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Re: [TLS] I-D Action: draft-ietf-tls-negotiated-ff-dhe-10.txt

Tony Arcieri <bascule@gmail.com> Wed, 03 June 2015 06:36 UTC

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From: Tony Arcieri <bascule@gmail.com>
Date: Tue, 02 Jun 2015 23:35:46 -0700
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To: Geoffrey Keating <geoffk@geoffk.org>
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Cc: TLS WG <tls@ietf.org>
Subject: Re: [TLS] I-D Action: draft-ietf-tls-negotiated-ff-dhe-10.txt
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On Tue, Jun 2, 2015 at 11:32 PM, Geoffrey Keating <geoffk@geoffk.org> wrote:

> It's covered in section 4:
>
>    If at least one FFDHE ciphersuite is present in the client
>    ciphersuite list, and the Supported Groups extension is either absent
>    from the ClientHello


Unless I'm mistaken, unless you configure the jdk.tls.disabledAlgorithms
property explicitly (with e.g. "DHE keySize > 2048"), Java clients are
aborting *before* they send the ClientHello. Please let me know if you're
seeing otherwise. I could be mistaken and perhaps there's a server-side
workaround for this that isn't "disable all DHE ciphersuites". But this is
what I've personally observed and have been advising people about.

I'm not saying it can't be fixed with additional configuration/errata/etc,
I'm arguing that it's *breaking clients in the field right now*

tl;dr: I am seeing *widespread TLS breakages* because of this resulting in
*huge outages* for Java clients

-- 
Tony Arcieri

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