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

Viktor Dukhovni <ietf-dane@dukhovni.org> Mon, 25 July 2016 20:36 UTC

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From: Viktor Dukhovni <ietf-dane@dukhovni.org>
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Date: Mon, 25 Jul 2016 16:36:27 -0400
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Subject: Re: [TLS] weird ECDSA interop problem with cloudflare/nginx
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> 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

Which is not AES_128_GCM.  The IANA registry seems to agree:

https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#tls-parameters-4

  0xCC,0xA9	TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256	Y	[RFC7905]

-- 
	Viktor.