Have been experimenting with using gocryptfs reverse mode (mount virtual encrypted folder that mirrors an actual folder) and adding encrypted virtual folder to Syncthing as send only for backup. Since it’s backup turn folder on every month or so and otherwise leave paused.
Would anyone be interested in community backup project where encrypted data gets backed up to others machines? Ideally data would be in three locations but probably two to start. Users would be asked to accept backups equal to what is used. Everything can be organized in a simple website/ spreadsheet.
Possibly there is no demand, or potentially it works. Does this interest other Syncthing users?
Right now Windows users cannot not use gocryptfs for this purpose (because a .stfolder cannot be added to a read-only gocryotfs reverse volume on Windows). While this prevents many from participating for a beta test of the concept maybe this is acceptable. Advanced Windows users aware of risks could participate with EncFs (not recommended), solely contribute with backing up others data until works on Windows, or participate by running gocryptfs through the Windows Subsystem for Linux.
Some things to note. gocrytfs has been audited but the reverse mode has not. Still trust more than any proprietary cloud backup solution that is supposedly encrypted (where the company holds the keys literally and figuratively). Adding an unknown device to Syncthing does not appear to be a large risk. Folders must still be accepted. This concept works better with Syncthing than rysnc/ similar because allowing an unknown device to connect in Syncthing is much different/ much more secure than allowing SSH access. Windows implemntation of gocryptfs found here: https://github.com/bailey27/cppcryptfs