Signal does have backups, it just refuses to reveal anything about them. Fortunately thanks to reverse engineering efforts you can now do pretty much whatever you want with them: https://github.com/bepaald/signalbackup-tools
That's essentially an Android system backup, i.e. a disk dump of the app data folder, right?
Almost nobody uses these in practice, so I think my point largely still stands.
I'm pretty sure that, given their stance on this issue on iOS, they'd start locally encrypting the message database using a key stored in the Android Keystore system (which won't be backed up or extracted).
No as in, this is not the Android backup system, but rather something custom-built by Signal? If so, how do I enable this on my phone, and what's that passphrase the tool alludes to? I don't see an option to set one in the Android app.
Yes it's custom-built by Signal. I thought it was enabled by default — I don't remember ever turning it on — but it might not be. Here is how to do it:
> Your backup folder is listed under Signal Settings profile_avatar.png > Chats > Chat backups > Backup folder. Use the files app or plug your phone into a computer to go to the folder.
> For older versions of Signal, the backup file signal-year-month-date-time.backup can be found at /Internal Storage/Signal/Backups or /sdcard/Signal/Backups
Almost nobody uses these in practice, so I think my point largely still stands.
I'm pretty sure that, given their stance on this issue on iOS, they'd start locally encrypting the message database using a key stored in the Android Keystore system (which won't be backed up or extracted).