It’s about damn time that we should be able to get intermediate signing certs that are domain limited from a public ca and issue out own “real” certs. This is fully supported in the standards. Anyone offering this product affordably yet?
Name constraints are an optional feature in the standards. A client can ignore the constraints and be completely standards compliant.
Should the CAs issue intermediate certs that are only secure if a client implements an optional feature?
And even if most web browsers support name constraints properly - who knows if that cheap network webcam does, or that old mail client, or that 20 year old retro PC game?
If you want to uphold the name constraints in your CA cert, mark the field as critical. At that point clients that don’t understand them should fail validation of the CA cert.
So it may have limited use-cases today if you require full compat for all clients. For example internal controlled networks like discussed in the article.
Just like you presumably already wouldn't issue LE certs when you need to support clients with ancient CA bundles.
Interesting idea. What use cases would this make easier or even possible? At first, it sounds like more work (you’re now your own CA but without full freedom of a truly self hosted one).
The main advantage is that this CA and all downstream certificates would be globally-trusted (limited to the domain), which is not the case for a custom CA.
Security-wise it shouldn't be any worse than wildcard certificates which are already a thing. It would actually improve things, because the user can now issue downstream certificates much more granularly without having to interact with the root CA (so you can issue fully offline for an intranet, or issue extremely-short-lived certificates that would otherwise run afoul of root CA's rate-limits).
It would improve things for everybody but the certificate authorities.
They're selling something with a marginal cost of zero for $50 each. A wildcard certificate costs more not because it is materially different or "harder" to issue, but because it replaces many $50 certificates. Thus, it "must" cost more, or everybody would just use wildcard certificates everywhere and reduce profits at the large public CAs.
It is actually possible to get a domain-specific CA like the one you're thinking of. I saw one at a large department of education. It allowed unlimited issuance of certificates such as HTTPS, mail-signing, document-signing, and some other types that could be locked to a DNS domain. However, there was still a cost per certificate and the up-front cost was huge, something like $100K.
I made a comment up-thread, but name-constrained CAs can issue for anything. It's enforced client-side, and not supported in far, far too many places to work. You'd be giving everyone the ability to issue for anything.
Not to mention that running any kind of public CA is harder to do properly than most people thing.
I get the negativity towards public CAs, but much of what you said isn't quite right, either.
The only "safe" way to introduce these would be to make a certificate format that's intentionally incompatible with existing implementations; that way only new implementations (which are aware of the domain constraint) will accept it where as old implementations would just reject the certificate as invalid/corrupt.
