Encrypted Client Hello

> This means that whenever a user visits a website on Cloudflare that has ECH enabled, no one except for the user and the website will be able to determine which website was visited.

But if you look at the inner/outer SNI part:

> The outer SNI is a common name that, in our case, represents that a user is trying to visit an encrypted website on Cloudflare. We chose cloudflare-ech.com as the SNI that all websites will share on Cloudflare. Because Cloudflare controls that domain we have the appropriate certificates to be able to negotiate a TLS handshake for that server name.

> The inner SNI contains the actual server name that the user is trying to visit. This is encrypted using a public key and can only be read by Cloudflare. Once the handshake completes the web page is loaded as normal, just like any other website loaded over TLS.

So Cloudflare sees it? That's definitely not the same as what they're describing, it's more of a wink-wink Applesque "trust me bro" style of "privacy" - a consolidation of traffic under the pretext of something else.

I also looked at the draft document they linked, and that seems to match up with what I'm understanding.

> If ECHClientHello.type is outer, then the server acts as a client- facing server and proceeds as described in Section 7.1 to extract a ClientHelloInner, if available.

So what does this actually protect against? Who will this benefit? Mostly people in censored countries and companies. This removes the last piece of information that can be used to block HTTPS traffic based on the site your visiting without being a party to the exchange.

I still think DoH is hot garbage and the way it has been implemented across browsers is an atrocity. It's actively harmful to security even if the spirit is in the right place. I've got no complaints about ECH.

This is bad if you are a government, company, school or user that wants to inspect traffic coming out of black-box devices: it's harder to block all of Cloudflare. But this is good if you live in a country where service X is blocked because it threatens the local political power. For example, when Signal was blocked in some countries, it used a method named domain fronting to work around that. It relied on a mismatch between SNI and HTTP domains, and all CDNs blocked it in the end. ECH allows having the same result but with plausible deniability for the CDN.

Now of course, there's always a catch… Cloudflare used to provide its services to kiwifarms; and what constitutes a legal, or moral thing to do tends to vary around the world.

And that will cause blocks by IP. It's not like authorities in those countries care that much if a user can't access a not-blocked site, as long as they can't access a blocked one.