storage backup with encryption on-the-fly ?

[lejeczek]

Hi guys.

Is there a solution, perhaps a function of libvirt, to 
backup guest's storage and encrypt the resulting image file?
On-the-fly ideally.
If not ready/built-in solution then perhaps a best technique 
you recommend/use?
I currently use 'backup-begin' on qcow2s, which are LUKS 
encrypted.

many thanks, L.