Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-4.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1YPWnM-0006bs-RP for bitcoin-development@lists.sourceforge.net; Sun, 22 Feb 2015 13:42:04 +0000 Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.217.176 as permitted sender) client-ip=209.85.217.176; envelope-from=elombrozo@gmail.com; helo=mail-lb0-f176.google.com; Received: from mail-lb0-f176.google.com ([209.85.217.176]) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1YPWnL-0004Nj-6h for bitcoin-development@lists.sourceforge.net; Sun, 22 Feb 2015 13:42:04 +0000 Received: by lbjb6 with SMTP id b6so13923879lbj.12 for ; Sun, 22 Feb 2015 05:41:56 -0800 (PST) MIME-Version: 1.0 X-Received: by 10.152.246.41 with SMTP id xt9mr5805481lac.110.1424612516770; Sun, 22 Feb 2015 05:41:56 -0800 (PST) Received: by 10.112.201.67 with HTTP; Sun, 22 Feb 2015 05:41:56 -0800 (PST) In-Reply-To: References: <20150212064719.GA6563@savin.petertodd.org> <20150215212512.GR14804@nl.grid.coop> <54E11248.6090401@gmail.com> <20150219085604.GT14804@nl.grid.coop> Date: Sun, 22 Feb 2015 05:41:56 -0800 Message-ID: From: Eric Lombrozo To: Jeff Garzik Content-Type: multipart/alternative; boundary=001a1133b024013b4d050fad7355 X-Spam-Score: 1.3 (+) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (elombrozo[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 1.9 FUZZY_AMBIEN BODY: Attempt to obfuscate words in spam 1.0 HTML_MESSAGE BODY: HTML included in message -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-Headers-End: 1YPWnL-0004Nj-6h Cc: Bitcoin Dev Subject: Re: [Bitcoin-development] replace-by-fee v0.10.0rc4 X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 22 Feb 2015 13:42:04 -0000 --001a1133b024013b4d050fad7355 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable In case it wasn't clear in my earlier post, there's of course a third possibility - namely, some outputs are kept but not all. Here, it is generally impossible to tell whether the motivation was fee replacement, output replacement, or both. My proposal is to always treat these instances as output replacement and punish the sender. The sender needs to make it unambiguously clear it's only a fee replacement by creating a new transaction that produces an output with the desired extra fee and then adding an input that spends it to the original transaction. - Eric Lombrozo On Sunday, February 22, 2015, Eric Lombrozo wrote: > I should note that my proposal does require a change to the consensus > rules...but getting bitcoin to scale will require this no matter what. > > - Eric Lombrozo > On Feb 22, 2015 3:41 AM, "Eric Lombrozo" > wrote: > >> It seems to me we're confusing two completely different motivations for >> double-spending. One is the ability to replace a fee, the other is the >> ability to replace outputs. >> >> If the double-spend were to merely add or remove inputs (but keep at >> least one input in common, of course), it seems fairly safe to assume it= 's >> the former, a genuine fee replacement. Even allowing for things like >> coinjoin, none of the payees would really care either way. >> >> Conversely, if at least one of the inputs were kept but none of the >> outputs were, we can be confident it's the the latter. >> >> It is possible to build a wallet that always does the former when doing >> fee replacement by using another transaction to create an output with >> exactly the additional desired fee. >> >> If we can clearly distinguish these two cases then the fee replacement >> case can be handled by relaying both and letting miners pick one or the >> other while the output replacement case could be handled by rewarding >> everything to a miner (essentially all outputs are voided...made >> unredeemable...and all inputs are added to coinbase) if the miner includ= es >> the two conflicting transactions in the same block. >> >> Wouldn't this essentially solve the problem? >> >> - Eric Lombrozo >> On Feb 21, 2015 8:09 PM, "Jeff Garzik" > > wrote: >> >>> On Sat, Feb 21, 2015 at 10:25 PM, Jorge Tim=C3=B3n w= rote: >>> > On Sat, Feb 21, 2015 at 11:47 PM, Jeff Garzik >> > wrote: >>> >> This isn't some theoretical exercise. Like it or not many use >>> >> insecure 0-conf transactions for rapid payments. Deploying somethin= g >>> >> that makes 0-conf transactions unusable would have a wide, negative >>> >> impact on present day bitcoin payments, thus "scorched earth" >>> >>> > And maybe by maintaining first seen policies we're harming the system >>> > in the long term by encouraging people to widely deploy systems based >>> > on extremely weak assumptions. >>> >>> Lacking a coded, reviewed alternative, that's only a platitude. >>> Widely used 0-conf payments are where we're at today. Simply ceasing >>> the "maintaining [of] first seen policies" alone is simply not a >>> realistic option. The negative impact to today's userbase would be >>> huge. >>> >>> Instant payments need a security upgrade, yes. >>> >>> -- >>> Jeff Garzik >>> Bitcoin core developer and open source evangelist >>> BitPay, Inc. https://bitpay.com/ >>> >>> >>> -----------------------------------------------------------------------= ------- >>> Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server >>> from Actuate! Instantly Supercharge Your Business Reports and Dashboard= s >>> with Interactivity, Sharing, Native Excel Exports, App Integration & mo= re >>> Get technology previously reserved for billion-dollar corporations, FRE= E >>> >>> http://pubads.g.doubleclick.net/gampad/clk?id=3D190641631&iu=3D/4140/os= tg.clktrk >>> _______________________________________________ >>> Bitcoin-development mailing list >>> Bitcoin-development@lists.sourceforge.net >>> >>> https://lists.sourceforge.net/lists/listinfo/bitcoin-development >>> >> --001a1133b024013b4d050fad7355 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

