Date: Fri, 9 Mar 2018 13:28:03 -0500
From: Peter Todd <pete@petertodd.org>
To: "Russell O'Connor" <roconnor@blockstream.io>
Message-ID: <20180309182803.GE2786@fedora-23-dvm>
References: <CAMZUoKnGx3p7=Kg96E3EEyJ8aFC7ezsvec_pAnN7oJz7-VbyLA@mail.gmail.com>
	<20180212225828.GB8551@fedora-23-dvm>
	<CAMZUoKnFBVFhaq61wKu_CcZgRKc5aoeTa-wq9h2CXH0WWHd3NQ@mail.gmail.com>
	<20180212234225.GA9131@fedora-23-dvm>
	<CAMZUoK=Htds5fu5vnqAhEoZDrwHALKe6uwqXnmJb17pa_peFFw@mail.gmail.com>
	<20180301151129.GA9373@fedora-23-dvm>
	<CAMZUoKkG8tbdb+6tGmpvgXb-=3Tu4JsTWXz77o3EC+4Bcbd17A@mail.gmail.com>
	<20180308183426.GA1093@fedora-23-dvm>
	<CAMZUoKkDnJv33H-DveHtwpnyALS5LoX-OAnabJyvPo4c1DBJRQ@mail.gmail.com>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha256;
	protocol="application/pgp-signature"; boundary="6e7ZaeXHKrTJCxdu"
Content-Disposition: inline
In-Reply-To: <CAMZUoKkDnJv33H-DveHtwpnyALS5LoX-OAnabJyvPo4c1DBJRQ@mail.gmail.com>
User-Agent: Mutt/1.5.23 (2014-03-12)
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Revisiting BIP 125 RBF policy.
Precedence: list


--6e7ZaeXHKrTJCxdu
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Thu, Mar 08, 2018 at 03:07:43PM -0500, Russell O'Connor wrote:
> On Thu, Mar 8, 2018 at 1:34 PM, Peter Todd <pete@petertodd.org> wrote:
> > But that's not a good argument: whether or not normal users are trying =
to
> > attack each other has nothing to do with whether or not you're opening =
up
> > an
> > attack by relaxing anti-DoS protections.
> >
>=20
> I'm not suggesting removing the anti-DoS protections.  I'm suggesting that
> replaced transaction require a fee increase of at least the min-fee-rate
> times the size of all the transactions being ejected (in addition to the
> other proposed requirements).

Fair: you're not removing them entirely, but you are weakening them compare=
d to
the status quo.

> > Equally, how often are normal users who aren't attacking each other
> > creating
> > issues anyway? You can always have your wallet code just skip use of RBF
> >
> replacements in the event that someone does spend an unconfirmed output t=
hat
> > you sent them; how often does this actually happen in practice?
>=20
>=20
> Just ask rhavar.  It happens regularly.
>=20
> Not many wallets let you spend unconfirmed outputs that you didn't create.
> >
>=20
> The problem is with institutional wallets sweeping incoming payments.  It
> seems that in practice they are happy to sweep unconfirmed outputs.

Pity, that does sound like a problem. :(

> Setting all of the above aside for a moment.  We need to understand that
> rational miners are going to prefer to transactions with higher package f=
ee
> rates regardless of whatever your personal preferred RBF policy is.  If we
> do not bring the RBF policy to alignment with what is economically
> rational, then miners are going to change their own policies anyways,
> probably all in slightly different ways.  It behooves everyone to develop=
 a
> reasonable standard RBF policy, that is still robust against possible DoS
> vectors, and aligns with miner incentives, so that all participants know
> what behaviour they can reasonably expect.  It is simply a bonus that this
> change in RBF policy also partially mitigates the problem of pinned
> transactions.

Miners and full nodes have slightly different priorities here; it's not cle=
ar
to me why it matters that they implement slightly different policies.


Still, re-reading your initital post, I'm convinced that the weakening of t=
he
DoS protections is probably not a huge problem, so maybe lets try this in a
release and see what happens.

Notably, if people actually use this new replacement behavior, the institut=
ions
doing these sweeps of unconfirmed outputs might stop doing that! That's
probably a good thing, as respends of potentially conflicted unconfirmed
outputs can be dangerous in reorgs; we're better off if outputs are buried
deeply before being spent again.

--=20
https://petertodd.org 'peter'[:-1]@petertodd.org

--6e7ZaeXHKrTJCxdu
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: Digital signature

-----BEGIN PGP SIGNATURE-----

iQGSBAEBCAB8FiEEFcyURjhyM68BBPYTJIFAPaXwkfsFAlqi0jBeFIAAAAAAFQBA
YmxvY2toYXNoQGJpdGNvaW4ub3JnMDAwMDAwMDAwMDAwMDAwMDAwMzFmOTYxY2Ri
YjQ3MjliNjcxMGVmOTg5MWY4M2QxMDljODA0ODg5NTllMDFjYwAKCRAkgUA9pfCR
+4brB/kBjoZmGhMZ1Gj7NcvHRRhxYVMyO0Uze8DzzRqj+Nn/e3HI/Zdy0p6/bndq
oByRKyUWywrlYi3RcfRdfkt0zDbrF62yfr6MTS4C1v4/8nCNG87lP3nuL/wJvYSX
pBH/3ecWQfx8Vi8IoHXKwTOuONfmp22NSL3NzNhrT+3hqFQqQfZvmcNUcKV9US4H
YfCjyyiWro8vMtv4jTWfeGhgp7Gl3h6R/MHdbQAgMBL6zGf9M81J9W43B2qrJsvp
wwWeHdjM9tO4D//ed2H4axKyIGU+sqqiIK02mw5hRo7D91eQJiZQiy+3C3IMvlw4
5TGR8mP6c7ir4MynrON4ak9RJoyl
=A9/W
-----END PGP SIGNATURE-----

--6e7ZaeXHKrTJCxdu--