorp.com.au Tue Feb 9 23:14:46 2016 From: rusty at rustcorp.com.au (Rusty Russell) Date: Wed, 10 Feb 2016 09:44:46 +1030 Subject: [Lightning-dev] HTLCs using OP_CHECKSEQUENCEVERIFY/OP_LOCKTIMEVERIFY and revocation hashes. In-Reply-To: <20160209085956.GA22145@sapphire.erisian.com.au> References: <87fv51eqjl.fsf@rustcorp.com.au> <87bnf2qssy.fsf@rustcorp.com.au> <1454969273.1633.35.camel@ultimatestunts.nl> <87fux2pyan.fsf@rustcorp.com.au> <20160209085956.GA22145@sapphire.erisian.com.au> Message-ID: <87wpqdzdax.fsf@rustcorp.com.au> Anthony Towns writes: > On Tue, Feb 09, 2016 at 10:09:12AM +1030, Rusty Russell wrote: >> Otherwise, if you want to do a unilateral close, there's some game >> theory as you'd rather convince the other side to do it so your own >> funds aren't locked up. > > I think the options are: > > a) keep the channel open > b) they close the channel unilaterally > c) you close the channel unilaterally > d) you both close the channel cooperatively > > At any point, I believe the preferences are strictly: d > b > c > > (b) is better than (c) because of the OP_CSV delay; and (d) is better > than (b) if you can use a lower transaction fee than you use for your > commitment transactions, or spend directly to a useful output address > (opening up a new channel eg). > > If you find yourself trying to convince the other person to do (b) > to avoid doing (c) yourself, I think it's a dominating strategy to > simply do (d) -- you prefer that over (b) anyway, and they will prefer > it over (c). > > With the current arrangement, I don't think your counterparty can > realistically make any threats: "you'll close the channel? okay, > that's better than me closing it!" and "you'll close the channel > unilaterally? well, that's a lot worse for you as it is for me, > so whatever". > > With an OP_CSV on both sides of HTLCs, you can make a somewhat > realistic threat: "if you don't pay me $x to do a cooperative close, > I'll close unilaterally which will lock your funds up. sure you can > close unilaterally yourself, but your funds will still be locked up that > way too." > > So changing seems like it would make things marginally worse, but no > better, to me. Fair point. The issue will improve when we have close with outstanding HTLCs. Meanwhile it disturbs me that the party which goes offline pays the least penalty; their counterparties have their funds tied though. Cheers, Rusty.