This is completely solved by SSH certificates. You still have the same private key in the hardware, but instead of using the public key directly, you issue temporary (~1 hour) SSH key certificates. I even automated it using an SSH proxy.
replyThe target machines then just need to put the CA cert in the authorized_keys files.
> The target machines then just need to put the CA cert in the authorized_keys files.
replyThe word "just" is doing a lot of work there. You update authorized_keys every hour for your entire fleet?
No, the ssh CA model works like this: servers trust one CA, and the CA signs user keys.
No more distributing individual public keys to every machine.
replyIt is the user machine that needs new certificate signed by the CA once the short-lived one expires.
Understood. Not a bad idea.
replySounds like a job for dnssec and sshfp records
replyAhh, now you have three problems…hrm