Re: [TLS] Working Group Last Call for draft-ietf-tls-downgrade-scsv-00
Hubert Kario <hkario@redhat.com> Thu, 16 October 2014 14:28 UTC
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Date: Thu, 16 Oct 2014 10:28:25 -0400
From: Hubert Kario <hkario@redhat.com>
To: Manuel Pégourié-Gonnard <mpg@polarssl.org>
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Thread-Topic: Working Group Last Call for draft-ietf-tls-downgrade-scsv-00
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Cc: Florian Weimer <fweimer@redhat.com>, tls@ietf.org
Subject: Re: [TLS] Working Group Last Call for draft-ietf-tls-downgrade-scsv-00
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----- Original Message ----- > From: "Manuel Pégourié-Gonnard" <mpg@polarssl.org> > To: "Florian Weimer" <fweimer@redhat.com>, "Martin Thomson" <martin.thomson@gmail.com>, "Bodo Moeller" > <bmoeller@acm.org> > Cc: tls@ietf.org > Sent: Thursday, 16 October, 2014 3:48:00 PM > Subject: Re: [TLS] Working Group Last Call for draft-ietf-tls-downgrade-scsv-00 > > On 16/10/2014 15:41, Florian Weimer wrote: > > On 10/16/2014 12:40 PM, Manuel Pégourié-Gonnard wrote: > >> On 16/10/2014 12:06, Florian Weimer wrote: > >>> Interesting things will start to happen once there is TLS 1.3. > >>> TLS_FALLBACK_SCSV could really complicate its deployment. > >>> > >> I'm afraid I don't understand which interesting things you're referring > >> to. > >> Could you please elaborate on that? > >> > > A widely-deployed client might use TLS 1.2 with FALLBACK_SCSV > > unconditionally. This client would break once servers start supporting > > TLS 1.3. That's just one example of what could go wrong which could not > > go wrong before. > > > I'm sorry, but wouldn't that be very stupid of the client? Maybe the draft > could > include wording that clients MUST NOT do that, to be extra clear, but IMHO > it's > already quite clear. > > Besides clients doing this stupid thing, do you see other bad things related > to > FALLBACK_SCSV that could happen when TLS 1.3 will start being deployed? I don't see any. Both NSS and OpenSSL when they receive TLS1.2 client hello with this SCSV accept and continue connection. Both NSS and OpenSSL when they are limited by configuration to a lower protocol version (e.g. TLS1.0) and receive Client Hello with the same or higher version and this SCSV accept the connection. In other words. If, for any reason, a future client (one that supports TLS1.3) decides that it needs to downgrade the connection (and indicate that by adding the SCSV) to interoperate with current implementations, it will work correctly. Of course, if a client sets this SCSV always, even on first connection attempt, then it will fail after the server upgrades to TLS1.3, or it uses the library that doesn't support higher protocol versions (like 0.9.8), but that's incorrect use of the SCSV. -- Regards, Hubert Kario Quality Engineer, QE BaseOS Security team Email: hkario@redhat.com Web: www.cz.redhat.com Red Hat Czech s.r.o., Purkyňova 99/71, 612 45, Brno, Czech Republic
- [TLS] Working Group Last Call for draft-ietf-tls-… Joseph Salowey (jsalowey)
- Re: [TLS] Working Group Last Call for draft-ietf-… Martin Thomson
- Re: [TLS] Working Group Last Call for draft-ietf-… Martin Thomson
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Martin Thomson
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Andrei Popov
- Re: [TLS] Working Group Last Call for draft-ietf-… Adam Langley
- Re: [TLS] Working Group Last Call for draft-ietf-… Andrei Popov
- Re: [TLS] Working Group Last Call for draft-ietf-… Adam Langley
- Re: [TLS] Working Group Last Call for draft-ietf-… Andrei Popov
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Andrei Popov
- Re: [TLS] Working Group Last Call for draft-ietf-… Brian Smith
- Re: [TLS] Working Group Last Call for draft-ietf-… Brian Smith
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Brian Smith
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Brian Smith
- Re: [TLS] Working Group Last Call for draft-ietf-… Martin Rex
- Re: [TLS] Working Group Last Call for draft-ietf-… Martin Rex
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Martin Thomson
