From: Eric Murray <ericm@lne.com>
Date: Sat, 30 Sep 95 16:22:50 PDT
To: jbass@dmsd.com (John L. Bass)
Subject: Re: NetScape's dependence upon RSA down for the count!
In-Reply-To: <9509302239.AA11407@dmsd.com>
Message-ID: <199509302336.QAA23456@slack.lne.com>
MIME-Version: 1.0
Content-Type: text/plain


 
> >   jbass@dmsd.com writes:
> >    > client ->       filter                          Client sends packet with K(c)
> >                 filter ->       Server          filter forwards packet with K(f)                filter       <- Server          Server sends encrypts with K(f)
> >    > client       <- filter                          filter re-encrypts with K(c)
> >    >
> >    > As the protocol progresses the filter also uses the master key,
> >    > and follows the renegotiation as the master key expires.
> > 
> > Yeah, but in order for this to work, the fake server needs to know
> > netscape.com's private (secret) key, no?
> > 
> > -jon
> 
> No ... the public part of any server private key is held by the filter
> and not returned to the client. The client only encrypts with public
> keys provided by the filter. The Server only encrypts with public keys
> provided by the filter. The filter has cleartext of the entire session.

What you have described is the classic 'man in the middle' attack.
Netscape claims that SSL V.3 is immune to the MITM attack in
appendix D.4 of the SSL V.3 spec. 

You will need to get the 'filter' (MITM) key signed by Verisign.
Or hack Verisign's server-key-signing key.


BTW your 'offer' is silly- this is not a trivial amount of work, and you
would not deserve any credit for coming up with so ordinary an
attack.  Write the code yourself, or pay the market rate for it.

-- 
Eric Murray  ericm@lne.com  ericm@motorcycle.com  http://www.lne.com/ericm
PGP keyid:E03F65E5 fingerprint:50 B0 A2 4C 7D 86 FC 03  92 E8 AC E6 7E 27 29 AF