Restriction for segwit OP_IF argument as a policy has got a few concept ACK. I would like to have more people to ACK or NACK, especially the real users of OP_IF. I think Lightning network would use that at lot.
Pull request: https://github.com/bitcoin/bitcoin/pull/8526 more related discussion could be found at https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2016-August/013036.html It does have impact if your script uses the combination of "OP_SIZE OP_IF" or "OP_DEPTH OP_IF". With this policy/softfork, you need to use "OP_SIZE OP_0NOTEQUAL OP_IF" or "OP_DEPTH OP_0NOTEQUAL OP_IF", or reconstruct your scripts. > > On August 16, 2016 at 1:53 PM Johnson Lau via bitcoin-dev > <bitcoin-dev@lists.linuxfoundation.org> wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA512 > > A new BIP is prepared to deal with OP_IF and OP_NOTIF malleability in > P2WSH: > https://github.com/jl2012/bips/blob/minimalif/bip-minimalif.mediawiki > https://github.com/bitcoin/bitcoin/pull/8526 > > BIP: x > Title: Dealing with OP_IF and OP_NOTIF malleability in P2WSH > Author: Johnson Lau <jl2...@xbt.hk> > Status: Draft > Type: Standards Track > Created: 2016-08-17 > > Abstract > > This document specifies proposed changes to the Bitcoin script validity > rules in order to make transaction malleability related to OP_IF and OP_NOTIF > impossible in pay-to-witness-script-hash (P2WSH) scripts. > > Motivation > > OP_IF and OP_NOTIF are flow control codes in the Bitcoin script system. > The programme flow is decided by whether the top stake value is True or > False. However, this behaviour opens a source of malleability as a third > party may replace a True (False) stack item with any other True (False) value > without invalidating the transaction. > > The proposed rules apply only to pay-to-witness-script-hash (P2WSH) > scripts described in BIP141, which has not been activated on the Bitcoin > mainnet as of writing. To ensure OP_IF and OP_NOTIF transactions created > before the introduction of this BIP will still be accepted by the network, > the new rules are not applied to non-segregated witness scripts. > > Specification > > In P2WSH, the argument for OP_IF and OP_NOTIF MUST be exactly an empty > vector or 0x01, or the script evaluation fails immediately. > > This is deployed using BIP9 after segregated witness (BIP141) is > activated. Details TBD. > > Compatibility > > This is a softfork on top of BIP141. The rules are enforced as a relay > policy by the reference client since the first release of BIP141 (v0.13.1). > To avoid risks of fund loss, users MUST NOT create P2WSH scripts that are > incompatible with this BIP. An OP_0NOTEQUAL may be used before OP_IF or > OP_NOTIF to imitate the original behaviour (which may also re-enable the > malleability vector depending on the exact script). > > Implementation > > https://github.com/bitcoin/bitcoin/pull/8526 > > Copyright > > This work is placed in the public domain. > -----BEGIN PGP SIGNATURE----- > Comment: GPGTools - https://gpgtools.org > > iQGcBAEBCgAGBQJXs1LgAAoJEO6eVSA0viTSrJQL/A/womJKgi4FuyBTL9oykCss > aBMNN9+SLtmuH7SBgEUGZ8TFxa2st+6RP6Imu+Vvn4O5sXQl3DIXV+X38X93sUYk > wrjdpvdpqFFYJezPDESz6pR/6bZ1ES0aO2QqX578/8sqr8GO6L388s66vJeIGj4n > 0LWW8sdEypMuV3HUG/9FFdUNHgiVX1U0sS1rT3P4aN30JYtb7PQpd7r8KTMta7Rt > L1VOZB+W3m2m2YZ9gB7IRmMfzzNm2QXRTPIZXt2x3mYDBuMkp+zEd5+ogA4sBpgP > wp2+l/aos686v0w8QYiNUX2+9Qpe7+238qUpw75d2XJYmLzdotWFvmp4g1hP+awX > HEfwe4BUM+El17LjrHkNeMWNJXMlhTtXb2i0XMj8tU5lZVHep4WpQ+LEahrNlsUl > FdFsi3q8HeWh8JsGaNCL41Bgbg/rKb5hUXyF6hTRHa//E6llOrpXRnsloKgBLv8c > QezgKTAPwwgdjcS6Ek0AqgLp7bCFRijCduYH9i9uaQ== > =lLIZ > -----END PGP SIGNATURE----- > > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >
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