Re: [TLS] WGLC: draft-ietf-tls-prohibiting-rc4-00

Hubert Kario <hkario@redhat.com> Fri, 08 August 2014 15:23 UTC

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Date: Fri, 8 Aug 2014 11:23:10 -0400 (EDT)
From: Hubert Kario <hkario@redhat.com>
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Subject: Re: [TLS] WGLC: draft-ietf-tls-prohibiting-rc4-00
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----- Original Message -----
> From: "Martin Rex" <mrex@sap.com>
> To: "Hubert Kario" <hkario@redhat.com>
> Cc: mrex@sap.com, "Sean Turner" <TurnerS@ieca.com>om>, "TLS@ietf.org (tls@ietf.org)" <tls@ietf.org>
> Sent: Friday, 8 August, 2014 4:56:58 PM
> Subject: Re: [TLS] WGLC: draft-ietf-tls-prohibiting-rc4-00
> 
> Hubert Kario wrote:
> > 
> >> There currently exists *no* known attack against the integrity
> >> protection of the TLS handshake, so this looks primarily like an
> >> attempt to promote "planned obsolesence", and a poor excuse for
> >> Microsoft to actively break interop with Windows XP (and potentially
> >> other installed base).
> > 
> > 3DES remains an option if you need to interoperate with very old
> > systems. It doesn't break interoperability with Windows XP.
> > 
> >  0 - http://blog.cloudflare.com/killing-rc4-the-long-goodbye
> 
> 
> This is the theory.
> In theory, theory an practice are the same, in practice they differ.
> 
> There seems to be stuff that breaks with TLS cipher suites that
> use padding.  This is just Windows stuff, I've also seen such
> interop problems with Java (J2SE) client (using nio it seems),
> that will simply not interop with 3DES-EDE (nor AES128-SHA),
> and RC4 is the only alternative that works.

Those are bugs, if you _need_ to work around them, then work around them,
that's what MUST means.

But don't deploy those workarounds unless you're:
 1). sure that they are needed
 2). sure that this is the only way to workaround the issue

-- 
Regards,
Hubert Kario