From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194] helo=mx.sourceforge.net) by sfs-ml-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1Z1QQy-00036Y-Ql for bitcoin-development@lists.sourceforge.net; Sun, 07 Jun 2015 02:35:36 +0000 Received-SPF: pass (sog-mx-4.v43.ch3.sourceforge.com: domain of petertodd.org designates 62.13.148.108 as permitted sender) client-ip=62.13.148.108; envelope-from=pete@petertodd.org; helo=outmail148108.authsmtp.net; Received: from outmail148108.authsmtp.net ([62.13.148.108]) by sog-mx-4.v43.ch3.sourceforge.com with esmtp (Exim 4.76) id 1Z1QQx-00008g-2L for bitcoin-development@lists.sourceforge.net; Sun, 07 Jun 2015 02:35:36 +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 t572ZSLj023588; Sun, 7 Jun 2015 03:35:28 +0100 (BST) Received: from savin.petertodd.org (75-119-251-161.dsl.teksavvy.com [75.119.251.161]) (authenticated bits=128) by mail.authsmtp.com (8.14.2/8.14.2/) with ESMTP id t572ZNsI046322 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Sun, 7 Jun 2015 03:35:26 +0100 (BST) Date: Sat, 6 Jun 2015 22:35:23 -0400 From: Peter Todd To: Kristov Atlas Message-ID: <20150607023523.GB1570@savin.petertodd.org> References: <44BE16F9-AB24-4A8E-BC7F-03A6C590FCE7@gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="/NkBOFFp2J2Af1nK" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Server-Quench: db0171c6-0cbd-11e5-9f74-002590a135d3 X-AuthReport-Spam: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-AuthRoute: OCd2Yg0TA1ZNQRgX IjsJECJaVQIpKltL GxAVKBZePFsRUQkR aQdMdgUUEkAaAgsB AmMbW1deU1h7W2U7 bA9PbARUfEhLXhtr VklWR1pVCwQmRRkG BHRgEWBycwNFenw+ Z0drXnQVCBZ6dEF8 EUhJFT5UMXphaTUa TUkOcAdJcANIexZF O1F8UScOLwdSbGoL NQ4vNDcwO3BTJTpY RgYVKF8UXXNDOjMs RhsFEi8mBU0ETCw3 Zz0gJlMMHUAeekI8 eWc7UFQDOhQOCwpY fQlsBjdEO0JJTiwn RSRHQVYDDCY1 X-Authentic-SMTP: 61633532353630.1024:706 X-AuthFastPath: 0 (Was 255) X-AuthSMTP-Origin: 75.119.251.161/587 X-AuthVirus-Status: No virus detected - but ensure you scan with your own anti-virus system. X-Spam-Score: -1.5 (-) 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 SPF_PASS SPF: sender matches SPF record X-Headers-End: 1Z1QQx-00008g-2L 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: Sun, 07 Jun 2015 02:35:36 -0000 --/NkBOFFp2J2Af1nK Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Jun 06, 2015 at 08:06:56PM -0400, Kristov Atlas wrote: In general I think this is a good idea, and should be implemented; we've had a depressing number of wallets fail to implement randomization properly, if at all. > I've updated the draft BIP in two ways: > -Making it clear that sorting is algorithmically agnostic, but should > conform to the output of the example algorithms written in python > -The BIP now handles schemes that create an input/output dependency, such > as SIGHASH_SINGLE: >=20 > Handling Input/Output Dependencies >=20 > Some uncommon forms of transactions create an ordering dependency between > inputs and outputs of a transaction. Wallets forming these transactions > should first sort inputs according to the methodology outlined in section > =E2=80=9CTransaction Inputs=E2=80=9D of this BIP. Then, they should fix t= he output indices > that depend on the input order, and sort the remaining outputs around the= m. > If there are no outputs that do not depend on input order, then all outpu= ts > will simply be ordered based on the expected scheme. The following are the > known cases of input/output dependency that must be handled specially: >=20 > * SIGHASH_SINGLE hash type. [5] Clients seeking to verify LI01 compliance > for a transaction must inspect the last byte of the scriptSig of each inp= ut > to determine the signature hash type. In the case of SIGHASH_SINGLE (0x03) > for input =E2=80=9Cn=E2=80=9D, the verifier should expect that output =E2= =80=9Cn=E2=80=9D will be fixed > when considering output ordering. 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. As for IsStandard() rules - let alone soft forks - better to leave discussion of them out for now. In particular, for the soft-fork case mandating certain transaction orders will very likely cause problems in the future for future OP_CHECKSIG upgrades. For SIGHASH_ANYONECANPAY, it might be appropriate for nodes to enforce a certain ordering, but that can be a separate BIP. (actually implementing that in Bitcoin Core would be annoying and ugly right now; without replace-by-fee ANYONECANPAY has a silly DoS attack (adding low-fee inputs) so I can't recommend wallets use it in the general case yet) "and a sequence number currently set to 0xFFFFFFFF." <- Actually, this will be changed in Bitcoin Core as of v0.11.0, which implements anti-fee-sniping w/ nLockTime.(1) (I need to write up a full BIP describing it) Do you have a patch implementing deterministic tx ordering for Bitcoin Core yet? 1) https://github.com/bitcoin/bitcoin/pull/2340 --=20 'peter'[:-1]@petertodd.org 0000000000000000079693d8d175b476081a04af9c1d00ea2dbe0efb011bd79e --/NkBOFFp2J2Af1nK Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- iQGrBAEBCACVBQJVc63lXhSAAAAAABUAQGJsb2NraGFzaEBiaXRjb2luLm9yZzAw MDAwMDAwMDAwMDAwMDAwOWJiMjc0NTJhMGM5ZmQ2YWYzYmNhZDJlMjA0MjJlNjA3 MDUxMTI4NDg2MDcwMjAvFIAAAAAAFQARcGthLWFkZHJlc3NAZ251cGcub3JncGV0 ZUBwZXRlcnRvZC5vcmcACgkQJIFAPaXwkfsStggAqZLEovRLRcQ2UUL+lWDQYT51 5hDt5HAgL/oUaPjjwomevmsBq69MCqyparHM8Qp2ZYjBa4UpM6K46wW+KXqqPW6q SyQ7XMc5moiTPe9tGKMhWZiL3Q07oKb5hzoM8Cf3X1unimQTdA5ZulY3WmpcsLMu n1rkg6IwFhBEC9KxErGzlHUGgJjbQUcNEVXsqyTjBIesvemF/3Pw5+ZzyyXieRJb Gj4YkazkjfyhCvx1ScC4HFnEFUff+b8wjDuNeBoHdL2OUYZAX6R6ef2njlGeOvKH KthREehR7EzafXKPqRdPzaiE1EpF4WSicwPPGaTcSbkMUVVNns3V9C2AhebEmg== =sEyk -----END PGP SIGNATURE----- --/NkBOFFp2J2Af1nK--