Re: [TLS] I-D Action: draft-ietf-tls-curve25519-01.txt

[Hubert Kario <[e-mail]>]

On Monday 20 July 2015 14:39:03 Ilari Liusvaara wrote:
> On Mon, Jul 20, 2015 at 12:55:37PM +0200, Hubert Kario wrote:
> > On Tuesday 14 July 2015 17:23:44 Simon Josefsson wrote:
> > > Compare how we "reuse" the ECDHE ciphersuite values to refer to
> > > Curve25519 (instead of defining new ciphersuites for Curve25519), and
> > > how we are "reusing" the "uncompressed" code point to refer to
> > > Curve25519-compressed code points (instead of defining new
> > > ECPointFormat).
> > 
> > the point is, that if Ed25519 for signatures is defined, an implementation
> > that doesn't understand it[1] can't advertise that fact
> 
> Are you thinking about 1.0/1.1? In 1.2 it can: signature_algorithms
> (I'm not confident new signature algorithm would work without either
> that nor new ciphersuites).
> 
> 
> There are other shortcomings tho:
> - If Ed25519 is supported, one also needs to support Curve25519.
> - If Ed25519 and Curve448 are supported, one needs to support
>   Curve25519 and Ed448.
> - And the cross case from previous.
> 
> So with the same, in TLS 1.2, the following combinations would
> be possible:
> - None at all.
> - Curve25519
> - Curve448
> - Curve25519 & Curve448
> - Curve25519 & Ed25519
> - Curve448 & Ed448
> - Curve25519 & Curve448 & Ed25519 & Ed448.

if we define separate codepoints for Curve25519 and Ed25519, yes
-- 
Regards,
Hubert Kario
Quality Engineer, QE BaseOS Security team
Web: www.cz.redhat.com
Red Hat Czech s.r.o., Purkyňova 99/71, 612 45, Brno, Czech Republic