Re: [TLS] Accepting that other SNI name types will never work.

Richard Moore <rich@kde.org> Tue, 08 March 2016 19:56 UTC

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Date: Tue, 8 Mar 2016 19:55:58 +0000
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From: Richard Moore <rich@kde.org>
To: Martin Thomson <martin.thomson@gmail.com>
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Cc: Adam Langley <agl@imperialviolet.org>, "tls@ietf.org" <tls@ietf.org>
Subject: Re: [TLS] Accepting that other SNI name types will never work.
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On 7 March 2016 at 12:32, Martin Thomson <martin.thomson@gmail.com> wrote:

> On 7 March 2016 at 23:02, Hubert Kario <hkario@redhat.com> wrote:
> > well, if some people don't care about their implementation being
> > fingerprintable, let them be, but there should but at least a
> > recommendation what to do if you want to avoid that.
>
> I'd be very surprised if this added anything to the fingerprinting
> entropy already present in TLS implementations.  You can't use this
> sort of thing to distinguish one user of NSS from another NSS user.
>
>
​No, but you can use this sort of thing in combination to determine the
version a server is running not just the implementation. If there was a
recommended alert for a given situation I imagine (perhaps over
optimistically) that it would be harder.



> BTW, I'm pretty much not willing to volunteer to review the patch that
> made NSS less fingerprintable as NSS.  I'm pretty sure that involves
> replacing NSS with OpenSSL.
>

​Making it hard (or at least harder) to distinguish the two would
definitely not involve that. That said, I haven't fingerprinted NSS as a
server in anywhere near as many configurations as openssl though this is
mainly because I see it used that way less frequently.

Cheers

Rich.