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

[Hubert Kario <[e-mail]>]

On Monday, 25 July 2016 21:08:49 CEST Martin Rex wrote:
> I've just run into a weird interoperability problem with an (alleged)
> cloudflare/nginx TLS server and my personal Firefox settings.
> 
> https://regmedia.co.uk/2015/07/14/giant_weta_mike_locke_flicker_cc_20.jpg
> 
> 
> Traditionally I have all TLS ciphersuites with ECDSA disabled through
> about:config, but it seems that recently two new TLS ciphersuites were
> added to FF, which caused complete loss of interop with regmedia.co.uk
> for me with my existing configuration. (Loss of pictures&media on the
> www.theregister.co.uk news site).
> 
> 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.
> 
> It looks like a bug in the cloudflare/nginx cipher suites selection
> algorithm, which appears to blindly go for ECDSA, even though there is
> no actual ECDSA cipher suite available which the server supports.

could you post packet capture (pcap format, if possible) that shows that 
problem?

-- 
Regards,
Hubert Kario
Senior Quality Engineer, QE BaseOS Security team
Web: www.cz.redhat.com
Red Hat Czech s.r.o., Purkyňova 99/71, 612 45, Brno, Czech Republic