Using Volume Utility Tools with Cloud Storage and Volume Encryption

Hello,

I already sent this a while ago but never saw it in the list so I'm 
trying again.

We are using bacula (15.0.2) with our S3 compatible Ceph-RGW and the 
"Amazon" driver as storage and the new "Volume Encryption" feature for 
data encryption which works great but I recently thought how I could 
restore data in case the bacula database goes boom or I simply have 
backup data that is not in the database anymore.
I had similar cases in the past when using disk storage without data 
encryption and the Volume Utility Tools (ie. bls and bextract) always 
helped but with the current setup I wouldn't know how to:

a) Assemble the actual volume from the parts in the S3/RGW storage as we 
split it into 1GB parts before upload and

b) Decrypt the volume (of course given I have the key that was used to 
encrypt the volume)

This is purely out of curiosity, we have backups for our bacula database 
on separate storage so a complete data loss should not happen but I'd 
still like to know if I can restore data with only the split volumes in 
the S3/RGW and the respective key used for encryption.

Regards,

Martin