- Re: [TLS] Working Group Last Call for draft-ietf-… Brian Smith
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Martin Thomson
- Re: [TLS] Working Group Last Call for draft-ietf-… Brian Smith
- Re: [TLS] Working Group Last Call for draft-ietf-… Andrey Jivsov
- Re: [TLS] Working Group Last Call for draft-ietf-… Brian Smith
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Brian Smith
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Florian Weimer
- Re: [TLS] Working Group Last Call for draft-ietf-… Fabrice
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Salz, Rich
- Re: [TLS] Working Group Last Call for draft-ietf-… Nikos Mavrogiannopoulos
- Re: [TLS] Working Group Last Call for draft-ietf-… Hanno Böck
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Salz, Rich
- Re: [TLS] Working Group Last Call for draft-ietf-… CodesInChaos
- Re: [TLS] Working Group Last Call for draft-ietf-… Hanno Böck
- Re: [TLS] Working Group Last Call for draft-ietf-… Salz, Rich
- Re: [TLS] Working Group Last Call for draft-ietf-… Nikos Mavrogiannopoulos
- Re: [TLS] Working Group Last Call for draft-ietf-… Salz, Rich
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Tom Ritter
- Re: [TLS] Working Group Last Call for draft-ietf-… Florian Weimer
- Re: [TLS] Working Group Last Call for draft-ietf-… Florian Weimer
- Re: [TLS] Working Group Last Call for draft-ietf-… Florian Weimer
- Re: [TLS] Working Group Last Call for draft-ietf-… Florian Weimer
- Re: [TLS] Working Group Last Call for draft-ietf-… Florian Weimer
- Re: [TLS] Working Group Last Call for draft-ietf-… Salz, Rich
- Re: [TLS] Working Group Last Call for draft-ietf-… Florian Weimer
- Re: [TLS] Working Group Last Call for draft-ietf-… Salz, Rich
- Re: [TLS] Working Group Last Call for draft-ietf-… Salz, Rich
- Re: [TLS] Working Group Last Call for draft-ietf-… Florian Weimer
- Re: [TLS] Working Group Last Call for draft-ietf-… Salz, Rich
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Martin Thomson
- Re: [TLS] Working Group Last Call for draft-ietf-… Manuel Pégourié-Gonnard
- Re: [TLS] Working Group Last Call for draft-ietf-… Martin Rex
- Re: [TLS] Working Group Last Call for draft-ietf-… Watson Ladd
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Brian Smith
- Re: [TLS] Working Group Last Call for draft-ietf-… Brian Smith
- Re: [TLS] Working Group Last Call for draft-ietf-… Brian Smith
- Re: [TLS] Working Group Last Call for draft-ietf-… Fahima Ahmed Khan Etha
- Re: [TLS] Working Group Last Call for draft-ietf-… Florian Weimer
- Re: [TLS] Working Group Last Call for draft-ietf-… Florian Weimer
- Re: [TLS] Working Group Last Call for draft-ietf-… Hubert Kario
- Re: [TLS] Working Group Last Call for draft-ietf-… Hubert Kario
- Re: [TLS] Working Group Last Call for draft-ietf-… Manuel Pégourié-Gonnard
- Re: [TLS] Working Group Last Call for draft-ietf-… Florian Weimer
- Re: [TLS] Working Group Last Call for draft-ietf-… Salz, Rich
- Re: [TLS] Working Group Last Call for draft-ietf-… Manuel Pégourié-Gonnard
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Salz, Rich
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Nikos Mavrogiannopoulos
- Re: [TLS] Working Group Last Call for draft-ietf-… Salz, Rich
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Daniel Kahn Gillmor
- Re: [TLS] Working Group Last Call for draft-ietf-… Manuel Pégourié-Gonnard
- Re: [TLS] Working Group Last Call for draft-ietf-… Hubert Kario
- Re: [TLS] Working Group Last Call for draft-ietf-… Hubert Kario
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Florian Weimer
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Henrik Grubbström
- Re: [TLS] Working Group Last Call for draft-ietf-… Salz, Rich
- Re: [TLS] Working Group Last Call for draft-ietf-… Martin Thomson
- Re: [TLS] Working Group Last Call for draft-ietf-… Brian Smith
- Re: [TLS] Working Group Last Call for draft-ietf-… Peter Gutmann
- Re: [TLS] Working Group Last Call for draft-ietf-… Adam Langley
- Re: [TLS] Working Group Last Call for draft-ietf-… Martin Thomson
- Re: [TLS] Working Group Last Call for draft-ietf-… Andrey Jivsov
- [TLS] The TLS_FALLBACK_SCSV time bomb (was: Re: W… Florian Weimer
