Date: Mon, 17 Dec 2018 23:22:58 -0500
From: Peter Todd <pete@petertodd.org>
To: Johnson Lau <jl2012@xbt.hk>,
	Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Message-ID: <20181218042258.dfj7n5qmmcbbe2wo@petertodd.org>
References: <CAPg+sBhuPG-2GXc+Bp0yv5ywry2fk56LPLT4AY0Kcs+YEoz4FA@mail.gmail.com>
	<87ftv3xerx.fsf@rustcorp.com.au>
	<DAAB7568-A004-4897-B5B3-0FBBC6895246@xbt.hk>
	<87pnu6s3v5.fsf@rustcorp.com.au> <87h8fiqn1z.fsf@rustcorp.com.au>
	<20181214093002.p2nvfrlaycqblww3@erisian.com.au>
	<8736qyhsej.fsf@rustcorp.com.au>
	<6DE5291C-629D-4080-9B0C-E18BEFA28B16@xbt.hk>
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Subject: Re: [bitcoin-dev] Safer sighashes and more granular SIGHASH_NOINPUT
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On Tue, Dec 18, 2018 at 03:08:26AM +0800, Johnson Lau via bitcoin-dev wrote:
> >> If it's not safer in practice, we've spent a little extra complexity
> >> committing to a subset of the script in each signature to no gain. If
> >> it is safer in practice, we've prevented people from losing funds. I'm
> >> all for less complexity, but not for that tradeoff.
> >=20
> > There are many complexities we could add, each of which would prevent
> > loss of funds in some theoretical case.
>=20
> Every security measures are overkill, until someone get burnt. If these s=
ecurity measures are really effective, no one will get burnt. The inevitabl=
e conclusion is: every effective security measures are overkill.

This isn't really a security issue, it's a software reliability issue. And
you're making a trade-off between complexity of the core protocol and
complexity of wallet software.

A core protocol failure has high costs for every single Bitcoin user; a wal=
let
software failure affects a much smaller number of people. So I'd be incline=
d to
prioritise core protocol simplicity rather than stamping out one of many, m=
any,
ways that wallet software can screw up and lose money.

--=20
https://petertodd.org 'peter'[:-1]@petertodd.org

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