[flossly]

It's a definition question. E2ee means in this cases that "the server" cannot decipher the data: the keys to that are only on the client and never shared with the server.

This setup simply does fit the definition. And trying to say it is "e2ee practically" is a bit dishonest: there is no definition for "practical e2ee".

The point of e2ee is that you do not have to trust the server (see Bitwarden for instance).

[nicce]

I think that is a bit stretch.

Let's see e.g. Wikipedia:

> End-to-end encryption (E2EE) is a method of implementing a secure communication system where only the sender and intended recipient can read the messages

It is only about the sender and intended recipient. In this case, if they actually would self-host, the server and sending devices are in the same entity group and it is encrypted where it matters. In the case of Hetzner, it is not, because Hetzner can access the machines as they are not in the sender's or receivers basement.

But there are some other benefits with E2EE if going strictly with "client-to-client" model - if server is compromised by the bug, there is higher chance that then data gets stolen as plaintext.

[FabCH]

True. But the server is not completely unprotected even if not stored in my basement.

The disks are fully encrypted, so the attacker must be careful not to accidentally interrupt power or force a reboot.

And they can’t just log into the machine, it is still a normal Linux machine with passwords.

So they need to attach to a running system and actively hack it, which is completely possible but is not going to be done by a random employee for no reason.

[FabCH]

What is the relevant definition of client and server if they are both peer devices under roughly equal level of control of a single entity?

[sylens]

The client in your family members devices has encryption keys that you do not have in your client or on the server

[FabCH]

Ok but again, that is introducing an arbitrary split that is not based on tech. What if I have two phones? Would you expect phone A to see images taken by phone B? If yes, obviously my phones need to share keys.

So what is different in saying „All family devices should see images taken by any device“? They are all clients, including the storage&processing device.

Insisting that E2EE have „ends“ on clients is not useful. It’s much better to define „end“ based on control.

[colonCapitalDee]

E2EE, by definition, means that the server storing the data can't decrypt it. Your server can decrypt the data. Thus, it's not E2EE. Is this a problem? No. You've decided that the server is trusted (a "peer device"), so it's fine if the server can decrypt the data. That's a perfectly reasonable security posture, but it's still not E2EE.

[FabCH]

I don’t think there is a formal definition of E2EE.

Here’s Wikipedia’s definition:

„End-to-end encryption (E2EE) is a method of implementing a secure communication system where only the sender and intended recipient can read the messages“

Note the complete lack of client/server distinction. It’s simply about intended recipients.

[flossly]

In many cases "transport encryption" would also fit that definition.

E2ee is quite well established imho. The server at Hetzner (a.k.a. "someone else's computer") is NOT to be trusted in e2ee schemes. Until today I'd be willing to say everyone agrees on this, but now I doubt that :)