Thanks for your reply. I am trying to address the case in which an HSM is used. My guess is that, in such a case, the best that one can do using the Knot framework itself is to back up the KASP (which contains public keys and zone metadata, but no private keys) while relying on some external, HSM-dependent mechanism to back up (and restore, as needed) the matching private keys. Is this a correct assessment of things?
If I understood you correctly, the backup command that you mention would work (in 3.1) when using the default cryptographic provider alone - i.e. not with SoftHSM, or any actual HSM. Right?