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Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-rc4-01.txt

Hubert Kario <hkario@redhat.com> Fri, 03 October 2014 11:27 UTC

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Date: Fri, 03 Oct 2014 07:27:37 -0400
From: Hubert Kario <hkario@redhat.com>
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Thread-Topic: I-D Action: draft-ietf-tls-prohibiting-rc4-01.txt
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Archived-At: http://mailarchive.ietf.org/arch/msg/tls/wsBXgwBejEtKniDOBTWDh_w9Dv4
Subject: Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-rc4-01.txt
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----- Original Message -----
> From: "Hubert Kario" <hkario@redhat.com>
> To: tls@ietf.org
> Sent: Friday, 3 October, 2014 1:15:14 PM
> Subject: Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-rc4-01.txt
> 
> ----- Original Message -----
> > From: "Viktor Dukhovni" <ietf-dane@dukhovni.org>
> > To: tls@ietf.org
> > Sent: Friday, 3 October, 2014 6:24:18 AM
> > Subject: Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-rc4-01.txt
> > 
> > On Thu, Oct 02, 2014 at 09:13:08PM +0100, Alyssa Rowan wrote:
> > 
> > > RC4 is not sort of acceptable.
> > 
> > Recall that most applications are choosing RC4 over stronger options
> > through explicit operator configuration that no application or
> > SSL/TLS toolkit can reasonably override.
> 
> This is not the case.
> 
> Only about 1% of servers support only RC4 cipher, 1.5% if you're
> using Firefox[1].
> 
> On the other hand, over 21% of servers will negotiate a RC4 cipher
> in case you're using Firefox (and nearly 18% if you're using
> OpenSSL-like supported cipher list).
> 
> So by dropping RC4 from your first ClientHello (in case you do use
> fallback) may as well cut your RC4 usage by over 20%!

One more thing, it's not really changing for the better:
https://securitypitfalls.wordpress.com/2014/09/23/tls-landscape/
scroll to "Bad recommendations", or see this graph:
https://securitypitfalls.files.wordpress.com/2014/09/rc4-preferral.png

(that's "in general", for Firefox the situation is even worse)

-- 
Regards,
Hubert Kario

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