Date: Fri, 09 Mar 2018 13:40:34 -0500
To: Peter Todd <pete@petertodd.org>,
	Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
From: rhavar@protonmail.com
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Subject: Re: [bitcoin-dev] Revisiting BIP 125 RBF policy.
Precedence: list

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

Awesome! I very much agree. The relaxation of some of these DoS prevention =
rules I think will really open up a lot of use cases and adoption=20

> Notably, if people actually use this new replacement behavior, the instit=
utions
> doing these sweeps of unconfirmed outputs might stop doing that!=20

Agree, I'm pretty sure it's unintentional. I know a lot of services struggl=
e with coin selection, so what they do is conceptually have a receive walle=
t from which they can sweep to their hot wallet (or cold storage) to keep t=
heir utxo manageable.

Currently some of them are sweeping unconfirmed inputs with it, but I don't=
 think it's a conscious design choice, just something that happens to be wo=
rking well now.

(FWIW I observed this behavior like 6+ months ago, I haven't kept track of =
if it's still happening or how often. But at the time I had to write off th=
e idea of low-fee rbf batch transactions as it was happening too often to b=
e feasible)


=E2=80=8B-Ryan=E2=80=8B

=E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90 Original Me=
ssage =E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90

On March 9, 2018 1:28 PM, Peter Todd via bitcoin-dev <bitcoin-dev@lists.lin=
uxfoundation.org> wrote:

> =E2=80=8B=E2=80=8B
>=20
> On Thu, Mar 08, 2018 at 03:07:43PM -0500, Russell O'Connor wrote:
>=20
> > On Thu, Mar 8, 2018 at 1:34 PM, Peter Todd pete@petertodd.org wrote:
> >=20
> > > But that's not a good argument: whether or not normal users are tryin=
g to
> > >=20
> > > attack each other has nothing to do with whether or not you're openin=
g up
> > >=20
> > > an
> > >=20
> > > attack by relaxing anti-DoS protections.
> >=20
> > I'm not suggesting removing the anti-DoS protections. I'm suggesting th=
at
> >=20
> > replaced transaction require a fee increase of at least the min-fee-rat=
e
> >=20
> > times the size of all the transactions being ejected (in addition to th=
e
> >=20
> > other proposed requirements).
>=20
> Fair: you're not removing them entirely, but you are weakening them compa=
red to
>=20
> the status quo.
>=20
> > > Equally, how often are normal users who aren't attacking each other
> > >=20
> > > creating
> > >=20
> > > issues anyway? You can always have your wallet code just skip use of =
RBF
> >=20
> > replacements in the event that someone does spend an unconfirmed output=
 that
> >=20
> > > you sent them; how often does this actually happen in practice?
> >=20
> > Just ask rhavar. It happens regularly.
> >=20
> > Not many wallets let you spend unconfirmed outputs that you didn't crea=
te.
> >=20
> > >=20
> >=20
> > The problem is with institutional wallets sweeping incoming payments. I=
t
> >=20
> > seems that in practice they are happy to sweep unconfirmed outputs.
>=20
> Pity, that does sound like a problem. :(
>=20
> > Setting all of the above aside for a moment. We need to understand that
> >=20
> > rational miners are going to prefer to transactions with higher package=
 fee
> >=20
> > rates regardless of whatever your personal preferred RBF policy is. If =
we
> >=20
> > do not bring the RBF policy to alignment with what is economically
> >=20
> > rational, then miners are going to change their own policies anyways,
> >=20
> > probably all in slightly different ways. It behooves everyone to develo=
p a
> >=20
> > reasonable standard RBF policy, that is still robust against possible D=
oS
> >=20
> > vectors, and aligns with miner incentives, so that all participants kno=
w
> >=20
> > what behaviour they can reasonably expect. It is simply a bonus that th=
is
> >=20
> > change in RBF policy also partially mitigates the problem of pinned
> >=20
> > transactions.
>=20
> Miners and full nodes have slightly different priorities here; it's not c=
lear
>=20
> to me why it matters that they implement slightly different policies.
>=20
> Still, re-reading your initital post, I'm convinced that the weakening of=
 the
>=20
> DoS protections is probably not a huge problem, so maybe lets try this in=
 a
>=20
> release and see what happens.
>=20
> Notably, if people actually use this new replacement behavior, the instit=
utions
>=20
> doing these sweeps of unconfirmed outputs might stop doing that! That's
>=20
> probably a good thing, as respends of potentially conflicted unconfirmed
>=20
> outputs can be dangerous in reorgs; we're better off if outputs are burie=
d
>=20
> deeply before being spent again.
>=20
>=20
> -------------------------------------------------------------------------=
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----
>=20
> https://petertodd.org 'peter'\[:-1\]@petertodd.org
>=20
> bitcoin-dev mailing list
>=20
> bitcoin-dev@lists.linuxfoundation.org
>=20
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev