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62 points terminalbraid | 2 comments | | HN request time: 0.424s | source
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infogulch ◴[] No.43563676[source]
Glad to see DNS validation from multiple perspectives, that's a scary attack vector.

I wonder if we can ever hope for CA/B to permit name constrained, short lifespan, automatically issued intermediate CAs, authenticated with something like a DNS-01 challenge. I've advocated for this before [1][2], but here's my pitch again:

I want to issue certificates from my own ICA for my homelab and office, to avoid ratelimits and hide hostnames for private services. I submit that issuing a 90-day ICA certificate with a name constraint that only allows it to issue certificates for the specific domain is no more dangerous than issuing a wildcard certificate, and offers enough utility that it should be considered seriously.

Objection 1: "Just use a wildcard cert." Wildcard certs are not sufficient here because they don't support nested wildcards, and — more importantly — they don't allow you to isolate hosts since any host can serve all subdomains. I'd rather not give some rando vibecoded nodejs app the same certificate that I use to handle auth.

Objection 2: "Just install a self-signed CA on all your devices." Installing and managing self-signed CAs on every device is tedious, error prone, and arguably more dangerous than issuing a 90-day name-constrained ICA.

Objection 3: "Aren't name constraints not supported by all clients?" On the contrary, they've had wide support for almost a decade, and for those just set the critical bit.

I understand this is not a "just ship it lmao" kind of change, but if we want this by 2030 planning for it needs to start happening now.

[1]: https://news.ycombinator.com/item?id=37537689

[2]: https://news.ycombinator.com/item?id=29808233

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1. pabs3 ◴[] No.43569375[source]
I feel like that BGP attacks (and outright mistakes) haven't gone away, so I wonder how useful MPIC is these days. Also, hosting companies have been known to MITM their customers connections in order to get valid fake certs.

https://isbgpsafeyet.com/ https://notes.valdikss.org.ru/jabber.ru-mitm/

replies(1): >>43572055 #
2. zinekeller ◴[] No.43572055[source]
> I feel like that BGP attacks (and outright mistakes) haven't gone away, so I wonder how useful MPIC is these days.

The actual wording is this:

> The goal of this proposal is to make it more difficult for adversaries to successfully launch equally-specific prefix attacks against the domain validation processes described in the TLS BRs. [emphasis added]

Everyone (everyone in the CA system at least) knows that it will not result to 100% security, but raising the attack from "fooling the sole ISP that the CA used" to "you need to effectively hijack the whole world and that would be very obvious". This is part of the "Swiss cheese" defense-in-depth.

> Also, hosting companies have been known to MITM their customers connections in order to get valid fake certs.

I am not sure if there is a feasible solution here except to be very vigilant (like looking at certificate logs). This is a breach of trust between the hosting company and the server operator.