On Mon, 1 Aug 2005, Ralf Baechle DL5RB wrote:

On Fri, Jul 29, 2005 at 06:31:09PM -0700, Bill - WA7NWP wrote:

quoted

Suppose I captured all the packets of a SSH encrypted exchange.   Would 
it be possible to decode the contents of the exchange IF one had both 
the public and private keys?

ssh uses the Diffie-Hellman algorithm to exchange randomly generated
session keys.  These keys are generated on the fly and destroyed at the
end of the session or replaced after a certain time with new keys.  The
special propertie of the Diffie-Hellman algorithm is that it permits the
secure exchange of the session keys even if the session is being evedropped
uppon.  Diffie-Hellman is vulnerable against a man in the middle attack
however, so the data packets used in the key exchange are secured against
this kind of attach using public key cryptography.  The bottom line of
all this is no, publishing the RSA or DSA public keys is useless as they're
not being used for cryptography nor can their knowledge be used to
decrypt anything.  Ssh is a pretty smart protocol :-)

Thanks Ralf.  It looks like it's back to getting encryption type NONE going
in SSH for our amatuer activities.

It was a good try.

73,
Bill - WA7NWP