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From: Steve Davis <steven.charles.davis@gmail.com>
In-Reply-To: <20170225214018.GA16524@savin.petertodd.org>
Date: Sat, 25 Feb 2017 15:54:16 -0600
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To: Peter Todd <pete@petertodd.org>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] SHA1 collisions make Git vulnerable to attakcs by
 third-parties, not just repo maintainers
Precedence: list

Hi Peter,

> On Feb 25, 2017, at 3:40 PM, Peter Todd <pete@petertodd.org> wrote:
>=20
> On Sat, Feb 25, 2017 at 03:34:33PM -0600, Steve Davis wrote:
>> Yea, well. I don=E2=80=99t think it is ethical to post instructions =
without an associated remediation (BIP) if you don=E2=80=99t see the =
potential attack.
>=20
> I can't agree with you at all there: we're still at the point where =
the
> computational costs of such attacks limit their real-world impact, =
which is
> exactly when you want the *maximum* exposure to what they are and what =
the
> risks are, so that people develop mitigations.
>=20

I agree with the latter part of your statement but am actually much less =
confident about the first part=E2=80=A6 I need to run some numbers on =
that.

> Keeping details secret tends to keep the attacks out of public view, =
which
> might be a good trade-off in a situation where the attacks are =
immediately
> practical and the need to deploy a fix is well understood. But we're =
in the
> exact opposite situation.
>=20
>> I was rather hoping that we could have a fuller discussion of what =
the best practical response would be to such an issue?
>=20
> Deploying segwit's 256-bit digests is a response that's already fully =
coded and
> ready to deploy, with the one exception of a new address format. That =
address
> format is being actively worked on, and could be deployed relatively =
quickly if
> needed.
>=20

I really, really don=E2=80=99t want to get into it but segwit has many =
aspects that are less appealing, not least of which being the amount of =
time it would take to reach the critical mass.=20

Surely there's a number of alternative approaches which could be =
explored, even if only to make a fair assessment of a best response?

/s=