[RC5] DES 2 (in preparation of)

Charles W. Hubbard chubbard at owt.com
Fri Jan 2 17:44:42 EST 1998


> 1) As I understand it, there is a central server controlling the distribution 
> of each of the quadzillion (or more) packets to be tested for the hidden 
> message so that each is only processed once.  Anyone participating (ie 
> contributing their spare processor time) has a client on their machine that 
> downloads a set of packets when they dial-in and connect to the Internet, and 
> uploads any completed 'results' from the previous batch once processed by 
> their client - which all happens behind the scenes when their computer/LAN is 
>doing nothing else.  Is this understanding right?

Yep.  That's exactly right.

> 2) As far as the competition is concerned, how is the 'winner' discerned?  If
> all the calculations, etc are being handled in the background, how would you
> know if one of 'your' packets held the solution?  I assume the distributing
> server keeps a record of who had what or the individual clients break into a
> 'celebration' algorythm?

In short, the packets you send back are tagged with you e-mail address.
If your computer finds the winning key you will be notified at that
e-mail. Also...

>From the FAQ:

Q: How will I know if my computer found the key?

A: Initially you won't. We've set the clients up intentionally so as not
to
alert the user if a candidate key is found. There are several reasons
for this. 
First, we have gone to a lot of effort to make this project successful.
We want 
to make sure that we maintain control over the winning key until RSA has
been 
notified. Secondly, a lot of people running the clients don't want the
client 
playing Yankee Doodle Dandy if it finds the key. They run the clients in
their 
office, on there secretary's machines, etc. and aren't looking for a lot
of
attention. Finally, the clients only perform a partial message
decryption and it 
is possible (although unlikely) for them to generate false positives.
There is 
no need to get excited until the key has been verified. 

If your computer does find the winning key you will be notified by
e-mail after 
the key has been verified by RSA. This is one reason why it is so
important that 
you submit keys using a valid e-mail address! 

(Not in the FAQ but should be...) d.net also periodically sends out
"test blocks". These blocks contain a piece of ciphertext and a key that
WILL BE properly decrypted.  The clients will report these as false
positives. They are used to make sure the system is working correctly.

> 3) When up/downloading packets during a dial-in, how long will it take to
> complete the transaction?  Ie, how long @ 28k8 (for example) will the process
> need the line kept open for?

Not long.  The keyblocks are small and the newest client sends a few
keyblocks a second so typically you only need to be connected for a few
minutes.  Also...

>From the FAQ:

Q: Is my modem OK or do I need to have a faster connection?

A: Any modem is just fine! You computer will only want to communicate
when it needs to download new blocks or report the status of old ones.
Depending on the 
buffer sizes you select this may only need to happen once every several
days. 
The amount of information that is transferred to and from your computer
is tiny 
(about 125 bytes per block) so even when moving a large number of blocks
over a 
slow modem it doesn't take too long. 


4) And finally;
>No, the current personal proxies will not support DES.
>(ie, you can't just delete your rc5-64 buffers and have them replaced
>with DES buffers)
>You will need to upgrade to the DES/RC5-64 clients, and upgrade your
>proxy.
When and where will these programs be available?

The new "dual-core" clients and pproxies have not been released yet. I
don't have an *official* word on when they might be released but Duncan
recently said on IRC he hoped they'd be out about 5 days before the
DES-II contest begins. Maybe someone here has more up to date
information? Anyway, when they are released they should be available for
download off the Bovine Project web page

   http://www.distributed.net/rc5/

under the "Downloads" section (along the left side of the page)


Best Regards,


Charlie Hubbard
Tri-Cities RC5-64 Community Cracking Effort
http://www.owt.com/users/chubbard/rc5-64/
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