On Wed, May 27, 2015 at 08:18:52AM +0000, Gregory Maxwell wrote: > On Wed, May 27, 2015 at 7:47 AM, Peter Todd <[email protected]> wrote: > > Equally this proposal is no more "consensus enforcement" than simply > > increasing the fee (and possibly decreasing the absolute nLockTime) for > > You've misunderstood it, I think-- Functionally nlocktime but relative > to each txin's height. > > But the construction gives the sequence numbers a rational meaning, > they count down the earliest position a transaction can be included. > (e.g. the highest possible sequence number can be included any time > the inputs are included) the next lower sequence number can only be > included one block later than the input its assigned to is included, > the next lower one block beyond that. All consensus enforced. A > miner could opt to not include the higher sequence number (which is > the only one of the set which it _can_ include) it the hopes of > collecting more fees later on the next block, similar to how someone > could ignore an eligible locked transaction in the hopes that a future > double spend will be more profitable (and that it'll enjoy that > profit) but in both cases it must take nothing at all this block, and > risk being cut off by someone else (and, of course, nothing requires > users use sequence numbers only one apart...).
I understand that part.
I'm just saying it's not clear to me what's the functional difference in
practice between it and having both parties sign a decreasing absolute
nLockTime. For instance, you and I could setup a payment channel using
the following transaction t0:
1.0 BTC: PT -> 1.0 BTC: PT && (GM || <expiry> CLTV)
1.0 BTC: GM -> 1.0 BTC: GM && (PT || <expiry> CLTV)
After <expiry> both of us are guaranteed to get our funds back
regardless. I can then give you funds by signing my part of t1a:
t0.vout[0] <PT sig> <blank> -> 0.5 BTC: PT
t0.vout[1] <blank> <PT sig> -> 1.5 BTC: GM
nLockTime = <expiry - 1>
You can then give me funds with t1b:
t0.vout[0] <blank> <GM sig> -> 1.5 BTC: PT
t0.vout[1] <GM sig> <blank> -> 0.5 BTC: GM
nLockTime = <expiry - 2>
etc. etc. We can close the channel by signing a non-nLockTime'd tx at
any time. If you don't co-operate, I have to wait, and hope I get my tx
mined before you get yours.
What I'm not seeing is how the relative nLockTime that nSequence
provides fundamentally changes any of this.
--
'peter'[:-1]@petertodd.org
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