Subject: Re: [bitcoin-dev] SIGHASH_NOINPUT in Segregated Witness

From: Bryan Bishop <[email-masked]>
Date: Thu, 25 Feb 2016 19:34:24 -0600

On Thu, Feb 25, 2016 at 7:07 PM, Joseph Poon wrote:
> This would be achieved using a SIGHASH flag, termed SIGHASH_NOINPUT. It
> does not include as part of the signature, the outpoint being spent
> (txid and index), nor the amount. It however, would include the spent
> outpoint's script as part of the signature. Note that this is just a

Well if you are bothering to draft up a BIP about that SIGHASH flag,
then perhaps also consider some other SIGHASH flag types as well while
you are at it?

Various proposed sighash types:
http://lists.linuxfoundation.org/pipermail/bitcoin-dev/2015-August/010759.html

"Build your own nHashType" proposal draft:
https://github.com/scmorse/bitcoin-misc/blob/master/sighash_proposal.md

jl2012's reply:
http://lists.linuxfoundation.org/pipermail/bitcoin-dev/2015-August/010779.html

petertodd's reply about OP_CODESEPARATOR linked back to this thread
regarding "Build your own nHashType":
http://lists.linuxfoundation.org/pipermail/bitcoin-dev/2015-April/007771.html
http://lists.linuxfoundation.org/pipermail/bitcoin-dev/2015-April/007802.html
http://gnusha.org/bitcoin-wizards/2014-12-09.log

((That particular thread had other replies which can be viewed here:
http://lists.linuxfoundation.org/pipermail/bitcoin-dev/2015-April/thread.html
))

Also, there was a draft implementation of SIGHASH_NOINPUT:
https://github.com/Roasbeef/bitcoin/commit/4b3c3f1baf7985208ceb6887261ee150ab6e3328
https://github.com/Roasbeef/btcd/commit/67830e506fa135d5239177340918cea39909e6a4

FWIW there was some concern about replay using SIGHAHS_NOINPUT or something:
http://gnusha.org/bitcoin-wizards/2015-04-07.log

- Bryan
http://heybryan.org/
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