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Re: [TLS] Fallback SCSV summary

Martin Thomson <martin.thomson@gmail.com> Mon, 10 November 2014 20:46 UTC

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Date: Mon, 10 Nov 2014 12:45:53 -0800
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From: Martin Thomson <martin.thomson@gmail.com>
To: Bodo Moeller <bmoeller@acm.org>
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Subject: Re: [TLS] Fallback SCSV summary
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On 10 November 2014 12:40, Bodo Moeller <bmoeller@acm.org> wrote:
> So ... unless I'm misunderstanding what you describe here, these servers
> plainly don't tolerate new (= unknown, to them) cipher suites in the list?!
> Interesting.

There's a suggestion that some implementations only look at the second
byte.  A legacy of SSLv2, I believe.

I'm not going to lose sleep over this.  The SCSV fortuitously or
otherwise, has a zero value on the second byte, which those
implementations might recognize as TLS_NULL_WITH_NULL_NULL.  Changing
that might fix some of the issues, but I'm not sure that I want to
take the cost.

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