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Re: Discussion of 9.2.2

From: Michael Sweet <msweet@apple.com>
Date: Sat, 27 Sep 2014 16:34:15 -0400
Cc: Eric Rescorla <ekr@rtfm.com>, Jason Greene <jason.greene@redhat.com>, Martin Thomson <martin.thomson@gmail.com>, Mark Nottingham <mnot@mnot.net>, HTTP Working Group <ietf-http-wg@w3.org>
Message-id: <024AF99B-FC93-4028-8CA1-B9DAC5F3F15C@apple.com>
To: Willy Tarreau <w@1wt.eu>

> On Sep 27, 2014, at 3:39 AM, Willy Tarreau <w@1wt.eu> wrote:
> On Fri, Sep 26, 2014 at 09:13:23AM -0700, Michael Sweet wrote:
>> Eric,
>> If you have a multi-protocol client that opportunistically uses HTTP/2 (which
>> will likely be the case for a very long time for any web browser at least),
>> then you can't simply require TLS/1.2 or omit non-HTTP/2 cipher suites from
>> negotiation because that will cause existing HTTP/1.1 (and SPDY) servers to
>> stop working if they don't support the specific TLS/1.2 ciphers or cannot
>> negotiate TLS/1.2 at all.
> I'm suddenly wondering about something : why is it that we have to support
> different ciphers for H1 and H2 despite transporting the exact same contents ?
> If some ciphers are not acceptable for H2, that makes me think they are at
> risk for H1 as well, so shouldn't we say that if an agent wants to support
> H1 as a fallback to H2 during a handshake, then it should only support the
> ciphers that are compatible with both, even if this means the handshake
> might fail on some old H1 servers (hence they'll have to retry with H1 only
> and more ciphers). That would also probably speed up H2 adoption and clean up
> of older ciphers.

I suspect that someone deploying a H2 server will not want something that degrades the user experience of those using H1.  So I don't think that it will speed up H2 adoption - quite the opposite, in fact.

Michael Sweet, Senior Printing System Engineer, PWG Chair
Received on Saturday, 27 September 2014 20:34:46 UTC

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