Encryption chapter(s) revision(s)

The Encryption chapter needs some love.

Note: WIP (expect this list to change/get updated as changes are made/PRs are merged/etc)

TODO:

(Mostly being addressed via PR #13754)

• Add: Mention E2EE != the encryption documented in the Admin Manual Encryption chapter
• Add: Warning that E2EE not to be used with default encryption
• Fix: Old remarks about "Encrypting files increases their size by roughly 35%" isn't accurate since the base64 -> binary change
• Add context in the overview (or wherever it ends up making sense) of different ways of encrypting day / comparisons (without getting too down in the weeds) so that reader can make informed decision regarding server-side, client-side, disk encryption, etc.
• Streamline and re-organize (and expand where appropriate) the general setup process
• Get some feedback from various other relevant folks
• (probably some other things which will get added here)

After:

• Review open server-side encryption related issues here in docs
• Identify additional documentation related changes / add TODO items (or create additional follow-up Issues where deemed out of scope or not practical just yet)
• Review open server-side encryption related issues in the server repo (since many are either doc matters or a mixture of docs+implementation adjustments)

Then (will probably move the below to their own issue and revise the list after the above is completed):

• Better document legacy stuff
• Add basic info about recovery tools stuff
• Review open client-side encryption related issues here in docs
• Identify additional documentation related changes / add TODO items (or create additional follow-up Issues where deemed out of scope or not practical just yet)
• Review open client-side encryption related issues in the server repo (since many are either doc matters or a mixture of docs+implementation adjustments)
• Consider establishing an E2EE chapter/section
• See if anything from nextcloud/end_to_end_encryption#538 should be incorporated

Out of scope but related:

• Add a setup check or warning if both encryption and end_to_end_encryption apps are enabled together (not a supported configuration)
• Encryption details section could use some love
• Consider/assess downsides (if any) to changing encryption app name from Default encryption module to Server-side encryption module to greater clarity

Thanks for helping improve our documentation!

• There is always room for improvement!
• All contributions (changes and change ideas) - from the largest to the tiniest - help make Nextcloud better and easier to use!

Notes

• Please be patient: this is a large open source project that is overseen by a mixture of volunteers and non-volunteers which are all ultimately busy.
• If your suggestion is a troubleshooting scenario or one you're not 100% certain about, please post for feedback on the Nextcloud Help Forum first.
  • Then return here to bring back your experience to help improve the documentation for clarity, etc. (and link back to the forum discussion in your report!)

Protip: If you want to help move things along (or just help out in other ways too) here are some suggestions:

• Look for areas where you can assist - even seemingly unrelated areas - because doing so frees up resources for your favorite topics and ideas.
• Submit a proposed change - that attempts to addresses your issue - as a pull request.
• Participate in a discussion on some other unresolved submitted idea ("issues") to help move it along.
• Post a comment or review on someone else's proposed change ("pull request") to help move it along.