From: Peter Todd <pete@petertodd•org>
To: Gregory Maxwell <gmaxwell@gmail•com>
Cc: Bitcoin Development <bitcoin-development@lists•sourceforge.net>
Subject: Re: [Bitcoin-development] Consensus-enforced transaction replacement via sequence numbers
Date: Wed, 27 May 2015 06:58:05 -0400 [thread overview]
Message-ID: <20150527105805.GC25814@savin.petertodd.org> (raw)
In-Reply-To: <CAAS2fgSjT-dtS8cNoRjvEhtBeG9SUi4OsKAAGkAf_WkxEyg=9g@mail.gmail.com>
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On Wed, May 27, 2015 at 08:18:52AM +0000, Gregory Maxwell wrote:
> On Wed, May 27, 2015 at 7:47 AM, Peter Todd <pete@petertodd•org> 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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next prev parent reply other threads:[~2015-05-27 10:58 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-27 1:50 Mark Friedenbach
2015-05-27 7:47 ` Peter Todd
2015-05-27 8:18 ` Gregory Maxwell
2015-05-27 10:00 ` Tier Nolan
2015-05-27 10:58 ` Peter Todd [this message]
2015-05-27 17:07 ` Jorge Timón
2015-05-27 8:04 ` Telephone Lemien
2015-05-27 10:11 ` Mike Hearn
2015-05-27 15:26 ` Mark Friedenbach
2015-05-27 17:39 ` Mike Hearn
2015-05-28 9:56 ` Mark Friedenbach
2015-05-28 10:23 ` Mike Hearn
2015-05-28 10:30 ` Tier Nolan
2015-05-28 12:04 ` Peter Todd
2015-05-28 13:35 ` Tier Nolan
2015-05-28 16:22 ` s7r
2015-05-28 17:21 ` Tier Nolan
2015-05-28 14:59 ` Mark Friedenbach
2015-05-28 15:18 ` Tier Nolan
2015-05-28 15:38 ` Mark Friedenbach
2015-05-28 15:57 ` Tier Nolan
2015-06-10 2:40 ` Rusty Russell
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