This does not mean that every browser will do it.
True, but if FF is able to stick with this, and roll it out into production,
that's a strong indication that other browsers may be able to do the same. And,
of course, this eliminates the fallback problem at the root.
One remaining issue, however, is reported high rates of TLS 1.3 version
intolerance.
Cheers,
Andrei
-----Original Message-----
From: TLS [mailto:tls-bounces(_at_)ietf(_dot_)org] On Behalf Of Yuhong Bao
Sent: Friday, January 16, 2015 12:05 PM
To: Hanno Böck; tls(_at_)ietf(_dot_)org
Cc: ietf(_at_)ietf(_dot_)org
Subject: Re: [TLS] Last Call: <draft-ietf-tls-downgrade-scsv-03.txt> (TLS
Fallback Signaling Cipher Suite Value (SCSV) for Preventing Protocol Downgrade
Attacks) to Proposed Standard
This does not mean that every browser will do it.
----------------------------------------
Date: Fri, 16 Jan 2015 21:03:27 +0100
From: hanno(_at_)hboeck(_dot_)de
To: tls(_at_)ietf(_dot_)org
CC: ietf(_at_)ietf(_dot_)org
Subject: Re: [TLS] Last Call: <draft-ietf-tls-downgrade-scsv-03.txt> (TLS
Fallback Signaling Cipher Suite Value (SCSV) for Preventing Protocol Downgrade
Attacks) to Proposed Standard
Recently Mozilla has disabled the now so-called protocol dance, which makes
adding another workaround (SCSV) pretty much obsolete:
https://bugzilla.mozilla.org/show_bug.cgi?id=1084025#c7
And a few days ago mozilla dev Brian Smith tweetet this:
"Fx experiment to disable non-secure TLS version fallback is going even better
than expected. Starting to feel silly for delaying it so long."
https://twitter.com/BRIAN_____/status/555138042428526593
I think this adds further evidence that adding another workaround layer
(SCSV) is the wrong thing to do. Instead browsers should just stop doing weird
things with protocols that compromise security and drop the protocol dance
completely.
(By the way: Has anyone thought what happens when people implement TLS hardware
that is version intolerant to versions> 1.2 and at the same time send SCSV in
the handshake? I'm pretty sure that at some point some hardware will appear
that does exactly that. Will we need another SCSV standard for every TLS
version then?)
--
Hanno Böck
http://hboeck.de/
mail/jabber: hanno(_at_)hboeck(_dot_)de
GPG: BBB51E42
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