Crypt + Backblaze B2 hashes


I’m trying to understand from the documentation how Crypt works with Backblaze B2 along with file hashes.

The crypt documentation states :

Modified time and hashes
Crypt stores modification times using the underlying remote so support depends on that.

Hashes are not stored for crypt. However the data integrity is protected by an extremely strong crypto authenticator.

Note that you should use the rclone cryptcheck command to check the integrity of a crypted remote instead of rclone check which can’t check the checksums properly.

Does this mean B2 SHA-1 hashes are not used at all when attempting to do a sync (only files size and date) ?

I want to avoid having to download every file when wanted check if files have been modified and/or integrity check them.

That is correct.

To integrity check them you want to use rclone crypcheck. This doesn’t download the whole file, just a small part from the start so it can use the b2 hashes to check the integrity.

Rclone will use the file size and date to check whether files needs syncing - this is pretty accurate usually.