Update: Apple's role in adding extra location data to your request has been added to this post
Apple and a couple other providers have been experimenting with a multi-hop system of making your connections private.
Here's what a competitor, Invisiv, says.
Both pages are pretty hard to parse (IMO Cloudflare uses more jargony language: "ingress"/"egress server" - really?) but they get to the same point.
Your data takes a path like this
- Your computer, your IP address, your message to a destination gets encrypted in a couple layers and passed on.
- Your ISP knows exactly who you are and that you're reaching out to server 1. They can't see your data but to them, you're using a VPN probably.
- The first server also necessarily knows who you are, unpacks one layer of your request and sends it on to a second server (in Invisiv's case, Fastly; in Apple's, Cloudflare).
- The second server now knows that data was requested from the first server, and it can see the name of the domain you're requesting (YouTube, for example) but because the request came from the first server, it theoretically won't know it's you making that request
- The data moves on from the second server to the destination, with the destination only knowing it's receiving data from the second server, and not knowing about the first server.
The obvious issues here:
- Do you trust the people providing the multi-hop VPN-like service?
- Do you trust the two servers, which have necessarily entered into an agreement of some sort, to not collaborate regarding transmitting data?
- How easy is it to audit the code we can see?
- What else is going on with your data?
In the case of Apple/Cloudflare, reputation is rather poor. From PRISM to false advertising to notification telemetry, Apple hasn't exactly delivered on their promise. In terms of Invisiv, the company has some big names on board but Fastly and Cloudflare both have a rather significant grip on the internet (with Cloudflare's being bigger) but any CDN gets a good view into personal data most of the time.
Update: in the case of Cloudflare/Apple, Apple adds additional location data to your request, making its "private" relay leak approximate location data the same way your IP address could leak it. To wit:
Apple relays geolocate user IP addresses and translate them into a “geohash”. Geohashes are compact representations of latitude and longitude.
But on the bright side: a VPN has far more issues than either of these, as it's basically #4 above except the same service also has your identity by necessity. An untrustworthy VPN is as harmful as an untrustworthy ISP, with very little separating them.