[RC5] Cracking 40 bits in realtime

gindrup at okway.okstate.edu gindrup at okway.okstate.edu
Tue Jan 6 10:52:49 EST 1998


     Fine.  Only return a hash of the decrypted message.  This is 
     thoroughly discussed in the theory of zero-knowledge proofs.  We can 
     prove that we know the decrypted message while giving away none of its 
     contents.  Schneier covers this in the "Advanced Protocols" section of 
     Applied Cryptography.
            -- Eric Gindrup ! gindrup at Okway.okstate.edu


______________________________ Reply Separator _________________________________
Subject: Re: [RC5] Cracking 40 bits in realtime 
Author:  <rc5 at llamas.net > at SMTP
Date:    1/2/98 7:45 PM


Matt Perry (matt at primefactor.com) wrote:
     
> My suggestion involved people like you and me submitting 40 bit encrypted 
> message to which we know the plain text.  Just like RSA.  But EVERYONE can 
> do it.  I'll submit the first and I'll tell you what the first 30
> characters of the message are.  Just like RSA.  My neighbours will be 
> next, submitting their own 40 bit encrypted message to be cracked.
     
And after a week or so, John Q. Hax0r will submit an encrypted message 
which just happens to contain a sniffed credit card transaction.
     
I have to agree with Skip here.  As neat as this concept is, it's way too 
open to abuse.  Distributed.net would get in a *lot* of legal trouble if 
the scenario described above took place and J.Q.H. used the credit card 
information illegally.  Chances are the 10000+ of us cracking the blocks 
wouldn't be prosecuted, simply because we're too numerous, but d.net 
would almost certainly be shut down.  I'd really hate to see that happen.
     
-- 
# Greg Wooledge                         # "Daddy, why do those people have to 
# wooledge at kellnet.com                  #   use Microsoft Windows?"
# http://kellnet.com/wooledge/main.html # "Don't stare, son; it's not polite." 
#        --  Crack RC5-64 now! http://www.distributed.net/rc5/  --
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