You don't protect the wiring, you protect the start protocol. Similar to asking "Can we protect the internet by protecting the ethernet cables?" Put a public

You don't protect the wiring, you protect the start protocol. Similar to asking "Can we protect the internet by protecting the ethernet cables?" Put a public key on the engine controller, have it challenge the key with a random start number, have the key respond with the signature of that number, engine starts. You can do that challenge over the can bus.