From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191] helo=mx.sourceforge.net) by sfs-ml-3.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1Z2Pv9-0003vT-9F for bitcoin-development@lists.sourceforge.net; Tue, 09 Jun 2015 20:14:51 +0000 Received-SPF: pass (sog-mx-1.v43.ch3.sourceforge.com: domain of petertodd.org designates 62.13.149.77 as permitted sender) client-ip=62.13.149.77; envelope-from=pete@petertodd.org; helo=outmail149077.authsmtp.com; Received: from outmail149077.authsmtp.com ([62.13.149.77]) by sog-mx-1.v43.ch3.sourceforge.com with esmtp (Exim 4.76) id 1Z2Pv7-0007zf-Fe for bitcoin-development@lists.sourceforge.net; Tue, 09 Jun 2015 20:14:51 +0000 Received: from mail-c237.authsmtp.com (mail-c237.authsmtp.com [62.13.128.237]) by punt15.authsmtp.com (8.14.2/8.14.2/) with ESMTP id t59KEfFE050338; Tue, 9 Jun 2015 21:14:41 +0100 (BST) Received: from muck (bas3-cooksville17-1176330008.dsl.bell.ca [70.29.95.24]) (authenticated bits=128) by mail.authsmtp.com (8.14.2/8.14.2/) with ESMTP id t59KEahj072965 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Tue, 9 Jun 2015 21:14:38 +0100 (BST) Date: Tue, 9 Jun 2015 16:14:36 -0400 From: Peter Todd To: Kristov Atlas Message-ID: <20150609201436.GD28093@muck> References: <44BE16F9-AB24-4A8E-BC7F-03A6C590FCE7@gmail.com> <20150607023523.GB1570@savin.petertodd.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="GpGaEY17fSl8rd50" Content-Disposition: inline In-Reply-To: X-Server-Quench: 28688a9b-0ee4-11e5-9f74-002590a135d3 X-AuthReport-Spam: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-AuthRoute: OCd2Yg0TA1ZNQRgX IjsJECJaVQIpKltL GxAVKBZePFsRUQkR aQdMdgsUEkAaAgsB AmMbWVVeUVl7Wmo7 bApPbwxDa09QXQF1 VUBOXVMcUABhemlQ XkQeVRt7cQAIenZx bU4sXHhdVEwrfBRg QhsBEXAHZDJldWlJ V0RFdwNWdQpKLx5G bwR8GhFYa3VsFCMk FAgyOXU9MCtSLCNN RwwLMWdaZUsbHzU7 SAoLBTUuFkQBDwQ1 IxE2K1gTVEEfenko OF06UFkEMhgUaEV/ GVlQHDQRLl8NDw02 ERtHQVV2 X-Authentic-SMTP: 61633532353630.1024:706 X-AuthFastPath: 0 (Was 255) X-AuthSMTP-Origin: 70.29.95.24/587 X-AuthVirus-Status: No virus detected - but ensure you scan with your own anti-virus system. 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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 SPF_PASS SPF: sender matches SPF record -0.0 AWL AWL: Adjusted score from AWL reputation of From: address X-Headers-End: 1Z2Pv7-0007zf-Fe 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: Tue, 09 Jun 2015 20:14:51 -0000 --GpGaEY17fSl8rd50 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable 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: >=20 > > Why mention SIGHASH_SINGLE at all? Its use-case is highly specialized > > 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 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 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 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 be > > changed. > > >=20 > 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. >=20 > "Applicability: This BIP applies to all transactions of signature hash ty= pe > SIGHASH_ALL. Additionally, software compliant with this BIP that allows > later parties to update the transaction (e.g. using signature hash types > 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 transactions = 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 Bitcoin > > Core yet? > > >=20 > 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 will. 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. --=20 'peter'[:-1]@petertodd.org 0000000000000000127ab1d576dc851f374424f1269c4700ccaba2c42d97e778 --GpGaEY17fSl8rd50 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- iQGrBAEBCACVBQJVd0kpXhSAAAAAABUAQGJsb2NraGFzaEBiaXRjb2luLm9yZzAw MDAwMDAwMDAwMDAwMDAxMjdhYjFkNTc2ZGM4NTFmMzc0NDI0ZjEyNjljNDcwMGNj YWJhMmM0MmQ5N2U3NzgvFIAAAAAAFQARcGthLWFkZHJlc3NAZ251cGcub3JncGV0 ZUBwZXRlcnRvZC5vcmcACgkQwIXyHOf0udyLeAf/enae2UIoQSANKPtvVBqJLiZB hGQmjaDTfjDEcq0Gae+xqtOc7wUAGWejUzTo5nVy8VcmcbsbQ370Hjgz5BxfgYit H1X4BQvxULBpsSoa6TeMairyRNf17fKdm106QeXDZBrAa9tE7y+XKfsfeQMaOu9L MJ/eSxTZuC6+qpnSolperUN86vog+MR5026iT/hn3grP9xWnqkVu22zizKub9SLc lL3+pk6qf2HfcS0NR7rAS9/Ukr9SkIWYKQLXF1OvzRbyseBnsWPpYijT4/hRCyIA XjV3s/c1/ZfqSfGUUw7YltW/U+Eed+9TATzGhf0MqoPJSXBcopJJgztRePjLgA== =lQ+z -----END PGP SIGNATURE----- --GpGaEY17fSl8rd50--