Re: [Acme] High level comments on draft-barnes-acme (the GitHub version)

Jonathan Rudenberg <jonathan@titanous.com> Wed, 25 March 2015 19:50 UTC

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From: Jonathan Rudenberg <jonathan@titanous.com>
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Date: Wed, 25 Mar 2015 12:50:30 -0700
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To: John Mattsson <john.mattsson@ericsson.com>
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Subject: Re: [Acme] High level comments on draft-barnes-acme (the GitHub version)
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> On Mar 25, 2015, at 12:42 PM, John Mattsson <john.mattsson@ericsson.com> wrote:
> 
>> On 25 Mar 2015, at 13:24, Jonathan Rudenberg <jonathan@titanous.com> wrote:
>>> 7. Using any other method of confirmation, provided that the CA maintains documented evidence that the method of confirmation establishes that the Applicant is the Domain Name Registrant or has control over the FQDN to at least the same level of assurance as those methods previously described.
>> 
>> The current status quo is that many CAs allow “put this meta tag or text file on the HTTP server” as a challenge, which is *less* secure than the proposed DVSNI and Simple HTTPS challenge methods.
> 
> Yes, but that CAs is doing something does not mean that IETF should standardise or recommend something. I think DVSNI and Simple HTTPS challenge methods are fundamentally different. In DVSNI and “put this meta tag or text file on the HTTP server” the root of trust is being on-path. In the Simple HTTPS challenge the root of trust is the HTTPS certificate.

I’m not clear on your definition of “on-path” and distinction between the two challenges. Both Simple HTTPS and DVSNI allow anyone who can respond to TCP connections to a domain to request a certificate for it.

>> If the only automated challenge method available is DNS, this puts a *huge* damper on the usability of the system.
> 
> I would prefer dropping DVSNI and only use Simple HTTPS and DNS. That would damper the usability somewhat, but I think it’s worth it. But in the end it boils done to what presenting a domain certificate is supposed to prove...
> 
>  The point that DNS configuration damper the usability indicates that somebody should look at automatic DNS management as well….

Sure, but practically speaking this isn’t going to happen any time soon.

Jonathan