Don't Recommend Nextcloud E2EE

In my opinion, the recommendation to use a Nextcloud provider with E2E, or even to enable it on your own installation should be removed.

I haven’t found any Nextcloud provider that actually supports E2E in my previous research. And even if you do, contacts and calendar information will still be both synced and stored fully unencrypted. Not even with server-side encryption.

Then there’s the matter of Nextcloud’s end-to-end encryption being practically unusable. Just look at the reviews on End-to-End Encryption - Apps - App Store - Nextcloud.

It doesn’t support the Nextcloud web client, so you can no longer view files from there with it enabled, and it is in general extremely unreliable. Not to mention that, as I said, it doesn’t apply to contacts or calendar information.

The best thing you can do, and what should be recommended, is to simply not use a provider, and to self-host, with or without enabling E2E on your installation.

For NextcloudPi users, there’s an option to encrypt the Nextcloud data directory, which means a password is required on every boot. This protects against an attacker with physical access, who can access your server-side encryption key.

If you host Nextcloud using another method, you will have to do this yourself. I’m not sure how exactly, as it’s not my case, but this is definitely the best method to ensure your data is safe, both from a physical attack, and from the extremely unreliable E2E “support” Nextcloud has.

Fully agreeing here. The e2ee is flawed, a malicious servers can obtain encrypted files without user interaction (does require an active client) so there is not much benefit in enabling it.

Personally I am awaiting proton drive to get sync. That would have been my go on writing the above and voting for total removal of Nextcloud. Nextcloud is a pain to maintain. Has many known issues with unreliable backup systems, data loss and corruption in the clients, and upgrades more than often lead to database failures. Instead of investing time in this and in the speed issues Nextcloud has (it is very heavy) they all the time seem to loose focus and yet introduce a new app be it automations, social parts, video calling etc.

On the other hand we don’t have (m)any alternatives when it comes to hosting documents, contacts and calendars. Especially for collaboration. Although I have never seen any OnlyOffice or Collabora installation for Nextcloud that works really well with multiple users.

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I dont think we should remove it, just change it so that it suggest self hosting via a VPS.

Also IIRC Weibo Hosting allows for a managed paid tier with their Nextcloud Admin service offering. It gives you the option to enable E2EE and server side encryption (and pick which app yoi want activated) unlike all of the free tiers offered in the Nextcloud website.

I don’t think we should be recommending any third party hosting. Self hosted cab be okayish but one needs to trust the hosting provider. As the website currently doesn’t list any hosting providers it may not be the best. I know a few providers that can host Nextcloud instances that are quite alright. But I am generally hesitant to recommend it. The providers are Owncube (AT) and Hetzner (DE). Owncube allows you to install apps too.

I have never heard of the provider you mention and also cannot find any information on it. But as said the e2ee is flawed so this doesn’t really matter whether you have it on or not. The provider can obtain your documents.

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This is actually something we’ve been thinking of doing internally for a while now.

If it is removed, perhaps it should be replaced with a warning as well.

Many people even think SSE instances are secure, despite being demonstrated otherwise.

I thought the whole point of E2EE was that you did not need to trust the provider because the encryption happened on your side) assuming the encryption was properly implemented. I dont work in computer security, can you elaborate (or at least give your source) on how flawed it is, exactly? I did try to expore the data directory and it at least, seemed encrypted with randomly generated file names and directories.

About the hosting provider you asked:

I am aware of 5 security issues with Nextcloud’s e2ee. I have no idea of the status as they never replied to my reports.

  1. The private key of e2ee is stored on the server.
  2. The directory info and meta is not encrypted. This is also enabling 3 an 4.
  3. It was/is possible to move files manually and db actions to have to a none encrypted folder. This makes/made the desktop client move the non encrypted file and upload it to the web server in plain. So you could/can instruct the desktop client to upload all files as a malicious server.
  4. It was/is possible to delete files from the web client, after sync with desktop client the file was/is present unprecedentedly in the trash.
  5. The e2ee has a few times prevented the Nextcloud instances from updating as it was not kept up to date and prevented upgrades to new versions due to incompatibility. This issue is common with many nextcloud apps.

Additionally I am aware of several issues with double key generation causing existence of multiple key-pairs per user and making it impossible to sync files and several issues with files getting locked indefinitely.

Conclusion, it’s flawed, they don’t know what they are doing, and it is very unstable.


Actually another less of an issue problem. Nextcloud uses low entropy passphrases. This may be a problem for some trying to get an certification. If your organization follows NIST or NSA recommendations this will not pass. ANSSI allows this kind of entropy untill 3030. Yet no plans for change have been made so it may be good to be aware of this.

In your previous post you wrote Weibo, which is some Chinese twitter-like platform. I have never heard of this provider.

By now I actually know that Owncube also uses Hetzner but they manage it for you. Their data center is ISO27001 certified. It’s a baseline but it does at least show they meet it.

Given the locations listed on the website of Webo I think they use Hetzner too. Webo is just a lot more expensive than Owncube while offering the same services.

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Where did you get the information that the e2ee key was stored on the server? That would defeat the entire purpose, and I would think the Privacy Guides team would know about that, or they wouldn’t recommend it?

No it doesn’t defeat the purpose. I haven’t phrased this very well I must admit. Afaik the private key is encrypted using the passphrase. They key is kept on the server and the user decrypts this with the passphrase. This is quite a common practice. It can however lead to several security issues when one doesn’t trust the server. And in my later post I explained also that the passphrase used could be improved. That’s why some people take issue with this.

Oh, that makes more sense. It’s still unstable though, and when self-hosting, it makes a lot more sense to simply encrypt your installation itself.

I dont know how to feel about this. I am currently using nextcloud as a contacts and calendar sync online and store some critical files on a VPS to avoid exposing my local network directly to the internet. Looks like I will be moving the whole thing to the local network and let stuff sync at home instead.

So what actual functioning alternatives do we have? I dont want to go all in on Protonmail because they are already having my email and it doesnt seem wise to put it all eggs on one basket, so they say.

I think given how many details of your contacts and appointments are in email i doubt it make much if a difference. I personally don’t use proton for it because it doesn’t meet my needs. But if it does for you i would just use it.
Unfortunately there are not many options.

Alternatives to Nextcloud for files? Only Proton Drive really, and it’s not great in its current state.

For contacts and calendar through, you can use EteSync, which is end-to-end encrypted, but it costs $24 a year, unless you self-host.

When self-hosting EteSync or Nextcloud, you can use tailscale to avoid exposing your local network to the outside.

Etesync just got removed from the website last week. Unfortunately its not being maintained.
It’s a though situation. Hopefully Proton is improving soon. But its not a great situation to be so limited in options.

Is self hosting Nextcloud at home and exposing it to the internet via wireguard the only sane way to do the stuff that a VPS hosted Nextcloud can do? Specifically for cardDAV/calDAV sync and other nextcloud apps like gpodder sync?

Depends on your threat model. Can’t answer this for you. I would say normally this should be okay, but i don’t know your home circumstances, your exposure etc.

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Changes to this are being made in Recommend against Nextcloud E2EE by dngray · Pull Request #1901 · privacyguides/ · GitHub