The mobile apps are paid. The question is are they open source? Because, if they are open source someone could download them from GitHub and compile them without purchasing a donation key.
If they are not open source, how to check if there are flaws or backdoors in them?
Also, are separate donation keys are needed for Android, iOS and Dark Mode Desktop?
Finally, can the file masterkey.cryptomator be stored locally for extra security?
Hi
No. Often discussed in this board. For example here
It’s open core. The used encryption library is open source
See description here:
There is no donation key for the mobile apps. You pay for them a onetime fee.
If you want Darkmode for the desktop app you need a donation key (means you support the Open source desktop app with a donation)
Of course. Feel free to make backups and store them where you want. But there has to be a Masterkey file in the root of your vault folder. But if you want to achieve this „extra“ security by moving this file out of the vault then the answer is: no, that’s not possible. And btw would not bring any extra security because it does not contain unencrypted data or makes the file encryption weak in any way.