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From: Johnson Lau <jl2012@xbt.hk>
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Subject: [bitcoin-dev] Making OP_CODESEPARATOR and FindAndDelete in
non-segwit scripts non-standard
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In https://github.com/bitcoin/bitcoin/pull/11423 =
<https://github.com/bitcoin/bitcoin/pull/11423> I propose to make =
OP_CODESEPARATOR and FindAndDelete in non-segwit scripts non-standard
I think FindAndDelete() is one of the most useless and complicated =
functions in the script language. It is omitted from segwit (BIP143), =
but we still need to support it in non-segwit scripts. Actually, =
FindAndDelete() would only be triggered in some weird edge cases like =
using out-of-range SIGHASH_SINGLE.
Non-segwit scripts also use a FindAndDelete()-like function to remove =
OP_CODESEPARATOR from scriptCode. Note that in BIP143, only executed =
OP_CODESEPARATOR are removed so it doesn=E2=80=99t have the =
FindAndDelete()-like function. OP_CODESEPARATOR in segwit scripts are =
useful for Tumblebit so it is not disabled in this proposal
By disabling both, it guarantees that scriptCode serialized inside =
SignatureHash() must be constant
If we use a softfork to remove FindAndDelete() and OP_CODESEPARATOR from =
non-segwit scripts, we could completely remove FindAndDelete() from the =
consensus code later by whitelisting all blocks before the softfork =
block. The first step is to make them non-standard in the next release.
=20=
--Apple-Mail=_EAEAEC1D-74EB-4710-BC74-98E80427051B
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<html><head><meta http-equiv=3D"Content-Type" content=3D"text/html; =
charset=3Dutf-8"></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; line-break: after-white-space;" =
class=3D"">In <a =
href=3D"https://github.com/bitcoin/bitcoin/pull/11423" =
class=3D"">https://github.com/bitcoin/bitcoin/pull/11423</a> I =
propose to make OP_CODESEPARATOR and FindAndDelete in non-segwit =
scripts non-standard<div class=3D""><br class=3D""></div><div class=3D"">I=
think FindAndDelete() is one of the most useless and complicated =
functions in the script language. It is omitted from segwit (BIP143), =
but we still need to support it in non-segwit scripts. Actually, =
FindAndDelete() would only be triggered in some weird edge cases like =
using out-of-range SIGHASH_SINGLE.</div><div class=3D""><br =
class=3D""></div><div class=3D"">Non-segwit scripts also use a =
FindAndDelete()-like function to remove OP_CODESEPARATOR from =
scriptCode. Note that in BIP143, only executed OP_CODESEPARATOR are =
removed so it doesn=E2=80=99t have the FindAndDelete()-like function. =
OP_CODESEPARATOR in segwit scripts are useful for Tumblebit so it is not =
disabled in this proposal</div><div class=3D""><br class=3D""></div><div =
class=3D"">By disabling both, it guarantees that scriptCode serialized =
inside SignatureHash() must be constant</div><div class=3D""><br =
class=3D""></div><div class=3D"">If we use a softfork to remove =
FindAndDelete() and OP_CODESEPARATOR from non-segwit scripts, we could =
completely remove FindAndDelete() from the consensus code later by =
whitelisting all blocks before the softfork block. The first step is to =
make them non-standard in the next release.</div><div class=3D""><br =
class=3D""></div><div class=3D""><br class=3D""></div><div =
class=3D""> </div></body></html>=
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