We have a collaborator that specifies in the step for creating an SSH key:
It is not allowed to use an empty passphrase. We consider an empty passphrase as a violation of elementary security policies and will shut out any user doing so from further usage of our systems.
I use a small GPG smartcard (Yubikey) which is solely protected by a PIN and by me carrying it around on my key ring. However, the private key itself is - to my understanding - not encrypted on the card itself. I know that a password protected (private) key would be stored encrypted on my hard drive, while a password-less key would be stored in a plain format.
My question: As they will never see my private key I'm wondering if it is at all possible to "sniff" (through
ssh) if my private key is encrypted or not?