Client side encryption for a user with multiple devices
I am currently developing an app that sends the data encrypted to a server, because the important thing with the app is that the server should never know what data is there, only the client should decrypt this data.
I have already searched a lot on the Internet and thought about it myself and the idea came to my mind that you generate a key and then simply scan it with a QR code on another device and then you also have this key there to decrypt.
But now I ask myself if it is somehow possible even better and if you could send the key somehow different or if there is a better way to implement this scenario.
Because the thing with the QR code is bad for the user experience and if the user deletes the app on all devices and he installs it again like after 1 month he can never use the app again, because the key is gone forever.
