Re: [TLS] Simplifying signature algorithm negotiation

Eric Rescorla <ekr@rtfm.com> Sun, 20 March 2016 17:51 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Sun, 20 Mar 2016 10:50:40 -0700
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To: Ilari Liusvaara <ilariliusvaara@welho.com>
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Cc: ekr <notifications@github.com>, "tls@ietf.org" <tls@ietf.org>
Subject: Re: [TLS] Simplifying signature algorithm negotiation
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It sounds like we have general consensus here. Does anyone object to my
merging
this PR?

-Ekr


On Thu, Mar 17, 2016 at 10:34 AM, Ilari Liusvaara <ilariliusvaara@welho.com>;
wrote:

> On Tue, Mar 15, 2016 at 05:37:20PM +0000, David Benjamin wrote:
> > On Mon, Mar 14, 2016 at 8:22 PM Eric Rescorla <ekr@rtfm.com>; wrote:
> >
> >
> > I would probably characterize it less as suites vs orthogonality, but as
> > wanting to keep divisions in meaningful and universal places and not
> > splitting up tightly-coupled decisions. The flexibility from
> orthogonality
> > can be handy, but going too far---as I believe TLS 1.2 did with
> signature,
> > prehash, and curve---complicates everything. Imagine if negotiating
> > AES_128_GCM required separately negotiating block cipher AES-128, mode
> CTR,
> > and MAC GHASH.
>
> It isn't even orthogonal, it is coupled, which is way worse and quite
> difficult to implement correctly.
>
> I now consider the way TLS 1.3 draft / RFC4492bis draft currently does
> EdDSA negotiation a bad idea (what is proposed here is vast improvement).
>
>
> -Ilari
>