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 1Z3WdM-00048t-US for bitcoin-development@lists.sourceforge.net; Fri, 12 Jun 2015 21:37:04 +0000 Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.215.68 as permitted sender) client-ip=209.85.215.68; envelope-from=kristovatlas.lists@gmail.com; helo=mail-la0-f68.google.com; Received: from mail-la0-f68.google.com ([209.85.215.68]) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1Z3WdL-0006Xa-3z for bitcoin-development@lists.sourceforge.net; Fri, 12 Jun 2015 21:37:04 +0000 Received: by lamq1 with SMTP id q1so7434721lam.0 for ; Fri, 12 Jun 2015 14:36:56 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.112.201.74 with SMTP id jy10mr16894013lbc.94.1434145016728; Fri, 12 Jun 2015 14:36:56 -0700 (PDT) Received: by 10.152.163.98 with HTTP; Fri, 12 Jun 2015 14:36:56 -0700 (PDT) In-Reply-To: <20150609201436.GD28093@muck> References: <44BE16F9-AB24-4A8E-BC7F-03A6C590FCE7@gmail.com> <20150607023523.GB1570@savin.petertodd.org> <20150609201436.GD28093@muck> Date: Fri, 12 Jun 2015 17:36:56 -0400 Message-ID: From: Kristov Atlas To: Peter Todd Content-Type: multipart/alternative; boundary=001a11c36c9647547c051858e806 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 (kristovatlas.lists[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: 1Z3WdL-0006Xa-3z Cc: Bitcoin development mailing list Subject: Re: [Bitcoin-development] Lexicographical Indexing of Transaction Inputs and Outputs 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: Fri, 12 Jun 2015 21:37:05 -0000 --001a11c36c9647547c051858e806 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Since everyone's busy, I went ahead and made a pull request to add this as an informational BIP 79 to the bips directory. https://github.com/bitcoin/bips/pull/157 Regards, Kristov On Tue, Jun 9, 2015 at 4:14 PM, Peter Todd wrote: > On Mon, Jun 08, 2015 at 06:53:54PM -0400, Kristov Atlas wrote: > > Two other things: > > > > > On Sat, Jun 6, 2015 at 10:35 PM, Peter Todd wrote: > > > > > Why mention SIGHASH_SINGLE at all? Its use-case is highly specialized > > > protocols; you haven't taken into account the needs of those protocol= s. > > > For BIP's it's better to stick to the use-cases where the need is cle= ar > > > and there exists running code that to speculate too much on future > uses. > > > With signature hashing in particular it's not yet clear at all what > > > future OP_CHECKSIG's will look like, let alone the various ways peopl= e > > > will use sighash for smart contract type stuff. > > > > > > You'd be better off presenting the BIP in terms of a generic statemen= t > > > that "except when otherwise prevented by advanced signature hashing > > > requirements, wallet software must emit transactions sorted according > to > > > the following" You can then specify the two common cases in detail: > > > > > > 1) SIGHASH_ALL: input and output order signed, so sort appropriately > > > > > > 2) SIGHASH_ANYONECANPAY: input order not signed, so software should > emit > > > transactions sorted, recognising that the actual mined order may b= e > > > changed. > > > > > > > That makes sense. I updated the language as follows -- your thoughts? > Keep > > in mind this BIP is informational, and so people are free to ignore it. > > > > "Applicability: This BIP applies to all transactions of signature hash > type > > SIGHASH_ALL. Additionally, software compliant with this BIP that allow= s > > later parties to update the transaction (e.g. using signature hash type= s > > SIGHASH_NONE or a variant of SIGHASH_ANYONECANPAY) should emit > > lexicographically sorted inputs and outputs, although they may later be > > modified. Transactions that have index dependencies between transaction= s > or > > within the same transaction are covered under the section of this BIP > > entitled =E2=80=9CHandling Input/Output Dependencies.