[Libvirt] SSH with certificates

Hello everybody, We are trying to use libvirt with qemu over ssh and our goal is to have authentication done by certificates. Therefore I created a keypair on the client and send the public key to the server. Std. SSH connections work without an password prompt as expected (ssh <ip> -l user), but if I try "sudo virsh -c qemu+ssh://user@<ip>/system" it prompts for a password (Beside that password prompt it works as expected). Is there anything else I have to do beside registering the public key at the server? Thanks for your help and best regards, Christian