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Re: [TLS] Should we require compressed points

Eric Rescorla <ekr@rtfm.com> Tue, 28 October 2014 14:55 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Tue, 28 Oct 2014 07:54:32 -0700
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Subject: Re: [TLS] Should we require compressed points
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On Tue, Oct 28, 2014 at 7:52 AM, Viktor Dukhovni <ietf-dane@dukhovni.org>
wrote:

> On Tue, Oct 28, 2014 at 10:35:25AM +0100, Manuel P?gouri?-Gonnard wrote:
>
> > On 27/10/2014 23:10, Eric Rescorla wrote:
> > > As I said above, I'm principally trying to get rid of negotiation so
> we have
> > > one point format for each curve. I could certainly live with requiring
> > > uncompressed only for the X9.62 curves and then defining a new, cleaner
> > > format for the new CFRG curves.
> >
> > If the goal is to get rid of negotiation, would it be reasonable to say
> that
> > implementations MUST support both formats?
>
> I think that Bodo's suggestion of separate IANA assignments for
> compressed and uncompressed variants of curves makes the most sense.
>
> With that, clients that need to interoperate with TLS <= 1.2 can
> send the point format extension indicating uncompressed format for
> legacy curves, and include the code points for the legacy
> format-ambiguous curves, and send new code points for (some of the
> same underlying) curves that have an implied format.
>
> Brand new curves would then ideally be registered with a single
> preferred point format that is most suitable for the curve.


This seems perfectly reasonable to me.

-Ekr

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