Subject: PKINIT comments (was PKINIT -18 comments)

From: "Liqiang(Larry) Zhu" <[email-masked]>
Date: Mon, 12 Apr 2004 14:32:48 -0700

Nicolas Williams wrote:
> "Ephemeral-ephemeral DH" means, AFAICS, "DH key exchange with
ephemeral [i.e., randomly generated, one-time use] > 
> exponents."

Ephemeral-ephemeral DH is not in RFC 2631, could Brian provide either a
reference or a definition for "Ephemeral-ephemeral DH" in the next
revision?

What are the recommended key sizes of the DH keys when used in
conjunction with 256-bit AES keys, for example?

> More interesting would be how to do "ephemeral-static DH" which, with
the addition of the new pre-auth framework would 
> give us a way to protect PA-ENC-TIMESTAMP.

Have we considered a similar approach to the one used in IPSEC with
predefined domain parameters?

Larry

-----Original Message-----
From: Nicolas Williams [mailto:[email-masked]] 
Sent: Monday, April 12, 2004 1:53 PM
To: Liqiang(Larry) Zhu
Cc: [email-masked]
Subject: Re: PKINIT-18 comments

On Thu, Apr 08, 2004 at 09:49:00PM -0700, Liqiang(Larry) Zhu wrote:
> 3.2.1.  Client Request
> > Finally, if the clientPublicValue is filled in, indicating that the 
> > client wishes to use ephemeral-ephemeral Diffie-Hellman, the KDC 
> > checks to see if the parameters satisfy its policy.
> 
> If anyone knows of works that study this ephemeral-ephemeral 
> Diffie-Hellman mode in detail, I would appreciate pointers.

"Ephemeral-ephemeral DH" means, AFAICS, "DH key exchange with ephemeral
[i.e., randomly generated, one-time use] exponents."

I'm not sure how one can do ephemeral-ephemeral DH with PKINIT -- it's
just not clear from the draft.  Presumably PKINIT in this mode does not
authenticate either of the client or target principals to the other, but
that's not clear either.

More interesting would be how to do "ephemeral-static DH" which, with
the addition of the new pre-auth framework would give us a way to
protect PA-ENC-TIMESTAMP.

So, we need more detail on PKINIT w/ DH exchanges other than
static-static...

Cheers,

Nico
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