=E2=80=9D" > > I'd keep it even simpler than that, and just say for now that such > use-cases are out of the scope of this BIP, however those standards > should come up with some kind of deterministic standard that meets the > needs of the protocol. Again, there's a bunch of possible use-cases here > and we just can't predict them; focus on the fact that the *spirit* of > what this BIP is about is applicable and future standards should be > developed. > > So I'd change the "Applicability" section to: > > This BIP applies to all transactions where the order of inputs and > outputs does not matter. This is true for the vast majority of > transactions as they simply move funds from one place to another. > > Currently this generally refers to transactions where SIGHASH_ALL is > used, in which case the signatures commit to the exact order of input > and outputs. In the case where SIGHASH_ANYONECANPAY and/or SIGHASH_NONE > has been used (e.g. crowdfunds) the order of inputs and/or outputs may > not be signed, however compliant software should still emit transactions > with sorted inputs and outputs, even though they may later be modified > by others. > > In the event that future protocol upgrades introduce new signature hash > types, compliant software should apply the lexographic ordering > principle analogously. > > While out of scope of this BIP, protocols that do require a specified > order of inputs/outputs (e.g. due to use of SIGHASH_SINGLE) should > consider the goals of this BIP and how best to adapt them to the > specifics needs of those protocols. > > > Then remove the "handling input/output deps" section. > > > > Do you have a patch implementing deterministic tx ordering for Bitcoi= n > > > Core yet? > > > > > > > I'm not a frequent C programmer, so I'd prefer to let someone else take > > care of it, as a frequent committer of code would do a faster and more > > stylistically consistent job of it. If no one else will, however, I wil= l. > > > > re: the actual ordering algorithm, having txids be sorted by with the > hex-based algorithm is odd. I'd simply say they're sorted as > little-endian byte arrays, or in other words, with the bytearr_cmp() > function, but with the order of bytes reversed. You also should say that > we're doing that to make the user see them in visually sorted order to > match expectations because txids are displayed as little-endian. > > For outputs, don't say "locking script", say "scriptPubKey". Secondly, > scriptPubKeys are not in little-endian representation - they have no > endianness to them. With output amount, there's no need to say that > they're unsigned or little-endian satoshies, just say they're sorted > largest/smallest amount first. > > "For the sake of efficiency, amounts will be considered first for > sorting, since they contain fewer bytes of information (7 bytes) > compared to a standard P2PKH locking script (800 bytes)." <- where the > heck did you get these numbers from? Amounts are 8 bytes, and P2PKH > scriptPubKeys are 25 bytes. > > > "Backwards Compatibility" <- I'd just remove this whole section; we're > unlikely to make this an IsStandard() rule anytime soon. > > -- > 'peter'[:-1]@petertodd.org > 0000000000000000127ab1d576dc851f374424f1269c4700ccaba2c42d97e778 > --001a11c36c9647547c051858e806 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Since everyone's busy, I went ahead and made= a pull request to add this as an informational BIP 79 to the bips director= y.

https://gith= ub.com/bitcoin/bips/pull/157

Regards,
Kristov
=

On Tue, Jun= 9, 2015 at 4:14 PM, Peter Todd <pete@petertodd.org> wrote:=
On Mon, Jun 08, 2015 at 06:53:54PM -0400= , Kristov Atlas wrote:

Two other things:



> On Sat, Jun 6, 2015 at 10:35 PM, Peter Todd <pete@petertodd.org> wrote:
>
> > Why mention SIGHASH_SINGLE at all? Its use-case is highly special= ized
> > protocols; you haven't taken into account the needs of those = protocols.
> > For BIP's it's better to stick to the use-cases where the= need is clear
> > and there exists running code that to speculate too much on futur= e uses.
> > With signature hashing in particular it's not yet clear at al= l what
> > future OP_CHECKSIG's will look like, let alone the various wa= ys people
> > will use sighash for smart contract type stuff.
> >
> > You'd be better off presenting the BIP in terms of a generic = statement
> > that "except when otherwise prevented by advanced signature = hashing
> > requirements, wallet software must emit transactions sorted accor= ding to
> > the following" You can then specify the two common cases in = detail:
> >
> > 1) SIGHASH_ALL: input and output order signed, so sort appropriat= ely
> >
> > 2) SIGHASH_ANYONECANPAY: input order not signed, so software shou= ld emit
> >=C2=A0 =C2=A0 transactions sorted, recognising that the actual min= ed order may be
> >=C2=A0 =C2=A0 changed.
> >
>
> That makes sense. I updated the language as follows -- your thoughts? = Keep
> in mind this BIP is informational, and so people are free to ignore it= .
>
> "Applicability: This BIP applies to all transactions of signature= hash type
> SIGHASH_ALL. Additionally,=C2=A0 software compliant with this BIP that= allows
> later parties to update the transaction (e.g. using signature hash typ= es
> SIGHASH_NONE or a variant of SIGHASH_ANYONECANPAY) should emit
> lexicographically sorted inputs and outputs, although they may later b= e
> modified. Transactions that have index dependencies between transactio= ns or
> within the same transaction are covered under the section of this BIP<= br> > entitled =E2=80=9CHandling Input/Output Dependencies.=E2=80=9D"
I'd keep it even simpler than that, and just say for now th= at such
use-cases are out of the scope of this BIP, however those standards
should come up with some kind of deterministic standard that meets the
needs of the protocol. Again, there's a bunch of possible use-cases her= e
and we just can't predict them; focus on the fact that the *spirit* of<= br> what this BIP is about is applicable and future standards should be
developed.

So I'd change the "Applicability" section to:

This BIP applies to all transactions where the order of inputs and
outputs does not matter. This is true for the vast majority of
transactions as they simply move funds from one place to another.

Currently this generally refers to transactions where SIGHASH_ALL is
used, in which case the signatures commit to the exact order of input
and outputs. In the case where SIGHASH_ANYONECANPAY and/or SIGHASH_NONE
has been used (e.g. crowdfunds) the order of inputs and/or outputs may
not be signed, however compliant software should still emit transactions with sorted inputs and outputs, even though they may later be modified
by others.

In the event that future protocol upgrades introduce new signature hash
types, compliant software should apply the lexographic ordering
principle analogously.

While out of scope of this BIP, protocols that do require a specified
order of inputs/outputs (e.g. due to use of SIGHASH_SINGLE) should
consider the goals of this BIP and how best to adapt them to the
specifics needs of those protocols.


Then remove the "handling input/output deps" section.

> > Do you have a patch implementing deterministic tx ordering for Bi= tcoin
> > Core yet?
> >
>
> I'm not a frequent C programmer, so I'd prefer to let someone = else take
> care of it, as a frequent committer of code would do a faster and more=
> stylistically consistent job of it. If no one else will, however, I wi= ll.



re: the actual ordering algorithm, having txids be sorted by with th= e
hex-based algorithm is odd. I'd simply say they're sorted as
little-endian byte arrays, or in other words, with the bytearr_cmp()
function, but with the order of bytes reversed. You also should say that we're doing that to make the user see them in visually sorted order to<= br> match expectations because txids are displayed as little-endian.

For outputs, don't say "locking script", say "scriptPubK= ey". Secondly,
scriptPubKeys are not in little-endian representation - they have no
endianness to them. With output amount, there's no need to say that
they're unsigned or little-endian satoshies, just say they're sorte= d
largest/smallest amount first.

"For the sake of efficiency, amounts will be considered first for
sorting, since they contain fewer bytes of information (7 bytes)
compared to a standard P2PKH locking script (800 bytes)." <- where = the
heck did you get these numbers from? Amounts are 8 bytes, and P2PKH
scriptPubKeys are 25 bytes.


"Backwards Compatibility" <- I'd just remove this whole se= ction; we're
unlikely to make this an IsStandard() rule anytime soon.

--
'peter'[:-1]@petertodd.org
0000000000000000127ab1d576dc851f374424f1269c4700ccaba2c42d97e778

--001a11c36c9647547c051858e806--