[rc5] Counter-spoofing

Henry W Miller mill0440 at gold.tc.umn.edu
Fri Jun 20 08:34:21 EDT 1997

On Thu, 19 Jun 1997, Greg Hewgill wrote:

> > From: Henry W Miller <mill0440 at gold.tc.umn.edu>
> > We may from time to time give you a key block that is known to contain a
> > solution.  If we suspect spoofing expect to see a lot of these.  (but it
> > will lower the overall rate, so please dont' spoof)  
> Okay, stupid question - if you were to give out a key block that is "known"
> to contain a solution, wouldn't we be done since there is only one solution?
> I'm not sure I understand your statement.

not really stupid, it sounds logical.  I don't want to go into too many
details, but basicly: When RSA started this contest they made two keys, on
different texts.  Both started with the message "the seceret..."  and then
the text changed.  Rsa released one key to the public with the encrypted
text, and told us to find the second key to win the $10,000.  The servers
send you a block that contains both the encrypted text and the the key
block.  Thus we can give you a known solution to a different text, and
make sure you report the solution.

The proxies are already doing this in fact for testing purposes, all
coders are suppposed to be testing their code against the known solution
before using it on the real thing.  (to make sure there isnt' a bug where
the clinet doesn't find the solution)

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