Re: [TLS] weird ECDSA interop problem with cloudflare/nginx

Ilari Liusvaara <ilariliusvaara@welho.com> Mon, 25 July 2016 21:00 UTC

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Date: Tue, 26 Jul 2016 00:00:21 +0300
From: Ilari Liusvaara <ilariliusvaara@welho.com>
To: tls@ietf.org
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Subject: Re: [TLS] weird ECDSA interop problem with cloudflare/nginx
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On Mon, Jul 25, 2016 at 04:36:27PM -0400, Viktor Dukhovni wrote:
> 
> > On Jul 25, 2016, at 3:08 PM, Martin Rex <mrex@sap.com> wrote:
> > 
> > specifically, after the FF update, this new TLS ciphersuite:
> > 
> >   security.ssl3.ecdhe_ecdsa_aes_128_gcm_sha256  (0xcc, 0xa9)
> > 
> > was the only ECDSA cipher suite enabled in my Firefox 47.0.1, and this
> > kills connectivity (TLS handshake_failure alert) with regmedia.co.uk.
> 
> OpenSSL lists "CC, A9" as:
> 
> 0xCC,0xA9 - ECDHE-ECDSA-CHACHA20-POLY1305 TLSv1.2 Kx=ECDH     Au=ECDSA Enc=CHACHA20/POLY1305(256) Mac=AEAD

I wonder what is happening is that having ECDSA ciphersuite enabled
causes Firefox to include the ECDSA signatures in signature_algorithms
and the server end sees ECDSA supported, tries to choose that, but
then blows up when it does not find any enabled ciphersuites it knows
that support ECDSA...



-Ilari