I have an SSH key that has never once existed as a file on my disk. It lives only inside an encrypted password manager vault, and every time it's used, I get a prompt to approve it. Here's why I set that up, and the near-miss that convinced me it was worth the extra friction.
The near-miss
I once pasted a private key into an AI chat window and asked, essentially, "is this the right one?" It felt harmless — I just wanted to confirm an identity before deploying something. It wasn't harmless: the moment a private key is pasted anywhere — a chat, a file, a terminal that logs history — it has to be treated as compromised, because that transcript persists and gets processed elsewhere.
Fortunately it was a freshly generated, not-yet-deployed key. I rotated it immediately — regenerated it, deployed the new one, deleted the old one everywhere — before it was ever used for anything real. But it was a clean demonstration of the actual rule: verify a key's identity by its fingerprint, never by looking at (or pasting) the raw key material.
ssh-keygen -lf ~/.ssh/some_key.pub
