[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Please kill preshared key.

On Fri, 7 Dec 2001, david chen wrote:
> > > What I infered is that
> > > the pre-shared symmetric key can be used for both authentication and
> > > encryption without key-exchange (KE) ...
> > Your inference is incorrect.  That is not how today's IPSec PSK works.
>
> Agree,..
> However, do you agree my statement make sense?

Only if the preshared key is fairly high quality, which it often isn't.
Using a poor key only for gateway authentication exposes you to
impersonation attacks, but those are typically much more difficult to
mount than eavesdropping attacks, which are the dominant failure mode with
a poor encryption key. 

                                                          Henry Spencer
                                                       henry@spsystems.net
Follow-Ups: References: