Re: DES-Busting Screen Savers?

Tim and others have discussed the effectiveness of random search
vs. centralized servers, problems of cheating, scaling, etc.
My take is that, if you can ignore scaling, the best approach
is probably to have a central server that doles out keyspace
and wraps around when it reaches 100%, and doesn't worry too much
about collecting results - even if there are cheaters, machine
failures, etc., and people don't finish their keyspace,
it'll be more likely to cover the whole space than randoms.
(Make it a web page, and use cut&paste to transfer to the
search programs so they don't need to be network-equipped.)

To support scaling, make it easy for people to run subset servers;
grab a chunk of keyspace from the main server and dole it out
to people who ask you for it.  If you want to get fancy,
hack a DNS server to allow people to register their machines
as NNN.descrack.org, 0<=NNN<1000, so that people can find 
subsets without having to ask the main server.

>>> a brute force "screen saver" for

>-- By the time the total amount of computons expended has equalled the
>amount that would have been expended in a "no duplications" allocated
>search, the Poisson probability distribution says that 1/e = 36.8% of the
>keyspace will not have been searched; the rest of the probabilty lies in
>keyspace searched once, twice, three times, etc.

#				Thanks;  Bill
# Bill Stewart +1-415-442-2215 stewarts@ix.netcom.com
# http://www.idiom.com/~wcs
#				Confuse Authority!

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On Wed, 24 Jul 1996, Bill Stewart wrote:

> Date: Wed, 24 Jul 1996 02:24:58 -0700
> From: Bill Stewart <stewarts@ix.netcom.com>
> To: cypherpunks@toad.com
> Subject: Re: DES-Busting Screen Savers?
> 
> Tim and others have discussed the effectiveness of random search
> vs. centralized servers, problems of cheating, scaling, etc.
> My take is that, if you can ignore scaling, the best approach
> is probably to have a central server that doles out keyspace
> and wraps around when it reaches 100%, and doesn't worry too much
> about collecting results - even if there are cheaters, machine
> failures, etc., and people don't finish their keyspace,
> it'll be more likely to cover the whole space than randoms.
> (Make it a web page, and use cut&paste to transfer to the
> search programs so they don't need to be network-equipped.)
> 

Agreed.  Also, we might want to keep the plaintext on, say, a floppy disk,
as to discourage the recovery technique (which, admitidly, is easier than
actually cracking the key).  I might suggest, also, to put the disks in
the hands of someone who has little or no reason to help.  Sadly, the best
person for the job that _I_ can think of would have to be "Dr." Dave.

> 
> To support scaling, make it easy for people to run subset servers;
> grab a chunk of keyspace from the main server and dole it out
> to people who ask you for it.  If you want to get fancy,
> hack a DNS server to allow people to register their machines
> as NNN.descrack.org, 0<=NNN<1000, so that people can find 
> subsets without having to ask the main server.
> 

Or hack it to use a 56 bit IP netmask-ish thing, and keep track of keys
that way (i'm not endorsing this idea, just pointing it out)

 --Deviant
"I understand by 'freedom of Spirit' something quite definite -
the unconditional will to say No, where it is dangerous to say
No.
           Friedrich Nietzsche


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