feat: Add documentation about e2ee

[artonge]

@marinofaggiana @mgallien @alperozturk96 can you add screenshots for your respective platform?

Note: the android screenshots are in French, so they need to be replaced.

Fix nextcloud/end_to_end_encryption#936

[alexanderdd]

Hello, some suggestions:

• from one of your device -> from one of your devices
• "On the browser, you'll first have to enable e2ee in the browser" -> "In the browser, you'll first have to allow end to end encryption in the personal settings."
• I would put the section "encrypting a folder" right after "enabling e2ee", and put the section "adding an e2ee device" after that. IMO this better represents the most common workflow.
• in "encrypting a folder", maybe first show how to create a new folder in the client, which can then be encrypted (probably the most common use case, and users might not know that you can create folders via the ...-menu)
• in "adding an e2ee device > web" maybe add that it is currently read-only, and that these folders cannot be shared with users/groups

Thank you for this documentation!

[alperozturk96]

@artonge If these are okay I can update the PR.

e2ee-android-add

e2ee-android-mnemonic

e2ee-android-setup

[artonge]

@artonge If these are okay I can update the PR.

I would invert add and mnemonic, no?

[alperozturk96]

@artonge If these are okay I can update the PR.

I would invert add and mnemonic, no?

Ahh, yes that's right. I fixed the titles

[artonge]

Ping @mgallien @marinofaggiana

[marinofaggiana]

X	A	B	C
Not configured
Configured

[alexanderdd]

ideally also include documentation on how to share an e2ee folder with groups and how to create a file drop link, according to https://nextcloud.com/blog/desktop-3-8-end-to-end-encryption-levels-up-with-sharing-and-file-drop/ this is already possible

[gerbrent]

Great work here!! Really nice to see this progressing. 🎉

I would love to see added:

• Description about the mnemonic, such as what it is (i.e. like a password), that it must be kept secret.
• Description of what happens to the folder of encrypted files if all devices are disconnected from the folder, i.e. all clients are deleted/logged out. I believe the files remain in the folder, but inaccessible unless the mnemonic is known by the user. If the mnemonic is not known in this case, the files are lost forever and can not be recovered! Not even/especially by the administrator.
• Limitations of typical Files operations when E2EE is enabled (sharing, copying, etc)

[gerbrent]

• replace re French Android UI (known already)

[gerbrent]

• Add iOS screenshot (missing? 404..)

[gerbrent]

• Add iOS screenshot (missing? 404..)

[artonge]

@alperozturk96 still some missing screenshots:

• images/e2ee-android-encrypt.png - View showing how to set up encryption for a folder
• images/e2ee-android-add.png - View showing how to set up encryption when it was already set on another device

@marinofaggiana still some missing screenshots:

• images/e2ee-ios-encrypt.png - View showing how to set up encryption for a folder
• images/e2ee-ios-add.png - View showing how to set up encryption when it was already set on another device

@alperozturk96 @marinofaggiana @mgallien can all of you also add screenshots for the sharing flow?

[alperozturk96]

@artonge I added the missing screenshots. What do you mean by sharing flow?

[artonge]

What do you mean by sharing flow?

Sharing an E2EE folder with someone else. But thinking about it, it is probably the exact same as for non E2EE folders. Feel free to ignore if this is the case.

[alperozturk96]

What do you mean by sharing flow?

Sharing an E2EE folder with someone else. But thinking about it, it is probably the exact same as for non E2EE folders. Feel free to ignore if this is the case.

There is no "Share" option in the three-dot menu when I checked it on the Web. On Android, I also noticed empty tabs. We should add these.

Could you check it for iOS @marinofaggiana ?