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Hubert Kario
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Bodo Moeller
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Hubert Kario
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Andrey Jivsov
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Martin Thomson
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Andrei Popov
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Martin Thomson
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Jeffrey Walton
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Andrei Popov
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Marsh Ray
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Andrei Popov
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Martin Thomson
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Andrei Popov
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Yuhong Bao
- Re: [TLS] Working Group Last Call for draft-ietf-… Andrey Jivsov
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Hubert Kario
- Re: [TLS] Working Group Last Call for draft-ietf-… Nikos Mavrogiannopoulos
- Re: [TLS] Working Group Last Call for draft-ietf-… Martin Thomson
- Re: [TLS] Working Group Last Call for draft-ietf-… Martin Thomson
- Re: [TLS] Working Group Last Call for draft-ietf-… Nikos Mavrogiannopoulos
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Manuel Pégourié-Gonnard
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Manuel Pégourié-Gonnard
- Re: [TLS] Working Group Last Call for draft-ietf-… Nikos Mavrogiannopoulos
- Re: [TLS] Working Group Last Call for draft-ietf-… Brian Smith
- Re: [TLS] Working Group Last Call for draft-ietf-… Watson Ladd
- Re: [TLS] Working Group Last Call for draft-ietf-… Brian Smith
- Re: [TLS] Working Group Last Call for draft-ietf-… Salz, Rich
- Re: [TLS] Working Group Last Call for draft-ietf-… Manuel Pégourié-Gonnard
- Re: [TLS] Working Group Last Call for draft-ietf-… Salz, Rich
- Re: [TLS] Working Group Last Call for draft-ietf-… Manuel Pégourié-Gonnard
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Andrei Popov
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Salz, Rich
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Andrei Popov
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Andrei Popov
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Bodo Moeller
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Marsh Ray
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Bodo Moeller
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: R… Andrei Popov
- Re: [TLS] Working Group Last Call fordraft-ietf-t… Rob Stradling
- Re: [TLS] Working Group Last Call fordraft-ietf-t… Ilari Liusvaara
- Re: [TLS] Working Group Last Call for draft-ietf-… Bill Frantz
- Re: [TLS] Working Group Last Call for draft-ietf-… Brian Smith
- Re: [TLS] Working Group Last Call fordraft-ietf-t… Brian Smith
- Re: [TLS] Working Group Last Call for draft-ietf-… Andrey Jivsov
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Andrey Jivsov
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Andrey Jivsov
- Re: [TLS] Working Group Last Call for draft-ietf-… Martin Thomson
- Re: [TLS] Working Group Last Call for draft-ietf-… Andrey Jivsov
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb Florian Weimer
- Re: [TLS] Working Group Last Call for draft-ietf-… Andrey Jivsov
- Re: [TLS] Working Group Last Call for draft-ietf-… Brian Smith
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb Andrei Popov
- Re: [TLS] Working Group Last Call for draft-ietf-… Andrey Jivsov
- Re: [TLS] The TLS_FALLBACK_SCSV time bomb Florian Weimer
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Daniel Kahn Gillmor
- Re: [TLS] Working Group Last Call for draft-ietf-… Andrey Jivsov
- Re: [TLS] Working Group Last Call for draft-ietf-… Daniel Kahn Gillmor
- Re: [TLS] Working Group Last Call for draft-ietf-… Martin Rex
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Florian Weimer
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller
- Re: [TLS] Working Group Last Call for draft-ietf-… Martin Rex
- Re: [TLS] Working Group Last Call for draft-ietf-… Bodo Moeller