Antwort: Re: ... Re: dangerous implementation of rep-sharing cache for fsfs

Hello Mark,

Thanks for your wishes,
but it seems that I will never be famous:

?Hash Function Update Due to Potential Weakness Found in SHA-1?
http://www.rsa.com/rsalabs/node.asp?id=2834

Greetings

Michael Felke
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Mark Mielke <mark_at_mark.mielke.cc>
30.06.2010 20:37
 
        An: michael.felke_at_evonik.com
        Kopie: "dev_at_subversion.apache.org" <dev_at_subversion.apache.org>,
Daniel Shahaf <d.s_at_daniel.shahaf.name>, ghudson_at_mit.edu, Mark Phippard
<markphip_at_gmail.com>, mf_at_rola.ch
        Thema: Re: Antwort: Re: ... Re: dangerous implementation of
rep-sharing cache for fsfs

I think if you could find a real life collision - you might be able to
get some sort of award. Good luck. :-)

Cheers,
mark

On 06/30/2010 05:57 AM, michael.felke_at_evonik.com wrote:
> Hello,
>
> O.K., it seems there is really a need to discuss the problem of
> SHA-1 collisions more deeply.
>
> ...
> But one is missing!
>
> 4. The set of one kind of data and that of another kind are overlapping
> very infrequent, if at all. They could be seen as highly
discriminable
> and separated parts of the sample set of all possible data.
> So SHA-1 hashes will wildly spread on the first set, doing the best
> of its job, and also, but independently, spread on the other set as
> wide as it?s expected to do.
>
> What is the result, when two or more sets of hash values, each widely
> spread of the same value range, are used together in one fetch index?
>
> Perhaps, some can see a danger now, too.
>
> I? am working on a practical demonstration, which everybody could
> reproduce with his or her spreadsheet program.
> But please be patient, I have other things to do, as well.
>
> Greetings,
>
> P.S. Thanks for the warning; we are not going to use 1.7.
> At the Moment we are not using 1.6 either,
> because of the SHA-1 rep-share cache.
>

-- 
Mark Mielke<mark_at_mielke.cc>