Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-3.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1Z37dD-0006wW-QQ for bitcoin-development@lists.sourceforge.net; Thu, 11 Jun 2015 18:55:15 +0000 Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.216.169 as permitted sender) client-ip=209.85.216.169; envelope-from=voisine@gmail.com; helo=mail-qc0-f169.google.com; Received: from mail-qc0-f169.google.com ([209.85.216.169]) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1Z37dC-0004yJ-Mj for bitcoin-development@lists.sourceforge.net; Thu, 11 Jun 2015 18:55:15 +0000 Received: by qcjl8 with SMTP id l8so4637452qcj.3 for ; Thu, 11 Jun 2015 11:55:09 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.140.107.228 with SMTP id h91mr13537038qgf.1.1434048909166; Thu, 11 Jun 2015 11:55:09 -0700 (PDT) Received: by 10.140.91.37 with HTTP; Thu, 11 Jun 2015 11:55:09 -0700 (PDT) In-Reply-To: References: <20150610200323.GA13724@savin.petertodd.org> Date: Thu, 11 Jun 2015 11:55:09 -0700 Message-ID: From: Aaron Voisine To: Nathan Wilcox Content-Type: multipart/alternative; boundary=001a113a360ed251a705184287b5 X-Spam-Score: -0.6 (/) 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 (voisine[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 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: 1Z37dC-0004yJ-Mj Cc: Bitcoin Development Subject: Re: [Bitcoin-development] Proposal: SPV Fee Discovery mechanism 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: Thu, 11 Jun 2015 18:55:15 -0000 --001a113a360ed251a705184287b5 Content-Type: text/plain; charset=UTF-8 > A Header-PoW-verifying client could still be given all transactions in a recent block, from which it can see the in-band fees directly. You don't know the fees paid by any given transaction unless you also have all it's inputs. Transaction inputs do not include an amount. You could however get the average fee-per-kb paid by all transactions in a block by looking at the coinbase transaction, subtracting the block reward, and dividing by the size of block minus the header. Aaron Voisine co-founder and CEO breadwallet.com On Thu, Jun 11, 2015 at 11:30 AM, Nathan Wilcox wrote: > On Wed, Jun 10, 2015 at 2:03 PM, Peter Todd wrote: > >> On Wed, Jun 10, 2015 at 02:00:27PM -0600, Nathan Wilcox wrote: >> > On Wed, Jun 10, 2015 at 1:19 PM, Aaron Voisine >> wrote: >> > >> > > It could be done by agreeing on a data format and encoding it in an >> > > op_return output in the coinbase transaction. If it catches on it >> could >> > > later be enforced with a soft fork. >> > > >> > > >> > Sounds plausible, except SPV protocols would need to include this >> coinbase >> > txn if it's going to help SPV clients. (Until a softfork is activated, >> SPV >> > clients should not rely on this encoding, since until that time the >> results >> > can be fabricated by individual miners.) >> >> Fee stats can always be fabricated by individual miners because fees can >> be paid out-of-band. >> >> > This is a point I hadn't considered carefully before. I don't understand > the marketplace here or why miners would want to move fees outside of > explicit inband fees. Implicit in this proposal is that the statistics only > cover in-band data, because that's the scope of consensus rules, and thus > the proposal is only as useful as the information of in-band fees is useful. > > I've also noticed a detracting technical argument given a particular > tradeoff: > > A Header-PoW-verifying client could still be given all transactions in a > recent block, from which it can see the in-band fees directly. The > trade-off is the size of those transactions versus the need to alter any > consensus rules or do soft forks. > > Notice how this trade-off's costs change with maximum block size. > > > > >> -- >> 'peter'[:-1]@petertodd.org >> 00000000000000001245bd2f5c99379ee76836227ded9c08324894faabc0d27f >> > > > > -- > Nathan Wilcox > Least Authoritarian > > email: nathan@leastauthority.com > twitter: @least_nathan > PGP: 11169993 / AAAC 5675 E3F7 514C 67ED E9C9 3BFE 5263 1116 9993 > --001a113a360ed251a705184287b5 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
>=C2=A0A Header-PoW-veri= fying client could still be given all transactions in a recent block, from = which it can see the in-band fees directly.=C2=A0

You don't know the fees paid by = any given transaction unless you also have all it's inputs. Transaction= inputs do not include an amount. You could however get the average fee-per= -kb paid by all transactions in a block by looking at the coinbase transact= ion, subtracting the block reward, and dividing by the size of block minus = the header.

Aaron Voisine
co-founder and CEO
breadwallet.com
=

On Thu, Jun 11, 2015 at 11:30 AM, Nathan Wil= cox <nathan@leastauthority.com> wrote:
On Wed, Jun 10, 2015= at 2:03 PM, Peter Todd <pete@petertodd.org> wrote:
<= blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px= #ccc solid;padding-left:1ex">On Wed, Jun 10, 2015 at 02:00:27PM -060= 0, Nathan Wilcox wrote:
> On Wed, Jun 10, 2015 at 1:19 PM, Aaron Voisine <voisine@gmail.com> wrote:
>
> > It could be done by agreeing on a data format and encoding it in = an
> > op_return output in the coinbase transaction. If it catches on it= could
> > later be enforced with a soft fork.
> >
> >
> Sounds plausible, except SPV protocols would need to include this coin= base
> txn if it's going to help SPV clients. (Until a softfork is activa= ted, SPV
> clients should not rely on this encoding, since until that time the re= sults
> can be fabricated by individual miners.)

Fee stats can always be fabricated by individual miners because fees= can
be paid out-of-band.


This is a point I hadn't considered carefully before. I do= n't understand the marketplace here or why miners would want to move fe= es outside of explicit inband fees. Implicit in this proposal is that the s= tatistics only cover in-band data, because that's the scope of consensu= s rules, and thus the proposal is only as useful as the information of in-b= and fees is useful.

I've also noticed a detracting technical arg= ument given a particular tradeoff:

A Header-PoW-verifying client cou= ld still be given all transactions in a recent block, from which it can see= the in-band fees directly.=C2=A0 The trade-off is the size of those transa= ctions versus the need to alter any consensus rules or do soft forks.
Notice how this trade-off's costs change with maximum bloc= k size.


=C2=A0
--
'peter'[:-1]@pet= ertodd.org
00000000000000001245bd2f5c99379ee76836227ded9c08324894faabc0d27f



--
Nathan Wilcox
Least Authoritarian

email: nathan@leastau= thority.com
twitter: @least_nathan
PGP: 11169993 / AAAC 5675 E3F7= 514C 67ED =C2=A0E9C9 3BFE 5263 1116 9993

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