I understand what you mean, thanks for the explanation.
But why would you want to do that? What problem does it solve? Just that you can connect without having a private key yourself? This doesn't sound very safe.
But why would you want to do that? What problem does it solve? Just that you can connect without having a private key yourself? This doesn't sound very safe.
I have n clients, m servers.
On clients, i sign the lokal keypair with the CA key and log-in via certificate. The client-side certificate basically replaces the line in the server-side authorized_keys. The editing stays locally.
On servers, i register the CA key as "Certificates signed by this keypair are trustable", the authorized_keys file stays empty. No further editing required.
During normal daywork, the CA key sits unused and can be shut away.
Key Advantage: I don't need to edit anything on the countless servers anymore.
I think people really get into trouble with SSH certificates trying to reason about the properties of certificates versus SSH keys versus passwords. The format isn't the point; making the endpoint keys dynamic is. If you built a secure messaging system that propagated one-time-use SSH keys, it would address the same problem. Nobody will, because certificates are easier and already work, but you could.