Re: Supporting hashes other than SHA-1

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: May 12, 2009, 14:06 UTC
Message-ID: <alpine.DEB.1.00.0905121604560.4447@intel-tinevez-2-302>
In-Reply-To: <4A0980C8.7060106@op5.se>

Hi,

On Tue, 12 May 2009, Andreas Ericsson wrote:

Show 20 quoted lines

> Jakub Narebski wrote:
> > Jakub Narebski <jnareb@gmail.com> writes:
> > 
> > > Chris Frey <cdfrey@foursquare.net> writes:
> > >
> > > > Considering the recent news regarding SHA-1's newly found weaknesses,
> > > > is there any general interest in making git flexible enough to support
> > > > other hashes in the future?
> > > First, there isn't as far as I know any 'known preimage' attack
> > > against SHA-1, and only that would truly matter for Git.
> > >
> > > Second, this issue was discussed in depth in the past; check git
> > > mailing list archives, please...
> > 
> > See also this blog entry (and comments):
> >   http://kitenet.net/~joey/blog/entry/sha-1/
> > 
> 
> It's a bit harder than that, since both pre-images have to be the same
> size.

They don't. The pre-images prefixed by the type identifier and the size in ASCII need to have the same hash. There is a difference.

Ciao, Dscho