Sounds great, this would lift a huge burden lifted from users. As noted by 
Joona in the "Trust and security" thread, foreseeable automation options for 
the existing DNS challenge are really lacking, and improvements there would 
either require a lot of retooling by e.g. DNS hosts, or convoluted solutions 
like end-users having to run their own ACME-DNS kinds of services.

One potential issue: there are number of DNS providers that do not permit 
underscores in CNAME (or NS for that matter) labels, whilst permitting them in 
TXT labels. It may be worthwhile to do a survey of DNS hosts of domains using 
Let's Encrypt to check what this looks like in the real world.

On Tue, Jan 23, 2018, at 12:09 PM, Jacob Hoffman-Andrews wrote:
>
> In
> effect, the CNAME record would act like a long-term delegation
> permitting the CA to issue continuously for the base domain.

I can imagine that this introduces a new risk of domain administrators 
"forgetting" about having made a long-term delegation of  _acme-challenge to 
the CA and unwittingly authorize an account key to issue certificates for any 
name longer than intended. Any need to mitigate this?

_______________________________________________
Acme mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/acme

Reply via email to