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Firefox rolls out ECH enabled by default in 118
(blog.mozilla.org)
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this post was submitted on 03 Oct 2023
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So, currently when you visit a https secured website the initial request to the server is not encrypted. I suspect the reason for this is that say you run a web server on 1.2.3.4. But there's 4 different websites hosted on that server each with their own SSL/TLS keys.
The server doesn't have a way to know which keys/certificates to use until it knows what site you want to access. So, the initial request is encrypted with a server key, and that server key is fetched via DNS over HTTPS.
Now, here's the question. Why MUST it be DoH? For email, DKIM, SPF and DMARC settings (including public keys) are configured using standard DNS (with DNSSEC). Why do they not allow DNSSEC AND/OR DoH?
Other than that weird limitation, I think it's a good thing.
It is encrypted, just not all of it. Back upon a time all of it was encrypted but it created a problem. It was impossible to host multiple different domains on the same IP over HTTPS because chicken and egg: couldn't get the domain from the host header without completing the encryption handshake, but to do that you had to know which domain's certificate to use.
To solve the problem they came up with a TLS extension called SNI that indicates the certificate during handshake, but does so by pulling the domain name out in the clear.
ECH aims to encrypt these parts left in the clear, but can't do it with the TLS certificate (chicken and egg above). So they resorted to the encryption used by DoH instead.
Hold on, these are orthogonal technologies.
DNSSEC signs DNS records so you know they're genuine and come straight from the authoritative nameservers for the domain.
DoH encrypts DNS traffic so nobody can eavesdrop on what domains you connect to, and masks it as HTTPS traffic so providers can't block it to force you to use their nameservers.
Regarding adoption: you can give a user DoH in the browser without them having to know about it, but you can't enable DNSSEC for a domain owner or nameserver admin without their explicit approval. This will naturally lead to some adoption disparity.
Actually, that's a pretty decent explanation of why they only want to use DoH. Makes sense to me now, cheers.