Re: SOI: preshared

"DavidChenNH" <davidchen_nh@hotmail.com> Wed, 21 November 2001 17:33 UTC

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From: DavidChenNH <davidchen_nh@hotmail.com>
To: Michael Thomas <mat@cisco.com>, Paul Hoffman / VPNC <paul.hoffman@vpnc.org>
Cc: IP Security List <ipsec@lists.tislabs.com>
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Subject: Re: SOI: preshared
Date: Tue, 20 Nov 2001 12:20:48 -0500
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Pardon me, but,
I have to say " set of trusted public keys" that is stored for
the self-certified public key is "chasing its own shadow".
How do you get the "set of trusted public key" initially?
It will make sense in the PKI that you start with a "trusted root public
key" and
accept any public key cert that is signed by this root key.
(and don't forget about revokation check... :-)
The entire PKI infrastructure (and "chain reaction") goes alive again.

Regards,

--- David


----- Original Message -----
From: "Michael Thomas" <mat@cisco.com>
To: "Paul Hoffman / VPNC" <paul.hoffman@vpnc.org>
Cc: "IP Security List" <ipsec@lists.tislabs.com>
Sent: Monday, November 19, 2001 6:05 PM
Subject: Re: SOI: preshared


>
> Sure. Same considerations apply though.
>
>    Mike
>
> Paul Hoffman / VPNC writes:
>  > At 11:45 AM -0800 11/19/01, Michael Thomas wrote:
>  > >The consequence of using naked public keys in lieu
>  > >of symmetric keys is that you incur the cost of
>  > >both a DH and a RSA operation. You could
>  > >conceivably get rid of the DH if you don't care
>  > >about identity, but for preshared keys it seems
>  > >questionable why you'd want to do _either_.
>  >
>  > It doesn't have to be a bare public key. A self-signed cert has other
>  > signed attributes in it, such as the key validity date and an
>  > identity. The recipient simply needs to pull the public key out of
>  > the cert to check that key against its set of trusted public keys.
>  > (One doesn't need to trust this as a root cert: it is easy to make a
>  > policy of "if I get a self-signed cert as an identifier, I won't do
>  > any chaining, even if the cert says chaining is OK").
>  >
>  > Using self-signed certs is the method that JFK currently uses to
>  > allow simple trust between two parties without needing a PKI. There
>  > is no shared-secret mode.
>  >
>  > --Paul Hoffman, Director
>  > --VPN Consortium
>