What ssh keys are specified in oneprovision

Good afternoon. We are using opennebula 6.6 now for tests. I am currently learning OneProvision and I have questions. I went to
fireedge/provision/settings and there are several tabs SSH public key , SSH private key, SSH private key passphrase . Could you please tell me why these items are needed and why they need to be filled in.
As I understand it is possible to specify here the keys that will be used to create a new cluster.
Or are these items for user management?
Thank you for your help.