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[TLS] advertizing the minimum TLS supported version [was: Last Call: <draft-ietf-tls-downgrade-scsv-03.txt>]

Nikos Mavrogiannopoulos <nmav@redhat.com> Thu, 22 January 2015 10:24 UTC

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From: Nikos Mavrogiannopoulos <nmav@redhat.com>
To: Michael Clark <michael@metaparadigm.com>
Date: Thu, 22 Jan 2015 11:24:49 +0100
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Subject: [TLS] advertizing the minimum TLS supported version [was: Last Call: <draft-ietf-tls-downgrade-scsv-03.txt>]
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On Thu, 2015-01-22 at 18:11 +0800, Michael Clark wrote:
> > 3. Forbidding SSL 3.0 version from the record layer breaks perfectly
> > valid clients, which advertise TLS 1.2. These clients can only use a
> > variant of fallback dance to connect to broken servers which impose
> > those limits. Please _DON'T CREATE MORE REASONS FOR FALLBACK DANCES_.
> OK. Then an extension to indicate supported versions would in fact be an
> improvement as it would be protected by verify_data.

Some time ago, I had proposed a method for clients to advertise the list
of protocols they support, for the same reason. To allow the server to
fallback to their preferred protocol:
https://tools.ietf.org/html/draft-mavrogiannopoulos-tls-more-extensions-00#section-4

regards,
Nikos

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