Re: Re: Fwd: Potential SHA 1 Hack Using Distributed Computing - Near Miss(es) May be Good Enough

Quoting Paul Hoffman <paul.hoffmanvpnc.org>:

> At 11:00 PM -0700 8/13/07, Aram Perez wrote:
>> Anyone know more about this?
>
> I have the same question. I could not find any
description of *why*  
> they think that finding near-misses is going to help
the research.  
> It's not clear if they are taking their own path, or
trying to  
> improve Wang's path, or what.

The mentioned article is indeed confusing, the information
in there  
took apparently several hops.

To address your questions: Indeed, we have our own
"path", but more  
importantly we developed a new method to speed-up generation
and  
testing of candidate message pairs and apply it to SHA-1.
The  
resulting work factor is still quite high, hence we ask for 

contributions via the BOINC framework.

More information on cryptanalytic details, type of
collision, and  
resulting work factor will appear later this year.

-Christian


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At 11:31 PM +0200 8/14/07, Christian Rechberger wrote:
>The mentioned article is indeed confusing, the
information in there 
>took apparently several hops.

Welcome to the world of public cryptography!  At least I
haven't 
seen anyone so far suggest that you will find pre-images.

>To address your questions: Indeed, we have our own
"path", but more 
>importantly we developed a new method to speed-up
generation and 
>testing of candidate message pairs and apply it to
SHA-1. The 
>resulting work factor is still quite high, hence we ask
for 
>contributions via the BOINC framework.

Is there any estimation of how high? Specifically, do you
believe 
there is a good chance of having less work effort than the
current 
Wang strategy? For example, if you are sure that your result
will be 
around 2^70, well that is interesting in theory but probably
not 
worth any publicity you have gotten so far. If you are sure
it will 
be around 2^55, I'll certainly give you some of my spare CPU
cycles.

>More information on cryptanalytic details, type of
collision, and 
>resulting work factor will appear later this year.

That's good to hear. It would also be interesting if you
could keep a 
running meter of approximately how much work you are getting
from the 
participants. This isn't nearly as "sexy" as
finding ETs or even 
protein folding...

--Paul Hoffman, Director
--VPN Consortium

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