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Re: [Gnu-arch-users] Re: MD5 is broken


From: Karel Gardas
Subject: Re: [Gnu-arch-users] Re: MD5 is broken
Date: Thu, 17 Mar 2005 08:42:12 +0100 (CET)

On Thu, 17 Mar 2005, Andreas Rottmann wrote:

> > Two, they're collision free.  This means that it is impossible to
> > find two messages that hash to the same hash value.  The
> > cryptographic reasoning behind these two properties is subtle, and I
> > invite curious readers to learn more in my book Applied
> > Cryptography."
> >
> This is completely bogus. It *is* possible (see my last mail) to find
> a collision for any hash function where the hash is shorter than the
> message. What _I_ think you mean by collison-free is this:
>
> http://mathworld.wolfram.com/Collision-FreeHashFunction.html

It is not bogus. You have just deleted ``(By 'impossible' I mean 'can't be
done in any reasonable amount of time.')'' from the paragraph which is
explanation for all `imposible' in a whole paragraph. Anyway this
definition is kind of explanation for people not so used in math and
problem complexity and in fact it is similar to your nice definition from
mathworld. Thanks for the link!

Cheers,
Karel
--
Karel Gardas                  address@hidden
ObjectSecurity Ltd.           http://www.objectsecurity.com





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