CDR: Public Key Infrastructure: An Artifact...

[Jeffrey Altman]

> On Sat, 18 Nov 2000, Ben Laurie wrote:
> 
> > Bram Cohen wrote:
> > > 
> > > Unless that problem is fixed, man in the middle is hardly made more
> > > difficult - for example, Mallory could break into some random machine on
> > > the net and steal it's public key, then hijack local DNS and when someone
> > > goes to amazon.com redirect them to amazon.hackeddomain.com, and then
> > > proxy to amazon.com - now even SSL says the connection is safe.
> > 
> > Yes, and Mallory can't read the data - so what was the point?
> 
> Yes he can - he's presenting the key for hackeddomain.com, which he stole,
> so he's quite capable of reading requests sent for it.
> 

No he can't.  What hackeddomain.com is sending is the certificate for 
hackeddomain.com which does not contain the host name www.amazon.com.
Therefore, it won't be accepted by the client.

If hackeddomain.com acts as a proxy, then the certificate that is
received by the client is the real one from www.amazon.com and so the
session is protected.  You can't have it both ways.




                  Jeffrey Altman * Sr.Software Designer
                 The Kermit Project * Columbia University
               612 West 115th St * New York, NY * 10025 * USA
     http://www.kermit-project.org/ * kermit-support at kermit-project.org