All well and good, but sadly this relies on the hosts managing DNS to include specific entries in their DNS configuration for keys to use during the encryption process. Unfortunately the vast majority of hosts probably won’t be bothered to do this, similar to DNSSEC.
Apparently, Cloudflare already supports ECH, and a not-insignificant number of websites use them.
Unfortunately though, is that it’s cloudflare
Wouldn’t it be better if reverse proxies simply had a “default key” meant to encrypt the SNI after an unencrypted “hello” is received?
Including DNS in this seems weird.
What would stop a MITM attacker from replacing the key? The server can’t sign the key if it doesn’t know which domain the client is trusting.
Does this mean your isp can’t see the sites you visit anymore?
Sort of. They can still see which IP address you’re connecting to, which by itself or in combination with some minor traffic analysis is quite often enough to identify which website you’ve visited. Perhaps it isn’t if the website puts absolutely everything through a giant CDN like Cloudflare, but in that case it’s Cloudflare which gets to see all the sites you visit which isn’t a whole lot better than the status quo.
Still, it’s a little less information given away at least some of the time. Better to do it than not do it.
in that case it’s Cloudflare which gets to see all the sites you visit
That’s the status quo. CF holds the private keys to all reverse proxy’d sites hosted on it.
To be more precise, my belief is that the main thing ECH does is make it more difficult some of the time (depending on the details of how the site works) for observers of network traffic to directly see which website you’ve visited if it’s one of those that have chosen to give all that data to Cloudflare or some similar system instead.
There also do still exist some simple web hosting setups that share many independent domain names on the same IP, but I think it’s not as common as it probably was when they first came up with the idea of encrypting the tls server name many years ago. Maybe it’ll make a comeback for sites whose users need to avoid censorship in this way if it’s true that domain fronting has generally become more difficult.
Well, for half of the internet they are going to see AWS ELBs addresses.
Yes. Use a VPN. I recommend https://mullvad.net/en
Using a VPN just hands all of this information to them instead. That could be an improvement, but how do you know?
Well they can see your browsing history, sure. But HTTPS will stop them from seeing the content you actually see on the web. At this point we are just getting into discussions of layers of trust, which are generally impossible to solve if you don’t trust anyone. If you don’t trust anyone don’t use the internet, ever. I do trust mullvad. They’re explicit about who is involved, I have the name of every team member, and through peer review I consider them trustworthy.
For more info about how they are transparent, you can read their article about how they responded to a search warrant earlier this year:
In line with our policies such customer data did not exist. We argued they had no reason to expect to find what they were looking for and any seizures would therefore be illegal under Swedish law. After demonstrating that this is indeed how our service works and them consulting the prosecutor they left without taking anything and without any customer information.
But HTTPS will stop them from seeing the content you actually see on the web.
Sure, but that was true for your ISP as well. I’m not questioning what data you’re leaking. I’m saying that it’s the same data and you only change who you leak it to if you choose to use a VPN.
It seems like you’ve thought about it and you have made an informed choice. That’s great and I don’t have anything to argue against here. The only reason I commented is that there seems to be a trend of “just use VPN and your data is protected” mentality, especially with all the ads in gaming/tech related content. There was no way for me to know if you or the other users who would read your initial comment were aware that using a VPN doesn’t magically protect your data if you don’t know who your provider is, so I though I’d point it out.
That’s how I understood it. With regular https your doing on those websites is already encrypted, but your ISP or whoever sits in between can still se which sites you’re visiting. As far as I understand this standard would encrypt this step too.
Cool. Nice work Mozilla.
When is this coming to ff mobile?
Does anyone know how to enable this for nginx?
It’s been a couple years since I was involved with ECH, but the implementations at the time were:
The one by the draft’s authors in golang (Cloudflare). This is the actual test server. It uses Cloudflare’s fork of golang with an enhanced crypto library. https://gist.github.com/cjpatton/da8814704b8daa48cb6c16eafdb8e402
BoringSSL used for chrome. There are nginx builds with BoringSSL, but I don’t know if the setting are exposed.
https://boringssl.googlesource.com/boringssl/+/refs/heads/master/ssl/encrypted_client_hello.cc
WolfSSL which I never got around to playing with.
https://www.wolfssl.com/encrypted-client-hello-ech-now-supported-wolfssl/
NSS which is Mozilla’s TLS library. There is a test server buried in there some place for unit testing.
https://firefox-source-docs.mozilla.org/security/nss/index.html
With that, you ALSO need a DNS server that supports DNS over HTTP (DoH) and HTTPS service binding records (https://datatracker.ietf.org/doc/draft-ietf-dnsop-svcb-https/).
Bind9 had branches for both and I was able merge the two to satisfy that requirement.
When connecting to such a server, you MUST NOT use a DNS resolver hosted by any origination along the path from client to server as they can correlate the host from the DNS request with your encrypted client hello. You can actually man-in-the-middle ECH to decrypt the client hello by overriding the hosts record when controlling the DNS resolver. My project was testing this for parental controls.
Keep in mind, ECH really only benefits users connecting to a CDN. That is, when multiple services are behind the same IP. It masks which host the user is going to for any hop between the client and server.
Any data mining company worth their evils will have an IP to DNS index to figure out the host when only one is behind an IP.
This marginally gives some privacy to users. It hides the host from your ISP. It REALLY benefits browser companies and CDN hosts. What hosts a user is visiting now becomes exclusive data for those companies thereby driving up the value of the data. Assuming you aren’t being stupid with your addons.
Users using DNS-based filtering may need to tweak their configuration in order to make use of ECH. Firefox needs to be configured with a DNS-over-HTTPS server in order to make use of ECH. Depending on whether the DNS filter is locally hosted or hosted by an online provider, instructions for connecting to it over DoH will differ and users of these services will need to check their accompanying documentation.
Sooo, I’m a bit lost here. How do I ensure everything’s working when I’m using a pihole? I don’t think I’m understanding everything correctly
I think it requires you shut your pihole. Um. sorry. Ill let myself out.
It sounds like you’ll have to set your Pihole as the DNS server in Firefox’s settings, and then maybe from there it’ll work itself out? Or maybe the Pihole documentation will be updated in the next few days with some instructions on enabling this. I’m unsure myself to be honest.
That would make sense, wouldn’t it? I think I’m going to wait for the pihole team to inform about this.
So with this the ISP, or someone else sitting in the middle, would not even know the URL you’re accessing?
I don’t think so, that’d be straight up impossible unless you’re behind a VPN. Your ISP can see every connection made between you and any other server, but a VPN uses encrypted payloads between their servers and you, and they make the requests using their servers, and pass the results to you. That way, your ISP only sees that you’re using a VPN, but can’t see anything else.
As far as I understand it, ECH uses DoH (DNS Over HTTPS) to encrypt the domain name of your connections, but a direct IP address is always required, and most of the times, it’s enough to determine the website, as the ISPs can locate just about anything easily. However, the ISP won’t be able to (easily) know anything else about the connection, which remains unbroken between you and the server you’re connecting with.
But still a very good feature nonetheless.
IPs of websites are fine to expose in this day and age, in my opinion and threat model.
Most sites being hosted in the cloud, with rotating IPs give you obscurity there.
Agreed. Most of the servers are behind proxies anyway.
In my opinion, Firefox should give an option to enable ECH forcefully for users like me who has AdGuardHome/Pi-Hole running on Home Network. Currently, if DOH is disabled in Firefox setting, ECH won’t work, as per Firefox. 😦
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