In case it wasn't clear in my earlier post, there's of course= a third possibility - namely, some outputs are kept but not all. Here, it = is generally impossible to tell whether the motivation was fee replacement,= output replacement, or both. My proposal is to always treat these instance= s as output replacement and punish the sender. The sender needs to make it = unambiguously clear it's only a fee replacement by creating a new trans= action that produces an output with the desired extra fee and then adding a= n input that spends it to the original transaction.

- Eric Lombrozo
=
On Sunday, February 22, 2015, Eric Lombrozo <elombrozo@gmail.com> wrote:

I should note that my proposal does req= uire a change to the consensus rules...but getting bitcoin to scale will re= quire this no matter what.

- Eric Lombrozo

On Feb 22, 2015 3:41 AM, "Eric Lombrozo&quo= t; <elombrozo@gmail.com> wrote:

It seems to me = we're confusing two completely different motivations for double-spendin= g. One is the ability to replace a fee, the other is the ability to replace= outputs.

If the double-spend were to merely add or remove inputs (but= keep at least one input in common, of course), it seems fairly safe to ass= ume it's the former, a genuine fee replacement. Even allowing for thing= s like coinjoin, none of the payees would really care either way.

Conversely, if at least one of the inputs were kept but none= of the outputs were, we can be confident it's the the latter.

It is possible to build a wallet that always does the former= when doing fee replacement by using another transaction to create an outpu= t with exactly the additional desired fee.

If we can clearly distinguish these two cases then the fee r= eplacement case can be handled by relaying both and letting miners pick one= or the other while the output replacement case could be handled by rewardi= ng everything to a miner (essentially all outputs are voided...made unredee= mable...and all inputs are added to coinbase) if the miner includes the two= conflicting transactions in the same block.

Wouldn't this essentially solve the problem?

- Eric Lombrozo

On Feb 21, 2015 8:09 PM, "Jeff Garzik"= <jgarzik@bitpay.com> wrote:
On Sat, Feb 21, 2015 at 10:25 PM, = Jorge Tim=C3=B3n <jtimon@jtimon.cc> wrote:
> On Sat, Feb 21, 2015 at 11:47 PM, Jeff Garzik <jgarzik@bitpay.com> wrote:
>> This isn't some theoretical exercise.=C2=A0 Like it or not man= y use
>> insecure 0-conf transactions for rapid payments.=C2=A0 Deploying s= omething
>> that makes 0-conf transactions unusable would have a wide, negativ= e
>> impact on present day bitcoin payments, thus "scorched earth&= quot;

> And maybe by maintaining first seen policies we're harming the sys= tem
> in the long term by encouraging people to widely deploy systems based<= br> > on extremely weak assumptions.

Lacking a coded, reviewed alternative, that's only a platitude.
Widely used 0-conf payments are where we're at today.=C2=A0 Simply ceas= ing
the "maintaining [of] first seen policies" alone is simply not a<= br> realistic option.=C2=A0 The negative impact to today's userbase would b= e
huge.

Instant payments need a security upgrade, yes.

--
Jeff Garzik
Bitcoin core developer and open source evangelist
BitPay, Inc.=C2=A0 =C2=A0 =C2=A0 https://bitpay.com/

---------------------------------------------------------------------------= ---
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from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & mo= re
Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gam= pad/clk?id=3D190641631&iu=3D/4140/ostg.clktrk
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