> Generate a separate private key on foo ... That is a TERRIBLE idea, if foo can be compromised. Even if you secure the private key with a passphrase, it still

> Generate a separate private key on foo ... That is a TERRIBLE idea, if foo can be compromised. Even if you secure the private key with a passphrase, it still needs to be loaded into foo's memory, by a binary resident on foo, which can be used to exfiltrate that private key. If you're confident foo cannot be compromised, then the whole point is moot anyway.