Re: [TLS] Working Group Last Call for draft-ietf-tls-downgrade-scsv-00
Bodo Moeller <bmoeller@acm.org> Fri, 24 October 2014 09:58 UTC
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Date: Fri, 24 Oct 2014 11:58:47 +0200
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From: Bodo Moeller <bmoeller@acm.org>
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Subject: Re: [TLS] Working Group Last Call for draft-ietf-tls-downgrade-scsv-00
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Andrey Jivsov <crypto@brainhub.org>: Client decides to drop to TLS1.1 (due to network glitch, etc). [...] The > server MUST fail with inappropriate_fallback per sec 3. > > Is it a good idea to reject a more secure protocol than the server can > possibly negotiate with this client? In this case, the connection really fails due to the network glitch. If the client wasn't attempting fallback retries, it would similarly fail. (This could happen independently of the cipher suites that the server accepts.) In the kind of hypothetical scenario that you describe, it indeed wouldn't cause a reduction in security to accept the connection instead of failing, but optimizing for corner cases like this one doesn't seem reasonable: it necessarily would make the mechanism more complex overall. (The server behavior that you describe also would be really odd. The CBC cipher suites are more broken in SSL 3.0 than in TLS 1.0, and more broken in TLS 1.0 than in TLS 1.1. If the server *does* support one of the newer protocol versions, why would it only support the most broken incarnation of that cipher suite? Also note that in the *specific* hypothetical scenario that you describe, the server actually would accept the fallback retry: you said that TLS 1.0 is the highest protocol version supported by the server; this is not higher than ClientHello.client_version in the TLS 1.1 retry, so the server wouldn't reject.) Bodo
- [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