Check app data integrity on‐storage

Seedvault 15 or newer uses the new v2 backup format where the beginning of each file name is the SHA-256 hash of its content. So for checking the integrity of a backup, one would enter the folder of one or more backup repositories. (The name of a backup repository is a (random) SHA-256 hash itself.) Inside this folder, there should be one or more [hash].snapshot files. Run sha256sum on them and ensure the output matches [hash]. Then do the same for the contents of the folders of the form 00 to FF.

As people write scripts for performing this check, we'll link it below.