Re: [Acme] Alternative proposal for fixing TLS-SNI / revisiting HTTPS-01 authorization

"Matthew D. Hardeman" <mhardeman@ipifony.com> Fri, 12 January 2018 16:28 UTC

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From: "Matthew D. Hardeman" <mhardeman@ipifony.com>
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Date: Fri, 12 Jan 2018 10:28:31 -0600
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To: "Gerd v. Egidy" <gerd.von.egidy@intra2net.com>
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Subject: Re: [Acme] Alternative proposal for fixing TLS-SNI / revisiting HTTPS-01 authorization
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> On Jan 12, 2018, at 10:20 AM, Gerd v. Egidy <gerd.von.egidy@intra2net.com> wrote:
> 
> - As TLS-SNI-01/02 before, it is done completely via HTTPS on TCP port 443. So 
> if HTTPS is the protocol you want to use the cert for, you wouldn't need  
> access to an additional TCP port like HTTP-01 does. This may not be important 
> for regular webhosting, but for a scenario where the certificate protects some 
> software running on a host behind a router or firewall only allowing port 443 
> through.
> 
> What do you think?
> 

As I’ve not yet considered the other aspects, I can’t comment as to the advisability.

I did want to say that if an acceptable mechanism is found in this manner, it does help with some but not all in-band TLS validation mechanisms.  It works for web server cases.  It does not fully replace the mechanisms of the TLS-SNI sort because it would not work for other protocols running over TLS (like SMTP/TLS).  The TLS-SNI mechanisms do facilitate that.  Still, if the risks are otherwise acceptable, such a challenge mechanism might be a path of least resistance for those impacted by the TLS-SNI-01 deprecation.