Date: Thu, 27 Jun 2019 11:07:45 -0400
From: "Peter D. Gray" <peter@coinkite.com>
To: Jonathan Underwood <junderwood@bitcoinbank.co.jp>
Message-ID: <20190627150745.GA1897@coinkite.com>
Reply-To: Peter Gray <peter@coinkite.com>
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Organization: Coinkite Cryptobank (www.coinkite.com)
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Cc: Bitcoin development mailing list <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] BIP174 extension proposal (Global Type:
 PSBT_GLOBAL_XPUB_SIGNATURE)
Precedence: list

I haven't studied the new proposal in depth, but my first impression is:

Wouldn't it just be easier and better to just sign the entire "outputs" section of the PSBT?

The signature would cover every byte, and therefore would cover any
future BIP additions to the outputs area, and also help non-multisig
cases today.

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Peter D. Gray  ||  Founder, Coinkite  ||  Twitter: @dochex  ||  GPG: A3A31BAD 5A2A5B10