Date: Fri, 24 Feb 2017 20:01:22 -0500
From: Peter Todd <pete@petertodd.org>
To: Steve Davis <steven.charles.davis@gmail.com>,
	Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Message-ID: <20170225010122.GA10233@savin.petertodd.org>
References: <mailman.22137.1487974823.31141.bitcoin-dev@lists.linuxfoundation.org>
	<8F096BE1-D305-43D4-AF10-2CC48837B14F@gmail.com>
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In-Reply-To: <8F096BE1-D305-43D4-AF10-2CC48837B14F@gmail.com>
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Subject: Re: [bitcoin-dev] SHA1 collisions make Git vulnerable to attakcs by
 third-parties, not just repo maintainers
Precedence: list


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On Fri, Feb 24, 2017 at 05:49:36PM -0600, Steve Davis via bitcoin-dev wrote:
> If the 20 byte SHA1 is now considered insecure (with good reason), what a=
bout RIPEMD-160 which is the foundation of Bitcoin addresses?

SHA1 is insecure because the SHA1 algorithm is insecure, not because 160bit=
s isn't enough.

AFAIK there aren't any known weaknesses in RIPEMD160, but it also hasn't be=
en
as closely studied as more common hash algorithms. That said, Bitcoin uses
RIPEMD160(SHA256(msg)), which may make creating collisions harder if an att=
ack
is found than if it used RIPEMD160 alone.

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

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