Re: [TLS] A la carte handshake negotiation

Dave Garrett <davemgarrett@gmail.com> Fri, 12 June 2015 15:40 UTC

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From: Dave Garrett <davemgarrett@gmail.com>
To: Eric Rescorla <ekr@rtfm.com>
Date: Fri, 12 Jun 2015 11:40:04 -0400
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Subject: Re: [TLS] A la carte handshake negotiation
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On Friday, June 12, 2015 11:23:06 am Eric Rescorla wrote:
> On Fri, Jun 12, 2015 at 11:20 AM, Dave Garrett <davemgarrett@gmail.com>;
> wrote:
> > On Friday, June 12, 2015 10:51:35 am Hubert Kario wrote:
> > > that would require definition of
> > > TLS_ECDHE_PSK_WITH_AES_128_GCM_SHA256
> > > TLS_ECDHE_PSK_WITH_256_GCM_SHA384
> > >
> > > to keep parity with already existing TLS_DHE_PSK_*
> >
> > Yes, all PSK would need ECDHE suites specified to be used with TLS 1.3+
> > under this proposal, as-is. I think that would in general already be
> > desired for PSK use-cases.
> 
> Sorry, do you mean that you couldn't use PSK without a public key key
> exchange? If so that's not going to work.

There's nothing explicitly prohibiting that in my proposal. TLS_DHE_PSK would need a TLS_ECDHE_PSK, but plain TLS_PSK is a separate issue. It's be effectively a "SHOULD NOT", though there was discussion of a separate application profile for IoT and the like which could say otherwise.


Dave